1
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Ahmad S, Eng J, Penfold TJ. Conformational Control of Donor-Acceptor Molecules Using Non-covalent Interactions. J Phys Chem A 2024; 128:8035-8044. [PMID: 39287185 PMCID: PMC11440601 DOI: 10.1021/acs.jpca.4c03711] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Revised: 09/04/2024] [Accepted: 09/05/2024] [Indexed: 09/19/2024]
Abstract
Controlling the architecture of organic molecules is an important aspect in tuning the functional properties of components in organic electronics. For purely organic thermally activated delayed fluorescence (TADF) molecules, design is focused upon orthogonality orientated donor and acceptor units. In these systems, the rotational dynamics around the donor and acceptor bond has been shown to be critical for activating TADF; however, too much conformational freedom can increase the non-radiative rate, leading to a large energy dispersion of the emitting states and conformers, which do not exhibit TADF. To date, control of the motion around the D-A bond has focused upon steric hindrance. In this work, we computationally investigate eight proposed donor-acceptor molecules, exhibiting a B-N bond between the donor and acceptor. We compare the effect of steric hindrance and noncovalent interactions, achieved using oxygen (sulfur) boron heteroatom interactions, in exerting fine conformational control of the excited state dynamics. This work reveals the potential for judiciously chosen noncovalent interactions to strongly influence the functional properties of TADF emitters, including the accessible conformers and the energy dispersion associated with the charge transfer states.
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Affiliation(s)
- Shawana Ahmad
- Chemistry—School of Natural
and Environmental Sciences, Newcastle University, Newcastle Upon-Tyne NE1
7RU, U.K.
| | - Julien Eng
- Chemistry—School of Natural
and Environmental Sciences, Newcastle University, Newcastle Upon-Tyne NE1
7RU, U.K.
| | - Thomas J. Penfold
- Chemistry—School of Natural
and Environmental Sciences, Newcastle University, Newcastle Upon-Tyne NE1
7RU, U.K.
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2
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Stuart AN, Bergmann K, Cho I, Kendrick WJ, Hudson ZM, Wong WWH, Lakhwani G. Triplet dynamics reveal loss pathways in multi-resonance thermally activated delayed fluorescence emitters. Chem Sci 2024:d4sc03649b. [PMID: 39144466 PMCID: PMC11318651 DOI: 10.1039/d4sc03649b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2024] [Accepted: 07/25/2024] [Indexed: 08/16/2024] Open
Abstract
Multi-resonance thermally activated delayed fluorescence (MR-TADF) materials are of interest for light-emitting applications due to their narrow emission bandwidths and high photoluminescence quantum yields. Whilst there have been numerous examples of multi-resonance molecules exhibiting efficient TADF, the photophysics and mechanism of TADF in multi-resonance emitters have not been investigated to the same extent as the more conventional spatially separated donor-acceptor TADF materials, limiting the development of MR-TADF devices. Here we study the photophysics of a multi-resonance TADF material, OQAO(mes)2, using transient absorption spectroscopy to spectrally resolve the triplet population(s). We identify multiple triplet populations with distinct spectral contributions, and resolve the dynamics between them. Unlike conventional donor-acceptor TADF materials that have previously been studied, we find these triplet states are not formed in equilibrium, instead exhibiting a slow evolution from a high-energy triplet to a low-energy triplet. Delayed fluorescence predominantly reflects the lifetime of the high-energy triplet state, indicating that the formation of the low-energy triplet is a loss pathway for TADF. We also find that greater amounts of the low-energy triplet are formed in a higher dielectric environment, which leads to less delayed fluorescence. These triplet dynamics have significant implications for TADF in devices, as depending on the identity of the triplet formed by electrical excitation, there will either be a significant barrier to TADF, or a competing nonradiative decay pathway.
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Affiliation(s)
- Alexandra N Stuart
- Department of Chemistry, The University of Sydney Camperdown New South Wales 2000 Australia
- Australian Research Council Centre of Excellence in Exciton Science Parkville 3010 Australia
| | - Katrina Bergmann
- Department of Chemistry, The University of British Columbia Vancouver British Columbia V6T 1Z1 Canada
| | - Inseong Cho
- Department of Chemistry, The University of Sydney Camperdown New South Wales 2000 Australia
- Australian Research Council Centre of Excellence in Exciton Science Parkville 3010 Australia
| | - William J Kendrick
- Australian Research Council Centre of Excellence in Exciton Science Parkville 3010 Australia
- School of Chemistry, The University of Melbourne Parkville 3010 VIC Australia
| | - Zachary M Hudson
- Department of Chemistry, The University of British Columbia Vancouver British Columbia V6T 1Z1 Canada
| | - Wallace W H Wong
- Australian Research Council Centre of Excellence in Exciton Science Parkville 3010 Australia
- School of Chemistry, The University of Melbourne Parkville 3010 VIC Australia
| | - Girish Lakhwani
- Department of Chemistry, The University of Sydney Camperdown New South Wales 2000 Australia
- Australian Research Council Centre of Excellence in Exciton Science Parkville 3010 Australia
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3
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Deng Z, Huang G, Li J, Pang J, He J, Phillips DL, Li MD. High-level reverse intersystem crossing of charge transfer compounds: to fluoresce or not to fluoresce? Phys Chem Chem Phys 2024; 26:17809-17816. [PMID: 38884121 DOI: 10.1039/d4cp01596g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Thermally activated delayed fluorescence (TADF) has been widely applied to electroluminescent materials to take the best advantage of triplet excitons. For some materials, the TADF originates from high-level reverse intersystem crossing (hRISC), and has attracted much attention due to its high efficiency for utilizing the triplet excitons. However, reports concerning the mechanistic studies on the hRISC-TADF process and structure-property correlation are sparse. In this study, we prepared three compounds containing triphenylamine and benzophenone with different substitution positions, o-TPA-BP, m-TPA-BP, and p-TPA-BP, in which only p-TPA-BP displays strong luminescence and hRISC-TADF features. To investigate the mechanism of the substituent-position-dependent hRISC-TADF, ultrafast time-resolved spectroscopy was utilized to observe the deactivation pathways with the assistance of theoretical calculations. The results show that o-TPA-BP will not generate triplet species, and the triplet species for m-TPA-BP will rapidly deactivate. Only p-TPA-BP can transition back to the singlet state from the T2 state effectively and exhibit a large gap between T1 and T2 to favor the hRISC route. These results illustrate how the substitution position affects the ISC and further influences the luminescence properties, which can provide new insights for developing new high-efficiency luminescent materials.
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Affiliation(s)
- Ziqi Deng
- College of Chemistry and Chemical Engineering, Key (Guangdong-Hong Kong Joint) Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Guangdong 515063, P. R. China.
- Department of Chemistry, The University of Hong Kong, Pokfulam, Hong Kong, China.
| | - Guanheng Huang
- Department of Chemistry, The University of Hong Kong, Pokfulam, Hong Kong, China.
| | - Jiayu Li
- College of Chemistry and Chemical Engineering, Key (Guangdong-Hong Kong Joint) Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Guangdong 515063, P. R. China.
| | - Junhong Pang
- College of Chemistry and Chemical Engineering, Key (Guangdong-Hong Kong Joint) Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Guangdong 515063, P. R. China.
| | - Jiaxing He
- College of Chemistry and Chemical Engineering, Key (Guangdong-Hong Kong Joint) Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Guangdong 515063, P. R. China.
- Department of Chemistry, The University of Hong Kong, Pokfulam, Hong Kong, China.
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam, Hong Kong, China.
| | - Ming-De Li
- College of Chemistry and Chemical Engineering, Key (Guangdong-Hong Kong Joint) Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Guangdong 515063, P. R. China.
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4
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Ni F, Huang Y, Qiu L, Yang C. Synthetic progress of organic thermally activated delayed fluorescence emitters via C-H activation and functionalization. Chem Soc Rev 2024; 53:5904-5955. [PMID: 38717257 DOI: 10.1039/d3cs00871a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
Thermally activated delayed fluorescence (TADF) emitters have become increasingly prominent due to their promising applications across various fields, prompting a continuous demand for developing reliable synthetic methods to access them. This review aims to highlight the progress made in the last decade in synthesizing organic TADF compounds through C-H bond activation and functionalization. The review begins with a brief introduction to the basic features and design principles of TADF emitters. It then provides an overview of the advantages and concise development of C-H bond transformations in constructing TADF emitters. Subsequently, it summarizes both transition-metal-catalyzed and non-transition-metal-promoted C-H bond transformations used for the synthesis of TADF emitters. Finally, the review gives an outlook on further challenges and potential directions in this field.
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Affiliation(s)
- Fan Ni
- National Engineering Lab of Special Display Technology, State Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Intelligent Interconnected Systems Laboratory of Anhui, Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, School of Instrument Science and Optoelectronic Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China.
| | - Yipan Huang
- National Engineering Lab of Special Display Technology, State Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Intelligent Interconnected Systems Laboratory of Anhui, Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, School of Instrument Science and Optoelectronic Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China.
| | - Longzhen Qiu
- National Engineering Lab of Special Display Technology, State Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Intelligent Interconnected Systems Laboratory of Anhui, Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, School of Instrument Science and Optoelectronic Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China.
| | - Chuluo Yang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, Guangdong 518060, P. R. China.
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5
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Liu M, Yang Z, Feng Z, Zhao N, Bian R, Wu J, Yang Q, Zhao S, Liu H, Yang B. Combining Functional Units to Design Organic Materials with Dynamic Room-Temperature Phosphorescence under Continuous Ultraviolet Irradiation. Molecules 2024; 29:2621. [PMID: 38893497 PMCID: PMC11173552 DOI: 10.3390/molecules29112621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 05/30/2024] [Accepted: 05/31/2024] [Indexed: 06/21/2024] Open
Abstract
Developing materials with dynamic room-temperature phosphorescence (RTP) properties is crucial for expanding the applications of organic light-emitting materials. In this study, we designed and synthesized two novel RTP molecules by combining functional units, incorporating the folded unit thianthrene into the classic luminescent cores thioxanthone or anthraquinone to construct TASO and TA2O. In this combination, the TA unit contributes to the enhancement of spin-orbit coupling (SOC), while the luminescent core governs the triplet energy level. After the strategic manipulation of SOC using the thianthrene unit, the target molecules exhibited a remarkable enhancement in RTP performance. This strategy led to the successful development of TASO and TA2O molecules with outstanding dynamic RTP properties when exposed to continuous ultraviolet irradiation, a result that can be ascribed to their efficient RTP, improved absorption ability, and oxygen-sensitive RTP properties. Leveraging the oxygen-mediated ultraviolet-radiation-induced RTP enhancement in TASO-doped polymer films, we developed a novel time-resolved detection technique for identifying phase separation in polymers with varying oxygen permeability. This research offers a promising approach for constructing materials with dynamic RTP properties.
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Affiliation(s)
- Meng Liu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Zhiqiang Yang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Zhe Feng
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Ningyuan Zhao
- College of Chemistry, Jilin University, Changchun 130012, China (J.W.)
| | - Ruihua Bian
- College of Chemistry, Jilin University, Changchun 130012, China (J.W.)
| | - Jinpu Wu
- College of Chemistry, Jilin University, Changchun 130012, China (J.W.)
| | - Qing Yang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Shuaiqiang Zhao
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Haichao Liu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Bing Yang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
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6
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Jodra A, Marazzi M, Frutos LM, García-Iriepa C. Modulating Efficiency and Color of Thermally Activated Delayed Fluorescence by Rationalizing the Substitution Effect. J Chem Theory Comput 2024; 20:4239-4253. [PMID: 38738688 PMCID: PMC11137832 DOI: 10.1021/acs.jctc.4c00009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Revised: 04/22/2024] [Accepted: 04/25/2024] [Indexed: 05/14/2024]
Abstract
Thermally activated delayed fluorescence (TADF) constitutes the process by which third-generation organic light-emitting diodes (OLEDs) are being designed and produced. Despite several years of trial-and-error attempts, mainly driven by chemical intuition about how to improve a certain aspect of the process, few studies focused on the in-depth description of its two key properties: efficiency of the T1 → S1 intersystem crossing and further S1 → S0 emission. Here, by means of a newly developed theoretical formalism, we propose a systematic rationalization of the substituent effect in a paradigmatic class of OLED compounds, based on phenothiazine-dibenzothiophene-S,S-dioxide, known as PTZ-DBTO2. Our methodology allows to discern among geometrical and electronic effects induced by the substituent, deeply understanding the relationships existing between charge transfer, spin density, geometrical deformations, and energy modulations between electronic states. By our results, we can finally elucidate, depending on the substituent, the fate of the overall TADF process, quantitatively assessing its efficiency and predicting the color emission. Moreover, the general terms by which this methodology was developed allow its application to any chromophore of interest.
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Affiliation(s)
- Alejandro Jodra
- Departamento
de Química Analítica, Química Física e
Ingeniería Química, Grupo de Reactividad y Estructura
Molecular (RESMOL), Universidad de Alcalá, Ctra. Madrid-Barcelona, Km 33.600, Alcalá de Henares, Madrid 28871, Spain
| | - Marco Marazzi
- Departamento
de Química Analítica, Química Física e
Ingeniería Química, Grupo de Reactividad y Estructura
Molecular (RESMOL), Universidad de Alcalá, Ctra. Madrid-Barcelona, Km 33.600, Alcalá de Henares, Madrid 28871, Spain
- Instituto
de Investigación Química “Andrés M. del
Río” (IQAR), Universidad de
Alcalá, Ctra.
Madrid-Barcelona, Km 33.600, Alcalá
de Henares, Madrid 28871, Spain
| | - Luis Manuel Frutos
- Departamento
de Química Analítica, Química Física e
Ingeniería Química, Grupo de Reactividad y Estructura
Molecular (RESMOL), Universidad de Alcalá, Ctra. Madrid-Barcelona, Km 33.600, Alcalá de Henares, Madrid 28871, Spain
- Instituto
de Investigación Química “Andrés M. del
Río” (IQAR), Universidad de
Alcalá, Ctra.
Madrid-Barcelona, Km 33.600, Alcalá
de Henares, Madrid 28871, Spain
| | - Cristina García-Iriepa
- Departamento
de Química Analítica, Química Física e
Ingeniería Química, Grupo de Reactividad y Estructura
Molecular (RESMOL), Universidad de Alcalá, Ctra. Madrid-Barcelona, Km 33.600, Alcalá de Henares, Madrid 28871, Spain
- Instituto
de Investigación Química “Andrés M. del
Río” (IQAR), Universidad de
Alcalá, Ctra.
Madrid-Barcelona, Km 33.600, Alcalá
de Henares, Madrid 28871, Spain
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7
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Di Maiolo F, Phan Huu DKA, Giavazzi D, Landi A, Racchi O, Painelli A. Shedding light on thermally-activated delayed fluorescence. Chem Sci 2024; 15:5434-5450. [PMID: 38638233 PMCID: PMC11023041 DOI: 10.1039/d4sc00033a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 02/17/2024] [Indexed: 04/20/2024] Open
Abstract
Thermally activated delayed fluorescence (TADF) is a hot research topic in view of its impressive applications in a wide variety of fields from organic LEDs to photodynamic therapy and metal-free photocatalysis. TADF is a rare and fragile phenomenon that requires a delicate equilibrium between tiny singlet-triplet gaps, sizable spin-orbit couplings, conformational flexibility and a balanced contribution of charge transfer and local excited states. To make the picture more complex, this precarious equilibrium is non-trivially affected by the interaction of the TADF dye with its local environment. The concurrent optimization of the dye and of the embedding medium is therefore of paramount importance to boost practical applications of TADF. Towards this aim, refined theoretical and computational approaches must be cleverly exploited, paying attention to the reliability of adopted approximations. In this perspective, we will address some of the most important issues in the field. Specifically, we will critically review theoretical and computational approaches to TADF rates, highlighting the limits of widespread approaches. Environmental effects on the TADF photophysics are discussed in detail, focusing on the major role played by dielectric and conformational disorder in liquid solutions and amorphous matrices.
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Affiliation(s)
- Francesco Di Maiolo
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
| | - D K Andrea Phan Huu
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
| | - Davide Giavazzi
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
| | - Andrea Landi
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
| | - Ottavia Racchi
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
| | - Anna Painelli
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
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8
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Wu Z, Bergmann K, Hudson ZM. Dopants Induce Persistent Room Temperature Phosphorescence in Triarylamine Boronate Esters. Angew Chem Int Ed Engl 2024; 63:e202319089. [PMID: 38277401 DOI: 10.1002/anie.202319089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 01/11/2024] [Accepted: 01/26/2024] [Indexed: 01/28/2024]
Abstract
Purely organic materials exhibiting room temperature phosphorescence (RTP) are promising candidates for oxygen sensors and information encryption owing to their cost-effective and environmentally friendly nature. Herein, we report a bimolecular RTP system where DTBU acts as the guest and TBBU serves as the host. In contrast to previously reported results, we find that both pure DTBU and TBBU do not exhibit RTP in the solid state even under N2 atmosphere. A DTBU/TBBU system with a low doping ratio (0.1 mol %) exhibits persistent yellowish-green afterglow with a lifetime of 340 ms and is highly sensitive to oxygen. A DTBU/TBBU system with a higher doping ratio (10 mol %) maintains a phosphorescence lifetime of 179 ms under air. Applications of DTBU/TBBU at varied doping ratios in both oxygen sensing and information encryption are demonstrated. We propose that the T1 state of TBBU acts as an energy transfer intermediate between Tn and T1 of DTBU, ultimately leading to the generation of persistent RTP. Overall, this work demonstrates the critical importance of material purity in the design of RTP systems, and how an understanding of host-guest doping enables their photophysical properties to be precisely tuned.
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Affiliation(s)
- Zhu Wu
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, V6T 1Z1, British Columbia, Canada
| | - Katrina Bergmann
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, V6T 1Z1, British Columbia, Canada
| | - Zachary M Hudson
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, V6T 1Z1, British Columbia, Canada
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9
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Das S, Batra A, Kundu S, Sharma R, Patra A. Unveiling autophagy and aging through time-resolved imaging of lysosomal polarity with a delayed fluorescent emitter. Chem Sci 2023; 15:102-112. [PMID: 38131076 PMCID: PMC10732132 DOI: 10.1039/d3sc02450d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 11/11/2023] [Indexed: 12/23/2023] Open
Abstract
Detecting the lysosomal microenvironmental changes like viscosity, pH, and polarity during their dynamic interorganelle interactions remains an intriguing area that facilitates the elucidation of cellular homeostasis. The subtle variation of physiological conditions can be assessed by deciphering the lysosomal microenvironments during lysosome-organelle interactions, closely related to autophagic pathways leading to various cellular disorders. Herein, we shed light on the dynamic lysosomal polarity in live cells and a multicellular model organism, Caenorhabditis elegans (C. elegans), through time-resolved imaging employing a thermally activated delayed fluorescent probe, DC-Lyso. The highly photostable and cytocompatible DC-Lyso rapidly labels the lysosomes (within 1 min of incubation) and exhibits red luminescence and polarity-sensitive long lifetime under the cellular environment. The distinct variation in the fluorescence lifetime of DC-Lyso suggests an increase in local polarity during the lysosomal dynamics and interorganelle interactions, including lipophagy and mitophagy. The lifetime imaging analysis reveals increasing lysosomal polarity as an indicator for probing the successive development of C. elegans during aging. The in vivo microsecond timescale imaging of various cancerous cell lines and C. elegans, as presented here, therefore, expands the scope of delayed fluorescent emitters for unveiling complex biological processes.
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Affiliation(s)
- Subhadeep Das
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal Bhopal Madhya Pradesh 462066 India
| | - Abhilasha Batra
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal Bhopal Madhya Pradesh 462066 India
| | - Subhankar Kundu
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal Bhopal Madhya Pradesh 462066 India
| | - Rati Sharma
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal Bhopal Madhya Pradesh 462066 India
| | - Abhijit Patra
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal Bhopal Madhya Pradesh 462066 India
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10
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Dey S, Pal AK, Upadhyay M, Datta A, Ray D. Modulation of Delayed Fluorescence Guided by Conformational Effect-Mediated Thermally Enhanced Phosphorescence in Phenothiazines-Quinoline-Cl Conjugates. J Phys Chem B 2023; 127:9833-9840. [PMID: 37913786 DOI: 10.1021/acs.jpcb.3c06274] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
Triplet energy harvesting via thermally activated delayed fluorescence (TADF) from pure organic systems has attracted great attention in organic light-emitting diodes, sensing, and photocatalysis. However, the realization of thermally enhanced phosphorescence (TEP)-guided efficient TADF with a high rate of reverse intersystem crossing (kRISC) still needs to be discovered. Herein, we report two phenothiazine-quinoline conjugates (P2QC, P2QMC) comprising two phenothiazine donors covalently attached to the chlorine-substituted quinolinyl acceptor. Spectroscopic analysis in conjunction with quantum chemistry calculations reveals that TEP in P2QC originated due to slow internal conversion from higher-lying triplet to lowest triplet (T2' → T1') of the quasi-axial (QA) conformer and TADF (kRISC = 1.44 × 108 s-1) originated from the quasi-equatorial (QE) conformer caused by a low singlet-triplet gap (ΔES1-T1 = 0.11 eV) and triplet energy transfer from QA to QE owing to the degenerate ground state of the conformers. In contrast, TADF (kRISC = 0.74 × 108 s-1) and dual phosphorescence under ambient conditions are observed in P2QMC. This study provides a sustainable guideline for developing efficient TADF emitters via conformation effects and energy transfer mechanisms.
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Affiliation(s)
- Suvendu Dey
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi NCR, NH-91, Tehsil Dadri, Gautam Buddha Nagar, Greater Noida, Uttar Pradesh 201314, India
| | - Arun K Pal
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, West Bengal 700032, India
| | - Manoj Upadhyay
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi NCR, NH-91, Tehsil Dadri, Gautam Buddha Nagar, Greater Noida, Uttar Pradesh 201314, India
| | - Ayan Datta
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A and 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, West Bengal 700032, India
| | - Debdas Ray
- Advanced Photofunctional Materials Laboratory, Department of Chemistry, Shiv Nadar Institution of Eminence, Delhi NCR, NH-91, Tehsil Dadri, Gautam Buddha Nagar, Greater Noida, Uttar Pradesh 201314, India
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11
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Cao L, Liu X, Zhang X, Zhao J, Yu F, Wan Y. The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads. Beilstein J Org Chem 2023; 19:1028-1046. [PMID: 37497052 PMCID: PMC10366440 DOI: 10.3762/bjoc.19.79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/07/2023] [Indexed: 07/28/2023] Open
Abstract
A series of 1,8-naphthalimide (NI)-phenothiazine (PTZ) electron donor-acceptor dyads were prepared to study the thermally activated delayed fluorescence (TADF) properties of the dyads, from a point of view of detection of the various transient species. The photophysical properties of the dyads were tuned by changing the electron-donating and the electron-withdrawing capability of the PTZ and NI moieties, respectively, by oxidation of the PTZ unit, or by using different aryl substituents attached to the NI unit. This tuning effect was manifested in the UV-vis absorption and fluorescence emission spectra, e.g., in the change of the charge transfer absorption bands. TADF was observed for the dyads containing the native PTZ unit, and the prompt and delayed fluorescence lifetimes changed with different aryl substituents on the imide part. In polar solvents, no TADF was observed. For the dyads with the PTZ unit oxidized, no TADF was observed as well. Femtosecond transient absorption spectra showed that the charge separation takes ca. 0.6 ps, and admixtures of locally excited (3LE) state and charge separated (1CS/3CS) states formed (in n-hexane). The subsequent charge recombination from the 1CS state takes ca. 7.92 ns. Upon oxidation of the PTZ unit, the beginning of charge separation is at 178 fs and formation of 3LE state takes 4.53 ns. Nanosecond transient absorption (ns-TA) spectra showed that both 3CS and 3LE states were observed for the dyads showing TADF, whereas only 3LE or 3CS states were observed for the systems lacking TADF. This is a rare but unambiguous experimental evidence that the spin-vibronic coupling of 3CS/3LE states is crucial for TADF. Without the mediating effect of the 3LE state, no TADF is resulted, even if the long-lived 3CS state is populated (lifetime τCS ≈ 140 ns). This experimental result confirms the 3CS → 1CS reverse intersystem crossing (rISC) is slow, without coupling with an approximate 3LE state. These studies are useful for an in-depth understanding of the photophysical mechanisms of the TADF emitters, as well as for molecular structure design of new electron donor-acceptor TADF emitters.
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Affiliation(s)
- Liyuan Cao
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, 2 Ling Gong Road, Dalian, 116024, P. R. China
| | - Xi Liu
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Xue Zhang
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, 2 Ling Gong Road, Dalian, 116024, P. R. China
| | - Jianzhang Zhao
- State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, 2 Ling Gong Road, Dalian, 116024, P. R. China
| | - Fabiao Yu
- Key Laboratory of Hainan Trauma and Disaster Rescue, The First Affiliated Hospital of Hainan Medical University, Hainan Medical University, Haikou 571199, P. R. China
| | - Yan Wan
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
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12
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Macionis S, Gudeika D, Volyniuk D, Mahmoudi M, Simokaitiene J, Andruleviciene V, Najafov M, Sadzeviciene R, Stoncius S, Grazulevicius JV. Effect of Substituents with the Different Electron-Donating Abilities on Optoelectronic Properties of Bipolar Thioxanthone Derivatives. ACS APPLIED ELECTRONIC MATERIALS 2023; 5:2227-2238. [PMID: 37124238 PMCID: PMC10134433 DOI: 10.1021/acsaelm.3c00092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 02/27/2023] [Indexed: 05/03/2023]
Abstract
The synthesis and optoelectronic properties of four simple-structure thioxanthone derivatives employing thioxanthone as an acceptor unit, coupled with moieties having very different electron-donating abilities such as phenoxazine, 3,6-di-tert-butylcarbazole, 3,7-di-tert-butylphenothiazine, or 2,7-di-tert-butyl-9,9-dimethylacridane, are reported. The compounds form molecular glasses with glass transition temperatures reaching 116 °C. Ionization potentials of the compounds estimated by photoelectron emission method range from 5.42 to 5.74 eV. Thioxanthone derivatives containing 3,6-tert-butylcarbazole or 2,7-di-tert-butyl-9,9-dimethylacridane moieties with weak electron-donating strengths were characterized by bipolar charge transport with relatively close hole and electron mobility values of 6.8 × 10-5/2.4 × 10-5 and 3.1 × 10-5/4.6 × 10-6 cm2/(V s) recorded at 3.6 × 105 V/cm. The other compounds demonstrated hole-transporting properties. The films of thioxanthones containing phenoxazine or 2,7-di-tert-butyl-9,9-dimethylacridane moieties showed efficient thermally activated delayed fluorescence with a photoluminescence quantum yield of up to 50% due to the solid-state luminescence enhancement. Organic-light-emitting diodes containing the synthesized compounds as emitters showed very different external quantum efficiencies (0.9-10.3%) and blue, sky blue, green, or yellow electroluminescence colors, thus reflecting the effects of donor substituents.
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Affiliation(s)
- Simas Macionis
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, K. Barsausko st. 59, LT-51423 Kaunas, Lithuania
| | - Dalius Gudeika
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, K. Barsausko st. 59, LT-51423 Kaunas, Lithuania
| | - Dmytro Volyniuk
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, K. Barsausko st. 59, LT-51423 Kaunas, Lithuania
| | - Malek Mahmoudi
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, K. Barsausko st. 59, LT-51423 Kaunas, Lithuania
| | - Jurate Simokaitiene
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, K. Barsausko st. 59, LT-51423 Kaunas, Lithuania
| | - Viktorija Andruleviciene
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, K. Barsausko st. 59, LT-51423 Kaunas, Lithuania
| | - Murad Najafov
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, K. Barsausko st. 59, LT-51423 Kaunas, Lithuania
| | - Rita Sadzeviciene
- Department
of Organic Chemistry, Center for Physical
Sciences and Technology, Sauletekio Ave. 3, LT-10257 Vilnius, Lithuania
| | - Sigitas Stoncius
- Department
of Organic Chemistry, Center for Physical
Sciences and Technology, Sauletekio Ave. 3, LT-10257 Vilnius, Lithuania
| | - Juozas V. Grazulevicius
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, K. Barsausko st. 59, LT-51423 Kaunas, Lithuania
- Email
for J.V.G.:
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13
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Urban M, Marek-Urban PH, Durka K, Luliński S, Pander P, Monkman AP. TADF Invariant of Host Polarity and Ultralong Fluorescence Lifetimes in a Donor-Acceptor Emitter Featuring a Hybrid Sulfone-Triarylboron Acceptor. Angew Chem Int Ed Engl 2023; 62:e202217530. [PMID: 36622736 DOI: 10.1002/anie.202217530] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/08/2023] [Accepted: 01/09/2023] [Indexed: 01/10/2023]
Abstract
10H-Dibenzo[b,e][1,4]thiaborinine 5,5-dioxide (SO2B)-a high triplet (T1 =3.05 eV) strongly electron-accepting boracycle was successfully utilised in thermally activated delayed fluorescence (TADF) emitters PXZ-Dipp-SO2B and CZ-Dipp-SO2B. We demonstrate the near-complete separation of highest occupied and lowest unoccupied molecular orbitals leading to a low oscillator strength of the S1 →S0 CT transition, resulting in very long ca. 83 ns and 400 ns prompt fluorescence lifetimes for CZ-Dipp-SO2B and PXZ-Dipp-SO2B, respectively, but retaining near unity photoluminescence quantum yield. OLEDs using CZ-Dipp-SO2B as the luminescent dopant display high external quantum efficiency (EQE) of 23.3 % and maximum luminance of 18600 cd m-2 with low efficiency roll off at high brightness. For CZ-Dipp-SO2B, reverse intersystem crossing (rISC) is mediated through the vibronic coupling of two charge transfer (CT) states, without involving the triplet local excited state (3 LE), resulting in remarkable rISC rate invariance to environmental polarity and polarisability whilst giving high organic light-emitting diode (OLED) efficiency. This new form of rISC allows stable OLED performance to be achieved in different host environments.
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Affiliation(s)
- Mateusz Urban
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland.,Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK
| | - Paulina H Marek-Urban
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland
| | - Krzysztof Durka
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland
| | - Sergiusz Luliński
- Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland
| | - Piotr Pander
- Faculty of Chemistry, Silesian University of Technology, Strzody 9, 44-100, Gliwice, Poland.,Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK
| | - Andrew P Monkman
- Department of Physics, Durham University, South Road, Durham, DH1 3LE, UK
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14
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Wu H, Shi YZ, Wang K, Yu J, Zhang XH. Conformational isomeric thermally activated delayed fluorescence (TADF) emitters: mechanism, applications, and perspectives. Phys Chem Chem Phys 2023; 25:2729-2741. [PMID: 36633179 DOI: 10.1039/d2cp05119b] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Thermally activated delayed fluorescence (TADF) materials have received enormous attention and the mechanism behind them has been investigated in depth. It has been found that some donor-acceptor (D-A) type TADF emitters could obviously exhibit dual stable conformations in the ground states and their distributions significantly affect the physical properties and device performances. Therefore, professional analysis and a summary of the relationship between molecular structures and performances are very important. In this review, we first summarize the mechanism and properties of TADF emitters with conformational isomerism. We also classify their recent progress according to their different applications, and provide an outlook on their perspectives.
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Affiliation(s)
- Hao Wu
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, P. R. China.
| | - Yi-Zhong Shi
- School of Materials Science and Engineering, Suzhou University of Science and Technology, Suzhou, 215009, P. R. China.
| | - Kai Wang
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, P. R. China. .,Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, 215123, Jiangsu, P. R. China
| | - Jia Yu
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, P. R. China. .,Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123, Jiangsu, P. R. China
| | - Xiao-Hong Zhang
- Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, 199 Ren'ai Road, Suzhou, 215123, Jiangsu, P. R. China. .,Jiangsu Key Laboratory of Advanced Negative Carbon Technologies, Soochow University, Suzhou, 215123, Jiangsu, P. R. China
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15
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Gao M, Tian Y, Li X, Gong Y, Fang M, Yang J, Li Z. The Effect of Molecular Conformations and Simulated "Self-Doping" in Phenothiazine Derivatives on Room-Temperature Phosphorescence. Angew Chem Int Ed Engl 2023; 62:e202214908. [PMID: 36449343 DOI: 10.1002/anie.202214908] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/29/2022] [Accepted: 11/30/2022] [Indexed: 12/03/2022]
Abstract
The research of purely organic room-temperature phosphorescence (RTP) materials has drawn great attention for their wide potential applications. Besides single-component and host-guest doping systems, the self-doping with same molecule but different conformations in one state is also a possible way to construct RTP materials, regardless of its rare investigation. In this work, twenty-four phenothiazine derivatives with two distinct molecular conformations were designed and their RTP behaviors in different states were systematically studied, with the aim to deeply understand the self-doping effect on the corresponding RTP property. While the phenothiazine derivatives with quasi-axial (ax) conformation presented better RTP performance in aggregated state, the quasi-equatorial (eq) ones were better in isolated state. Accordingly, the much promoted RTP performance was achieved in the stimulated self-doping state with ax-conformer as host and eq-one as guest, demonstrating the significant influence of self-doping on RTP effect.
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Affiliation(s)
- Mingxue Gao
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China
| | - Yu Tian
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China
| | - Xiaoning Li
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China
| | - Yanxiang Gong
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China
| | - Manman Fang
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China
| | - Jie Yang
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China
| | - Zhen Li
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin, 300072, China.,Department of Chemistry, Wuhan University, Wuhan, 430072, China.,Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou, 350207, China.,Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China
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16
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Brannan AC, Phuoc NL, Linnolahti M, Romanov AS. Organic persistent room temperature phosphorescence enabled by carbazole impurity. Front Chem 2023; 10:1008658. [PMID: 36688032 PMCID: PMC9853050 DOI: 10.3389/fchem.2022.1008658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 12/15/2022] [Indexed: 01/09/2023] Open
Abstract
The molecular design of metal-free organic phosphors is essential for realizing persistent room-temperature phosphorescence (pRTP) despite its spin-forbidden nature. A series of halobenzonitrile-carbazoles has been prepared following a one-pot nucleophilic substitution protocol involving commercially available and laboratory-synthesized carbazoles. We demonstrate how halo- and cyano-substituents affect the molecular geometry in the crystal lattice, resulting in tilt and/or twist of the carbazole with respect to the phenyl moiety. Compounds obtained from the commercially available carbazole result in efficient pRTP of organic phosphors with a high quantum yield of up to 22% and a long excited state lifetime of up to 0.22 s. Compounds obtained from the laboratory-synthesized carbazole exhibit thermally activated delayed fluorescence with an excited state lifetime in the millisecond range. In-depth photophysical studies reveal that luminescence originates from the mixed locally excited state (3LE, nπ*)/charge transfer state.
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Affiliation(s)
- Alexander C. Brannan
- Department of Chemistry, The University of Manchester, Manchester, United Kingdom
| | - Nguyen Le Phuoc
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
| | - Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland,*Correspondence: Mikko Linnolahti, ; Alexander S. Romanov,
| | - Alexander S. Romanov
- Department of Chemistry, The University of Manchester, Manchester, United Kingdom,*Correspondence: Mikko Linnolahti, ; Alexander S. Romanov,
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17
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Pinosa E, Bassan E, Cetin S, Villa M, Potenti S, Calogero F, Gualandi A, Fermi A, Ceroni P, Cozzi PG. Light-Induced Access to Carbazole-1,3-dicarbonitrile: A Thermally Activated Delayed Fluorescent (TADF) Photocatalyst for Cobalt-Mediated Allylations. J Org Chem 2022; 88:6390-6400. [DOI: 10.1021/acs.joc.2c01825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Emanuele Pinosa
- Alma Mater Studiorum - Università di Bologna, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, 40126 Bologna, Italy
- Center for Chemical Catalysis - C3, Alma Mater Studiorum - Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Elena Bassan
- Alma Mater Studiorum - Università di Bologna, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, 40126 Bologna, Italy
- Center for Chemical Catalysis - C3, Alma Mater Studiorum - Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Sultan Cetin
- Alma Mater Studiorum - Università di Bologna, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, 40126 Bologna, Italy
| | - Marco Villa
- Alma Mater Studiorum - Università di Bologna, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, 40126 Bologna, Italy
- Center for Chemical Catalysis - C3, Alma Mater Studiorum - Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Simone Potenti
- Alma Mater Studiorum - Università di Bologna, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, 40126 Bologna, Italy
- Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - Francesco Calogero
- Alma Mater Studiorum - Università di Bologna, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, 40126 Bologna, Italy
- Center for Chemical Catalysis - C3, Alma Mater Studiorum - Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Andrea Gualandi
- Alma Mater Studiorum - Università di Bologna, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, 40126 Bologna, Italy
- Center for Chemical Catalysis - C3, Alma Mater Studiorum - Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Andrea Fermi
- Alma Mater Studiorum - Università di Bologna, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, 40126 Bologna, Italy
- Center for Chemical Catalysis - C3, Alma Mater Studiorum - Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Paola Ceroni
- Alma Mater Studiorum - Università di Bologna, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, 40126 Bologna, Italy
- Center for Chemical Catalysis - C3, Alma Mater Studiorum - Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Pier Giorgio Cozzi
- Alma Mater Studiorum - Università di Bologna, Dipartimento di Chimica “G. Ciamician”, Via Selmi 2, 40126 Bologna, Italy
- Center for Chemical Catalysis - C3, Alma Mater Studiorum - Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
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18
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Ye K, Cao L, van Raamsdonk DME, Wang Z, Zhao J, Escudero D, Jacquemin D. Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence. Beilstein J Org Chem 2022; 18:1435-1453. [PMID: 36300011 PMCID: PMC9577389 DOI: 10.3762/bjoc.18.149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 09/26/2022] [Indexed: 11/23/2022] Open
Abstract
In order to investigate the joint influence of the conformation flexibility and the matching of the energies of the charge-transfer (CT) and the localized triplet excited (3LE) states on the thermally activated delayed fluorescence (TADF) in electron donor-acceptor molecules, a series of compact electron donor-acceptor dyads and a triad were prepared, with naphthalimide (NI) as electron acceptor and phenothiazine (PTZ) as electron donor. The NI and PTZ moieties are either directly connected at the 3-position of NI and the N-position of the PTZ moiety via a C-N single bond, or they are linked through a phenyl group. The tuning of the energy order of the CT and LE states is achieved by oxidation of the PTZ unit into the corresponding sulfoxide, whereas conformation restriction is imposed by introducing ortho-methyl substituents on the phenyl linker, so that the coupling magnitude between the CT and the 3LE states can be controlled. The singlet oxygen quantum yield (ΦΔ) of NI-PTZ is moderate in n-hexane (HEX, ΦΔ = 19%). TADF was observed for the dyads, the biexponential luminescence lifetime are 16.0 ns (99.9%)/14.4 μs (0.1%) for the dyad and 7.2 ns (99.6%)/2.0 μs (0.4%) for the triad. Triplet state was observed in the nanosecond transient absorption spectra with lifetimes in the 4-48 μs range. Computational investigations show that the orthogonal electron donor-acceptor molecular structure is beneficial for TADF. These calculations indicate small energetic difference between the 3LE and 3CT states, which are helpful for interpreting the ns-TA spectra and the origins of TADF in NI-PTZ, which is ultimately due to the small energetic difference between the 3LE and 3CT states. Conversely, NI-PTZ-O, which has a higher CT state and bears a much more stabilized 3LE state, does not show TADF.
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Affiliation(s)
- Kaiyue Ye
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Liyuan Cao
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | | | - Zhijia Wang
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
| | - Jianzhang Zhao
- State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P. R. China
- State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources, College of Chemistry, Xinjiang University, Urumqi 830017, P. R. China
| | | | - Denis Jacquemin
- Nantes Université, CNRS, CEISAM UMR-6230, Nantes F-44000, France
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19
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Hempe M, Kukhta NA, Danos A, Batsanov AS, Monkman AP, Bryce MR. Intramolecular Hydrogen Bonding in Thermally Activated Delayed Fluorescence Emitters: Is There Evidence Beyond Reasonable Doubt? J Phys Chem Lett 2022; 13:8221-8227. [PMID: 36007139 PMCID: PMC9465681 DOI: 10.1021/acs.jpclett.2c00907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Intramolecular hydrogen bonding between donor and acceptor segments in thermally activated delayed fluorescence (TADF) materials is now frequently employed to─purportedly─rigidify the structure and improve the emission performance of these materials. However, direct evidence for these intramolecular interactions is often lacking or ambiguous, leading to assertions that are largely speculative. Here we investigate a series of TADF-active materials incorporating pyridine, which bestows the potential ability to form intramolecular H-bonding interactions. Despite possible indications of H-bonding from an X-ray analysis, an array of other experimental investigations proved largely inconclusive. Instead, after examining computational potential energy surfaces of the donor-acceptor torsion angle we conclude that the pyridine group primarily alleviates steric congestion in our case, rather than enabling an H-bond interaction as elsewhere assumed. We suggest that many previously reported "H-bonding" TADF materials featuring similar chemical motifs may instead operate similarly and that investigation of potential energy surfaces should become a key feature of future studies.
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Affiliation(s)
- Matthias Hempe
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Nadzeya A. Kukhta
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
- Materials
Science and Engineering Department, University
of Washington, Seattle, Washington 98195, United States
| | - Andrew Danos
- Physics
Department, Durham University, South Road, Durham, DH1 3LE, U.K.
| | - Andrei S. Batsanov
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Andrew P. Monkman
- Physics
Department, Durham University, South Road, Durham, DH1 3LE, U.K.
| | - Martin R. Bryce
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
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20
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Gu Q, Chotard F, Eng J, Reponen APM, Vitorica-Yrezabal IJ, Woodward AW, Penfold TJ, Credgington D, Bochmann M, Romanov AS. Excited-State Lifetime Modulation by Twisted and Tilted Molecular Design in Carbene-Metal-Amide Photoemitters. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2022; 34:7526-7542. [PMID: 36032551 PMCID: PMC9404540 DOI: 10.1021/acs.chemmater.2c01938] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Carbene-metal-amides (CMAs) are an emerging class of photoemitters based on a linear donor-linker-acceptor arrangement. They exhibit high flexibility about the carbene-metal and metal-amide bonds, leading to a conformational freedom which has a strong influence on their photophysical properties. Herein we report CMA complexes with (1) nearly coplanar, (2) twisted, (3) tilted, and (4) tilt-twisted orientations between donor and acceptor ligands and illustrate the influence of preferred ground-state conformations on both the luminescence quantum yields and excited-state lifetimes. The performance is found to be optimum for structures with partially twisted and/or tilted conformations, resulting in radiative rates exceeding 1 × 106 s-1. Although the metal atoms make only small contributions to HOMOs and LUMOs, they provide sufficient spin-orbit coupling between the low-lying excited states to reduce the excited-state lifetimes down to 500 ns. At the same time, high photoluminescence quantum yields are maintained for a strongly tilted emitter in a host matrix. Proof-of-concept organic light-emitting diodes (OLEDs) based on these new emitter designs were fabricated, with a maximum external quantum efficiency (EQE) of 19.1% with low device roll-off efficiency. Transient electroluminescence studies indicate that molecular design concepts for new CMA emitters can be successfully translated into the OLED device.
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Affiliation(s)
- Qinying Gu
- Department
of Physics, Cavendish Laboratory, Cambridge
University, Cambridge CB3 0HF, U.K.
| | - Florian Chotard
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, U.K.
| | - Julien Eng
- School
of Chemistry, Newcastle University, Bedson Building, Newcastle upon Tyne, NE1 7RU, U.K.
| | - Antti-Pekka M. Reponen
- Department
of Physics, Cavendish Laboratory, Cambridge
University, Cambridge CB3 0HF, U.K.
| | | | - Adam W. Woodward
- Department
of Chemistry, University of Manchester, Manchester, M13 9PL, U.K.
| | - Thomas J. Penfold
- School
of Chemistry, Newcastle University, Bedson Building, Newcastle upon Tyne, NE1 7RU, U.K.
| | - Dan Credgington
- Department
of Physics, Cavendish Laboratory, Cambridge
University, Cambridge CB3 0HF, U.K.
| | - Manfred Bochmann
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, U.K.
| | - Alexander S. Romanov
- School
of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, U.K.
- Department
of Chemistry, University of Manchester, Manchester, M13 9PL, U.K.
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21
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Kelly D, Franca LG, Stavrou K, Danos A, Monkman AP. Laplace Transform Fitting as a Tool To Uncover Distributions of Reverse Intersystem Crossing Rates in TADF Systems. J Phys Chem Lett 2022; 13:6981-6986. [PMID: 35881847 PMCID: PMC9358706 DOI: 10.1021/acs.jpclett.2c01864] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 07/18/2022] [Indexed: 05/22/2023]
Abstract
Donor-acceptor (D-A) thermally activated delayed fluorescence (TADF) molecules are exquisitely sensitive to D-A dihedral angle. Although commonly simplified to an average value, these D-A angles nonetheless exist as distributions across the individual molecules embedded in films. The presence of these angle distributions translates to distributions in the rates of reverse intersystem crossing (krISC), observed as time dependent spectral shifts and multiexponential components in the emission decay, which are difficult to directly quantify. Here we apply inverse Laplace transform fitting of delayed fluorescence to directly reveal these distributions. Rather than a single average value, the crucial krISC rate is instead extracted as a density of rates. The modes and widths of these distributions vary with temperature, host environment, and intrinsic D-A torsional rigidity of different TADF molecules. This method gives new insights and deeper understanding of TADF host-guest interactions, as well as verifies future design strategies that target D-A bond rigidity.
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22
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Jena S, Eyyathiyil J, Behera SK, Kitahara M, Imai Y, Thilagar P. Crystallization induced room-temperature phosphorescence and chiral photoluminescence properties of phosphoramides. Chem Sci 2022; 13:5893-5901. [PMID: 35685799 PMCID: PMC9132070 DOI: 10.1039/d2sc00990k] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/06/2022] [Indexed: 11/21/2022] Open
Abstract
We report the design and synthesis of a series of room temperature phosphorescent phosphoramides TPTZPO, TPTZPS, and TPTZPSe with a donor (phenothiazine)-acceptor (P = X, X = O, S, and Se) architecture. All the compounds show structureless fluorescence with a nanosecond lifetime in dilute solutions. However, these compounds show dual fluorescence and room temperature phosphorescence (RTP) in the solid state. Both the intensity and energy of luminescence depend on the heteroatom attached to the phosphorus center. For example, compound TPTZPO with the P[double bond, length as m-dash]O unit exhibits fluorescence at a higher energy region than TPTZPS and TPTZPSe with the P[double bond, length as m-dash]S and P[double bond, length as m-dash]Se groups, respectively. Crystalline samples of TPTZPO, TPTZPS, and TPTZPSe show stronger RTP than the amorphous powder of respective compounds. Detailed steady-state, time-resolved photoluminescence and computational studies established that the 3n-π* state dominated by the phenothiazine moiety is the emissive state of these compounds. Although TPTZPS and TPTZPSe crystallized in the chiral space group, only TPTZPSe showed chiroptical properties in the solid state. The luminescence dissymmetry factor (g lum) value of TPTZPS is small and below the detection limit, and a CPL spectrum could not be observed for this compound.
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Affiliation(s)
- Satyam Jena
- Department of Inorganic and Physical Chemistry, Indian Institute of Science Bangalore India - 560012
| | - Jusaina Eyyathiyil
- Department of Inorganic and Physical Chemistry, Indian Institute of Science Bangalore India - 560012
| | - Santosh Kumar Behera
- Department of Inorganic and Physical Chemistry, Indian Institute of Science Bangalore India - 560012
| | - Maho Kitahara
- Department of Applied Chemistry, Faculty of Science and Engineering, Kindai University 3-4-1 Kowakae, Higashi-Osaka Osaka 577-8502 Japan
| | - Yoshitane Imai
- Department of Applied Chemistry, Faculty of Science and Engineering, Kindai University 3-4-1 Kowakae, Higashi-Osaka Osaka 577-8502 Japan
| | - Pakkirisamy Thilagar
- Department of Inorganic and Physical Chemistry, Indian Institute of Science Bangalore India - 560012
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23
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Liu K, Li S, Fu L, Lei Y, Liao Q, Fu H. Cocrystallization tailoring radiative decay pathways for thermally activated delayed fluorescence and room-temperature phosphorescence emission. NANOSCALE 2022; 14:6305-6311. [PMID: 35420117 DOI: 10.1039/d2nr00757f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Modulation of excited-state processes in binary organic cocrystals has been rarely explored so far. Here, we develop two charge-transfer (CT) cocrystal microrods with a 1 : 1 stoichiometric ratio where halogenated dibenzothiophene (DBT) compounds act as π-electron donors and 1,2,4,5-tetracyanobenzene (TCNB) acts as an acceptor. Unexpectedly, the cocrystal containing one bromine (Br) atom at the 3-position of DBT (3-BrTC) presents thermally activated delayed fluorescence (TADF), while the other one comprising one Br atom at the 4-position of DBT (4-BrTC) exhibits both TADF and room-temperature phosphorescence (RTP). Experimental and theoretical calculation results reveal that CT interactions in 3- and 4-BrTC decrease the S1-T2 energy gap, whereas abundant lone-pair electrons from the Br atom in 4-BrTC facilitate the n → π* transition. As a consequence, single TADF and dual-emissive TADF/RTP were realized, respectively. The present work offers wonderful insight into the effect of molecular structures on the excited-state pathways of organic CT cocrystals.
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Affiliation(s)
- Kun Liu
- Institute of Molecule Plus (IMP), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Shuai Li
- Institute of Molecule Plus (IMP), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
| | - Liyuan Fu
- Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry, Capital Normal University, Beijing, 100048, China.
| | - Yilong Lei
- Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
| | - Qing Liao
- Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry, Capital Normal University, Beijing, 100048, China.
| | - Hongbing Fu
- Institute of Molecule Plus (IMP), School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.
- Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry, Capital Normal University, Beijing, 100048, China.
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24
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Gao Y, Liao Q, Li M, Han M, Huang A, Dang Q, Li Q, Li Z. Expounding the Relationship between Molecular Conformation and Room-Temperature Phosphorescence Property by Deviation Angle. J Phys Chem Lett 2022; 13:3251-3260. [PMID: 35388692 DOI: 10.1021/acs.jpclett.2c00597] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Room-temperature phosphorescence (RTP) emitters with ultralong lifetimes are attracting more and more attention for their wide applications. However, it is still a big challenge to achieve persistent organic afterglow because of the undefined relationship between molecular structures and RTP effect. Herein, diphenylamine (DPA) as a commonly used building block is selected as the molecular skeleton. Through incorporation of various alkyl moieties by ortho-substitution in different numbers and positions, RTP lifetimes can increase from 129 to 661 ms with the subtle adjustment of molecular conformations. It is summarized that the deviation angle (θ) of phenyl units in the DPA skeleton from the ideal p-π conjugated plane can act as the key parameter determining RTP lifetime, and the larger the θ values, the longer the RTP lifetimes. Furthermore, this result has been successfully applied as the universal principle to explain the RTP properties of various organic luminogens with DPA blocks and similar structures.
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Affiliation(s)
- Yuan Gao
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China
| | - Qiuyan Liao
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China
| | - Menghan Li
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China
| | - Mengmeng Han
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China
| | - Arui Huang
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China
| | - Qianxi Dang
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China
| | - Qianqian Li
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China
| | - Zhen Li
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, P.R. China
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25
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Hall D, Stavrou K, Duda E, Danos A, Bagnich S, Warriner S, Slawin AMZ, Beljonne D, Köhler A, Monkman A, Olivier Y, Zysman-Colman E. Diindolocarbazole - achieving multiresonant thermally activated delayed fluorescence without the need for acceptor units. MATERIALS HORIZONS 2022; 9:1068-1080. [PMID: 35067689 DOI: 10.1039/d1mh01383a] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In this work we present a new multi-resonance thermally activated delayed fluorescence (MR-TADF) emitter paradigm, demonstrating that the structure need not require the presence of acceptor atoms. Based on an in silico design, the compound DiICzMes4 possesses a red-shifted emission, enhanced photoluminescence quantum yield, and smaller singlet-triplet energy gap, ΔEST, than the parent indolocarbazole that induces MR-TADF properties. Coupled cluster calculations accurately predict the magnitude of the ΔEST when the optimized singlet and triplet geometries are used. Slow yet optically detectable reverse intersystem crossing contributes to low efficiency in organic light-emitting diodes using DiICzMes4 as the emitter. However, when used as a terminal emitter in combination with a TADF assistant dopant within a hyperfluorescence device architecture, maximum external quantum efficiencies of up to 16.5% were achieved at CIE (0.15, 0.11). This represents one of the bluest hyperfluorescent devices reported to date. Simultaneously, recognising that MR-TADF emitters do not require acceptor atoms reveals an unexplored frontier in materials design, where yet greater performance may yet be discovered.
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Affiliation(s)
- David Hall
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK.
- Laboratory for Chemistry of Novel Materials, University of Mons, 7000, Mons, Belgium
| | - Kleitos Stavrou
- Department of Physics, Durham University, Durham, DH1 3LE, UK.
| | - Eimantas Duda
- Soft Matter Optoelectronics, BIMF & BPI, University of Bayreuth, Universitätsstraße 30, Bayreuth 95447, Germany.
| | - Andrew Danos
- Department of Physics, Durham University, Durham, DH1 3LE, UK.
| | - Sergey Bagnich
- Soft Matter Optoelectronics, BIMF & BPI, University of Bayreuth, Universitätsstraße 30, Bayreuth 95447, Germany.
| | - Stuart Warriner
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, UK
| | - Alexandra M Z Slawin
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK.
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons, 7000, Mons, Belgium
| | - Anna Köhler
- Soft Matter Optoelectronics, BIMF & BPI, University of Bayreuth, Universitätsstraße 30, Bayreuth 95447, Germany.
| | - Andrew Monkman
- Department of Physics, Durham University, Durham, DH1 3LE, UK.
| | - Yoann Olivier
- Laboratory for Computational Modeling of Functional Materials, Namur Institute of Structured Matter, University of Namur, Rue de Bruxelles, 61, Namur 5000, Belgium.
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK.
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26
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Masimukku N, Gudeika D, Volyniuk D, Bezvikonnyi O, Simokaitiene J, Matulis V, Lyakhov D, Azovskyi V, Gražulevičius JV. Bipolar 1,8-naphthalimides showing high electron mobility and red AIE-active TADF for OLED applications. Phys Chem Chem Phys 2022; 24:5070-5082. [PMID: 35146498 DOI: 10.1039/d1cp05942d] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Aiming to design bipolar organic semiconductors with high electron mobility and efficient red thermally activated delayed fluorescence (TADF), three donor-acceptor compounds were designed and synthesized selecting 1,8-naphthalimide as an acceptor and phenoxazine, 3,7-di-tert-butylphenothiazine or 2,7-di-tert-butyldimethyl-9,10-dihydroacridine as donor moieties. Aggregation induced emission enhancement was detected for the compounds causing efficient TADF in the solid-state. Photoluminescence quantum yields up to 77% were observed for the films of the compounds doped in a host. The compounds exhibited small singlet-triplet splitting (0.03-0.05 eV), and high reverse intersystem crossing rates of 2.08 × 105-1.13 × 106 s-1. The compounds were characterized by satisfactory hole and electron-injecting properties with ionization potentials of 5.72-5.83 eV and electron affinities of 2.79-2.91 eV. Bipolar charge transport was revealed by time of flight measurements. Electron transport with low dispersity and mobilities exceeding 2 × 10-3 cm2 V-1 s-1 was observed at an electric field of 4.6 × 105 V cm-1. The compounds were used as emitters in red electroluminescent devices, which showed maximum external quantum efficiencies up to 8.2%. Utilization of host-guest systems as light-emitting materials with hosts preferably transporting holes and TADF guests which preferably transport electrons allowed maximum efficiencies to be achieved at a practical brightness of 700-2200 cd m-2. DFT calculations of the geometry, electronic structure, absorption and photoluminescence spectra of all compounds were carried out to prove the conclusions drawn from the experiment. The results of the calculations clearly show that the first excited state for all compounds is the intramolecular charge transfer state. Quantitative analysis of the separation degree of electronic density during excitation allows the observed dependence of the blue shift value in the absorption and emission spectra on the increasing polarity of the solvent to be explained.
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Affiliation(s)
- Naveen Masimukku
- Kaunas University of Technology, Department of Polymer Chemistry and Technology, K. Baršausko g. 59, LT51423, Kaunas, Lithuania.
| | - Dalius Gudeika
- Kaunas University of Technology, Department of Polymer Chemistry and Technology, K. Baršausko g. 59, LT51423, Kaunas, Lithuania.
| | - Dmytro Volyniuk
- Kaunas University of Technology, Department of Polymer Chemistry and Technology, K. Baršausko g. 59, LT51423, Kaunas, Lithuania.
| | - Oleksandr Bezvikonnyi
- Kaunas University of Technology, Department of Polymer Chemistry and Technology, K. Baršausko g. 59, LT51423, Kaunas, Lithuania.
| | - Jurate Simokaitiene
- Kaunas University of Technology, Department of Polymer Chemistry and Technology, K. Baršausko g. 59, LT51423, Kaunas, Lithuania.
| | - Vitaly Matulis
- Belarusian State University, 4, Nezavisimosti Avenue, 220030, Minsk, Republic of Belarus
| | - Dmitry Lyakhov
- Computer, Electrical and Mathematical Science and Engineering Division, 4700 King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Volodymyr Azovskyi
- Faculty of Physics, Taras Shevchenko National University of Kyiv, 64/13 Volodymyrs'ka Str., 01601 Kyiv, Ukraine
| | - Juozas Vidas Gražulevičius
- Kaunas University of Technology, Department of Polymer Chemistry and Technology, K. Baršausko g. 59, LT51423, Kaunas, Lithuania.
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27
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Serevičius T, Skaisgiris R, Gudeika D, Kazlauskas K, Juršėnas S. Conformational disorder enabled emission phenomena in heavily doped TADF films. Phys Chem Chem Phys 2021; 24:313-320. [PMID: 34889323 DOI: 10.1039/d1cp04905d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Thermally activated delayed fluorescence (TADF) compounds doped in solid hosts are prone to undergo solvation effects, similar to those in the solution state. Emission peak shifts and changes in emission decay rates usually follow solid-state solvation (SSS). However, here we show that typical SSS behavior in heavily doped TADF films could be of a completely different origin, mistakenly attributed to SSS. Typically, increasing the doping load was found to redshift the emission peak wavelength and enhance the rISC rate. However, more in-depth analysis revealed that SSS actually is negligible and both phenomena are caused by the specific behavior of delayed emission. Increasing the concentration of the TADF compound was shown to enhance the concentration quenching of long-lived delayed fluorescence from conformer states with the largest singlet energy, eventually leading to a gradual redshift of the delayed emission peak wavelength. Concomitantly, the loss of long-lived delayed fluorescence entailed reverse intersystem crossing rate enhancement, though the rate-governing singlet-triplet energy gap was gradually increasing. The observed phenomena are highly unwanted, burdening molecular structure and OLED performance optimization.
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Affiliation(s)
- Tomas Serevičius
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania.
| | - Rokas Skaisgiris
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania.
| | - Dalius Gudeika
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu 19, LT-50254 Kaunas, Lithuania
| | - Karolis Kazlauskas
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania.
| | - Saulius Juršėnas
- Institute of Photonics and Nanotechnology, Vilnius University, Sauletekio 3, LT-10257 Vilnius, Lithuania.
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28
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Yu J, Ma H, Huang W, Liang Z, Zhou K, Lv A, Li XG, He Z. Purely Organic Room-Temperature Phosphorescence Endowing Fast Intersystem Crossing from Through-Space Spin-Orbit Coupling. JACS AU 2021; 1:1694-1699. [PMID: 34723272 PMCID: PMC8549040 DOI: 10.1021/jacsau.1c00290] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Indexed: 05/25/2023]
Abstract
Purely organic room-temperature phosphorescence endowing very fast intersystem crossing from through-space systems has not been well investigated. Here we report three space-confined bridged phosphors, where phenothiazine is linked with dibenzothiophene, dibenzofuran, and carbazole by a 9,9-dimethylxanthene bridge. Nearly pure phosphorescence is observed in the crystals at room temperature. Interestingly, phosphorescence comes solely from the phenothiazine segment. Experimental results indicate that bridged counterparts of dibenzothiophene, dibenzofuran, and carbazole contribute as close-lying triplet states with locally excited (LE) character. The through-space spin-orbit coupling principle is proposed in these bridged systems, as their 1LE and 3LE states have intrinsic spatial overlap, degenerate energy levels, and tilting face-to-face alignment. The resulting effective through-space spin-orbit coupling leads to efficient intersystem crossing a with rate constant as high as 109 s-1 and an overwhelming triplet decay channel of the singlet excited state.
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Affiliation(s)
- Jie Yu
- School
of Science, Harbin Institute of Technology, Shenzhen, Guangdong518055, People’s Republic
of China
| | - Huili Ma
- Key
Laboratory of Flexible Electronics & Institute of Advanced Materials
Jiangsu National Synergistic Innovation Center for Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211800, People’s Republic
of China
| | - Wenbin Huang
- School
of Science, Harbin Institute of Technology, Shenzhen, Guangdong518055, People’s Republic
of China
| | - Zhiwei Liang
- School
of Science, Harbin Institute of Technology, Shenzhen, Guangdong518055, People’s Republic
of China
| | - Kang Zhou
- Hoffmann
Institute of Advanced Materials, Shenzhen
Polytechnic, Shenzhen, Guangdong 518055, People’s Republic of China
| | - Anqi Lv
- Key
Laboratory of Flexible Electronics & Institute of Advanced Materials
Jiangsu National Synergistic Innovation Center for Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, Nanjing 211800, People’s Republic
of China
| | - Xin-Gui Li
- State Key
Laboratory of Pollution Control and Resource Reuse, and Shanghai Institute
of Pollution Control and Ecological Security, College of Environmental
Science and Engineering, Tongji University, 1239 SiPing Road, Shanghai 200092, People’s Republic of China
| | - Zikai He
- School
of Science, Harbin Institute of Technology, Shenzhen, Guangdong518055, People’s Republic
of China
- School
of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin, Heilongjiang 150001, People’s Republic of China
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29
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Tsiko U, Bezvikonnyi O, Sych G, Keruckiene R, Volyniuk D, Simokaitiene J, Danyliv I, Danyliv Y, Bucinskas A, Tan X, Grazulevicius JV. Multifunctional derivatives of pyrimidine-5-carbonitrile and differently substituted carbazoles for doping-free sky-blue OLEDs and luminescent sensors of oxygen. J Adv Res 2021; 33:41-51. [PMID: 34603777 PMCID: PMC8463962 DOI: 10.1016/j.jare.2021.01.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 01/06/2021] [Accepted: 01/23/2021] [Indexed: 12/21/2022] Open
Abstract
Pyrimidine-5-carbonitrile-based compounds with efficient TADF exceeding reverse intersystem crossing rates of 106 s−1. AIEE properties for the designed compounds allowing to reach PLQYs up to 50% in solid state. Bipolar charge-transporting properties showing hole mobility of 1.6 × 10-4 cm2/V·s and electron mobility of 1.37 × 10-5 cm2/V·s. Non-doped sky-blue OLED with external quantum efficiency of 12.8%. Oxygen probes with fast response, high sensitivity and good stability.
Introduction Evolution of organic light-emitting diodes (OLEDs) reached the point, which allows to obtain maximum internal quantum efficiency of 100% partly using heavy-metal-free emitters exhibiting thermally activated delayed fluorescence (TADF). Such emitters are also predictively perfect candidates for new generation of optical sensors since triplet harvesting can be sensitive to different analytes (at least to oxygen). Although many organic TADF emitters have been reported so far as OLED emitters, the investigation of materials suitable for both OLEDs and optical sensors remains extremely rare. Objectives Aiming to achieve high photoluminescence quantum yields in solid-state and triplet harvesting abilities of organic semiconductors with efficient bipolar charge transport required for application in both blue OLEDs and optical sensors, symmetrical donor–acceptor-donor organic emitters containing pyrimidine-5-carbonitrile electron-withdrawing scaffold and carbazole, tert-butylcarbazole and methoxy carbazole donor moieties were designed, synthesized and investigated as the main objectives of this study. Methods New compounds were tested by many experimental methods including optical and photoelectron spectroscopy, time of flight technique, electrochemistry and thermal analyses. Results Demonstrating advantages of the molecular design, the synthesized emitters exhibited sky-blue efficient TADF with reverse intersystem crossing rates exceeding 106 s−1, aggregation-induced emission enhancement with photoluminescence quantum yields in solid state exceeding 50%, hole and electron transporting properties with charge mobilities exceeding 10-4 cm2/V·s, glass-forming properties with glass transition temperatures reaching 177 °C. Sky-blue OLEDs with non-doped light-emitting layers of the synthesized emitter showed maximum external efficiency of 12.8% while the doped device with the same emitter exhibited maximum external efficiency of 14%. The synthesized emitters were also used as oxygen probes for optical sensors with oxygen sensitivity estimated by the Stern-Volmer constant of 3.24·10-5 ppm−1. Conclusion The developed bipolar TADF emitters with pyrimidine-5-carbonitrile and carbazole moieties showed effective applicability in both blue OLEDs and optical sensors.
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Affiliation(s)
- Uliana Tsiko
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas, Lithuania
| | - Oleksandr Bezvikonnyi
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas, Lithuania
| | - Galyna Sych
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas, Lithuania
| | - Rasa Keruckiene
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas, Lithuania
| | - Dmytro Volyniuk
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas, Lithuania
| | - Jurate Simokaitiene
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas, Lithuania
| | - Iryna Danyliv
- Department of Electronic Devices, Lviv Polytechnic National University, S. Bandera 12, 79013 Lviv, Ukraine
| | - Yan Danyliv
- Department of Electronic Devices, Lviv Polytechnic National University, S. Bandera 12, 79013 Lviv, Ukraine
| | - Audrius Bucinskas
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas, Lithuania
| | - Xiaofeng Tan
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas, Lithuania
| | - Juozas Vidas Grazulevicius
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas, Lithuania
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30
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Li H, Wang X, Yuan K, Lv L, Li Z. Insights from QM/MM-ONIOM calculations: the TADF phenomenon of phenanthro[9,10- d]imidazole-anthraquinone in the solid state. Phys Chem Chem Phys 2021; 23:20218-20229. [PMID: 34474457 DOI: 10.1039/d1cp00578b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In this paper, we employed first-principles methods and the QM/MM technique to study the thermally activated delayed fluorescence (TADF) phenomenon of a near-infrared molecule (PIPAQ) in vacuum, solution, and the aggregation state. Our calculated results show that (1) the cluster can decrease the energy gap between the first singlet excited state (S1) and the first triplet state (T1) compared with the monomer, furthermore, the T1 state and S1 state in the cluster are energetically closer to each other, which implies that the energy gap is smaller in comparison with that in solution and can promote the intersystem crossing (ISC) process due to the surrounding effect; (2) the optimally tuned range-separated functional is applicable to simulation of excited states and the outcomes are in good agreement with experimental values; (3) the reorganization energies associated with ISC and the reverse intersystem crossing (RISC) processes between the S1 and T1 states are sensitive to the calculated methods and the environments, and thus the following calculated ISC and RISC rates vary dramatically according to different reorganization energies; (4) all radiative and nonradiative rates are insensitive to temperature, but sensitive to environments, all the radiative rates increase in the cluster while the nonradiative rates decrease, which enhances the fluorescence quantum efficiency and agrees with the observed value. The above results demonstrate that the surrounding effects are very important for modulating the photophysical properties of the PIPAQ compound. Finally, this studied conclusion can give a helpful insight into the TADF mechanism for the title compounds, by which novel TADF materials with excellent performance could be rationally designed.
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Affiliation(s)
- Huixue Li
- School of Chemical Engineering and Technology, Tianshui Normal University, Tianshui, Gansu 741001, China.
| | - Xiaofeng Wang
- School of Chemical Engineering and Technology, Tianshui Normal University, Tianshui, Gansu 741001, China.
| | - Kun Yuan
- School of Chemical Engineering and Technology, Tianshui Normal University, Tianshui, Gansu 741001, China.
| | - Lingling Lv
- School of Chemical Engineering and Technology, Tianshui Normal University, Tianshui, Gansu 741001, China.
| | - Zhifeng Li
- School of Chemical Engineering and Technology, Tianshui Normal University, Tianshui, Gansu 741001, China.
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31
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Xu Z, Hean D, Climent C, Casanova D, Wolf MO. Switching between TADF and RTP: anion-regulated photoluminescence in organic salts and co-crystals. MATERIALS ADVANCES 2021; 2:5777-5784. [PMID: 34527950 PMCID: PMC8406714 DOI: 10.1039/d1ma00314c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 07/28/2021] [Indexed: 06/13/2023]
Abstract
Thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) are two photophysical phenomena which utilize triplet excitons. In this work, we demonstrate how variation of the anion in organic salts with carbazole and phenothiazine-5,5-dioxide donors and pyridinium and quinolinium acceptors may be used to switch between TADF and RTP. These compounds adopt similar molecular structures and packing modes with different anions and exhibit different types of photophysical behavior due to the electronic effects of the anions. With bromide anions, the salts exhibit TADF with some RTP. These compounds show fast reverse intersystem crossing and a short delayed lifetime, which is key to application in efficient and robust OLEDs. With BF4 - and PF6 - anions, RTP with long-lived lifetimes and afterglow are observed by eye. This behavior can be utilized for data encryption and anti-counterfeiting applications. Emission wavelengths and lifetimes are also anion-dependent. These results open up an avenue for developing novel luminescent materials through anion tuning and present a molecular model to understand the interplay of RTP and TADF.
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Affiliation(s)
- Zhen Xu
- Department of Chemistry, University of British Columbia 2036 Main Mall Vancouver BC V6T 1Z1 Canada
| | - Duane Hean
- Department of Chemistry, University of British Columbia 2036 Main Mall Vancouver BC V6T 1Z1 Canada
| | - Clàudia Climent
- Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid E-28049 Madrid Spain
| | - David Casanova
- Donostia International Physics Center (DIPC) Paseo Manuel de Lardizabal 4 20018 Donostia Euskadi Spain
- IKERBASQUE, Basque Foundation for Science 48013 Bilbao Euskadi Spain
| | - Michael O Wolf
- Department of Chemistry, University of British Columbia 2036 Main Mall Vancouver BC V6T 1Z1 Canada
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32
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Paisley NR, Halldorson SV, Tran MV, Gupta R, Kamal S, Algar WR, Hudson ZM. Near‐Infrared‐Emitting Boron‐Difluoride‐Curcuminoid‐Based Polymers Exhibiting Thermally Activated Delayed Fluorescence as Biological Imaging Probes. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202103965] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Nathan R. Paisley
- Department of Chemistry The University of British Columbia 2036 Main Mall Vancouver British Columbia V6T 1Z1 Canada
| | - Sarah V. Halldorson
- Department of Chemistry The University of British Columbia 2036 Main Mall Vancouver British Columbia V6T 1Z1 Canada
| | - Michael V. Tran
- Department of Chemistry The University of British Columbia 2036 Main Mall Vancouver British Columbia V6T 1Z1 Canada
| | - Rupsa Gupta
- Department of Chemistry The University of British Columbia 2036 Main Mall Vancouver British Columbia V6T 1Z1 Canada
| | - Saeid Kamal
- Department of Chemistry The University of British Columbia 2036 Main Mall Vancouver British Columbia V6T 1Z1 Canada
| | - W. Russ Algar
- Department of Chemistry The University of British Columbia 2036 Main Mall Vancouver British Columbia V6T 1Z1 Canada
| | - Zachary M. Hudson
- Department of Chemistry The University of British Columbia 2036 Main Mall Vancouver British Columbia V6T 1Z1 Canada
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33
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de Sousa LE, de Silva P. Unified Framework for Photophysical Rate Calculations in TADF Molecules. J Chem Theory Comput 2021; 17:5816-5824. [PMID: 34383498 DOI: 10.1021/acs.jctc.1c00476] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
One of the challenges in organic light-emitting diodes research is finding ways to increase device efficiency by making use of the triplet excitons that are inevitably generated in the process of electroluminescence. One way to do so is by thermally activated delayed fluorescence (TADF), a process in which triplet excitons undergo upconversion to singlet states, allowing them to relax radiatively. The discovery of this phenomenon has ensued a quest for new materials that are able to effectively take advantage of this mechanism. From a theoretical standpoint, this requires the capacity to estimate the rates of the various processes involved in the photophysics of candidate molecules, such as intersystem crossing, reverse intersystem crossing, fluorescence, and phosphorescence. Here, we present a method that is able to, within a single framework, compute all of these rates and predict the photophysics of new molecules. We apply the method to two TADF molecules and show that results compare favorably with other theoretical approaches and experimental results. Finally, we use a kinetic model to show how the calculated rates act in concert to produce different photophysical behavior.
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Affiliation(s)
- Leonardo Evaristo de Sousa
- Department of Energy Conversion and Storage, Technical University of Denmark, Anker Engelunds Vej 301, 2800 Kongens Lyngby, Denmark
| | - Piotr de Silva
- Department of Energy Conversion and Storage, Technical University of Denmark, Anker Engelunds Vej 301, 2800 Kongens Lyngby, Denmark
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34
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Paisley NR, Halldorson SV, Tran MV, Gupta R, Kamal S, Algar WR, Hudson ZM. Near-Infrared-Emitting Boron-Difluoride-Curcuminoid-Based Polymers Exhibiting Thermally Activated Delayed Fluorescence as Biological Imaging Probes. Angew Chem Int Ed Engl 2021; 60:18630-18638. [PMID: 34133838 DOI: 10.1002/anie.202103965] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 05/14/2021] [Indexed: 12/16/2022]
Abstract
Near-infrared-emitting polymers were prepared using four boron-difluoride-curcuminoid-based monomers using ring-opening metathesis polymerization (ROMP). Well-defined polymers with molecular weights of ≈20 kDa and dispersities <1.07 were produced and exhibited near-infrared (NIR) emission in solution and in the solid state with photoluminescence quantum yields (ΦPL ) as high as 0.72 and 0.18, respectively. Time-resolved emission spectroscopy revealed thermally activated delayed fluorescence (TADF) in polymers containing highly planar dopants, whereas room-temperature phosphorescence dominated with twisted species. Density functional theory demonstrated that rotation about the donor-acceptor linker can give rise to TADF, even where none would be expected based on calculations using ground-state geometries. Incorporation of TADF-active materials into water-soluble polymer dots (Pdots) gave NIR-emissive nanoparticles, and conjugation of these Pdots with antibodies enabled immunofluorescent labeling of SK-BR3 human breast-cancer cells.
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Affiliation(s)
- Nathan R Paisley
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Sarah V Halldorson
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Michael V Tran
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Rupsa Gupta
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Saeid Kamal
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - W Russ Algar
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Zachary M Hudson
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, V6T 1Z1, Canada
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35
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Ansari R, Shao W, Yoon SJ, Kim J, Kieffer J. Charge Transfer as the Key Parameter Affecting the Color Purity of Thermally Activated Delayed Fluorescence Emitters. ACS APPLIED MATERIALS & INTERFACES 2021; 13:28529-28537. [PMID: 34106677 DOI: 10.1021/acsami.1c02943] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The key factors determining the emission bandwidth of thermally activated delayed fluorescence (TADF) are investigated by combining computational and experimental approaches. To achieve high internal quantum efficiencies in a metal-free organic light-emitting diode via TADF, the first triplet (T1) to first singlet (S1) reverse intersystem crossing is promoted by configuring molecules in an electron donor-acceptor (D-A) alternation with a large dihedral angle, which results in a small energy gap (ΔEST) between S1 and T1 levels. This allows for effective non-radiative up-conversion of triplet excitons to singlet excitons that fluoresce. However, this traditional molecular design of TADF results in broad emission spectral bands (full-width at half-maximum = 70-100 nm). Despite reports suggesting that suppressing the D-A dihedral rotation narrows the emission band, the origin of emission broadening remains elusive. Indeed, our results suggest that the intrinsic TADF emission bandwidth is primarily determined by the charge transfer character of the molecule, rather than its propensity for rotational motion, which offers a renewed perspective on the rational molecular design of organic emitters exhibiting sharp emission spectra.
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Affiliation(s)
- Ramin Ansari
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-1382, United States
| | - Wenhao Shao
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1382, United States
| | - Seong-Jun Yoon
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-1382, United States
| | - Jinsang Kim
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109-1382, United States
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1382, United States
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-1382, United States
- Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-1382, United States
| | - John Kieffer
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109-1382, United States
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36
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Hempe M, Kukhta NA, Danos A, Fox MA, Batsanov AS, Monkman AP, Bryce MR. Vibrational Damping Reveals Vibronic Coupling in Thermally Activated Delayed Fluorescence Materials. CHEMISTRY OF MATERIALS : A PUBLICATION OF THE AMERICAN CHEMICAL SOCIETY 2021; 33:3066-3080. [PMID: 34267422 PMCID: PMC8273894 DOI: 10.1021/acs.chemmater.0c03783] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 04/05/2021] [Indexed: 05/18/2023]
Abstract
We investigate a series of D-A molecules consisting of spiro[acridan-9,9'-fluorene] as the donor and 2-phenylenepyrimidine as the acceptor. In two of the materials, a spiro center effectively electronically isolates the D unit from (consequently) optically innocent yet structurally influential adamantyl side groups. In a third material, adamantyl groups attached directly to the acceptor strongly influence the electronic properties. Steady-state and time-resolved photophysical studies in solution, Zeonex polymer matrix, and neat films reveal that the substituents impact the efficiency of vibronic coupling between singlet and triplet states relevant to reverse intersystem crossing (rISC) and thermally activated delayed fluorescence (TADF), without significantly changing the singlet-triplet gap in the materials. The adamantyl groups serve to raise the segmental mass and inertia, thereby damping intramolecular motions (both vibrational and rotational). This substitution pattern reveals the role of large-amplitude (primarily D-A dihedral angle rocking) motions on reverse intersystem crossing (rISC), as well as smaller contributions from low-amplitude or dampened vibrations in solid state. We demonstrate that rISC still occurs when the high-amplitude motions are suppressed in Zeonex and discuss various vibronic coupling scenarios that point to an underappreciated role of intersegmental motions that persist in rigid solids. Our results underline the complexity of vibronic couplings in the mediation of rISC and provide a synthetic tool to enable future investigations of vibronic coupling through selective mechanical dampening with no impact on electronic systems.
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Affiliation(s)
- Matthias Hempe
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Nadzeya A. Kukhta
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Andrew Danos
- Physics
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Mark A. Fox
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Andrei S. Batsanov
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Andrew P. Monkman
- Physics
Department, Durham University, South Road, Durham DH1 3LE, U.K.
| | - Martin R. Bryce
- Chemistry
Department, Durham University, South Road, Durham DH1 3LE, U.K.
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37
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Pander P, Daniels R, Zaytsev AV, Horn A, Sil A, Penfold TJ, Williams JAG, Kozhevnikov VN, Dias FB. Exceptionally fast radiative decay of a dinuclear platinum complex through thermally activated delayed fluorescence. Chem Sci 2021; 12:6172-6180. [PMID: 33996015 PMCID: PMC8098751 DOI: 10.1039/d1sc00160d] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/19/2021] [Indexed: 12/13/2022] Open
Abstract
A novel dinuclear platinum(ii) complex featuring a ditopic, bis-tetradentate ligand has been prepared. The ligand offers each metal ion a planar O^N^C^N coordination environment, with the two metal ions bound to the nitrogen atoms of a bridging pyrimidine unit. The complex is brightly luminescent in the red region of the spectrum with a photoluminescence quantum yield of 83% in deoxygenated methylcyclohexane solution at ambient temperature, and shows a remarkably short excited state lifetime of 2.1 μs. These properties are the result of an unusually high radiative rate constant of around 4 × 105 s-1, a value which is comparable to that of the very best performing Ir(iii) complexes. This unusual behaviour is the result of efficient thermally activated reverse intersystem crossing, promoted by a small singlet-triplet energy difference of only 69 ± 3 meV. The complex was incorporated into solution-processed OLEDs achieving EQEmax = 7.4%. We believe this to be the first fully evidenced report of a Pt(ii) complex showing thermally activated delayed fluorescence (TADF) at room temperature, and indeed of a Pt(ii)-based delayed fluorescence emitter to be incorporated into an OLED.
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Affiliation(s)
- Piotr Pander
- Department of Physics, Durham University South Road Durham DH1 3LE UK
| | - Ruth Daniels
- Department of Applied Sciences, Northumbria University Ellison Building Newcastle upon Tyne NE1 8ST UK
| | - Andrey V Zaytsev
- Department of Applied Sciences, Northumbria University Ellison Building Newcastle upon Tyne NE1 8ST UK
| | - Ashleigh Horn
- Department of Applied Sciences, Northumbria University Ellison Building Newcastle upon Tyne NE1 8ST UK
| | - Amit Sil
- Department of Chemistry, Durham University South Road Durham DH1 3LE UK
| | - Thomas J Penfold
- Chemistry - School of Natural and Environmental Sciences, Newcastle University Newcastle upon Tyne NE1 7RU UK
| | | | - Valery N Kozhevnikov
- Department of Applied Sciences, Northumbria University Ellison Building Newcastle upon Tyne NE1 8ST UK
| | - Fernando B Dias
- Department of Physics, Durham University South Road Durham DH1 3LE UK
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38
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Serdiuk IE, Mońka M, Kozakiewicz K, Liberek B, Bojarski P, Park SY. Vibrationally Assisted Direct Intersystem Crossing between the Same Charge-Transfer States for Thermally Activated Delayed Fluorescence: Analysis by Marcus-Hush Theory Including Reorganization Energy. J Phys Chem B 2021; 125:2696-2706. [PMID: 33661000 PMCID: PMC8028332 DOI: 10.1021/acs.jpcb.0c10605] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
![]()
Thermally activated
delayed fluorescence (TADF) has recently become
an extensively investigated phenomenon due to its high potential for
application in organic optoelectronics. Currently, there is still
lack of a model describing correctly basic photophysical parameters
of organic TADF emitters. This article presents such a photophysical
model describing the rates of intersystem crossing (ISC), reverse
ISC (rISC), and radiative deactivation in various media and emphasizing
key importance of molecular vibrations on the example of a popular
TADF dye 9,10-dihydro-9,9-dimethyl-10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-acridine
(DMAC-TRZ). The presented experimental and theoretical investigations
prove that ISC and rISC can occur efficiently between the singlet
and triplet states of the same charge-transfer nature (1CT and 3CT, respectively). In emitters with the orthogonal
donor and acceptor fragments, such spin-forbidden 1CT ↔ 3CT transitions are activated by molecular vibrations. Namely,
the change of dihedral angle between the donor and the acceptor affords
reasonable spin–orbit coupling, which together with a small
energy gap and reorganization energy enable 1CT ↔ 3CT transition rates reaching 1 × 107 s–1. Evidence of direct 1CT ↔ 3CT spin-flip and negligible role of a second triplet state,
widely believed as a key parameter in the design of (r)ISC materials,
change significantly the current understanding of TADF mechanism.
In authors’ opinion, photophysics, and molecular design principles
of TADF emitters should be revised considering the importance of vibrationally
enhanced 1CT ↔ 3CT transitions.
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Affiliation(s)
- Illia E Serdiuk
- Faculty of Mathematics, Physics and Informatics, University of Gdańsk, Wita Stwosza 57, 80-308 Gdańsk, Poland
| | - Michał Mońka
- Faculty of Mathematics, Physics and Informatics, University of Gdańsk, Wita Stwosza 57, 80-308 Gdańsk, Poland
| | - Karol Kozakiewicz
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Beata Liberek
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Piotr Bojarski
- Faculty of Mathematics, Physics and Informatics, University of Gdańsk, Wita Stwosza 57, 80-308 Gdańsk, Poland
| | - Soo Young Park
- Center for Supramolecular Optoelectronic Materials, Department of Materials Science and Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, 151-744 Seoul, Republic of Korea
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39
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Shimizu M, Sakurai T. Metal-Free Organic Luminophores that Exhibit Dual Fluorescence and Phosphorescence Emission at Room Temperature. Chempluschem 2021; 86:446-459. [PMID: 33689234 DOI: 10.1002/cplu.202000783] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 03/02/2021] [Indexed: 01/24/2023]
Abstract
Dual-fluorescent-phosphorescent compounds have attracted increasing attention in various fields, such as bio-imaging, data protection/encryption, ratiometric luminescence sensing, and white-light emission. Conventional dual-emissive compounds contain a phosphorescent organometallic complex of a precious metal, such as iridium or platinum. However, the use of precious metals in organic materials has several drawbacks. This Minireview focuses on precious-metal-free organic light-emitting materials that exhibit dual fluorescence and phosphorescence emission in the solid state at room temperature to produce bimodal steady-state emission spectra. The dual emitters presented herein are categorized into the following six compound classes: (1) difluoroboron diaroylmethanes, (2) diarylketones, (3) diarylsulfones, (4) triazines and pyrimidines, (5) fused phenazines, and (6) N-arylcarbazoles.
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Affiliation(s)
- Masaki Shimizu
- Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology, 1 Hashikami-cho, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Tsuneaki Sakurai
- Faculty of Molecular Chemistry and Engineering, Kyoto Institute of Technology, 1 Hashikami-cho, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
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40
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Wang T, Hu Z, Nie X, Huang L, Hui M, Sun X, Zhang G. Thermochromic aggregation-induced dual phosphorescence via temperature-dependent sp 3-linked donor-acceptor electronic coupling. Nat Commun 2021; 12:1364. [PMID: 33649318 PMCID: PMC7921125 DOI: 10.1038/s41467-021-21676-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 02/08/2021] [Indexed: 12/21/2022] Open
Abstract
Aggregation-induced emission (AIE) has proven to be a viable strategy to achieve highly efficient room temperature phosphorescence (RTP) in bulk by restricting molecular motions. Here, we show that by utilizing triphenylamine (TPA) as an electronic donor that connects to an acceptor via an sp3 linker, six TPA-based AIE-active RTP luminophores were obtained. Distinct dual phosphorescence bands emitting from largely localized donor and acceptor triplet emitting states could be recorded at lowered temperatures; at room temperature, only a merged RTP band is present. Theoretical investigations reveal that the two temperature-dependent phosphorescence bands both originate from local/global minima from the lowest triplet excited state (T1). The reported molecular construct serves as an intermediary case between a fully conjugated donor-acceptor system and a donor/acceptor binary mix, which may provide important clues on the design and control of high-freedom molecular systems with complex excited-state dynamics.
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Affiliation(s)
- Tao Wang
- Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, China
| | - Zhubin Hu
- Division of Arts and Science, NYU-ECNU Center for Computational Chemistry, NYU Shanghai, Shanghai, China
| | - Xiancheng Nie
- Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, China
| | - Linkun Huang
- Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, China
| | - Miao Hui
- Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, China
| | - Xiang Sun
- Division of Arts and Science, NYU-ECNU Center for Computational Chemistry, NYU Shanghai, Shanghai, China. .,Department of Chemistry, New York University, New York, NY, USA.
| | - Guoqing Zhang
- Hefei National Laboratory for Physical Science at the Microscale, University of Science and Technology of China, Hefei, China.
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41
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Franca LG, Long Y, Li C, Danos A, Monkman A. The Critical Role of nπ* States in the Photophysics and Thermally Activated Delayed Fluorescence of Spiro Acridine-Anthracenone. J Phys Chem Lett 2021; 12:1490-1500. [PMID: 33533617 PMCID: PMC7886023 DOI: 10.1021/acs.jpclett.0c03314] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/28/2021] [Indexed: 05/29/2023]
Abstract
The molecular photophysics and thermally activated delayed fluorescence (TADF) in spiro compounds are distinct because of the rigid orthogonal C-C bridging bond between donor and acceptor. The photophysics is found to be highly complex, with unprecedented multiple anti-Kasha emissions from three different singlet states, two of which are one-photon forbidden. The TADF mechanism is critically controlled by local acceptor nπ* states; the singlet nπ* state undergoes rapid intersystem crossing populating an energetically close acceptor ππ* triplet state. The acceptor triplet nπ* state couples nonadiabatically to a CT triplet state mediating reverse intersystem crossing. When the nπ* and CT states are energetically close, TADF is greatly enhanced with rISC rate reaching 107 s-1. We observe neither DF from the singlet nπ* state nor electron transfer (ET) to form the 1CT because there is no ET driving force; however, ET from the higher-energy donor singlet ππ* state readily occurs along with donor emission.
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42
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Li W, Li M, Li W, Xu Z, Gan L, Liu K, Zheng N, Ning C, Chen D, Wu YC, Su SJ. Spiral Donor Design Strategy for Blue Thermally Activated Delayed Fluorescence Emitters. ACS APPLIED MATERIALS & INTERFACES 2021; 13:5302-5311. [PMID: 33470809 DOI: 10.1021/acsami.0c19302] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Thermally activated delayed fluorescence (TADF) emitters with a spiral donor show tremendous potential toward high-level efficient blue organic light-emitting diodes (OLEDs). However, the underlying design strategy of the spiral donor used for blue TADF emitters remains unclear. As a consequence, researchers often do "try and error" work in the development of new functional spiral donor fragments, making it slow and inefficient. Herein, we demonstrate that the energy level relationships between the spiral donor and the luminophore lead to a significant effect on the photoluminescent quantum yields (PLQYs) of the target materials. In addition, a method involving quantum chemistry simulations that can accurately predict the aforementioned energy level relationships by simulating the spin density distributions of the triplet excited states of the spiral donor and corresponding TADF emitters and the triplet excited natural transition orbitals of the TADF emitters is established. Moreover, it also revealed that the steric hindrance in this series of molecules can form a nearly unchanged singlet (S1) state geometry, leading to a reduced nonradiative decay and high PLQY, while a moderated donor-acceptor (D-A) torsion in the triplet (T1) state can induce a strong vibronic coupling between the charge-transfer triplet (3CT) state and the local triplet (3LE) state, achieving an effective reverse intersystem crossing (RISC) process. Furthermore, an electric-magnetic coupling is formed between the high-lying 3LE state and the charge-transfer singlet (1CT) state, which may open another RISC channel. Remarkably, in company with the optimized molecular structure and energy alignment, the pivotal TADF emitter DspiroS-TRZ achieved 99.9% PLQY, an external quantum efficiency (EQE) of 38.4%, which is the highest among all blue TADF emitters reported to date.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Guangzhou 510640, Guangdong Province, P. R. China
| | - Mengke Li
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Guangzhou 510640, Guangdong Province, P. R. China
| | - Wenqi Li
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Guangzhou 510640, Guangdong Province, P. R. China
| | - Zhida Xu
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Guangzhou 510640, Guangdong Province, P. R. China
| | - Lin Gan
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Guangzhou 510640, Guangdong Province, P. R. China
| | - Kunkun Liu
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Guangzhou 510640, Guangdong Province, P. R. China
| | - Nan Zheng
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Guangzhou 510640, Guangdong Province, P. R. China
| | - Chengyun Ning
- Key Laboratory of Biomedical Engineering of Guangdong Province, South China University of Technology, Wushan Road 381, Guangzhou 510640, Guangdong Province, P. R. China
| | - Dongcheng Chen
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Guangzhou 510640, Guangdong Province, P. R. China
| | - Yuan-Chun Wu
- Shenzhen China Star Optoelectronics Semiconductor Display Technology Co., Ltd., No.9-2, Tang Ming Avenue, Guang Ming District, Shenzhen 518132, Guangdong Province, P. R. China
| | - Shi-Jian Su
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Wushan Road 381, Guangzhou 510640, Guangdong Province, P. R. China
- South China Institute of Collaborative Innovation, Dongguan 523808, Guangdong Province, P. R. China
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43
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Higginbotham HF, Okazaki M, de Silva P, Minakata S, Takeda Y, Data P. Heavy-Atom-Free Room-Temperature Phosphorescent Organic Light-Emitting Diodes Enabled by Excited States Engineering. ACS APPLIED MATERIALS & INTERFACES 2021; 13:2899-2907. [PMID: 33404215 DOI: 10.1021/acsami.0c17295] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Room temperature phosphorescence materials offer great opportunities for applications in optoelectronics, due to their unique photophysical characteristics. However, heavy-atom-free organic emitters that can realize distinct electrophosphorescence are rarely exploited. Herein a new approach for designing heavy-atom-free organic room temperature phosphorescence emitters for organic light-emitting diodes is presented. The subtle tuning of the singlet and triplet excited states energies by appropriate choice of host matrix allows tailored emission properties and switching of emission channels between thermally activated delayed fluorescence and room temperature phosphorescence. Moreover, an efficient and heavy-atom-free room temperature phosphorescence organic light-emitting diode using the developed emitter is realized.
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Affiliation(s)
- Heather F Higginbotham
- School of Science, Swinburne University of Technology, Hawthorne, Victoria 3122, Australia
| | - Masato Okazaki
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan
| | - Piotr de Silva
- Department of Energy Conversion and Storage, Technical University of Denmark, Anker Engelunds Vej 301, 2800 Kongens Lyngby, Denmark
| | - Satoshi Minakata
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan
| | - Youhei Takeda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan
| | - Przemyslaw Data
- Faculty of Chemistry, Silesian University of Technology, M. Strzody 9, 44-100 Gliwice, Poland
- Physics Department, Durham University, South Road, Durham DH1 3LE, United Kingdom
- Centre of Polymer and Carbon Materials, Polish Academy of Sciences, M. Curie-Sklodowskiej 34, 41-819 Zabrze, Poland
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44
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Sych G, Pashazadeh R, Danyliv Y, Bezvikonnyi O, Volyniuk D, Lazauskas A, Grazulevicius JV. Reversibly Switchable Phase-Dependent Emission of Quinoline and Phenothiazine Derivatives towards Applications in Optical Sensing and Information Multicoding. Chemistry 2021; 27:2826-2836. [PMID: 33140873 DOI: 10.1002/chem.202004657] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Indexed: 02/02/2023]
Abstract
Three new quinoline and di-tert-butyl phenothiazine isomeric derivatives were synthesized and characterized towards applications for oxygen sensing and optical information multicoding. The compounds with phenylene linker showed outstanding phase-dependent reversibility between ON/OFF states (low and high emission intensity, drastic shifting of emission colors, short- and long-lived fluorescence) in systematic grinding/fuming cycles, as required for multichannel memory devices based on optical information multicoding. The conformational diversity of the phenothiazine unit resulted in dual emission of the doped films implemented by the different luminescence mechanisms with peaks located at 414/530, 416/540, and 440/582 nm. The presence of a phenylene linker and thus two rotational degrees of freedom resulted in quenching of the delayed fluorescence of quasi-equatorial conformers in the solid state. The compound containing no phenylene bridge was characterized by two different driving photoluminescence mechanisms of the doped films: short fluorescence of the quasi-axial conformer and thermally activated delayed fluorescence of the quasi-equatorial form. This compound showed oxygen sensitivity with a Stern-Volmer constant of 7.5×10-4 ppm-1 .
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Affiliation(s)
- Galyna Sych
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, 50254, Kaunas, Lithuania
| | - Ramin Pashazadeh
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, 50254, Kaunas, Lithuania
| | - Yan Danyliv
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, 50254, Kaunas, Lithuania
| | - Oleksandr Bezvikonnyi
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, 50254, Kaunas, Lithuania
| | - Dmytro Volyniuk
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, 50254, Kaunas, Lithuania
| | - Algirdas Lazauskas
- Institute of Materials Science, Kaunas University of Technology, K. Baršausko St. 59, 51423, Kaunas, Lithuania
| | - Juozas V Grazulevicius
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilenu pl. 19, 50254, Kaunas, Lithuania
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45
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Hempe M, Harrison AK, Ward JS, Batsanov AS, Fox MA, Dias FB, Bryce MR. Cyclophane Molecules Exhibiting Thermally Activated Delayed Fluorescence: Linking Donor Units to Influence Molecular Conformation. J Org Chem 2021; 86:429-445. [PMID: 33251794 DOI: 10.1021/acs.joc.0c02174] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The synthetic methodology to covalently link donors to form cyclophane-based thermally activated delayed fluorescence (TADF) molecules is presented. These are the first reported examples of TADF cyclophanes with "electronically innocent" bridges between the donor units. Using a phenothiazine-dibenzothiophene-S,S-dioxide donor-acceptor-donor (D-A-D) system, the two phenothiazine (PTZ) donor units were linked by three different strategies: (i) ester condensation, (ii) ether synthesis, and (iii) ring closing metathesis. Detailed X-ray crystallographic, photophysical and computational analyses show that the cyclophane molecular architecture alters the conformational distribution of the PTZ units, while retaining a certain degree of rotational freedom of the intersegmental D-A axes that is crucial for efficient TADF. Despite their different structures, the cyclophanes and their nonbridged precursors have similar photophysical properties since they emit through similar excited states resulting from the presence of the equatorial conformation of their PTZ donor segments. In particular, the axial-axial conformations, known to be detrimental to the TADF process, are suppressed by linking the PTZ units to form a cyclophane. The work establishes a versatile linking strategy that could be used in further functionalization while retaining the excellent photophysical properties of the parent D-A-D system.
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Affiliation(s)
- Matthias Hempe
- Chemistry Department, Durham University, South Road, Durham DH1 3LE, U.K
| | | | - Jonathan S Ward
- Chemistry Department, Durham University, South Road, Durham DH1 3LE, U.K
| | - Andrei S Batsanov
- Chemistry Department, Durham University, South Road, Durham DH1 3LE, U.K
| | - Mark A Fox
- Chemistry Department, Durham University, South Road, Durham DH1 3LE, U.K
| | - Fernando B Dias
- Physics Department, Durham University, South Road, Durham DH1 3LE, U.K
| | - Martin R Bryce
- Chemistry Department, Durham University, South Road, Durham DH1 3LE, U.K
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46
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Rani P, Husain A, Shukla A, Singla N, Srivastava AK, Kumar G, Bhasin KK, Kumar G. Functionalized naphthalenediimide based supramolecular charge-transfer complexes via self-assembly and their photophysical properties. CrystEngComm 2021. [DOI: 10.1039/d0ce01719a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Two new intermolecular CT complexes having large Stokes shift (>170 nm) and significant fluorescence life-time (∼1.55 ns) have been prepared and exploited for cell imaging application.
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Affiliation(s)
- Pooja Rani
- Department of Chemistry & Centre for Advanced Studies in Chemistry
- Panjab University
- Chandigarh-160014
- India
| | - Ahmad Husain
- Department of Chemistry
- DAV University Jalandhar
- India
| | - Ananya Shukla
- Department of Biophysics
- Panjab University
- Chandigarh-160014
- India
| | - Neha Singla
- Department of Biophysics
- Panjab University
- Chandigarh-160014
- India
| | | | - Gulshan Kumar
- Department of Chemistry & Centre for Advanced Studies in Chemistry
- Panjab University
- Chandigarh-160014
- India
| | - K. K. Bhasin
- Department of Chemistry & Centre for Advanced Studies in Chemistry
- Panjab University
- Chandigarh-160014
- India
| | - Girijesh Kumar
- Department of Chemistry & Centre for Advanced Studies in Chemistry
- Panjab University
- Chandigarh-160014
- India
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47
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Kukhta NA, Bryce MR. Dual emission in purely organic materials for optoelectronic applications. MATERIALS HORIZONS 2021; 8:33-55. [PMID: 34821289 DOI: 10.1039/d0mh01316a] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Purely organic molecules, which emit light by dual emissive (DE) pathways, have received increased attention in the last decade. These materials are now being utilized in practical optoelectronic, sensing and biomedical applications. In order to further extend the application of the DE emitters, it is crucial to gain a fundamental understanding of the links between the molecular structure and the underlying photophysical processes. This review categorizes the types of DE according to the spin multiplicity and time range of the emission, with emphasis on recent experimental advances. The design rules towards novel DE molecular candidates, the most perspective types of DE and possible future applications are outlined. These exciting developments highlight the opportunities for new materials synthesis and pave the way for accelerated future innovation and developments in this area.
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Affiliation(s)
- Nadzeya A Kukhta
- Department of Chemistry, Durham University, Lower Mountjoy, Stockton Road, Durham, DH1 3LE, UK.
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48
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Yang SY, Tian QS, Yu YJ, Zou SN, Li HC, Khan A, Wu QH, Jiang ZQ, Liao LS. Sky-Blue Thermally Activated Delayed Fluorescence with Intramolecular Spatial Charge Transfer Based on a Dibenzothiophene Sulfone Emitter. J Org Chem 2020; 85:10628-10637. [PMID: 32806105 DOI: 10.1021/acs.joc.0c01200] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intramolecular spatial charge transfer (ISCT) plays a critical role in determining the optical and charge transport properties of thermally activated delayed fluorescence (TADF) materials. Herein, a new donor/acceptor-type TADF compound based on rigid dibenzothiophene sulfone (DBTS) moiety, STF-DBTS, was designed and synthesized. Fluorene unit was used as a rigid linker to position the rigid acceptor and donor subunit in close vicinity with control over their spacing and molecular structure and to achieve high photoluminescence quantum yield (∼53%) and TADF property. For comparison purposes, we constructed the more flexible STF-DPS with a less rotationally constrained diphenylsulphone (DPS) acceptor instead of the rigid DBTS units, and STF-DPS showed no TADF properties and lower PLQY (16.0%). Organic light-emitting diodes (OLEDs) based on STF-DBTS achieve an external quantum efficiency (EQE) of 10.3% at 488 nm, which is a fivefold improvement in EQE with respect to STF-DPS.
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Affiliation(s)
- Sheng-Yi Yang
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China
| | - Qi-Sheng Tian
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China
| | - You-Jun Yu
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China
| | - Sheng-Nan Zou
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China
| | - Hong-Cheng Li
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China
| | - Aziz Khan
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China
| | - Qian-Han Wu
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China
| | - Zuo-Quan Jiang
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China
| | - Liang-Sheng Liao
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou, Jiangsu 215123, China.,Institute of Organic Optoelectronics, Jiangsu Industrial Technology Research Institute (JITRI), Wujiang, Suzhou, Jiangsu 215211, China
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49
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Jena S, Dhanalakshmi P, Bano G, Thilagar P. Delayed Fluorescence, Room Temperature Phosphorescence, and Mechanofluorochromic Naphthalimides: Differential Imaging of Normoxia and Hypoxia Live Cancer Cells. J Phys Chem B 2020; 124:5393-5406. [PMID: 32501697 DOI: 10.1021/acs.jpcb.0c04115] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We study the effect of molecular conformation on the electronic coupling between the donor amines and acceptor 1,8-naphthalimide (NPI) in a series of D-A systems 1-4 (A = NPI; D = phenothiazine, phenoxazine, carbazole, diphenylamine, respectively, for 1, 2, 3, and 4). Weakly coupled systems show dual emission in the solution state, while strongly coupled systems show single emission bands. The energy of transitions and photoluminescence (PL) quantum yield are sensitive to the molecular conformation and donor strength. These compounds show delayed emission in the solutions and aggregated state and phosphorescence in the solid state. Compounds 3 and 4 with weak donors exhibit intermolecular slipped π···π interactions in the solid state and consequently exhibit dual (intra- and inter-) phosphorescence at low temperature. Steady state and time-resolved PL studies at variable temperature together with computational and crystal structure analysis were used to rationalize the optical properties of these compounds. The delayed emission of these compounds is sensitive to molecular oxygen; accordingly, these molecules are utilized for differential imaging of normoxia and hypoxia cancer cells.
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Affiliation(s)
- Satyam Jena
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, India 560012
| | - Pandi Dhanalakshmi
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, India 560012
| | - Gulista Bano
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, India 560012
| | - Pakkirisamy Thilagar
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, India 560012
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50
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Chen M, Lee Y, Huang Z, Chen D, Chou P. Tuning Electron‐Withdrawing Strength on Phenothiazine Derivatives: Achieving 100 % Photoluminescence Quantum Yield by NO
2
Substitution. Chemistry 2020; 26:7124-7130. [DOI: 10.1002/chem.202000754] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Indexed: 12/12/2022]
Affiliation(s)
- Meng‐Chi Chen
- Department of Chemistry National (Taiwan) University No. 1, Section 4, Roosevelt Road Taipei 10617 Taiwan
| | - Yao‐Lin Lee
- Department of Chemistry National (Taiwan) University No. 1, Section 4, Roosevelt Road Taipei 10617 Taiwan
| | - Zhi‐Xuan Huang
- Department of Chemistry National (Taiwan) University No. 1, Section 4, Roosevelt Road Taipei 10617 Taiwan
| | - Deng‐Gao Chen
- Department of Chemistry National (Taiwan) University No. 1, Section 4, Roosevelt Road Taipei 10617 Taiwan
| | - Pi‐Tai Chou
- Department of Chemistry National (Taiwan) University No. 1, Section 4, Roosevelt Road Taipei 10617 Taiwan
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