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Wu SJ, Fu XF, Zhang DH, Sun YF, Lu X, Lin FL, Meng L, Chen XL, Lu CZ. Thermally Activated Delayed Fluorescence with Nanosecond Emission Lifetimes and Minor Concentration Quenching: Achieving High-Performance Nondoped and Doped Blue OLEDs. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2401724. [PMID: 38575151 DOI: 10.1002/adma.202401724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 03/27/2024] [Indexed: 04/06/2024]
Abstract
Simultaneously achieving a high photoluminescence quantum yield (PLQY), ultrashort exciton lifetime, and suppressed concentration quenching in thermally activated delayed fluorescence (TADF) materials is desirable yet challenging. Here, a novel acceptor-donor-acceptor type TADF emitter, namely, 2BO-sQA, wherein two oxygen-bridged triarylboron (BO) acceptors are arranged with cofacial alignment and positioned nearly orthogonal to the rigid dispirofluorene-quinolinoacridine (sQA) donor is reported. This molecular design enables the compound to achieve highly efficient (PLQYs up to 99%) and short-lived (nanosecond-scale) blue TADF with effectively suppressed concentration quenching in films. Consequently, the doped organic light-emitting diodes (OLEDs) base on 2BO-sQA achieve exceptional electroluminescence performance across a broad range of doping concentrations, maintaining maximum external quantum efficiencies (EQEs) at over 30% for doping concentrations ranging from 10 to 70 wt%. Remarkably, the nondoped blue OLED achieves a record-high maximum EQE of 26.6% with a small efficiency roll-off of 14.0% at 1000 candelas per square meter. By using 2BO-sQA as the sensitizer for the multiresonance TADF emitter ν-DABNA, TADF-sensitized fluorescence OLEDs achieve high-efficiency deep-blue emission. These results demonstrate the feasibility of this molecular design in developing TADF emitters with high efficiency, ultrashort exciton lifetime, and minimal concentration quenching.
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Affiliation(s)
- Shao-Jie Wu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen, Fujian, 361021, China
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350108, China
| | - Xi-Feng Fu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen, Fujian, 361021, China
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350108, China
| | - Dong-Hai Zhang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen, Fujian, 361021, China
| | - Yu-Fu Sun
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen, Fujian, 361021, China
| | - Xin Lu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen, Fujian, 361021, China
| | - Fu-Lin Lin
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen, Fujian, 361021, China
| | - Lingyi Meng
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen, Fujian, 361021, China
| | - Xu-Lin Chen
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen, Fujian, 361021, China
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350108, China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian, 350108, China
| | - Can-Zhong Lu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China
- Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials, Xiamen Institute of Rare Earth Materials, Haixi Institutes, Chinese Academy of Sciences, Xiamen, Fujian, 361021, China
- College of Chemistry, Fuzhou University, Fuzhou, Fujian, 350108, China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian, 350108, China
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Chen X, Luo X, Wang K, You X, Xu J, Peng S, Wu D, Xia J. Efficient Intersystem Crossing in Extended Helical Perylene Diimide Dimers with Chalcogen-Annulation. J Phys Chem B 2024; 128:3964-3971. [PMID: 38602495 DOI: 10.1021/acs.jpcb.4c00668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
The properties and formation mechanisms of the triplet state have been widely investigated since they are crucial intermediates in photo functional devices. Specifically, helical PDI dimers, horizontal expanded π-conjugated derivatives of PDI, have shown outstanding performance as electron acceptors in enhancing the performance of photovoltaics. Therefore, the exploration of triplet generation in helical PDI dimers plays a crucial role in understanding the mechanisms and excavating their further application. We make use of Se-annulation to induce intersystem crossing (ISC) in helical PDI dimers and further explore the triplet evolution process systematically as the number of Se atoms increases by transient absorption spectroscopy and the hole-electron analysis method. It shows that the twisted molecular conformation has paved the way for potential ISC in a parent molecule PDI2. The incorporation of Se atoms can result in evident promotion in the efficiency of ISC (ϕTPDI2-2Se = 96.9%) compared to the parent molecule PDI2 (ϕTPDI2 = 26.5%), indicating that chalcogen-annulation is also an efficient strategy in a π-extended system. Our results provide useful insights for understanding the triplet evolution process, which can help broaden the application of the π-extended PDI system into high-performance photovoltaics.
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Affiliation(s)
- Xingyu Chen
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - Xiaoqi Luo
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Kangwei Wang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Xiaoxiao You
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Jingwen Xu
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - Shaoqian Peng
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
| | - Di Wu
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
| | - Jianlong Xia
- International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Center of Smart Materials and Devices, Wuhan University of Technology, Wuhan 430070, China
- School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, China
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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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Su N, Chen B, Ding J. Two Birds with One Stone: Polymerized Thermally Activated Delayed Fluorescence Small Molecules. Chemistry 2024; 30:e202304095. [PMID: 38246880 DOI: 10.1002/chem.202304095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/15/2024] [Accepted: 01/18/2024] [Indexed: 01/23/2024]
Abstract
Thermally activated delayed fluorescence (TADF) polymers show a great potential in low-cost, large-area and flexible full-color flat-panel displays. One of the most promising design rules is based on TADF+Linker, where a small molecular TADF unit is bonded to each other by a simple linker. Unlike the expensive vacuum deposition for small molecules, these polymerized TADF small molecules (Poly-TADF-SMs) are capable of cost-effective solution processing. Meanwhile, the good luminescent property of small molecular TADF emitters can be well inherited by Poly-TADF-SMs so as to bridge the efficiency gap between small molecules and polymers. Herein, we will highlight the recent progress of Poly-TADF-SMs, together with emphasis on their molecular design, photophysical and electroluminescence properties.
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Affiliation(s)
- Ning Su
- School of Chemical Science and Technology, Yunnan University, Kunming, 650091, P. R. China
| | - Bitian Chen
- School of Chemical Science and Technology, Yunnan University, Kunming, 650091, P. R. China
- Southwest United Graduate School, Kunming, 650092, P. R. China
| | - Junqiao Ding
- School of Chemical Science and Technology, Yunnan University, Kunming, 650091, P. R. China
- Southwest United Graduate School, Kunming, 650092, P. R. China
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Yang X, Waterhouse GIN, Lu S, Yu J. Recent advances in the design of afterglow materials: mechanisms, structural regulation strategies and applications. Chem Soc Rev 2023; 52:8005-8058. [PMID: 37880991 DOI: 10.1039/d2cs00993e] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
Abstract
Afterglow materials are attracting widespread attention owing to their distinctive and long-lived optical emission properties which create exciting opportunities in various fields. Recent research has led to the discovery of many new afterglow materials featuring high photoluminescence quantum yields (PLQY) and lifetimes of up to several hours under ambient conditions. Afterglow materials are typically categorized according to their luminescence mechanism, such as long-persistent luminescence (LPL), room temperature phosphorescence (RTP), or thermally activated delayed fluorescence (TADF). Through rational design and novel synthetic strategies to modulate spin-orbit coupling (SOC) and populate triplet exciton states (T1), luminophores with long lifetimes and bright afterglow characteristics can be realized. Initial research towards afterglow materials focused mainly on pure inorganic materials, many of which possessed inherent disadvantages such as metal toxicity or low energy emissions. In recent years, organic-inorganic hybrid afterglow materials (OIHAMs) have been developed with high PLQY and long lifetimes. These hybrid materials exploit the tunable structure and easy processing of organic molecules, as well as enhanced SOC and intersystem crossing (ISC) processes involving heavy atom dopants, to achieve excellent afterglow performance. In this review, we begin by briefly discussing the structure and composition of inorganic and organic-inorganic hybrid afterglow materials, including strategies for regulating their lifetime, PLQY and luminescence wavelength. The specific advantages of organic-inorganic hybrid afterglow materials, including low manufacturing costs, diverse molecular/electronic structures, tunable structures and optical properties, and compatibility with a variety of substrates, are emphasized. Subsequently, we discuss in detail the fundamental mechanisms used by afterglow materials, their classification, design principles, and end applications (including sensing, anticounterfeiting, and photoelectric devices, among others). Finally, existing challenges and promising future directions are discussed, laying a platform for the design of afterglow materials for specific applications.
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Affiliation(s)
- Xin Yang
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, China.
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou 450001, China.
- International Center of Future Science, Jilin University, Changchun 130012, China
| | | | - Siyu Lu
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou 450001, China.
| | - Jihong Yu
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, China.
- International Center of Future Science, Jilin University, Changchun 130012, China
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Zhang X, Chong KC, Xie Z, Liu B. Color-Tunable Dual-Mode Organic Afterglow for White-Light Emission and Information Encryption Based on Carbazole Doping. Angew Chem Int Ed Engl 2023; 62:e202310335. [PMID: 37726259 DOI: 10.1002/anie.202310335] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 09/10/2023] [Accepted: 09/18/2023] [Indexed: 09/21/2023]
Abstract
Dual-mode emission materials, combining phosphorescence and delayed fluorescence, offer promising opportunities for white-light afterglow. However, the delayed fluorescence lifetime is usually significantly shorter than that of phosphorescence, limiting the duration of white-light emission. In this study, a carbazole-based host-guest system that can be activated by both ultraviolet (UV) and visible light is reported to achieve balanced phosphorescence and delayed fluorescence, resulting in a long-lived white-light afterglow. Our study demonstrated the critical role of a charge transfer state in the afterglow mechanism, where the charge separation and recombination process directly determined the lifetime of afterglow. Simultaneously, an efficient reversed intersystem crossing process was obtained between the singlet and triplet charge transfer states, which facilitating the delayed fluorescence properties of host-guest system. As a result, delayed fluorescence lifetime was successfully prolonged to approach that of phosphorescence. This work presents a delayed fluorescence lifetime improvement strategy via doping method to realize durable white-light afterglow.
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Affiliation(s)
- Xianhe Zhang
- Integrative Sciences and Engineering Program, NUS Graduate School, National University of Singapore, Singapore, 117585, Singapore
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117585, Singapore
| | - Kok Chan Chong
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117585, Singapore
| | - Zongliang Xie
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117585, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117585, Singapore
| | - Bin Liu
- Integrative Sciences and Engineering Program, NUS Graduate School, National University of Singapore, Singapore, 117585, Singapore
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117585, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, 117585, Singapore
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7
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Zhao Z, Yan S, Ren Z. Regulating the Nature of Triplet Excited States of Thermally Activated Delayed Fluorescence Emitters. Acc Chem Res 2023. [PMID: 37364229 DOI: 10.1021/acs.accounts.3c00175] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
ConspectusCharacterized by the reverse intersystem crossing (RISC) process from the triplet state (T1) to the singlet state (S1), thermally activated delayed fluorescence (TADF) emitters, which produce light by harvesting both triplet and singlet excitons without noble metals, are considered to be third-generation organic electroluminescent materials. Rapid advances in molecular design criteria, understanding the photophysics underlying TADF, and applications of TADF materials as emitters in organic light-emitting diodes (OLEDs) have been achieved. Theoretically, enhanced spin-orbit coupling (SOC) between singlet and triplet states can result in a fast RISC process and thus a high light-emitting efficiency according to Fermi's golden rule. Therefore, regulating the nature of triplet excited states by elaborate molecular design to improve SOC is an effective approach to high-efficiency TADF-based OLEDs. Generally, on one hand, the increased local excited (LE) populations of the excited triplet state can significantly improve the nature flips between S1 and T1. On other hand, the reduced energy gap between S1 and the lowest triplet with a charge transfer (CT) characteristic can also enhance their vibronic coupling. Consequently, it is vital to determine how to regulate the nature of triplet excited states by molecular design to guide the material synthesis, especially for polymeric emitters.In this Account, we focus on modulating the strategy of triplet excited states for TADF emitters and an in-depth understanding of the photophysical processes, leading to optimized OLED device performance. We include several kinds of strategies to control the nature of triplet excited states to guide the synthesis of small-molecule and polymer TADF emitters: (1) Modulating the electronic distribution of conjugated polymeric backbones by copolymerizing the electron-donating host: accordingly, the nature of excited states can be changed, especially for triplets. Meanwhile, the utilization of excitons can be systematically improved by adjusting the electronic structure of triplet states with long-range distribution in the conjugated polymeric backbones. (2) Halogenating acceptors of TADF units: the introduced halogen atoms would reestablish the electronic distribution of the triplet and relocate the hole orbits, resulting in a CT and LE hybrid nature of a triplet transformed into a LE-predominant state, which favors the RISC process. (3) Stereostructure regulation: by constructing a diverse arrangement of three-dimensional spatial configurations or conjugated architectures, the nature of the triplet can also be finely tuned, such as hyperbranched structures with multiple triplet-singlet vibration couplings, half-dendronized-half-encapsulated asymmetric systems, trinaphtho[3,3,3] propeller-based three-dimensional spatial interspersed structures, intramolecular close-packed donor-acceptor systems, and so on. We hope that this Account will provide insights into new structures and mechanisms for achieving high-performance OLEDs based on regulating the nature of triplet excited states.
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Affiliation(s)
- Zhennan Zhao
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Shouke Yan
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
- Key Laboratory of Rubber-Plastics, Ministry of Education, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Zhongjie Ren
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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Xie Y, Hua L, Wang Z, Liu Y, Ying S, Liu Y, Ren Z, Yan S. Constructing an efficient deep-blue TADF emitter by host-guest interactions towards solution-processed OLEDs with narrowband emission. Sci China Chem 2023. [DOI: 10.1007/s11426-022-1447-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Constructing high-efficiency orange-red thermally activated delayed fluorescence emitters by three-dimension molecular engineering. Nat Commun 2022; 13:7828. [PMID: 36535962 PMCID: PMC9763412 DOI: 10.1038/s41467-022-35591-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022] Open
Abstract
Preparing high-efficiency solution-processable orange-red thermally activated delayed fluorescence (TADF) emitters remains challenging. Herein, we design a series of emitters consisting of trinaphtho[3,3,3]propellane (TNP) core derivatized with different TADF units. Benefiting from the unique hexagonal stacking architecture of TNPs, TADF units are thus kept in the cavities between two TNPs, which decrease concentration quenching and annihilation of long-lived triplet excitons. According to the molecular engineering of TADF and host units, the excited states can further be regulated to effectively enhance spin-orbit coupling (SOC) processes. We observe a high-efficiency orange-red emission at 604 nm in one instance with high SOC value of 0.862 cm-1 and high photoluminescence quantum yield of 70.9%. Solution-processable organic light-emitting diodes exhibit a maximum external quantum efficiency of 24.74%. This study provides a universal strategy for designing high-performance TADF emitters through molecular packing and excited state regulation.
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Jiang W, Zhao G, Tian W, Sun Y. Aggregation-Induced Intermolecular Charge Transfer Emission for Solution-Processable Bipolar Host Material via Adjusting the Length of Alkyl Chain. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27228099. [PMID: 36432201 PMCID: PMC9698787 DOI: 10.3390/molecules27228099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/14/2022] [Accepted: 11/15/2022] [Indexed: 11/23/2022]
Abstract
Molecules with donor-spacer-acceptor configuration have been developed rapidly given their peculiar properties. How to utilize intermolecular interactions and charge transfers for solution-processed organic light-emitting diodes (OLEDs) greatly relies on molecular design strategy. Herein, soluble luminophores with D-spacer-A motif were constructed via shortening the alkyl chain from nonane to propane, where the alkyl chain was utilized as a spatial linker between the donor and acceptor. The alkyl chain blocks the molecular conjugation and induces the existence of aggregation-induced intermolecular CT emission, as well as the improved solubility and morphology in a solid-state film. In addition, the length of the alkyl chain affects the glass transition temperature, carrier transport and balance properties. The mCP-3C-TRZ with nonane as the spacer shows better thermal stability and bipolar carrier transport ability, so the corresponding solution-processable phosphorescent organic light-emitting diodes exhibit superior external quantum efficiency of 9.8% when using mCP-3C-TRZ as a host material. This work offers a promising strategy to establish a bipolar host via utilizing intermolecular charge transfer process in an aggregated state.
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Huang Z, Lei B, Yang D, Ma D, Bin Z, You J. Modified Intramolecular‐Lock Strategy Enables Efficient Thermally Activated Delayed Fluorescence Emitters for Non‐Doped OLEDs. Angew Chem Int Ed Engl 2022; 61:e202213157. [DOI: 10.1002/anie.202213157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Indexed: 11/17/2022]
Affiliation(s)
- Zhenmei Huang
- Key Laboratory of Green Chemistry and Technology of Ministry of Education College of Chemistry Sichuan University Chengdu 610064 P. R. of China
| | - Bowen Lei
- Key Laboratory of Green Chemistry and Technology of Ministry of Education College of Chemistry Sichuan University Chengdu 610064 P. R. of 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
| | - Zhengyang Bin
- Key Laboratory of Green Chemistry and Technology of Ministry of Education College of Chemistry Sichuan University Chengdu 610064 P. R. of China
| | - Jingsong You
- Key Laboratory of Green Chemistry and Technology of Ministry of Education College of Chemistry Sichuan University Chengdu 610064 P. R. of China
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12
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Shi YZ, Wu H, Wang K, Yu J, Ou XM, Zhang XH. Recent progress in thermally activated delayed fluorescence emitters for nondoped organic light-emitting diodes. Chem Sci 2022; 13:3625-3651. [PMID: 35432901 PMCID: PMC8966661 DOI: 10.1039/d1sc07180g] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 02/21/2022] [Indexed: 11/25/2022] Open
Abstract
Nondoped organic light-emitting diodes (OLEDs) have drawn immense attention due to their merits of process simplicity, reduced fabrication cost, etc. To realize high-performance nondoped OLEDs, all electrogenerated excitons should be fully utilized. The thermally activated delayed fluorescence (TADF) mechanism can theoretically realize 100% internal quantum efficiency (IQE) through an effective upconversion process from nonradiative triplet excitons to radiative singlet ones. Nevertheless, exciton quenching, especially related to triplet excitons, is generally very serious in TADF-based nondoped OLEDs, significantly hindering the pace of development. Enormous efforts have been devoted to alleviating the annoying exciton quenching process, and a number of TADF materials for highly efficient nondoped devices have been reported. In this review, we mainly discuss the mechanism, exciton leaking channels, and reported molecular design strategies of TADF emitters for nondoped devices. We further classify their molecular structures depending on the functional A groups and offer an outlook on their future prospects. It is anticipated that this review can entice researchers to recognize the importance of TADF-based nondoped OLEDs and provide a possible guide for their future development. The mechanism, exciton leaking channels, and reported molecular design strategies of TADF emitters for high-performance nondoped OLEDs are summarized. Their molecular structures depending on the functional A groups are further classified.![]()
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Affiliation(s)
- Yi-Zhong Shi
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University 199 Ren'ai Road Suzhou Jiangsu 215123 PR China
| | - Hao Wu
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University 199 Ren'ai Road Suzhou Jiangsu 215123 PR China
| | - Kai Wang
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University 199 Ren'ai Road Suzhou Jiangsu 215123 PR China
| | - Jia Yu
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University 199 Ren'ai Road Suzhou Jiangsu 215123 PR China
| | - Xue-Mei Ou
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University 199 Ren'ai Road Suzhou Jiangsu 215123 PR China
| | - Xiao-Hong Zhang
- Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University 199 Ren'ai Road Suzhou Jiangsu 215123 PR China
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