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Mohammadian-Sabet F, Shayesteh A. Multireference Ab Initio Calculations on Excited Electronic States of Carbazole-Based Organic Compounds for Thermally Activated Delayed Fluorescence. J Phys Chem A 2024; 128:4937-4949. [PMID: 38864150 DOI: 10.1021/acs.jpca.4c00427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
The emerging technology of organic light-emitting diodes takes advantage of the thermally activated delayed fluorescence (TADF) mechanism for improved efficiency. Carbazole-based organic molecules are suitable for TADF emission because of charge transfer excitations between the electron-donor carbazole and an electron-acceptor unit. Computational design of new TADF molecules with the desired properties is challenging because charge-transfer excitations cannot be predicted accurately by time-dependent density functional theory. Four groups of carbazole-based donor-acceptor molecules have been studied using multireference ab initio methods to understand the nature of excited electronic states. The state-averaged complete active space self-consistent field (SA-CASSCF) and the N-electron valence state perturbation theory (NEVPT2) were used to calculate energies and oscillator strengths for multiple excited electronic states. The number of active electrons and orbitals and the number of excited states included in state-averaged CASSCF were selected such that the accuracy of ab initio predictions could be improved systematically. The procedure introduced here for the calculation of multiple excited electronic states of TADF candidates can be used to accelerate the computational search for efficient TADF materials.
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Affiliation(s)
| | - Alireza Shayesteh
- School of Chemistry, College of Science, University of Tehran, Tehran 14176, Iran
- Department of Chemistry, State University of New York at Oswego, Oswego, New York 13126, United States
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2
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Kim J, Kang S, Kim T. Multifunctional Deep-Blue Thermally Activated Delayed Fluorescence Based on an Oxygen-Bridged Boron Acceptor for Highly Efficient Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2024. [PMID: 38663091 DOI: 10.1021/acsami.3c19467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
Until now, thermally activated delayed fluorescence (TADF) materials based on bridged boron-based acceptors have been primarily developed as dopants. However, in this study, we synthesized and characterized multifunctional deep-blue TADF materials─t-OBO-DMAC and t-OBO-DPAC─using bridged boron-based acceptors in combination with dimethylacridine or diphenylacridine as donors. These materials serve as both dopants and hosts. Theoretical calculations and experimentally measured photophysical properties of t-OBO-DMAC reveal a smaller singlet-triplet energy difference, higher photoluminescence quantum yield, and more efficient reverse intersystem crossing compared to t-OBO-DPAC. When evaluated as TADF emitters, t-OBO-DMAC and t-OBO-DPAC exhibited maximum external quantum efficiency (EQE) of 14.4 and 7.3% with deep-blue color coordinates of (0.14, 0.11) and (0.15, 0.07), respectively. Both materials were further assessed as hosts in various configurations, including host-only, TADF, phosphorescent, and phosphor-sensitized fluorescence (PSF)-emitting systems. Notably, t-OBO-DMAC demonstrated a high maximum EQE of 13.9% with deep-blue color coordinates of (0.15, 0.07) in a nondoped host-only device. Remarkably, both materials achieved EQEs exceeding 20% in the PSF devices. Our study marks a critical advancement in the field that breaks the conventional boundaries of the dopant and host and demonstrates unprecedented multifunctionalities for advanced organic light-emitting diodes.
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Affiliation(s)
- Jaesung Kim
- Department of Information Display, Hongik University, Seoul 04066, Republic of Korea
| | - Sunwoo Kang
- Department of Chemistry, Dankook University, Cheonan, Chungnam 31116, Republic of Korea
| | - Taekyung Kim
- Department of Information Display, Hongik University, Seoul 04066, Republic of Korea
- Department of Materials Science and Engineering, Hongik University, Sejong 30016, Republic of Korea
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3
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Zhang B, Liu S, Pei J, Luo M, Chen Y, Jia Q, Wu Z, Wang D. Efficient red thermally activated delayed fluorescence emitters achieved through precise control of excited state energy levels. Chem Sci 2024; 15:5746-5756. [PMID: 38638236 PMCID: PMC11023617 DOI: 10.1039/d4sc00535j] [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: 01/23/2024] [Accepted: 03/08/2024] [Indexed: 04/20/2024] Open
Abstract
The variety of highly efficient red/near-infrared (NIR) materials with thermally activated delayed fluorescence (TADF) feature is extremely limited so far, and it is necessary to expand the candidate pool of excellent red/deep-red emitters. However, how to control the energy level alignment of the 1CT (singlet charge transfer) state and the 3LE (triplet local excitation) state to improve the emission efficiency of materials remains a challenge. Herein, based on our previously reported green fluorescent material 67dTPA-FQ, three new donor-acceptor type TADF materials (TQ-oMeOTPA, TsQ-oMeOTPA and SQ-oMeOTPA) were designed by introducing 4,4'-dimethoxy triphenylamine (MeOTPA) as the donor, and introduced S atoms on the acceptors to enhance the spin-orbit coupling (SOC) and CT effects. The theoretical calculations showed that the newly introduced MeOTPA and S atom successfully enhanced the CT effect of the materials, not only shifting the luminescence peak to the deep red region but also effectively adjusting the energy level alignment of the excited state, accelerating the reverse intersystem crossing process. Finally, the organic light-emitting diodes based on SQ-oMeOTPA exhibit an external quantum efficiency of 19.1%, with an emission peak at 619 nm. This work not only expands the candidate inventory of red TADF materials, but also proves the feasibility of designing emitters by adjusting the excited state energy levels, greatly broadening the diversity of TADF emitters in design, and providing a powerful means for rapidly screening efficient emitters in the future.
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Affiliation(s)
- BoHua Zhang
- School of Chemistry, Xi'an Jiaotong University Xi'an 710049 P. R. China
| | - SiQi Liu
- School of Chemistry, Xi'an Jiaotong University Xi'an 710049 P. R. China
| | - JiangXue Pei
- School of Chemistry, Xi'an Jiaotong University Xi'an 710049 P. R. China
| | - MeiTing Luo
- School of Chemistry, Xi'an Jiaotong University Xi'an 710049 P. R. China
| | - Yi Chen
- School of Chemistry, Xi'an Jiaotong University Xi'an 710049 P. R. China
| | - QingYu Jia
- School of Chemistry, Xi'an Jiaotong University Xi'an 710049 P. R. China
| | - ZhaoXin Wu
- Key Laboratory for Physical Electronics and Devices of the Ministry of Education, Shaanxi Key Lab of Information Photonic Technique, School of Electronic and Information Engineering, Xi'an Jiaotong University Xi'an 710049 P. R. China
| | - DongDong Wang
- School of Chemistry, Xi'an Jiaotong University Xi'an 710049 P. R. China
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Guo Y, Guan H, Li P, Wang C, Wang Y, Zhang J, Zhao G. Non-adiabatic conformation distortion charge transfer enables dual emission of thermally activated delayed fluorescence and room temperature phosphorescence. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 311:124032. [PMID: 38364513 DOI: 10.1016/j.saa.2024.124032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 02/03/2024] [Accepted: 02/09/2024] [Indexed: 02/18/2024]
Abstract
In this work, we report for the first time that thiophenol-substituted naphthalimide can achieve thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) simultaneously through non-conjugated flexible connection. Herein, we explain that the enhancement of intersystem crossing (ISC) between the singlet excited state and triplet excited states in NISPh is mainly caused by the non-adiabatic conformation distortion charge transfer (CDCT) of the excited states. More precisely, CDCT results in the conformation matching and energy barrier decrease between the excited states. In addition, the electronic and vibration coupling is further enhanced in NISPh. Our work substantiates a rational design strategy for the development of simple purely organic materials to achieve dual emission of TADF and RTP.
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Affiliation(s)
- Yurong Guo
- School of Chemical and Biological Engineering, Qilu Institute of Technology, Jinan 250200, China
| | - Hongwei Guan
- Institute of Molecular Sciences and Engineering, Shandong University, Qingdao 266237, China
| | - Peng Li
- Institute of Molecular Sciences and Engineering, Shandong University, Qingdao 266237, China
| | - Chao Wang
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300354, China; National Engineering Research Center of Biomaterials, Nanjing Forestry University, Nanjing 210037, China
| | - Yanan Wang
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300354, China
| | - Jingran Zhang
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300354, China
| | - Guangjiu Zhao
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science, Tianjin University, Tianjin 300354, China.
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Qu C, Xu Y, Wang Y, Nie Y, Ye K, Zhang H, Zhang Z. Bridging of Cove Regions: A Strategy for Realizing Persistently Chiral Double Heterohelicenes with Attractive Luminescent Properties. Angew Chem Int Ed Engl 2024; 63:e202400661. [PMID: 38333930 DOI: 10.1002/anie.202400661] [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: 01/10/2024] [Revised: 02/06/2024] [Accepted: 02/08/2024] [Indexed: 02/10/2024]
Abstract
The racemization of chiral organic compounds is a common chemical phenomenon. However, it often poses configurational-stability issues to the application of this class of compounds. Achieving chiral organic compounds without the risk of racemization is fascinating, but it is challenging due to a lack of strategies. Here, we reveal the cove-regions bridging strategy for achieving persistently chiral multi-helicenes (incapable of racemization), based on the synthesized proof-of-concept double hetero[4]helicenes featuring macrocycle structures with a small 3D cavity. Additionally, we demonstrate that the strategy is also effective in tuning the electronic structures of multi-helicenes, resulting in a conversion from luminescence silence into thermally activated delayed fluorescence (TADF) for the present system. Furthermore, red circularly polarized TADF based on small double [4]helicene systems is achieved for the first time using this strategy. The disclosed cove-regions bridging strategy provides an opportunity to modulate the electronic structures and luminescent properties of multi-helicenes without concern for racemization, thus significantly enhancing the structural and property diversity of multi-helicenes for various applications.
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Affiliation(s)
- Cheng Qu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Yincai Xu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Yu Wang
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai, 200062, P. R. China
| | - Yufang Nie
- South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Kaiqi Ye
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Hongyu Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Zuolun Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
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Zhao X, Liu H, Mu Q, Fan J, Xu Y, Cai L. Modulating excited state properties of thermally activated delayed fluorescence molecules by hybrid long-range and short-range charge transfer strategy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 308:123684. [PMID: 38039645 DOI: 10.1016/j.saa.2023.123684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 11/08/2023] [Accepted: 11/21/2023] [Indexed: 12/03/2023]
Abstract
Balancing the rapid radiative decay process and the fast reverse intersystem crossing (RISC) process of thermally activated delayed fluorescence (TADF) molecule remains a great challenge and efficient molecular design strategies are highly desired. Herein, from a theoretical perspective, excited state properties of three reported TADF molecules (1TICz, 1BOICz and 2BOICz) are investigated based on density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations coupled with the thermal vibration correlation function (TVCF) method. Results indicate that, by introducing the multi-resonance (MR) acceptor, 1BOICz possesses hybrid long-range and short-range charge transfer features, balanced small energy gap (ΔEST) and large oscillator strength (f) is obtained. Furthermore, by incorporating double equivalent MR acceptors in 2BOICz, largely enhanced f with slightly changed ΔEST is achieved, inner mechanism for remarkable photophysical property is illustrated. Keep this strategy, seven new TADF molecules (2pDBA-bICz-1, 2pDBA-bICz-2, 2OSBA-bICz, 2DQAO-bICz, 2QAO-bICz, 2SQAO-bICz and 2OQAO-bICz) are theoretically designed, detailed physical parameters are analyzed and excited state energy consumption process is studied. Strong electrophilicity on acceptor is determined and the strength of nucleophilic sites on the bridge-phenyl of 2DQAO-bICz, 2QAO-bICz, 2SQAO-bICz and 2OQAO-bICz is increased, this promotes the short-range charge transfer property. In addition, the excitation processes for all studied molecules are dominated by long-range charge transfer from donor to acceptors, and supplemented by the short-range charge transfer on the bridge-phenyl with MR effect. Compromise energy gap and oscillator strength as well as large spin orbit coupling (SOC) constant are obtained for designed molecules. Thus, by regulating the long-range and short-range charge transfer ratios, excited state properties are successfully modulated and new efficient TADF molecules are proposed. Our research aims to provide deeper insight into long-range and short-range charge transfer features in balancing small ΔEST and large f, which could facilitate the development of novel efficient TADF molecules.
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Affiliation(s)
- Xin Zhao
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Materials and Clean Energy, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China
| | - Huanling Liu
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Materials and Clean Energy, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China
| | - Qingfang Mu
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Materials and Clean Energy, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China
| | - Jianzhong Fan
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Materials and Clean Energy, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
| | - Yuanyuan Xu
- School of Science, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
| | - Lei Cai
- Shandong Province Key Laboratory of Medical Physics and Image Processing Technology, Institute of Materials and Clean Energy, School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
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7
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Wang L, Ge Z, Xu L, Song Y. An effective method in modulating thermally activated delayed fluorescence (TADF) emitters from green to blue emission: the role of the phenyl ring. Phys Chem Chem Phys 2024; 26:5597-5606. [PMID: 38285054 DOI: 10.1039/d3cp05632e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
Developing efficient blue emitters with high performance and low cost is crucial for the further development of organic light-emitting diodes (OLEDs). Based on the two experimentally reported green thermally activated delayed fluorescence (TADF) emitters, which are thioxanthone derivatives consisting of carbazole as an electron donor and 9H-thioxanthen-9-one-S,S-dioxide (SOXO) as an electron acceptor with donor-acceptor (D-A) or donor-acceptor-donor (D-A-D) structures, two new blue TADF emitters are designed by simply inserting a phenyl ring between D and A units. The TADF processes of the four thioxanthone derivatives are studied systematically through first-principles calculations. The role of the introduced phenyl ring in the excited state properties of the designed molecules is explored by analyzing the changes in molecular geometries, frontier molecular orbital distributions, the lowest singlet-triplet energy splitting (ΔEST), the spin orbit coupling (SOC) constants, the radiative decay rates (kr) and the nonradiative decay rates (knr), as well as the intersystem crossing rates (kISC) and reverse intersystem crossing rates (kRISC). The results show that when incorporating phenyl units into the D-A and D-A-D structures, both high kr and enhanced kRISC are achieved in Cz-Ph-SOXO and DCz-DPh-SOXO, demonstrating that incorporating the phenyl unit in D-A and D-A-D structures is an efficient way for developing new SOXO-based TADF molecules. It is worth noting that the kRISC values for Cz-Ph-SOXO and DCz-DPh-SOXO are significantly increased with respect to those of the experimental molecules. The present results would provide helpful guidelines for developing new SOXO-based TADF molecules experimentally.
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Affiliation(s)
- Lijuan Wang
- School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, 2 West Wenhua Road, Weihai, 264209, China.
| | - Zhongqi Ge
- School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, 2 West Wenhua Road, Weihai, 264209, China.
| | - Lin Xu
- School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, 2 West Wenhua Road, Weihai, 264209, China.
| | - Yan Song
- School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, 2 West Wenhua Road, Weihai, 264209, China.
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Li H, Ren H, Wang J, Liu D, Li J. Cyano Decoration of π-Bridge to Boost Photoluminescence and Electroluminescence Quantum Yields of Triazine/Carbazole Based Blue TADF Emitter. Chemistry 2024; 30:e202303169. [PMID: 37965803 DOI: 10.1002/chem.202303169] [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: 09/28/2023] [Revised: 11/10/2023] [Accepted: 11/13/2023] [Indexed: 11/16/2023]
Abstract
In general, a large donor-acceptor dihedral angle is required to guarantee sufficient frontier molecular orbitals separation for thermally activated delayed fluorescence (TADF) emitters, which is intrinsically unfavorable for the radiative transition. We present a molecular design method favoring both reverse intersystem crossing (RISC) and radiative transitions even at a moderate D-A angle. A blue TADF emitter TrzBuCz-CN was designed with triazine/tert-butylcarbazole as donor/acceptor and cyano (CN) incorporated on the phenylene bridge. In comparison with the methyl decoration in similar way (TrzBuCz-Me), CN decoration reduced the D-A dihedral angle from 70° to 60°, which is intrinsically not favorable for sufficient FMO separation, but unexpectedly reduced the singlet and triplet energy gap (ΔEST ) and thus facilitated TADF feature by pulling down the lowest singlet state energy. While the reduced distorsion instead improved the HOMO-LUMO overlap and boosted the fluorescence quantum yield from 41 % to 94 %. The blue organic light-emitting diode of TrzBuCz-CN exhibited an external quantum efficiency of 13.7 % with emission peak at 466 nm, greatly superior to 6.0 % of TrzBuCz-Me. The result provides a feasible design strategy to facilitate both RISC and radiation processes by CN decoration of the linking bridge of TADF emitters.
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Affiliation(s)
- Huiting Li
- Key Laboratory of Natural Product Chemistry and Functional Molecular Synthesis, College of Chemistry and Materials, Inner Mongolia Minzu University, West Huolinhe Street, Tongliao, 028000, China
- Frontiers Science Center for Smart Materials, School of Chemistry, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Huicai Ren
- Yantai Sunera Limited Liability Company, Yantai Economic and Technological Development Zone, No. 7 Shaoxing Road, Yantai, China
| | - Jiahui Wang
- Frontiers Science Center for Smart Materials, School of Chemistry, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Di Liu
- Frontiers Science Center for Smart Materials, School of Chemistry, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Jiuyan Li
- Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai, Yantai Economic and Technological Development Zone, 300 Changjiang Road, Yantai, China
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Asiri JA, Hasan WMI, Jedidi A, Elroby SA, Aziz SG, Osman OI. Organoboron Complexes as Thermally Activated Delayed Fluorescence (TADF) Materials for Organic Light-Emitting Diodes (OLEDs): A Computational Study. Molecules 2023; 28:6952. [PMID: 37836795 PMCID: PMC10574585 DOI: 10.3390/molecules28196952] [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: 08/18/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/15/2023] Open
Abstract
We report on organoboron complexes characterized by very small energy gaps (ΔEST) between their singlet and triplet states, which allow for highly efficient harvesting of triplet excitons into singlet states for working as thermally activated delayed fluorescence (TADF) devices. Energy gaps ranging between 0.01 and 0.06 eV with dihedral angles of ca. 90° were registered. The spin-orbit couplings between the lowest excited S1 and T1 states yielded reversed intersystem crossing rate constants (KRISC) of an average of 105 s-1. This setup accomplished radiative decay rates of ca. 106 s-1, indicating highly potent electroluminescent devices, and hence, being suitable for application as organic light-emitting diodes.
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Affiliation(s)
- Jamilah A. Asiri
- Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (J.A.A.); (W.M.I.H.); (A.J.); (S.G.A.)
- Department of Chemistry, College of Arts and Sciences, Prince Sattam bin Abdulaziz University, Wadi Ad-Dwasir 18510, Saudi Arabia
| | - Walid M. I. Hasan
- Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (J.A.A.); (W.M.I.H.); (A.J.); (S.G.A.)
| | - Abdesslem Jedidi
- Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (J.A.A.); (W.M.I.H.); (A.J.); (S.G.A.)
| | - Shaaban A. Elroby
- Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (J.A.A.); (W.M.I.H.); (A.J.); (S.G.A.)
- Chemistry Department, Faculty of Science, Beni-Suif University, Beni-Suif 62521, Egypt
| | - Saadullah G. Aziz
- Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (J.A.A.); (W.M.I.H.); (A.J.); (S.G.A.)
| | - Osman I. Osman
- Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia; (J.A.A.); (W.M.I.H.); (A.J.); (S.G.A.)
- Chemistry Department, Faculty of Science, University of Khartoum, Khartoum P.O. Box 321, Sudan
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Zhang T, Xiao Y, Wang H, Kong S, Huang R, Ka-Man Au V, Yu T, Huang W. Highly Twisted Thermally Activated Delayed Fluorescence (TADF) Molecules and Their Applications in Organic Light-Emitting Diodes (OLEDs). Angew Chem Int Ed Engl 2023; 62:e202301896. [PMID: 37288654 DOI: 10.1002/anie.202301896] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 06/07/2023] [Accepted: 06/07/2023] [Indexed: 06/09/2023]
Abstract
Thermally activated delayed fluorescence (TADF) materials have attracted great potential in the field of organic light-emitting diodes (OLEDs). Among thousands of TADF materials, highly twisted TADF emitters have become a hotspot in recent years. Compared with traditional TADF materials, highly twisted TADF emitters tend to show multi-channel charge-transfer characters and form rigid molecular structures. This is advantageous for TADF materials, as non-radiative decay processes can be suppressed to facilitate efficient exciton utilization. Accordingly, OLEDs with excellent device performances have also been reported. In this Review, we have summarized recent progress in highly twisted TADF materials and related devices, and give an overview of the molecular design strategies, photophysical studies, and the performances of OLED devices. In addition, the challenges and perspectives of highly twisted TADF molecules and the related OLEDs are also discussed.
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Affiliation(s)
- Tiantian Zhang
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
| | - Yuxin Xiao
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
| | - Hailan Wang
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
| | - Shuting Kong
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
| | - Rongjuan Huang
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
| | - Vonika Ka-Man Au
- Department of Science and Environmental Studies, The Education University of Hong Kong, 10 Lo Ping Road, Tai Po, New Territories, Hong Kong, China
| | - Tao Yu
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
- Key Laboratory of Flexible Electronics of Zhejiang Province, Ningbo Institute of Northwestern Polytechnical University, 218 Qingyi Road, 315103, Ningbo, China
| | - Wei Huang
- Frontiers Science Center for Flexible Electronics (FSCFE), Xi'an Institute of Flexible Electronics (IFE), Northwestern Polytechnical University, 127 West Youyi Road, 710072, Xi'an, China
- Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, 30 South Puzhu Road, 211816, Nanjing, China
- State Key Laboratory of Organic Electronics and Information Displays &, Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, 210023, Nanjing, China
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Brannan AC, Beaumont EFP, Phuoc NL, Whitehead GFS, Linnolahti M, Romanov AS. Organic thermally activated delayed fluorescence material with strained benzoguanidine donor. Beilstein J Org Chem 2023; 19:1289-1298. [PMID: 37701304 PMCID: PMC10494236 DOI: 10.3762/bjoc.19.95] [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: 06/27/2023] [Accepted: 08/30/2023] [Indexed: 09/14/2023] Open
Abstract
Organic thermally activated delayed fluorescence (TADF) materials have been widely investigated due to their impressive electronic properties and applied potential for the third generation of organic light-emitting diodes (OLED). We present organic TADF material (4BGIPN) based on the strained benzoguanidine donor and compare it with the benchmark carbazole-based material (4CzIPN). Extended π-conjugation in 4BGIPN material results in yellow-green luminescence at 512 nm with a fast radiative rate of 5.5 × 10-5 s-1 and a photoluminescence quantum yield of 46% in methylcyclohexane solution. Such a nitrogen-rich 4BGIPN material has a significantly stabilized highest occupied molecular orbital (HOMO) at -6.4 eV while the lowest unoccupied molecular orbital (LUMO) at -4.0 eV, indicating potential suitability for application as the electron transport layer or TADF class III emitter in OLEDs.
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Affiliation(s)
- Alexander C Brannan
- Department of Chemistry, The University of Manchester, Manchester, United Kingdom
| | - Elvie F P Beaumont
- Department of Chemistry, The University of Manchester, Manchester, United Kingdom
| | - Nguyen Le Phuoc
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
| | - George F S Whitehead
- Department of Chemistry, The University of Manchester, Manchester, United Kingdom
| | - Mikko Linnolahti
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
| | - Alexander S Romanov
- Department of Chemistry, The University of Manchester, Manchester, United Kingdom
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12
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Fu Y, Ye Z, Liu D, Mu Y, Xiao J, Hu D, Ji S, Huo Y, Su SJ. Macrocyclic Engineering of Thermally Activated Delayed Fluorescent Emitters for High-Efficiency Organic Light-Emitting Diodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2301929. [PMID: 37178057 DOI: 10.1002/adma.202301929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/29/2023] [Indexed: 05/15/2023]
Abstract
Several thermally activated delayed fluorescence (TADF) materials have been studied and developed to realize high-performance organic light-emitting diodes (OLEDs). However, TADF macrocycles have not been sufficiently investigated owing to the synthetic challenges, resulting in limited exploration of their luminescent properties and the corresponding highly efficient OLEDs. In this study, a series of TADF macrocycles is synthesized using a modularly tunable strategy by introducing xanthones as acceptors and phenylamine derivatives as donors. A detailed analysis of their photophysical properties combined with fragment molecules reveals characteristics of high-performance macrocycles. The results indicate that: a) the ideal structure decreases the energy loss, which in turn reduces the non-radiative transitions; b) reasonable building blocks increase the oscillator strength providing a higher radiation transition rate; c) the horizontal dipole orientation (Θ) of the extended macrocyclic emitters is increased. Owing to the high photoluminescence quantum yields of ≈100% and 92% and excellent Θ of 80 and 79% for macrocycles MC-X and MC-XT in 5 wt% doped films, the corresponding devices exhibit record-high external quantum efficiencies of 31.6% and 26.9%, respectively, in the field of TADF macrocycles.
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Affiliation(s)
- Yu Fu
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, P. R. China
| | - Zecong Ye
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, P. R. China
| | - Denghui Liu
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Yingxiao Mu
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, P. R. China
| | - Jingping Xiao
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, P. R. China
| | - Dehua Hu
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, P. R. China
| | - Shaomin Ji
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, P. R. China
| | - Yanping Huo
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006, P. R. China
- Analytical & Testing Center, Guangdong University of Technology, Guangzhou, 510006, P. R. China
| | - Shi-Jian Su
- State Key Laboratory of Luminescent Materials and Devices, Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
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13
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Deng SL, Chen YK, Lei J, Jayakumar J, Ko CL, Hung WY, Wu TL, Cheng CH. Modifications of Pyridine-3,5-dicarbonitrile Acceptor for Highly Efficient Green-to-Red Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37418573 DOI: 10.1021/acsami.3c05243] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/09/2023]
Abstract
The strategy of acceptor modification is a powerful technique for tuning the emission color of thermally activated delayed fluorescence (TADF) emitters. In this study, we have successfully designed and synthesized three TADF emitters with donor-acceptor (D-A) structures using a 4-(diphenylamino)-2,6-dimethylphenyl (TPAm) donor and various pyridine-3,5-dicarbonitrile (PC) acceptor units. As a result, three compounds named TPAmbPPC, TPAm2NPC, and TPAmCPPC exhibited greenish-yellow to orange-red emissions with high photoluminescent quantum yields (76-100%) in thin films. Remarkably, a greenish-yellow device based on TPAmbPPC and TPAm2NPC showed a high maximum external quantum efficiency (EQEmax) of 39.1 and 39.0%, respectively. Furthermore, benefiting from the suitable steric hindrance between the acceptor and donor, the nondoped organic light-emitting diodes (OLEDs) based on TPAmbPPC demonstrated an exceptional EQEmax of 21.6%, indicating its promising potential as an efficient emitter for the application of OLED applications. Furthermore, orange-red OLED devices based on TPAmCPPC exhibited a high EQEmax of 26.2%, a CE of 50.1 cd A-1, and a PE of 52.4 lm W-1.
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Affiliation(s)
- Sheng-Lin Deng
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
| | - Yi-Kuan Chen
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
| | - Jian Lei
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | | | - Chang-Lun Ko
- Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 20224, Taiwan
| | - Wen-Yi Hung
- Institute of Optoelectronic Sciences, National Taiwan Ocean University, Keelung 20224, Taiwan
| | - Tien-Lin Wu
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
- College of Semiconductor Research, National Tsing Hua University, Hsinchu 300044, Taiwan
| | - Chien-Hong Cheng
- Department of Chemistry, National Tsing Hua University, Hsinchu 300044, Taiwan
- Department of Chemistry, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
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14
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Gawale Y, Ansari R, Naveen KR, Kwon JH. Forthcoming hyperfluorescence display technology: relevant factors to achieve high-performance stable organic light emitting diodes. Front Chem 2023; 11:1211345. [PMID: 37377883 PMCID: PMC10291061 DOI: 10.3389/fchem.2023.1211345] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 05/26/2023] [Indexed: 06/29/2023] Open
Abstract
Over the decade, there have been developments in purely organic thermally activated delayed fluorescent (TADF) materials for organic light-emitting diodes (OLEDs). However, achieving narrow full width at half maximum (FWHM) and high external quantum efficiency (EQE) is crucial for real display industries. To overcome these hurdles, hyperfluorescence (HF) technology was proposed for next-generation OLEDs. In this technology, the TADF material was considered a sensitizing host, the so-called TADF sensitized host (TSH), for use of triplet excitons via the reverse intersystem crossing (RISC) pathway. Since most of the TADF materials show bipolar characteristics, electrically generated singlet and triplet exciton energies can be transported to the final fluorescent emitter (FE) through Förster resonance energy transfer (FRET) rather than Dexter energy transfer (DET). This mechanism is possible from the S1 state of the TSH to the S1 state of the final fluorescent dopant (FD) as a long-range energy transfer. Considering this, some reports are available based on hyperfluorescence OLEDs, but the detailed analysis for highly efficient and stable devices for commercialization was unclear. So herein, we reviewed the relevant factors based on recent advancements to build a highly efficient and stable hyperfluorescence system. The factors include an energy transfer mechanism based on spectral overlapping, TSH requirements, electroluminescence study based on exciplex and polarity system, shielding effect, DET suppression, and FD orientation. Furthermore, the outlook and future positives with new directions were discussed to build high-performance OLEDs.
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Affiliation(s)
| | | | | | - Jang Hyuk Kwon
- *Correspondence: Kenkera Rayappa Naveen, ; Jang Hyuk Kwon,
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15
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Hall D, Sancho-García JC, Pershin A, Beljonne D, Zysman-Colman E, Olivier Y. Benchmarking DFT Functionals for Excited-State Calculations of Donor-Acceptor TADF Emitters: Insights on the Key Parameters Determining Reverse Inter-System Crossing. J Phys Chem A 2023. [PMID: 37196185 DOI: 10.1021/acs.jpca.2c08201] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The importance of intermediate triplet states and the nature of excited states has gained interest in recent years for the thermally activated delayed fluorescence (TADF) mechanism. It is widely accepted that simple conversion between charge transfer (CT) triplet and singlet excited states is too crude, and a more complex route involving higher-lying locally excited triplet excited states has to be invoked to witness the magnitude of the rate of reverse inter-system crossing (RISC) rates. The increased complexity has challenged the reliability of computational methods to accurately predict the relative energy between excited states as well as their nature. Here, we compare the results of widely used density functional theory (DFT) functionals, CAM-B3LYP, LC-ωPBE, LC-ω*PBE, LC-ω*HPBE, B3LYP, PBE0, and M06-2X, against a wavefunction-based reference method, Spin-Component Scaling second-order approximate Coupled Cluster (SCS-CC2), in 14 known TADF emitters possessing a diversity of chemical structures. Overall, the use of the Tamm-Dancoff Approximation (TDA) together with CAM-B3LYP, M06-2X, and the two ω-tuned range-separated functionals LC-ω*PBE and LC-ω*HPBE demonstrated the best agreement with SCS-CC2 calculations in predicting the absolute energy of the singlet S1, and triplet T1 and T2 excited states and their energy differences. However, consistently across the series and irrespective of the functional or the use of TDA, the nature of T1 and T2 is not as accurately captured as compared to S1. We also investigated the impact of the optimization of S1 and T1 excited states on ΔEST and the nature of these states for three different functionals (PBE0, CAM-B3LYP, and M06-2X). We observed large changes in ΔEST using CAM-B3LYP and PBE0 functionals associated with a large stabilization of T1 with CAM-B3LYP and a large stabilization of S1 with PBE0, while ΔEST is much less affected considering the M06-2X functional. The nature of the S1 state barely evolves after geometry optimization essentially because this state is CT by nature for the three functionals tested. However, the prediction of the T1 nature is more problematic since these functionals for some compounds interpret the nature of T1 very differently. SCS-CC2 calculations on top of the TDA-DFT optimized geometries lead to a large variation in terms of ΔEST and the excited-state nature depending on the chosen functionals, further stressing the large dependence of the excited-state features on the excited-state geometries. The presented work highlights that despite good agreement of energies, the description of the exact nature of the triplet states should be undertaken with caution.
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Affiliation(s)
- David Hall
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, KY16 9ST St Andrews, U.K
- Laboratory for Chemistry of Novel Materials, University of Mons, 7000 Mons, Belgium
| | | | - Anton Pershin
- Wigner Research Centre for Physics, P.O. Box 49, 1121 Budapest, Hungary
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons, 7000 Mons, Belgium
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, KY16 9ST St Andrews, U.K
| | - Yoann Olivier
- Laboratory for Computational Modeling of Functional Materials, Namur Institute of Structured Matter, University of Namur, Rue de Bruxelles, 61, 5000 Namur, Belgium
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16
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Meng G, Dai H, Wang Q, Zhou J, Fan T, Zeng X, Wang X, Zhang Y, Yang D, Ma D, Zhang D, Duan L. High-efficiency and stable short-delayed fluorescence emitters with hybrid long- and short-range charge-transfer excitations. Nat Commun 2023; 14:2394. [PMID: 37100785 PMCID: PMC10133342 DOI: 10.1038/s41467-023-38086-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 04/14/2023] [Indexed: 04/28/2023] Open
Abstract
The pursuit of ideal short-delayed thermally activated delayed fluorescence (TADF) emitters is hampered by the mutual exclusion of a small singlet-triplet energy gap (ΔEST) and a large oscillator strength (f). Here, by attaching an multiresonance-acceptor onto a sterically-uncrowded donor, we report TADF emitters bearing hybrid electronic excitations with a main donor-to-acceptor long-range (LR) and an auxiliary bridge-phenyl short-range (SR) charge-transfer characters, balancing a small ΔEST and a large f. Moreover, the incorporation of dual equivalent multiresonance-acceptors is found to double the f value without affecting the ΔEST. A large radiative decay rate over an order of magnitude higher than the intersystem crossing (ISC) rate, and a decent reverse ISC rate of >106 s-1 are simultaneously obtained in one emitter, leading to a short delayed-lifetime of ~0.88 μs. The corresponding organic light-emitting diode exhibits a record-high maximum external quantum efficiency of 40.4% with alleviated efficiency roll-off and extended lifetime.
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Affiliation(s)
- Guoyun Meng
- Key Laboratory of Organic Optoelectronics, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Hengyi Dai
- Key Laboratory of Organic Optoelectronics, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Qi Wang
- Key Laboratory of Organic Optoelectronics, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Jianping Zhou
- Key Laboratory of Organic Optoelectronics, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Tianjiao Fan
- Key Laboratory of Organic Optoelectronics, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Xuan Zeng
- Key Laboratory of Organic Optoelectronics, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Xiang Wang
- Key Laboratory of Organic Optoelectronics, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Yuewei Zhang
- Key Laboratory of Organic Optoelectronics, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China
| | - Dezhi Yang
- Institute of Polymer Optoelectronic Materials and Devices State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Dongge Ma
- Institute of Polymer Optoelectronic Materials and Devices State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Dongdong Zhang
- Key Laboratory of Organic Optoelectronics, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China.
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China.
| | - Lian Duan
- Key Laboratory of Organic Optoelectronics, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China.
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China.
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17
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Qian X, Chu F, Zhou W, Zheng Z, Chen X, Zhao Y. Design of Intramolecular Dihedral Angle between Electronic Donor and Acceptor in Thermally Activated Delayed Fluorescence Molecules. J Phys Chem Lett 2023; 14:3335-3342. [PMID: 36994861 DOI: 10.1021/acs.jpclett.3c00515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
In order to improve the exciton utilization efficiency (ηexc) of organic light-emitting materials, we addressed the ideal donor-acceptor dihedral angle (θD-A) in the TADF molecule by striking a balance between two photophysical processes. One is the conversion of triplet excitons into singlet excitons, and the other is the radiative process from a low-lying excited state to the ground state. Using a combination of first-principles calculations and molecular dynamics simulations, we investigated the impact of θD-A on the splitting energy and spin-orbit coupling between singlet and triplet excitons as well as the transition dipole moment for carbazole benzonitrile (CzBN) derivatives. By comparison with the reverse intersystem crossing rate (krISC), fluorescence emission rate (kr), and ηexc, we proposed a potential highest ηexc (of 94.4%) with the ideal θD-A of 77° for blue light CzBN derivatives; the calculated results have a good agreement with experimental measurement. The structure-efficiency physical connection between the molecular structure (θD-A) and efficiency provided an ideal parameter for a potential candidate for blue TADF-OLED materials.
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Affiliation(s)
- Xin Qian
- Faculty of Materials and Manufacturing, Faculty of Information Technology, Beijing University of Technology, Beijing 100124, P. R. China
| | - Feihong Chu
- Faculty of Materials and Manufacturing, Faculty of Information Technology, Beijing University of Technology, Beijing 100124, P. R. China
| | - Wencai Zhou
- Faculty of Materials and Manufacturing, Faculty of Information Technology, Beijing University of Technology, Beijing 100124, P. R. China
| | - Zilong Zheng
- Faculty of Materials and Manufacturing, Faculty of Information Technology, Beijing University of Technology, Beijing 100124, P. R. China
| | - Xiaoqing Chen
- Faculty of Materials and Manufacturing, Faculty of Information Technology, Beijing University of Technology, Beijing 100124, P. R. China
| | - Yi Zhao
- State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Fujian Provincial Key Lab of Theoretical and Computational Chemistry, and College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
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18
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Naveen KR, Palanisamy P, Chae MY, Kwon JH. Multiresonant TADF materials: triggering the reverse intersystem crossing to alleviate the efficiency roll-off in OLEDs. Chem Commun (Camb) 2023; 59:3685-3702. [PMID: 36857643 DOI: 10.1039/d2cc06802h] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
The hunt for narrow-band emissive pure organic molecules capable of harvesting both singlet and triplet excitons for light emission has garnered enormous attention to promote the advancement of organic light-emitting diodes (OLEDs). Over the past decade, organic thermally activated delayed fluorescence (TADF) materials based on donor (D)/acceptor (A) combinations have been researched for OLEDs in wide color gamut (RGB) regions. However, due to the strong intramolecular charge-transfer (CT) state, they exhibit broad emission with full-width-at-half maximum (FWHM) > 70 nm, which deviates from being detrimental to achieving high color purity for future high-end display electronics such as high-definition TVs and ultra-high-definition TVs (UHDTVs). Recently, the new development in the sub-class of TADF emitters called multi-resonant TADF (MR-TADF) emitters based on boron/nitrogen atoms has attracted much interest in ultra-high definition OLEDs. Consequently, MR-TADF emitters are appeal to their potentiality as promising candidates in fabricating the high-efficient OLEDs due to their numerous advantages such as high photoluminescence quantum yield (PLQY), unprecedented color purity, and narrow bandwidth (FWHM ≤ 40 nm). Until now many MR-TADF materials have been developed for ultra-gamut regions with different design concepts. However, most MR-TADF-OLEDs showed ruthless external quantum efficiency (EQE) roll-off characteristics at high brightness. Such EQE roll-off characteristics were derived mainly from the low reverse intersystem crossing (kRISC) rate values. This feature article primarily focuses on the design strategies to improve kRISC for MR-TADF materials with some supportive strategies including extending charge delocalization, heavy atom introduction, multi-donor/acceptor utilization, and a hyperfluorescence system approach. Furthermore, the outlook and prospects for future developments in MR-TADF skeletons are described.
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Affiliation(s)
- Kenkera Rayappa Naveen
- Organic Optoelectronic Device Lab (OODL), Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
| | - Paramasivam Palanisamy
- Organic Optoelectronic Device Lab (OODL), Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
| | - Mi Young Chae
- Organic Optoelectronic Device Lab (OODL), Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
| | - Jang Hyuk Kwon
- Organic Optoelectronic Device Lab (OODL), Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea.
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19
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Pei R, Xu Y, Miao J, Peng H, Chen Z, Zhou C, Liu H, Yang C. A Tetrahedral Bisacridine Donor Enables Fast Radiative Decay in Thermally Activated Delayed Fluorescence Emitter. Angew Chem Int Ed Engl 2023; 62:e202217080. [PMID: 36722386 DOI: 10.1002/anie.202217080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 01/16/2023] [Accepted: 01/30/2023] [Indexed: 02/02/2023]
Abstract
Achieving high efficiency and low efficiency roll-off simultaneously is of great significance for further application of thermally activated delayed fluorescent (TADF) emitters. A balance between radiative decay and reversed intersystem crossing must be carefully established. Herein, we propose a qunolino-acridine (QAc) donor composing two acridine with both planar (pAc) and bended (bAc) geometries. Combining with triazine, a TADF emitter QAc-TRZ is assembled. The pAc provides a well interaction with triazine which ensures a decent TADF behavior, while the bAc offers a delocalization of highest occupied molecular orbital (HOMO) which guarantees an enhancement of radiative decay. Remarkably, QAc-TRZ enables a highly efficient organic light emitting diode (OLED) with maximum external quantum efficiency (EQE) of 37.3 %. More importantly, the efficiencies under 100/1000 cd m-2 stay 36.3 % and 31.7 %, respectively, and remain 21.5 % even under 10 000 cd m-2 .
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Affiliation(s)
- Ranran Pei
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
| | - Yulin Xu
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
| | - Jingsheng Miao
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
| | - Hao Peng
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
| | - Zhanxiang Chen
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
| | - Changjiang Zhou
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China
| | - He Liu
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
| | - Chuluo Yang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, P. R. China
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20
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Sivasakthi P, Jacob JM, Ravva MK, Samanta PK. Theoretical Insights into the Optical and Excited State Properties of Donor-Phenyl Bridge-Acceptor Containing Through-Space Charge Transfer Molecules. J Phys Chem A 2023; 127:886-893. [PMID: 36653147 DOI: 10.1021/acs.jpca.2c07055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
A comparative new strategy to enhance thermally activated delayed fluorescence (TADF) of through-space charge transfer (CT) molecules in organic light-emitting diodes (OLEDs) is investigated. Generally, TADF molecules adopt a twisted donor and acceptor structure to get a sufficiently small ΔEST and a higher value of the spin-orbit coupling matrix element (SOCME). However, molecules containing donor-phenyl bridge-acceptor (D-p-A) units and featuring π-stacked architectures have intramolecular CT contribution through space and exhibit high TADF efficiency. We have explored the insights into the TADF mechanism in D-p-A molecules using the density functional theory (DFT) and time-dependent DFT methods. The calculated optical absorption and ΔEST values are found to be in good agreement with available experimental data. Interestingly, we found the origin of the SOCME to be the twisted orientation of the donor and bridge moieties. Also, we predicted similar molecules with enhanced OLED efficiency with different substitutions.
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Affiliation(s)
- Pandiyan Sivasakthi
- Department of Chemistry, School of Science, GITAM University, Hyderabad502329, India
| | - Jesni M Jacob
- Department of Chemistry, SRM University-AP, Amaravati522240, Andhra Pradesh, India
| | - Mahesh Kumar Ravva
- Department of Chemistry, SRM University-AP, Amaravati522240, Andhra Pradesh, India
| | - Pralok K Samanta
- Department of Chemistry, School of Science, GITAM University, Hyderabad502329, India
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21
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Bergmann K, Hojo R, Hudson ZM. Uncovering the Mechanism of Thermally Activated Delayed Fluorescence in Coplanar Emitters Using Potential Energy Surface Analysis. J Phys Chem Lett 2023; 14:310-317. [PMID: 36602966 DOI: 10.1021/acs.jpclett.2c03425] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Planarized emitters exhibiting thermally activated delayed fluorescence (TADF) have attracted attention due to their narrow emission spectra, improved photostability, and high quantum yields, but with large singlet-triplet energy gaps (ΔEST) and no heavy atoms, the origin of their TADF remains a subject of debate. Here we prepare two isomeric, coplanar donor-acceptor compounds, with HMAT-2PYM performing dual TADF and room-temperature phosphorescence but with HMAT-4PYM exhibiting only prompt fluorescence. Although conventional TADF design principles suggest that neither isomer should exhibit TADF, we reveal differences in the excited state potential energy surfaces that enable spin-flip processes in only one isomer. We also find that hydrogen bonding is absent between the planar units of these emitters, despite earlier claims of intramolecular hydrogen bonding in similar compounds. Overall, this work demonstrates that potential energy surface analysis is a practical strategy for designing coplanar TADF materials that might otherwise be overlooked by conventional TADF design metrics.
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Affiliation(s)
- Katrina Bergmann
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
| | - Ryoga Hojo
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
| | - Zachary M Hudson
- Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
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22
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Wu S, Kumar Gupta A, Yoshida K, Gong J, Hall D, Cordes DB, Slawin AMZ, Samuel IDW, Zysman‐Colman E. Highly Efficient Green and Red Narrowband Emissive Organic Light-Emitting Diodes Employing Multi-Resonant Thermally Activated Delayed Fluorescence Emitters. Angew Chem Int Ed Engl 2022; 61:e202213697. [PMID: 36300809 PMCID: PMC10100094 DOI: 10.1002/anie.202213697] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Indexed: 11/05/2022]
Abstract
Herein, we demonstrate how judicious selection of the donor decorating a central multi-resonant thermally activated delayed fluorescence (MR-TADF) core based on DiKTa can lead to very high-performance OLEDs. By decorating the DiKTa core with triphenylamine (TPA) and diphenylamine (DPA), 3TPA-DiKTa and 3DPA-DiKTa exhibit bright, narrowband green and red emission in doped films, respectively. The OLEDs based on these emitters showed record-high performance for this family of emitters with maximum external quantum efficiencies (EQEmax ) of 30.8 % for 3TPA-DiKTa at λEL of 551 nm and 16.7 % for 3DPA-DiKTa at λEL =613 nm. The efficiency roll-off in the OLEDs was improved significantly by using 4CzIPN as an assistant dopant in hyperfluorescence (HF) devices. The outstanding device performance has been attributed to preferential horizontal orientation of the transition dipole moments of 3TPA-DiKTa and 3DPA-DiKTa.
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Affiliation(s)
- Sen Wu
- Organic Semiconductor CentreEaStCHEM School of ChemistryUniversity of St AndrewsFifeKY16 9STSt AndrewsUK
| | - Abhishek Kumar Gupta
- Organic Semiconductor CentreEaStCHEM School of ChemistryUniversity of St AndrewsFifeKY16 9STSt AndrewsUK
- Organic Semiconductor CentreSUPA School of Physics and AstronomyUniversity of St AndrewsKY16 9SSSt AndrewsUK
| | - Kou Yoshida
- Organic Semiconductor CentreSUPA School of Physics and AstronomyUniversity of St AndrewsKY16 9SSSt AndrewsUK
| | - Junyi Gong
- Organic Semiconductor CentreSUPA School of Physics and AstronomyUniversity of St AndrewsKY16 9SSSt AndrewsUK
| | - David Hall
- Organic Semiconductor CentreEaStCHEM School of ChemistryUniversity of St AndrewsFifeKY16 9STSt AndrewsUK
| | - David B. Cordes
- Organic Semiconductor CentreEaStCHEM School of ChemistryUniversity of St AndrewsFifeKY16 9STSt AndrewsUK
| | - Alexandra M. Z. Slawin
- Organic Semiconductor CentreEaStCHEM School of ChemistryUniversity of St AndrewsFifeKY16 9STSt AndrewsUK
| | - Ifor D. W. Samuel
- Organic Semiconductor CentreSUPA School of Physics and AstronomyUniversity of St AndrewsKY16 9SSSt AndrewsUK
| | - Eli Zysman‐Colman
- Organic Semiconductor CentreEaStCHEM School of ChemistryUniversity of St AndrewsFifeKY16 9STSt AndrewsUK
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23
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Hao XL, Ren AM, Zhou L. Research and Design of Aggregation-Induced Phosphorescent Materials for Time-Resolved Two-Photon Excited Luminescence Imaging. J Phys Chem Lett 2022; 13:11745-11752. [PMID: 36516071 DOI: 10.1021/acs.jpclett.2c03338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Pure organic two-photon excited room temperature phosphorescent (RTP) materials have attracted great attention for time-resolved imaging due to their long emission lifetime and high resolution. The materials with an aromatic carbonyl group exhibit aggregation-induced emission (AIE) and RTP characteristics simultaneously. Here, we deeply explored the nature of aggregation-induced phosphorescence (AIP), especially the relationship between molecular configuration and optical properties. It was found that aggregation effect can suppress geometrical vibrations and regulate energy difference between S1 and T1. The aromatic carbonyl group plays significant roles in changing electronic configuration, resulting in large Stokes shift and spin-orbit coupling. It also leads to small transition dipole moment, decreasing two-photon absorption cross section and radiative decay rate. To improve two-photon absorption properties, we further designed a π-conjugated compound with large two-photon absorption cross section in the biological window (36.40 GM/656 nm) and AIP characteristics, which is a potential material in the application of time-resolved two-photon excited imaging.
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Affiliation(s)
- Xue-Li Hao
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
| | - Ai-Min Ren
- Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, People's Republic of China
| | - Liang Zhou
- State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
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24
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Ali U, Han G, Yi Y. Switching the Luminescence between TADF and RTP for Organic D‐A‐D Emitters: The Role of D‐A Connection Modes. ADVANCED THEORY AND SIMULATIONS 2022. [DOI: 10.1002/adts.202200725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Usman Ali
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids Institute of Chemistry, Chinese Academy of Sciences Beijing 100190 China
- School of Chemical Sciences University of Chinese Academy of Sciences Beijing 100049 China
| | - Guangchao Han
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids Institute of Chemistry, Chinese Academy of Sciences Beijing 100190 China
| | - Yuanping Yi
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids Institute of Chemistry, Chinese Academy of Sciences Beijing 100190 China
- School of Chemical Sciences University of Chinese Academy of Sciences Beijing 100049 China
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25
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He X, Lou J, Li B, Wang H, Peng X, Li G, Liu L, Huang Y, Zheng N, Xing L, Huo Y, Yang D, Ma D, Zhao Z, Wang Z, Tang BZ. An Ultraviolet Fluorophore with Narrowed Emission via Coplanar Molecular Strategy. Angew Chem Int Ed Engl 2022; 61:e202209425. [DOI: 10.1002/anie.202209425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Indexed: 11/19/2022]
Affiliation(s)
- Xin He
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Jingli Lou
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Baoxi Li
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Han Wang
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Xiaoluo Peng
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Ganggang Li
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Lu Liu
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Yu Huang
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Nan Zheng
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Longjiang Xing
- School of Chemical Engineering & Light Industry Guangdong University of Technology Guangzhou 510006 China
| | - Yanping Huo
- School of Chemical Engineering & Light Industry Guangdong University of Technology Guangzhou 510006 China
| | - Dezhi Yang
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Dongge Ma
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Zujin Zhao
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Zhiming Wang
- State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates Center for Aggregation-Induced Emission AIE Institute Guangzhou International Campus South China University of Technology Guangzhou 510640 China
| | - Ben Zhong Tang
- Shenzhen Institute of Aggregate Science and Technology School of Science and Engineering The Chinese University of Hong Kong, Shenzhen Shenzhen 518172 China
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26
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Double boron-embedded multiresonant thermally activated delayed fluorescent materials for organic light-emitting diodes. Commun Chem 2022; 5:149. [PMID: 36698018 PMCID: PMC9814903 DOI: 10.1038/s42004-022-00766-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 10/25/2022] [Indexed: 11/12/2022] Open
Abstract
The subclass of multi resonant thermally activated delayed fluorescent emitters (MR-TADF) containing boron atoms has garnered significant attention in the field of organic light emitting diode (OLED) research. Among boron-based MR-TADF emitters, double boron-embedded MR-TADF (DB-MR-TADF) emitters show excellent electroluminescence performances with high photoluminescence quantum yields, narrow band emission, and beneficially small singlet-triplet energy levels in all the full-color gamut regions. This article reviews recent progress in DB-MR-TADF emitters, with particular attention to molecular design concepts, synthetic routes, optoelectronic properties, and OLED performance, giving future prospects for real-world applications.
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27
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Chen H, Wen K, Lu Y, Zhang X, Shi Y, Shi Q, Ma H, Peng Q, Huang H. White-light-driven fluorescence switch for super-resolution imaging guided photodynamic and photoacid therapy. Sci China Chem 2022. [DOI: 10.1007/s11426-022-1369-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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28
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Zhu Y, Qu C, Ye J, Xu Y, Zhang Z, Wang Y. Donor-Acceptor Type of Fused-Ring Thermally Activated Delayed Fluorescence Compounds Constructed through an Oxygen-Containing Six-Membered Ring. ACS APPLIED MATERIALS & INTERFACES 2022; 14:47971-47980. [PMID: 36219720 DOI: 10.1021/acsami.2c12778] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Nowadays, thermally activated delayed fluorescence (TADF) compounds with a fused-ring core skeleton are getting increasing research interest because of their use in high-performance organic light-emitting diodes (OLEDs). In this study, TADF compounds featuring a D-A-type fused-ring core skeleton are developed. The challenging compatibility of a planarized D-A arrangement and the TADF property is achieved through linking the D and A moieties with two oxygen atoms within a six-membered ring. Compared with a single-oxygen analogue possessing a flexible skeleton and a twisted D-A arrangement, these fused-ring compounds with higher skeleton rigidity show higher photoluminescence quantum yields and narrower emission spectra in toluene and in doped thin films. Their electroluminescent devices achieve high external quantum efficiencies (up to 19.4%), suggesting the potential of rarely achieved D-A-type fused-ring TADF systems to serve as high-performance emitters of OLEDs.
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Affiliation(s)
- Yunlong Zhu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 P. R. China
| | - Cheng Qu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 P. R. China
| | - Jianjiang Ye
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 P. R. China
| | - Yincai Xu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 P. R. China
| | - Zuolun Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 P. R. China
| | - Yue Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012 P. R. China
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29
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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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30
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Wei Z, Jiang S, Qi F, Lv X, Song J, Gu J, Meng L, Lu C. Predicting and Designing Thermally Activated Delayed Fluorescence Molecules with Balanced Δ
E
ST
and Transition Dipole Moment. ADVANCED THEORY AND SIMULATIONS 2022. [DOI: 10.1002/adts.202200494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Zhuangzhuang Wei
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 P. R. China
- College of Chemistry and Materials Science Fujian Normal University Fuzhou Fujian 350007 P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth Materials Haixi Institutes Chinese Academy of Sciences Xiamen 361021 P. R. China
| | - Shanshan Jiang
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 P. R. China
- Department of Material Metallurgy and Chemistry Jiangxi University of Science and Technology Ganzhou Jiangxi 341000 P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth Materials Haixi Institutes Chinese Academy of Sciences Xiamen 361021 P. R. China
| | - Fangfang Qi
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 P. R. China
- College of Chemistry and Materials Science Fujian Normal University Fuzhou Fujian 350007 P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth Materials Haixi Institutes Chinese Academy of Sciences Xiamen 361021 P. R. China
| | - Xin Lv
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth Materials Haixi Institutes Chinese Academy of Sciences Xiamen 361021 P. R. China
| | - Jinhui Song
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth Materials Haixi Institutes Chinese Academy of Sciences Xiamen 361021 P. R. China
| | - Junjing Gu
- State Key Laboratory of Physical Chemistry of Solid Surfaces Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry and College of Chemistry and Chemical Engineering Xiamen University Xiamen Fujian 361005 P. R. China
| | - Lingyi Meng
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 P. R. China
- College of Chemistry and Materials Science Fujian Normal University Fuzhou Fujian 350007 P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth Materials Haixi Institutes Chinese Academy of Sciences Xiamen 361021 P. R. China
| | - Can‐Zhong Lu
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of Nanomaterials Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences Fuzhou Fujian 350002 P. R. China
- College of Chemistry and Materials Science Fujian Normal University Fuzhou Fujian 350007 P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth Materials Haixi Institutes Chinese Academy of Sciences Xiamen 361021 P. R. China
- University of Chinese Academy of Sciences Beijing 100049 P. R. China
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31
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Li B, Xiao T, Shen H, Deng M, Gu FL. An intramolecular-locked strategy for designing nonlinear optical materials with remarkable first hyperpolarizability. Phys Chem Chem Phys 2022; 24:21800-21805. [PMID: 36056682 DOI: 10.1039/d2cp02850f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To meet the expanding demands of high performance nonlinear optical (NLO) materials, an unprecedented intramolecular-locked strategy is proposed to design NLO materials with remarkable static first hyperpolarizability (β0). This strategy means that importing a large steric hindrance group diphenylmethane (DPM) decreases the torsion angles (θ) between the donor {triphenylamine (TPA)} and acceptor {9-H-thioxanthen-9-one-10,10-dioxide (TXO)} units, as well as between the donor (TPA) and π-bridge (benzene) fragments. The decrease of θ can accelerate the intramolecular charge transfer and enhance the contributions of the TPA, TXO and quinoxaline-6,7-dicarbo-nitrile (QCN) fragments to the axial component of the β0 value, and then the β0 values of TPA-TXO (β0 = 10 762 au) and TPA-QCN (β0 = 22 495 au) are increased by 14.9% and 34.4%, respectively. Overall, the intramolecular-locked strategy is very effective for designing high performance NLO materials.
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Affiliation(s)
- Bo Li
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Education University, Guiyang 550018, P. R. China.
| | - Tiejun Xiao
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Education University, Guiyang 550018, P. R. China.
| | - Hujun Shen
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Education University, Guiyang 550018, P. R. China.
| | - Mingsen Deng
- Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Education University, Guiyang 550018, P. R. China.
| | - Feng Long Gu
- MOE Key Laboratory of Environmental Theoretical Chemistry, South China Normal University, Guangzhou 510006, P. R. China. .,SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety, School of Environment, South China Normal University, Guangzhou 510006, P. R. China.
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32
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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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33
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Chen J, Xiao X, Li S, Duan Y, Wang G, Liao Y, Peng Q, Fu H, Geng H, Shuai Z. A Novel Strategy toward Thermally Activated Delayed Fluorescence from a Locally Excited State. J Phys Chem Lett 2022; 13:2653-2660. [PMID: 35297633 DOI: 10.1021/acs.jpclett.2c00224] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It is well-known that thermally activated delayed fluorescence (TADF) is always generated from charge-transfer (CT) excited states in donor-acceptor (D-A) systems, which limits its application owing to a slow radiative process and a small stimulated emission cross section. Herein, a design strategy is proposed for realizing TADF from a locally excited (LE) state without a typical donor-acceptor type structure through controlling the intersystem crossing (ISC) and reverse intersystem crossing (RISC) processes between the lowest excited singlet with LE character and higher triplet states. Using this strategy, a boron difluoride derivative is theoretically predicted and experimentally synthesized to exhibit locally excited TADF (LE-TADF) with a fairly large radiative rate of 1.12 × 108 s-1, extremely fast RISC rate of 5.09 × 1010 s-1, and a large stimulated emission cross section of 4.35 × 10-17 cm2, making this a promising organic amplified spontaneous emission (ASE) material. This work might open a new avenue to extend TADF materials, especially TADF laser emitters.
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Affiliation(s)
- Jingyao Chen
- Department of Chemistry, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing 100048, China
| | - Xiaoxiao Xiao
- Department of Chemistry, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing 100048, China
| | - Shuai Li
- Department of Chemistry, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing 100048, China
| | - Yuai Duan
- Department of Chemistry, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing 100048, China
| | - Guo Wang
- Department of Chemistry, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing 100048, China
| | - Yi Liao
- Department of Chemistry, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing 100048, China
| | - Qian Peng
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongbing Fu
- Department of Chemistry, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing 100048, China
| | - Hua Geng
- Department of Chemistry, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing 100048, China
| | - Zhigang Shuai
- Department of Chemistry, Tsinghua University, Beijing 100083, China
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34
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Tarleton AS, Garcia-Alvarez JC, Wynn A, Awbrey CM, Roberts TP, Gozem S. OS100: A Benchmark Set of 100 Digitized UV-Visible Spectra and Derived Experimental Oscillator Strengths. J Phys Chem A 2022; 126:435-443. [PMID: 35015532 DOI: 10.1021/acs.jpca.1c08988] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Excited-state quantum chemical calculations usually report excitation energies and oscillator strengths, f, for each electronic transition. On the other hand, UV-visible spectrophotometric experiments measure energy-dependent molar extinction/attenuation coefficients, ε(v), that give absorption band line shapes when plotted. ε(v) and f are related, but this relation is complicated by broadening and solvation effects. We fitted and integrated 100 experimental UV-visible spectra to obtain 164 fexp values for absorption bands appearing in these spectra. The 100 UV-visible spectra belong to solvated organic molecules ranging in size from 6-34 atoms. We estimated uncertainties in the fitting to indicate confidence level in the reported fexp values. The corresponding computed oscillator strengths (fcomp) were obtained with time-dependent density functional theory and a polarizable continuum solvent model. By expressing experimental and computed absorption strengths using a common quantity, we directly compared fcomp and fexp. Although fcomp and fexp are well correlated (linear regression R2 = 0.921), fcomp in most cases overestimated fexp (regression slope = 1.34). The agreement between absolute fcomp and fexp values was substantially improved by accounting for a solvent refractive index factor, as suggested in some derivations in the literature. The 100 digitized UV-visible spectra are included as plain text files in the Supporting Information to aid in benchmarking computational or machine learning methods that aim to simulate realistic UV-visible absorption spectra.
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Affiliation(s)
- Astrid S Tarleton
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Jorge C Garcia-Alvarez
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Anah Wynn
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Cade M Awbrey
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Tomas P Roberts
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Samer Gozem
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
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Barman D, Annadhasan M, Chandrasekar R, Iyer PK. Hot-exciton harvesting via through-space single-molecule based white-light emission and optical waveguides. Chem Sci 2022; 13:9004-9015. [PMID: 36091201 PMCID: PMC9365089 DOI: 10.1039/d2sc02172b] [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: 04/16/2022] [Accepted: 07/02/2022] [Indexed: 11/21/2022] Open
Abstract
Through-space donor–alkyl bridge–acceptor (D–σ–A) luminogens are developed as new organic single-molecule white light emitters (OSMWLEs) involving multiple higher lying singlet (Sn) and triplet (Tm) states (hot-excitons). Experimental and theoretical results confirm the origin of white light emission due to the co-existence of prompt fluorescence from locally excited states, thermally activated delayed fluorescence (TADF), and fast/slow dual phosphorescence color mixing simultaneously. Notably, the fast phosphorescence was observed due to trace amounts of isomeric impurities from commercial carbazole, while H-/J-aggregation resulted in slow phosphorescence. Crystal structure-packing-property analysis revealed that the alkyl chain length induced supramolecular self-assembly greatly influenced the solid-state optical properties. Remarkably, the 1D-microrod crystals of OSMWLEs demonstrated the first examples of triplet harvesting waveguides by self-guiding the generated phosphorescence through light propagation along their longitudinal axis. This work thus highlights an uncommon design strategy to achieve multi-functional OSMWLEs with in-depth mechanistic insights and optical waveguiding applications making them a potentially new class of white emissive materials. Through-space donor–alkyl bridge–acceptor multifunctional organic single molecules that simultaneously displayed white light emission, thermally activated delayed fluorescence, room temperature dual phosphorescence and optical wave-guiding properties.![]()
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Affiliation(s)
- Debasish Barman
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India
| | - Mari Annadhasan
- School of Chemistry and Centre for Nanotechnology, University of Hyderabad, Gachibowli, Prof. C. R. Rao Road, Hyderabad-500046, India
| | - Rajadurai Chandrasekar
- School of Chemistry and Centre for Nanotechnology, University of Hyderabad, Gachibowli, Prof. C. R. Rao Road, Hyderabad-500046, India
| | - Parameswar Krishnan Iyer
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India
- Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati-781039, Assam, India
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36
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Zhou L, Chen JX, Ji S, Chen WC, Huo Y. Research Progress of Red Thermally Activated Delayed Fluorescent Materials Based on Quinoxaline. ACTA CHIMICA SINICA 2022. [DOI: 10.6023/a21120587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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37
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Wei Z, Zuo T, Jiang S, Qi F, Yang M, Meng L, Lu CZ. Theoretically elucidating high photoluminescence performance of dimethylacridan-based blue-color thermally activated delayed fluorescent materials. NEW J CHEM 2022. [DOI: 10.1039/d1nj05251a] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Based on first-principles methods, we comprehensively quantify the luminous quantum efficiencies and related photophysical process rates of dimethylacridan-based blue-color TADF emitters.
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Affiliation(s)
- Zhuangzhuang Wei
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, P. R. China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Tao Zuo
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Shanshan Jiang
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Fangfang Qi
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, P. R. China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Mingxue Yang
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Lingyi Meng
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, P. R. China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
| | - Can-Zhong Lu
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, P. R. China
- CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen 361021, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
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38
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Usuba J, Fukazawa A. Thiophene-Fused 1,4-Diazapentalene: A Stable C=N-Containing π-Conjugated System with Restored Antiaromaticity. Chemistry 2021; 27:16127-16134. [PMID: 34605567 DOI: 10.1002/chem.202103122] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Indexed: 11/07/2022]
Abstract
A thiophene-fused 1,4-diazapentalene (TAP) was rationally designed and synthesized as a C=N-containing 4n π-electron system that exhibits restored antiaromaticity impaired by the doping with C=N bonds. X-ray crystallographic analysis and quantum chemical calculations revealed that the annulation of thiophene rings with the 1,4-diazapentalene moiety resulted in a much higher antiaromaticity than the pristine 1,4-diazapentalene. These effects can be ascribed to the reduced bond alternation of the eight-membered-ring periphery caused by stabilization of the less-stable bond-shifted resonance structure upon increasing the degree of substitution of imine moieties. Consequently, TAP underwent facile hydrogenation even under mild conditions because of its pronounced antiaromaticity and the high aromaticity of the corresponding hydrogenated product H2 -TAP. In addition, the electrophilic C=N moieties in TAP led to the formation of a dense π-stacked structure. These results highlight the effect of partial replacement of C=C bonds with C=N bonds in antiaromatic π-electron systems.
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Affiliation(s)
- Junichi Usuba
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS) Institute for Advanced Study, Kyoto University Yoshida, Sakyo-ku, Kyoto, 606-8501, Japan.,Department of Chemistry Graduate School of Science, Nagoya University Furo, Chikusa, Nagoya, 464-8602, Japan
| | - Aiko Fukazawa
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS) Institute for Advanced Study, Kyoto University Yoshida, Sakyo-ku, Kyoto, 606-8501, Japan
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Gao C, Wong WWH, Qin Z, Lo SC, Namdas EB, Dong H, Hu W. Application of Triplet-Triplet Annihilation Upconversion in Organic Optoelectronic Devices: Advances and Perspectives. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2100704. [PMID: 34596295 DOI: 10.1002/adma.202100704] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 08/06/2021] [Indexed: 06/13/2023]
Abstract
Organic semiconductor materials have been widely used in various optoelectronic devices due to their rich optical and/or electrical properties, which are highly related to their excited states. Therefore, how to manage and utilize the excited states in organic semiconductors is essential for the realization of high-performance optoelectronic devices. Triplet-triplet annihilation (TTA) upconversion is a unique process of converting two non-emissive triplet excitons to one singlet exciton with higher energy. Efficient optical-to-electrical devices can be realized by harvesting sub-bandgap photons through TTA-based upconversion. In electrical-to-optical devices, triplets generated after the combination of electrons and holes also can be efficiently utilized via TTA, which resulted in a high internal conversion efficiency of 62.5%. Currently, many interesting explorations and significant advances have been demonstrated in these fields. In this review, a comprehensive summary of these intriguing advances on developing efficient TTA upconversion materials and their application in optoelectronic devices is systematically given along with some discussions. Finally, the key challenges and perspectives of TTA upconversion systems for further improvement for optoelectronic devices and other related research directions are provided. This review hopes to provide valuable guidelines for future related research and advancement in organic optoelectronics.
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Affiliation(s)
- Can Gao
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wallace W H Wong
- ARC Centre of Excellence in Exciton Science, School of Chemistry, Bio21 Institute, The University of Melbourne, Melbourne, Victoria, 3010, Australia
| | - Zhengsheng Qin
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shih-Chun Lo
- Centre for Organic Photonics and Electronics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Ebinazar B Namdas
- Centre for Organic Photonics & Electronics, School of Mathematics and Physics, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Huanli Dong
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Wenping Hu
- Tianjin Key Laboratory of Molecular Optoelectronic Science, Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
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40
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Guo Y, Guan H, Li P, Wang C, Wu Z, Wang Y, Yu Z, Zhang Z, Wang S, Zhao G. Thermally Activated Delayed Fluorescence Enabled by Reversed Conformational Distortion for Blue Emitters. J Phys Chem Lett 2021; 12:9501-9507. [PMID: 34559539 DOI: 10.1021/acs.jpclett.1c02642] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In this work, we present for the first time a general strategy via molecular reversed conformational distortion for thermally activated delayed fluorescence (TADF). A model purely organic compound named BNNIO with a common fluorophore flexibly linked to benzene by an oxygen atom is rationally designed and successfully synthesized. Moreover, the rate constant of reverse intersystem crossing reaches 2.34 × 104 s-1 as determined by transient spectroscopy. As a result, TADF emission of BNNIO is observed with a photoluminescence quantum yield of 90.72% and a lifetime of 84.76 μs at 415 nm. This universal regulation strategy undoubtedly opens a new avenue for the development of novel purely organic blue light-emitting materials.
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Affiliation(s)
- Yurong Guo
- Department of Chemistry, Molecular Dynamic Chemistry Center, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, School of Science, Tianjin University, Tianjin 300354, China
| | - Hongwei Guan
- Institute of Molecular Sciences and Engineering, Shandong University, Qingdao 266237, China
| | - Peng Li
- Institute of Molecular Sciences and Engineering, Shandong University, Qingdao 266237, China
| | - Chao Wang
- Department of Chemistry, Molecular Dynamic Chemistry Center, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, School of Science, Tianjin University, Tianjin 300354, China
| | - Zibo Wu
- Department of Chemistry, Molecular Dynamic Chemistry Center, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, School of Science, Tianjin University, Tianjin 300354, China
| | - Yanan Wang
- Department of Chemistry, Molecular Dynamic Chemistry Center, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, School of Science, Tianjin University, Tianjin 300354, China
| | - Zhenyi Yu
- Department of Chemistry, Molecular Dynamic Chemistry Center, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, School of Science, Tianjin University, Tianjin 300354, China
| | - Zhen Zhang
- Department of Chemistry, Molecular Dynamic Chemistry Center, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, School of Science, Tianjin University, Tianjin 300354, China
| | - Shiping Wang
- Department of Chemistry, Molecular Dynamic Chemistry Center, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, School of Science, Tianjin University, Tianjin 300354, China
| | - Guangjiu Zhao
- Department of Chemistry, Molecular Dynamic Chemistry Center, Tianjin Key Laboratory of Molecular Optoelectronic Sciences, School of Science, Tianjin University, Tianjin 300354, China
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41
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Ma M, Li J, Liu D, Mei Y, Dong R. Rational Utilization of Intramolecular Hydrogen Bonds to Achieve Blue TADF with EQEs of Nearly 30% and Single Emissive Layer All-TADF WOLED. ACS APPLIED MATERIALS & INTERFACES 2021; 13:44615-44627. [PMID: 34517701 DOI: 10.1021/acsami.1c11812] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A series of highly efficient blue thermally activated delayed fluorescence (TADF) compounds, SON-Cz, SON-tBuCz, and SON-PhCz, were developed. Pyridinyl was introduced as the bridging unit between carbazole donors and sulfone acceptor. Intramolecular hydrogen bonds between the pyridine N atom and carbazole H atoms were detected in single crystals, which suppressed the twisting of carbazole rings and dramatically increased the molecular rigidity. At the same time, tert-butyl or phenyl were incorporated at the 3,6-sites of carbazole ring to tune electron donating ability or enlarge HOMO delocalization. All these hydrogen bonds featured TADF compounds exhibited much improved photoluminescence quantum yields (PLQYs) and excellent efficiencies in their doped blue organic light-emitting diodes. In particular, SON-tBuCz and SON-PhCz exhibited the maximum external quantum efficiencies (EQEs) of 29.59% and 28.22% with CIE coordinates of (0.17, 0.22) and (0.21, 0.36), respectively. The excellent performance benefits from the carbazole structure modification and the intramolecular hydrogen bonds, which bring more rigid structures and eliminate nonradiative transitions. Furthermore, a single emissive layer all-TADF white OLED was fabricated using SON-tBuCz as the blue emitter and 4CzTPN-Ph as the orange emitter to give an EQE of 23.51% with a high CRI of 71, which is among the top efficiencies ever reported for all-TADF WOLEDs so far.
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Affiliation(s)
- Mengyao Ma
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Jiuyan Li
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Di Liu
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
- State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, China
| | - Yongqiang Mei
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
| | - Ruizhi Dong
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology, 2 Linggong Road, Dalian, 116024, China
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Liu Y, Hua L, Zhao Z, Ying S, Ren Z, Yan S. High-Efficiency Solution-Processable OLEDs by Employing Thermally Activated Delayed Fluorescence Emitters with Multiple Conversion Channels of Triplet Excitons. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2101326. [PMID: 34313017 PMCID: PMC8456236 DOI: 10.1002/advs.202101326] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/30/2021] [Indexed: 05/29/2023]
Abstract
The state-of-the-art luminescent materials are gained widely by utilizing thermally activated delayed fluorescence (TADF) mechanism. However, the feasible molecular designing strategy of fully exploiting triplet excitons to enhance TADF properties is still in demand. Herein, TADF emitters with multiple conversion channels of triplet excitons are designed by concisely halogenating the electron acceptors containing carbonyl moiety. Compared with the chlorinated and brominated analogues, the fluorinated emitter exhibits distinguishing molecular stacking structures, participating in the formation of trimers through integrating CH···F and C═O···H hydrogen bonds together. It is also demonstrated that the multiple channels can be involved synergistically to accelerate the spin-flip of triplet excitons, and to take charge of the relatively superior reverse intersystem crossing constant rate of 6.20 × 105 s-1 , and thus excellent photoluminescence quantum yields over 90% can easily be achieved. Then the solution-processable organic light emitting diode based on fluorinated emitter can achieve a record-high external quantum efficiency value of 27.13% and relatively low efficiency roll-off with remaining 24.74% at 1000 cd m-2 . This result manifests the significance of enhancing photophysical properties through constructing multiple conversion channels of triplets excitons for high-efficiency TADF emitters and provides a guideline for the future study.
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Affiliation(s)
- Yuchao Liu
- State Key Laboratory of Chemical Resource EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China
- Key Laboratory of Rubber‐PlasticsMinistry of EducationQingdao University of Science & TechnologyQingdao266042P.R. China
| | - Lei Hua
- State Key Laboratory of Chemical Resource EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China
| | - Zhennan Zhao
- State Key Laboratory of Chemical Resource EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China
| | - Shian Ying
- Key Laboratory of Rubber‐PlasticsMinistry of EducationQingdao University of Science & TechnologyQingdao266042P.R. China
| | - Zhongjie Ren
- State Key Laboratory of Chemical Resource EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China
| | - Shouke Yan
- State Key Laboratory of Chemical Resource EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China
- Key Laboratory of Rubber‐PlasticsMinistry of EducationQingdao University of Science & TechnologyQingdao266042P.R. China
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Zoh I, Imai-Imada M, Bae J, Imada H, Tsuchiya Y, Adachi C, Kim Y. Visualization of Frontier Molecular Orbital Separation of a Single Thermally Activated Delayed Fluorescence Emitter by STM. J Phys Chem Lett 2021; 12:7512-7518. [PMID: 34342465 DOI: 10.1021/acs.jpclett.1c02140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Because the spatial distribution of frontier molecular orbitals (FMOs) regulates the thermally activated delayed fluorescence (TADF) property, researchers synthesize TADF emitters by designing their FMO distribution. However, it remains challenging to clarify how the FMO distribution is altered at molecular interfaces. Thus, visualizing the FMOs at molecular interfaces helps us to understand the working behavior of TADF emitters. Using scanning tunneling microscopy (STM), we investigated the electronic structure of a single TADF emitter, hexamethylazatriangulene-triazine, at molecule-metal and molecule-insulating film interfaces. FMOs at the molecule-metal interface were not spatially confined to the donor-acceptor moieties because of hybridization. Meanwhile, FMOs at the molecule-insulator interface exhibited spatially separated filled and empty states confined to each moiety, similar to the calculated gas-phase FMOs. These observations illustrate that the molecule-environment interaction alters the spatial distribution of FMOs, proving that STM is a powerful tool for studying TADF molecules.
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Affiliation(s)
- Inhae Zoh
- Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Biophysics and Chemical Biology, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea
| | - Miyabi Imai-Imada
- Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Jaehyun Bae
- Center for Organic Photonics and Electronics Research (OPERA) and Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Hiroshi Imada
- Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Kawaguchi 332-0012, Japan
| | - Youichi Tsuchiya
- Center for Organic Photonics and Electronics Research (OPERA) and Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA) and Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yousoo Kim
- Surface and Interface Science Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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Sobolewski AL, Domcke W. Are Heptazine-Based Organic Light-Emitting Diode Chromophores Thermally Activated Delayed Fluorescence or Inverted Singlet-Triplet Systems? J Phys Chem Lett 2021; 12:6852-6860. [PMID: 34279950 DOI: 10.1021/acs.jpclett.1c01926] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two chromophores derived from heptazine, HAP-3MF and HAP-3TPA, were synthesized and tested as emitters in light-emitting diodes (OLEDs) by Adachi and co-workers. Both emitters were shown to exhibit quantum efficiencies which exceed the theoretical maximum of conventional fluorescent OLEDs. The enhanced emission efficiency was explained by the mechanism of thermally activated delayed fluorescence (TADF). In the present work, the electronic excitation energies and essential features of the topography of the excited-state potential-energy surfaces of HAP-3MF and HAP-3TPA have been investigated with a wave function-based ab initio method (ADC(2)). It is found that HAP-3MF is an inverted singlet-triplet (IST) system; that is, the energies of the S1 and T1 states are robustly inverted in violation of Hund's multiplicity rule. Notably, HAP-3MF presumably is the first IST emitter which was implemented in an OLED device. In HAP-3TPA, on the other hand, the vertical excitation energies of the S1 and T1 states are essentially degenerate. The excited states exhibit vibrational stabilization energies of similar magnitude along different relaxation coordinates, resulting in adiabatic excitation energies which also are nearly degenerate. HAP-3TPA is found to be a chromophore at the borderline of TADF and IST systems. The spectroscopic data reported by Adachi and co-workers for HAP-3MF and HAP-3TPA are analyzed in light of these computational results.
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Affiliation(s)
| | - Wolfgang Domcke
- Department of Chemistry, Technical University of Munich, Garching, Germany
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Au-Yeung CC, Li LK, Tang MC, Lai SL, Cheung WL, Ng M, Chan MY, Yam VWW. Molecular design of efficient yellow- to red-emissive alkynylgold(iii) complexes for the realization of thermally activated delayed fluorescence (TADF) and their applications in solution-processed organic light-emitting devices. Chem Sci 2021; 12:9516-9527. [PMID: 34349927 PMCID: PMC8278967 DOI: 10.1039/d1sc02256c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/08/2021] [Indexed: 11/21/2022] Open
Abstract
Here, we report the design and synthesis of a new class of fused heterocyclic alkynyl ligand-containing gold(iii) complexes, which show tunable emission colors spanning from the yellow to red region in the solid state and exhibit thermally activated delayed fluorescence (TADF) properties. These complexes display high photoluminescence quantum yields of up to 0.87 and short excited-state lifetimes in sub-microsecond timescales, yielding high radiative decay rate constants on the order of up to 106 s−1. The observation of the drastic enhancement in the emission intensity of the complexes with insignificant change in the excited-state lifetime upon increasing the temperature from 200 to 360 K indicates an increasing radiative decay rate. The experimentally estimated energy splitting between the lowest-lying singlet excited state (S1) and the lowest-lying triplet excited state (T1), ΔES1–T1, is found to be as small as ∼0.03 eV (250 cm−1), comparable to the value of ∼0.05 eV (435 cm−1) obtained from computational studies. The delicate choice of the cyclometalating ligand and the fused heterocyclic ligand is deemed the key to induce TADF through the control of the energy levels of the intraligand and the ligand-to-ligand charge transfer excited states. This work represents the realization of highly emissive yellow- to red-emitting gold(iii) TADF complexes incorporated with fused heterocyclic alkynyl ligands and their applications in organic light-emitting devices. We report the design of a new class of fused heterocyclic alkynyl ligand-containing gold(iii) complexes, which shows tunable emission colors spanning yellow to red region and exhibits thermally activated delayed fluorescence (TADF) properties.![]()
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Affiliation(s)
- Cathay Chai Au-Yeung
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China +86-852-2857-1586 +86-852-2859-2153
| | - Lok-Kwan Li
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China +86-852-2857-1586 +86-852-2859-2153
| | - Man-Chung Tang
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China +86-852-2857-1586 +86-852-2859-2153
| | - Shiu-Lun Lai
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China +86-852-2857-1586 +86-852-2859-2153
| | - Wai-Lung Cheung
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China +86-852-2857-1586 +86-852-2859-2153
| | - Maggie Ng
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China +86-852-2857-1586 +86-852-2859-2153
| | - Mei-Yee Chan
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China +86-852-2857-1586 +86-852-2859-2153
| | - Vivian Wing-Wah Yam
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong Pokfulam Road Hong Kong P. R. China +86-852-2857-1586 +86-852-2859-2153
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Vieira AA, Farias G, Costa WC, Eccher J, Bechtold IH, Durola F, Bock H. Nematic Triphenyltriazine Triesters and the Induction of the Columnar Mesophase by Fluorine Substitution. Chemistry 2021; 27:9003-9010. [PMID: 33871125 DOI: 10.1002/chem.202005456] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Indexed: 11/06/2022]
Abstract
Whereas their para homologs are not mesogenic, the disk-shaped triphenyltriazine meta-trialkylesters obtained via trimerization of 3-cyanobenzoic alkylester, which are configurationally more flexible, exhibit a monotropic nematic mesophase. Introduction of fluorine atoms into the alkyl chains or into the phenyl moieties leads to the appearance of an enantiotropic columnar mesophase. If fluorine is introduced both in the chains and in the phenyl moieties, only a monotropic mesophase remains. Fluorination of either the alkyl chains or the aromatic core, but not both, appears thus as a simple means of inducing or stabilizing columnar self-assembly in disk-shaped systems. As the homeotropically alignable columnar mesophase can thus be made to persist at room temperature, as energies higher than 3 eV of the first excited triplet state are computed in agreement with the value reported for the parent arene, and as they are not fluorescent themselves, these compounds are of promise as aligning host matrices for blue-emitting TADF devices with improved light outcoupling. Dilution of a columnar with a nonmesogenic homolog induces the nematic state, indicating that the nanoscopic make-up of both mesophases is closely related.
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Affiliation(s)
- André A Vieira
- Instituto de Química, Universidade Federal da Bahia, 40170-115, Salvador, BA, Brazil
| | - Giliandro Farias
- Departamento de Química, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Wallison C Costa
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Juliana Eccher
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Ivan H Bechtold
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil
| | - Fabien Durola
- Centre de Recherche Paul Pascal, CNRS & Université de Bordeaux 115 av. Schweitzer, 33600, Pessac, France
| | - Harald Bock
- Centre de Recherche Paul Pascal, CNRS & Université de Bordeaux 115 av. Schweitzer, 33600, Pessac, France
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47
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Wang Y, Ren J, Shuai Z. Evaluating the anharmonicity contributions to the molecular excited state internal conversion rates with finite temperature TD-DMRG. J Chem Phys 2021; 154:214109. [PMID: 34240969 DOI: 10.1063/5.0052804] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, we propose a new method to calculate molecular nonradiative electronic relaxation rates based on the numerically exact time-dependent density matrix renormalization group theory. This method could go beyond the existing frameworks under the harmonic approximation (HA) of the potential energy surface (PES) so that the anharmonic effect could be considered, which is of vital importance when the electronic energy gap is much larger than the vibrational frequency. We calculate the internal conversion (IC) rates in a two-mode model with Morse potential to investigate the validity of HA. We find that HA is unsatisfactory unless only the lowest several vibrational states of the lower electronic state are involved in the transition process when the adiabatic excitation energy is relatively low. As the excitation energy increases, HA first underestimates and then overestimates the IC rates when the excited state PES shifts toward the dissociative side of the ground state PES. On the contrary, HA slightly overestimates the IC rates when the excited state PES shifts toward the repulsive side. In both cases, a higher temperature enlarges the error of HA. As a real example to demonstrate the effectiveness and scalability of the method, we calculate the IC rates of azulene from S1 to S0 on the ab initio anharmonic PES approximated by the one-mode representation. The calculated IC rates of azulene under HA are consistent with the analytically exact results. The rates on the anharmonic PES are 30%-40% higher than the rates under HA.
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Affiliation(s)
- Yuanheng Wang
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People's Republic of China
| | - Jiajun Ren
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People's Republic of China
| | - Zhigang Shuai
- MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People's Republic of China
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48
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Xu S, Duan Y, Manghnani P, Chen C, Kozlov SM, Liu B. Stereoisomerization during Molecular Packing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2100986. [PMID: 33914374 DOI: 10.1002/adma.202100986] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/03/2021] [Indexed: 06/12/2023]
Abstract
Isomerization is an essential chemical process that often evokes dramatic change of chemical, physical, or biological properties. For a long time, isomerization has been known as a transformation that is induced by certain external energy such as light, heat, or mechanical force. Herein, a new isomerization phenomenon is described, which does not require external energy but simply occurs during molecular packing. The proposed isomerization is demonstrated by a series of symmetric donor-acceptor-donor (D-A-D) molecules, the donor of which may adopt two different stereoisomeric forms. Based on the evidence of the asymmetric isomers in crystals, the occurrence of isomerization during molecular packing is proved. Moreover, the unique asymmetric geometry in the solid state favors the restriction of intramolecular motion, resulting in highly efficient organic solids with quantum yields approaching unity.
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Affiliation(s)
- Shidang Xu
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore
| | - Yukun Duan
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore
| | - Purnima Manghnani
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore
| | - Chengjian Chen
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore
| | - Sergey M Kozlov
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore
| | - Bin Liu
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore, 117585, Singapore
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou, 350207, China
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49
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Fortino M, Cozza C, Bonomi M, Pietropaolo A. Multi-replica biased sampling for photoswitchable π-conjugated polymers. J Chem Phys 2021; 154:174108. [PMID: 34241080 DOI: 10.1063/5.0045944] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In recent years, π-conjugated polymers are attracting considerable interest in view of their light-dependent torsional reorganization around the π-conjugated backbone, which determines peculiar light-emitting properties. Motivated by the interest in designing conjugated polymers with tunable photoswitchable pathways, we devised a computational framework to enhance the sampling of the torsional conformational space and, at the same time, estimate ground- to excited-state free-energy differences. This scheme is based on a combination of Hamiltonian Replica Exchange Method (REM), parallel bias metadynamics, and free-energy perturbation theory. In our scheme, each REM samples an intermediate unphysical state between the ground and the first two excited states, which are characterized by time-dependent density functional theory simulations at the B3LYP/6-31G* level of theory. We applied the method to a 5-mer of 9,9-dioctylfluorene and found that upon irradiation, this system can undergo a dihedral inversion from -155° to 155°, crossing a barrier that decreases from 0.1 eV in the ground state (S0) to 0.05 eV and 0.04 eV in the first (S1) and second (S2) excited states. Furthermore, S1 and even more S2 were predicted to stabilize coplanar dihedrals, with a local free-energy minimum located at ±44°. The presence of a free-energy barrier of 0.08 eV for the S1 state and 0.12 eV for the S2 state can trap this conformation in a basin far from the global free-energy minimum located at 155°. The simulation results were compared with the experimental emission spectrum, showing a quantitative agreement with the predictions provided by our framework.
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Affiliation(s)
- Mariagrazia Fortino
- Dipartimento di Scienze Della Salute, Università di Catanzaro, Viale Europa, 88100 Catanzaro, Italy
| | - Concetta Cozza
- Dipartimento di Scienze Della Salute, Università di Catanzaro, Viale Europa, 88100 Catanzaro, Italy
| | - Massimiliano Bonomi
- Structural Bioinformatics Unit, Department of Structural Biology and Chemistry; CNRS UMR 3528; C3BI, CNRS USR 3756; Institut Pasteur, Paris, France
| | - Adriana Pietropaolo
- Dipartimento di Scienze Della Salute, Università di Catanzaro, Viale Europa, 88100 Catanzaro, Italy
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50
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Boonnab S, Chaiwai C, Nalaoh P, Manyum T, Namuangruk S, Chitpakdee C, Sudyoadsuk T, Promarak V. Synthesis, Characterization, and Physical Properties of Pyrene‐Naphthalimide Derivatives as Emissive Materials for Electroluminescent Devices. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Sumita Boonnab
- School of Chemistry Institute of Science Suranaree University of Technology Muang District Nakhon Ratchasima 30000 Thailand
| | - Chaiyon Chaiwai
- Department of Materials Science and Engineering School of Molecular Science and Engineering Vidyasirimedhi Institute of Science and Technology Wangchan Rayong 21210 Thailand
| | - Phattananawee Nalaoh
- Department of Materials Science and Engineering School of Molecular Science and Engineering Vidyasirimedhi Institute of Science and Technology Wangchan Rayong 21210 Thailand
| | - Thanaporn Manyum
- School of Chemistry Institute of Science Suranaree University of Technology Muang District Nakhon Ratchasima 30000 Thailand
| | - Supawadee Namuangruk
- National Nanotechnology Center (NANOTEC) National Science and Technology Development Agency Klong Luang Pathum Thani 12120 Thailand
| | - Chirawat Chitpakdee
- National Nanotechnology Center (NANOTEC) National Science and Technology Development Agency Klong Luang Pathum Thani 12120 Thailand
| | - Taweesak Sudyoadsuk
- Department of Materials Science and Engineering School of Molecular Science and Engineering Vidyasirimedhi Institute of Science and Technology Wangchan Rayong 21210 Thailand
| | - Vinich Promarak
- Department of Materials Science and Engineering School of Molecular Science and Engineering Vidyasirimedhi Institute of Science and Technology Wangchan Rayong 21210 Thailand
- Research Network of NANOTEC-VISTEC on Nanotechnology for Energy Vidyasirimedhi Institute of Science and Technology Wangchan Rayong 21210 Thailand
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