1
|
Bae J, Imai-Imada M, Kim HS, Lee M, Imada H, Tsuchiya Y, Hatakeyama T, Adachi C, Kim Y. Visualization of Multiple-Resonance-Induced Frontier Molecular Orbitals in a Single Multiple-Resonance Thermally Activated Delayed Fluorescence Molecule. ACS NANO 2024. [PMID: 38934571 DOI: 10.1021/acsnano.4c04813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
Abstract
The spatial distribution and electronic properties of the frontier molecular orbitals (FMOs) in a thermally activated delayed fluorescence (TADF) molecule contribute significantly to the TADF properties, and thus, a detailed understanding and sophisticated control of the FMOs are fundamental to the design of TADF molecules. However, for multiple-resonance (MR)-TADF molecules that achieve spatial separation of FMOs by the MR effect, the distinctive distribution of these molecular orbitals poses significant challenges for conventional computational analysis and ensemble averaging methods to elucidate the FMOs' separation and the precise mechanism of luminescence. Therefore, the visualization and analysis of electronic states with the specific energy level of a single MR-TADF molecule will provide a deeper understanding of the TADF mechanism. Here, scanning tunneling microscopy/spectroscopy (STM/STS) was used to investigate the electronic states of the DABNA-1 molecule at the atomic scale. FMOs' visualization and local density of states analysis of the DABNA-1 molecule clearly show that MR-TADF molecules also have well-separated FMOs according to the internal heteroatom arrangement, providing insights that complement existing theoretical prediction methods.
Collapse
Affiliation(s)
- Jaehyun Bae
- Surface and Interface Science Laboratory (SISL), RIKEN, Wako, Saitama 351-0198, Japan
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan
| | - Miyabi Imai-Imada
- Surface and Interface Science Laboratory (SISL), RIKEN, Wako, Saitama 351-0198, Japan
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan
| | - Hyung Suk Kim
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan
| | - Minhui Lee
- Surface and Interface Science Laboratory (SISL), RIKEN, Wako, Saitama 351-0198, Japan
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 118-8656, Japan
| | - Hiroshi Imada
- Surface and Interface Science Laboratory (SISL), RIKEN, Wako, Saitama 351-0198, Japan
| | - Youichi Tsuchiya
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan
| | - Takuji Hatakeyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Sakyo 606-8502, Japan
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan
- Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395, Japan
| | - Yousoo Kim
- Surface and Interface Science Laboratory (SISL), RIKEN, Wako, Saitama 351-0198, Japan
- Department of Applied Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 118-8656, Japan
| |
Collapse
|
2
|
Jin P, Wei X, Yin B, Xu L, Guo Y, Zhang C. Stepwise Charge/Energy Transfer in MR-TADF Molecule-Doped Exciplex for Ultralong Persistent Luminescence Activated with Visible Light. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2400158. [PMID: 38847332 DOI: 10.1002/adma.202400158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 05/31/2024] [Indexed: 06/15/2024]
Abstract
Organic long-persistent luminescence (OLPL), which relies on energy storage for delayed light emission by the charge separation state, has attracted intense attention in various optical applications. However, charge separation (CS) is efficient only under ultraviolet excitation in most OLPL systems because it requires a driving force from the large energy difference between the local excited (LE) and charge transfer (CT) states. In this study, a multiresonance thermally activated delayed fluorescence (MR-TADF) molecule is incorporated into an exciplex system to achieve efficient OLPL in a composite material activated by visible light via a stepwise charge/energy transfer process. The enhanced absorption of the composite material facilitated a tenfold increase in the duration of the OLPL, which can last for several hours under visible light excitation. The excited state of the MR-TADF molecule tends to charge transfer to the acceptor, followed by energy transfer to the exciplex, which benefits from the small difference between the LE and CT states owing to the inherent CS characteristics of the opposing resonance effect. Afterglow displays of these composite materials are fabricated to demonstrate their considerable potential in encryption patterns and emergency lights, which take advantage of their excellent processability, visible light activation, and tunable luminescence properties.
Collapse
Affiliation(s)
- Pengfei Jin
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaofang Wei
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, China
| | - Baipeng Yin
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, China
| | - Lixin Xu
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yunlong Guo
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, China
| | - Chuang Zhang
- Beijing National Laboratory for Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, China
| |
Collapse
|
3
|
Ni F, Huang Y, Qiu L, Yang C. Synthetic progress of organic thermally activated delayed fluorescence emitters via C-H activation and functionalization. Chem Soc Rev 2024; 53:5904-5955. [PMID: 38717257 DOI: 10.1039/d3cs00871a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
Thermally activated delayed fluorescence (TADF) emitters have become increasingly prominent due to their promising applications across various fields, prompting a continuous demand for developing reliable synthetic methods to access them. This review aims to highlight the progress made in the last decade in synthesizing organic TADF compounds through C-H bond activation and functionalization. The review begins with a brief introduction to the basic features and design principles of TADF emitters. It then provides an overview of the advantages and concise development of C-H bond transformations in constructing TADF emitters. Subsequently, it summarizes both transition-metal-catalyzed and non-transition-metal-promoted C-H bond transformations used for the synthesis of TADF emitters. Finally, the review gives an outlook on further challenges and potential directions in this field.
Collapse
Affiliation(s)
- Fan Ni
- National Engineering Lab of Special Display Technology, State Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Intelligent Interconnected Systems Laboratory of Anhui, Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, School of Instrument Science and Optoelectronic Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China.
| | - Yipan Huang
- National Engineering Lab of Special Display Technology, State Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Intelligent Interconnected Systems Laboratory of Anhui, Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, School of Instrument Science and Optoelectronic Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China.
| | - Longzhen Qiu
- National Engineering Lab of Special Display Technology, State Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Intelligent Interconnected Systems Laboratory of Anhui, Anhui Province Key Laboratory of Measuring Theory and Precision Instrument, School of Instrument Science and Optoelectronic Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China.
| | - Chuluo Yang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, Guangdong 518060, P. R. China.
| |
Collapse
|
4
|
Feng Y, Xu Y, Qu C, Wang Q, Ye K, Liu Y, Wang Y. Structurally Tunable Donor-Bridge-Fluorophore Architecture Enables Highly Efficient and Concentration-Independent Narrowband Electroluminescence. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2403061. [PMID: 38782371 DOI: 10.1002/adma.202403061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 05/05/2024] [Indexed: 05/25/2024]
Abstract
Luminescent materials with narrowband emission have extraordinary significance for developing ultrahigh-definition display. B-N-containing multiple resonance thermally activated delayed fluorescence (MR-TADF) materials are strong contenders. However, their device performances pervasively encounter detrimental aggregation-caused quenching effect that is highly vulnerable to doping concentration, complicating device fabrication. Therefore, constructing highly efficient and concentration-independent MR-TADF emitters is of pragmatic importance for improving device controllability and reproducibility, simplifying manufacturing procedures, and conserving production costs. Here, by systematic arrangement of donor triphenylamine and fluorophore BNCz on distinct bridges, a spatial confinement strategy has been developed with a donor-bridge-fluorophore architecture. Structurally fine modulation and progressive evolution to construct molecular entities with congested steric hindrance effect that can suppress intermolecular interactions without substantially affecting the luminescence tone of fluorophore BNCz, resulting in highly efficient and concentration-independent narrowband emitters; through isomer engineering, two isomers BN-PCz-TPA and TPA-PCz-BN with different crystal stacking patterns are synthesized by altering the connection mode between triphenylamine and BNCz. As a result, BN-PCz-TPA-based device showcases maximum external quantum efficiency (EQE) of 36.3% with narrow full-width at half-maximum of 27 nm at 10 wt% doping concentration. Even at 20 wt% doping concentration, the maximum EQE remains at 32.5% and the emission spectrum is almost unchanged.
Collapse
Affiliation(s)
- Yu Feng
- 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
| | - Cheng Qu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Qingyang Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Kaiqi Ye
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Yu Liu
- 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
- Jihua Laboratory, 28 Huandao South Road, Foshan, Guangdong Province, 528200, P. R. China
| |
Collapse
|
5
|
Mamada M, Aoyama A, Uchida R, Ochi J, Oda S, Kondo Y, Kondo M, Hatakeyama T. Efficient Deep-Blue Multiple-Resonance Emitters Based on Azepine-Decorated ν-DABNA for CIE y below 0.06. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2402905. [PMID: 38695744 DOI: 10.1002/adma.202402905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/19/2024] [Indexed: 05/23/2024]
Abstract
Ultrapure deep-blue emitters are in high demand for organic light-emitting diodes (OLEDs). Although color coordinates serve as straightforward parameters for assessing color purity, precise control over the maximum wavelength and full-width at half-maximum is necessary to optimize OLED performance, including luminance efficiency and luminous efficacy. Multiple-resonance (MR) emitters are promising candidates for achieving ideal luminescence properties; consequently, a wide variety of MR frameworks have been developed. However, most of these emitters experience a wavelength displacement from the ideal color, which limits their practical applicability. Therefore, a molecular design that is compatible with MR emitters for modulating their energy levels and color output is particularly valuable. Here, it is demonstrated that the azepine donor unit induces an appropriate blue-shift in the emission maximum while maintaining efficient MR characteristics, including high photoluminescence quantum yield, narrow emission, and a fast reverse intersystem crossing rate. OLEDs using newly developed MR emitters based on the ν-DABNA framework simultaneously exhibit a high quantum efficiency of ≈30%, luminous efficacy of ≈20 lm W-1, exceptional color purity with Commission Internationale de l'Éclairage coordinates as low as (0.14, 0.06), and notably high operational stability. These results demonstrate unprecedentedly high levels compared with those observed in previously reported deep-blue emitters.
Collapse
Affiliation(s)
- Masashi Mamada
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Akio Aoyama
- Department of Chemistry, Graduate School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan
| | - Ryota Uchida
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Junki Ochi
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Susumu Oda
- Department of Applied Chemistry, Graduate School of Science and Engineering, Toyo University, 2100 Kujirai, Kawagoe, Saitama, 350-8585, Japan
| | - Yasuhiro Kondo
- SK JNC Japan Co., Ltd., 5-1 Goi Kaigan, Ichihara, Chiba, 290-8551, Japan
| | - Masakazu Kondo
- JNC Co., Ltd., 5-1 Goi Kaigan, Ichihara, Chiba, 290-8551, Japan
| | - Takuji Hatakeyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| |
Collapse
|
6
|
An RZ, Sun Y, Chen HY, Liu Y, Privitera A, Myers WK, Ronson TK, Gillett AJ, Greenham NC, Cui LS. Excited-State Engineering Enables Efficient Deep-Blue Light-Emitting Diodes Exhibiting BT.2020 Color Gamut. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2313602. [PMID: 38598847 DOI: 10.1002/adma.202313602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 04/01/2024] [Indexed: 04/12/2024]
Abstract
Organic luminescent materials that exhibit thermally activated delayed fluorescence (TADF) can convert non-emissive triplet excitons into emissive singlet states through a reverse intersystem crossing (RISC) process. Therefore, they have tremendous potential for applications in organic light-emitting diodes (OLEDs). However, with the development of ultra-high definition 4K/8K display technologies, designing efficient deep-blue TADF materials to achieve the Commission Internationale de l'Éclairage (CIE) coordinates fulfilling BT.2020 remains a significant challenge. Here, an effective approach is proposed to design deep-blue TADF molecules based on hybrid long- and short-range charge-transfer by incorporation of multiple donor moieties into organoboron multiple resonance acceptors. The resulting TADF molecule exhibits deep-blue emission at 414 nm with a full width at half maximum (FWHM) of 29 nm, together with a thousand-fold increase in RISC rate. OLEDs based on the champion material achieve a record maximum external quantum efficiency (EQE) of 22.8% with CIE coordinates of (0.163, 0.046), approaching the coordinates of the BT.2020 blue standard. Moreover, TADF-assisted fluorescence devices employing the designed material as a sensitizer exhibit an exceptional EQE of 33.1%. This work thus provides a blueprint for future development of efficient deep-blue TADF emitters, representing an important milestone towards meeting the blue color gamut standard of BT.2020.
Collapse
Affiliation(s)
- Rui-Zhi An
- Key Laboratory of Precision and Intelligent Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, China
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Yuqi Sun
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Hao-Yang Chen
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Yuan Liu
- Key Laboratory of the Ministry of Education for Optoelectronic Measurement Technology and Instrument, Beijing Information Science & Technology University, No. 12 Xiaoying East Road, Beijing, 100192, China
| | - Alberto Privitera
- Department of Industrial Engineering and INSTM Research Unit, University of Florence, Via Santa Marta 3, Firenze, 50139, Italy
| | - William K Myers
- Centre for Advanced Electron Spin Resonance, Inorganic Chemistry Laboratory, University of Oxford, Oxford, OX1 3QR, UK
| | - Tanya K Ronson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Alexander J Gillett
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Neil C Greenham
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Lin-Song Cui
- Key Laboratory of Precision and Intelligent Chemistry, University of Science and Technology of China, Hefei, Anhui, 230026, China
- CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China
| |
Collapse
|
7
|
Park JY, Kwon NY, Koh CW, Park SH, Kang MJ, Kwak H, Park CY, Chae WS, Hong CS, Park S, Cho MJ, Choi DH. Precision-Engineered Medium-Sized Molecular Host and Emitter for Ensuring Consistent Performance in Solution-Processed Narrowband OLEDs. ACS APPLIED MATERIALS & INTERFACES 2024; 16:16553-16562. [PMID: 38570940 DOI: 10.1021/acsami.3c18848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/05/2024]
Abstract
In this study, two novel multiple resonance (MR) emitters, DtCzBN and Cy-DtCzBN, were designed based on the well-known BCzBN structure and synthesized for narrowband solution-processed organic light-emitting diodes (OLEDs). Cy-DtCzBN possesses a dimeric V-shaped structure formed by coupling two individual DtCzBN units via a nonconjugated cyclohexane linker. When compared with DtCzBN, Cy-DtCzBN, as a medium-sized molecule, was found to maintain the optical and photophysical properties of the corresponding monomeric unit, DtCzBN, but exhibits high thermal stability, excellent solubility, and good film-forming ability. Additionally, solution-processed OLEDs were fabricated by using two sets of molecules: one set of small molecular hosts and emitters (i.e., mCP and DtCzBN) and the other set of medium-sized molecular hosts and emitters (i.e., Cy-mCP and Cy-DtCzBN). Notably, devices using medium-sized molecular hosts and emitters exhibited similar optical and photophysical properties but showed significantly improved reproducibility and thermal stability compared with those based on small molecular hosts and emitters. Our current study provides some insights into molecular design strategies for thermally stable hosts and emitters, which are highly suitable for solution-processed OLEDs.
Collapse
Affiliation(s)
- Jin Young Park
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Na Yeon Kwon
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Chang Woo Koh
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Su Hong Park
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Min Ji Kang
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Haeun Kwak
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Chae Yeong Park
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Weon-Sik Chae
- Daegu Center, Korea Basic Science Institute, 80 Daehakro, Bukgu, Daegu 41566, Republic of Korea
| | - Chang Seop Hong
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Sungnam Park
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Min Ju Cho
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| | - Dong Hoon Choi
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea
| |
Collapse
|
8
|
Diesing S, Zhang L, Zysman-Colman E, Samuel IDW. A figure of merit for efficiency roll-off in TADF-based organic LEDs. Nature 2024; 627:747-753. [PMID: 38538942 PMCID: PMC10972759 DOI: 10.1038/s41586-024-07149-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 02/01/2024] [Indexed: 04/01/2024]
Abstract
Organic light-emitting diodes (OLEDs) are a revolutionary light-emitting display technology that has been successfully commercialized in mobile phones and televisions1,2. The injected charges form both singlet and triplet excitons, and for high efficiency it is important to enable triplets as well as singlets to emit light. At present, materials that harvest triplets by thermally activated delayed fluorescence (TADF) are a very active field of research as an alternative to phosphorescent emitters that usually use heavy metal atoms3,4. Although excellent progress has been made, in most TADF OLEDs there is a severe decrease of efficiency as the drive current is increased, known as efficiency roll-off. So far, much of the literature suggests that efficiency roll-off should be reduced by minimizing the energy difference between singlet and triplet excited states (ΔEST) to maximize the rate of conversion of triplets to singlets by means of reverse intersystem crossing (kRISC)5-20. We analyse the efficiency roll-off in a wide range of TADF OLEDs and find that neither of these parameters fully accounts for the reported efficiency roll-off. By considering the dynamic equilibrium between singlets and triplets in TADF materials, we propose a figure of merit for materials design to reduce efficiency roll-off and discuss its correlation with reported data of TADF OLEDs. Our new figure of merit will guide the design and development of TADF materials that can reduce efficiency roll-off. It will help improve the efficiency of TADF OLEDs at realistic display operating conditions and expand the use of TADF materials to applications that require high brightness, such as lighting, augmented reality and lasing.
Collapse
Affiliation(s)
- S Diesing
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
- Organic Semiconductor Centre, EaStCHEM, School of Chemistry, St Andrews, UK
| | - L Zhang
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
- Organic Semiconductor Centre, EaStCHEM, School of Chemistry, St Andrews, UK
| | - E Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM, School of Chemistry, St Andrews, UK.
| | - I D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK.
| |
Collapse
|
9
|
Luo X, Jin Q, Du M, Wang D, Duan L, Zhang Y. An Ideal Molecular Construction Strategy for Ultra-Narrow-Band Deep-Blue Emitters: Balancing Bathochromic-Shift Emission, Spectral Narrowing, and Aggregation Suppression. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307675. [PMID: 38161235 PMCID: PMC10953554 DOI: 10.1002/advs.202307675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 12/02/2023] [Indexed: 01/03/2024]
Abstract
Narrowband emissive multiple resonance (MR) emitters promise high efficiency and stability in deep-blue organic light-emitting diodes (OLEDs). However, the construction of ideal ultra-narrow-band deep-blue MR emitters still faces formidable challenges, especially in balancing bathochromic-shift emission, spectral narrowing, and aggregation suppression. Here, DICz is chosen, which possesses the smallest full-width-at-half-maximum (FWHM) in MR structures, as the core and solved the above issue by tuning its peripheral substitution sites. The 1-substituted molecule Cz-DICz is able to show a bright deep-blue emission with a peak at 457 nm, an extremely small FWHM of 14 nm, and a CIE coordinate of (0.14, 0.08) in solution. The corresponding OLEDs exhibit high maximum external quantum efficiencies of 22.1%-25.6% and identical small FWHMs of 18 nm over the practical mass-production concentration range (1-4 wt.%). To the best of the knowledge, 14 and 18 nm are currently the smallest FWHM values for deep-blue MR emitters with similar emission maxima under photoluminescence and electroluminescence conditions, respectively. These discoveries will help drive the development of high-performance narrowband deep-blue emitters and bring about a revolution in OLED industry.
Collapse
Affiliation(s)
- Xiaofeng Luo
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of EducationDepartment of ChemistryTsinghua UniversityBeijing100084P. R. China
| | - Qian Jin
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of EducationDepartment of ChemistryTsinghua UniversityBeijing100084P. R. China
| | - Mingxu Du
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of EducationDepartment of ChemistryTsinghua UniversityBeijing100084P. R. China
| | - Dong Wang
- Laboratory of Flexible Electronics TechnologyTsinghua UniversityBeijing100084P. R. China
| | - Lian Duan
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of EducationDepartment of ChemistryTsinghua UniversityBeijing100084P. R. China
- Laboratory of Flexible Electronics TechnologyTsinghua UniversityBeijing100084P. R. China
| | - Yuewei Zhang
- Laboratory of Flexible Electronics TechnologyTsinghua UniversityBeijing100084P. R. China
- Applied Mechanics LabSchool of Aerospace EngineeringTsinghua UniversityBeijing100084P. R. China
| |
Collapse
|
10
|
Mamada M, Hayakawa M, Ochi J, Hatakeyama T. Organoboron-based multiple-resonance emitters: synthesis, structure-property correlations, and prospects. Chem Soc Rev 2024; 53:1624-1692. [PMID: 38168795 DOI: 10.1039/d3cs00837a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Boron-based multiple-resonance (MR) emitters exhibit the advantages of narrowband emission, high absolute photoluminescence quantum yield, thermally activated delayed fluorescence (TADF), and sufficient stability during the operation of organic light-emitting diodes (OLEDs). Thus, such MR emitters have been widely applied as blue emitters in triplet-triplet-annihilation-driven fluorescent devices used in smartphones and televisions. Moreover, they hold great promise as TADF or terminal emitters in TADF-assisted fluorescence or phosphor-sensitised fluorescent OLEDs. Herein we comprehensively review organoboron-based MR emitters based on their synthetic strategies, clarify structure-photophysical property correlations, and provide design guidelines and future development prospects.
Collapse
Affiliation(s)
- Masashi Mamada
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Masahiro Hayakawa
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Junki Ochi
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| | - Takuji Hatakeyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
| |
Collapse
|
11
|
Wang Q, Huang T, Qu Y, Song X, Xu Y, Wang Y. Frontier Molecular Orbital Engineering of Aromatic Donor Fusion: Modularly Constructing Highly Efficient Narrowband Yellow Electroluminescence. ACS APPLIED MATERIALS & INTERFACES 2024; 16:4948-4957. [PMID: 38235687 DOI: 10.1021/acsami.3c14514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2024]
Abstract
The development of high-performance multiple resonance thermally activated delayed fluorescence (MR-TADF) materials with narrowband yellow emission is highly critical for various applications in industries, such as the automotive, aerospace, and microelectronic industries. However, the modular construction approaches to expeditiously access narrowband yellow-emitting materials is relatively rare. Here, a unique molecular design concept based on frontier molecular orbital engineering (FMOE) of aromatic donor fusion is proposed to strategically address this issue. Donor fusion is a modular approach with a "leveraging effect"; through direct polycyclization of donor attached to the MR parent core, it is facile to achieve red-shifted emission by a large margin. As a result, two representative model molecules, namely BN-Cz and BN-Cb, have been constructed successfully. The BN-Cz- and BN-Cb-based sensitized organic light-emitting diodes (OLEDs) exhibit bright yellow emission with peaks of 560 and 556 nm, full-width at half-maxima (fwhm's) of 49 and 45 nm, Commission Internationale de L'Eclairage coordinates of (0.44, 0.55) and (0.43, 0.56), and maximum external quantum efficiencies (EQEs) of 32.9% and 29.7%, respectively. The excellent optoelectronic performances render BN-Cz and BN-Cb one of the most outstanding yellow-emitting MR-TADF materials.
Collapse
Affiliation(s)
- Qingyang Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Tingting Huang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Yupei Qu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Xiaoxian Song
- Jihua Laboratory, 28 Huandao South Road, Foshan 528200, Guangdong Province, P. R. China
- Jihua Hengye Electronic Materials CO. LTD., Foshan 528200, Guangdong Province, P. R. China
| | - Yincai Xu
- 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
- Jihua Hengye Electronic Materials CO. LTD., Foshan 528200, Guangdong Province, P. R. China
| |
Collapse
|
12
|
Ye Z, Wu H, Xu Y, Hua T, Chen G, Chen Z, Yin X, Huang M, Xu K, Song X, Huang Z, Lv X, Miao J, Cao X, Yang C. Deep-Blue Narrowband Hetero[6]helicenes Showing Circularly Polarized Thermally Activated Delayed Fluorescence Toward High-Performance OLEDs. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2308314. [PMID: 37963185 DOI: 10.1002/adma.202308314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/18/2023] [Indexed: 11/16/2023]
Abstract
Helicenes exhibit substantial potential as circularly polarized luminescence (CPL) active molecules. However, their application in circularly polarized organic light-emitting diodes (CP-OLEDs) is typically hindered by the challenge of integrating both high color purity and efficient triplet-harvesting capability, particularly in the blue spectral region. Herein, a series of hetero[6]helicene-based emitters that is strategically engineered through the helical extension of a deep-blue double-boron-based multiple resonance thermally activated delayed fluorescence (MR-TADF) motif, is introduced. Importantly, the helical extension does not cause apparent structural deformation or perturb frontier molecular orbitals; thus, preserving the deep-blue emission and MR-TADF characteristics of the parent molecule. This approach also leads to reduced reorganization energy, resulting in emitters with narrower linewidth and higher photoluminescence quantum yield. Further, the helical motif enhances the racemization barrier and leads to improved CPL performance with luminescence dissymmetry factor values up to 1.5 × 10-3 . Exploiting these merits, devices incorporating the chiral dopants demonstrate deep-blue emission within the Broadcast Service Television 2020 color-gamut range, record external quantum efficiencies (EQEs) up to 29.3%, and have distinctive circularly polarized electroluminescence (CPEL) signals. Overall, the authors' findings underscore the helical extension as a promising strategy for designing narrowband chiroptical materials and advancing high-definition displays.
Collapse
Affiliation(s)
- Zeyuan Ye
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Han Wu
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Yulin Xu
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Tao Hua
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Guohao Chen
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Zhanxiang Chen
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Xiaojun Yin
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Manli Huang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Ke Xu
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Xiufang Song
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Zhongyan Huang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Xialei Lv
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Jingsheng Miao
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Xiaosong Cao
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Chuluo Yang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| |
Collapse
|
13
|
Luo S, Wang J, Li N, Song XF, Wan X, Li K, Yang C. Regulation of Multiple Resonance Delayed Fluorescence via Through-Space Charge Transfer Excited State towards High-Efficiency and Stable Narrowband Electroluminescence. Angew Chem Int Ed Engl 2023; 62:e202310943. [PMID: 37851366 DOI: 10.1002/anie.202310943] [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: 07/30/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 10/19/2023]
Abstract
B- and N-embedded multiple resonance (MR) type thermally activated delayed fluorescence (TADF) emitters usually suffer from slow reverse intersystem crossing (RISC) process and aggregation-caused emission quenching. Here, we report the design of a sandwich structure by placing the B-N MR core between two electron-donating moieties, inducing through-space charge transfer (TSCT) states. The proper adjusting of the energy levels brings about a 10-fold higher RISC rate in comparison with the parent B-N molecule. In the meantime, a high photoluminescence quantum yield of 91 % and a good color purity were maintained. Organic light-emitting diodes based on the new MR emitter achieved a maximum external quantum efficiency of 31.7 % and small roll-offs at high brightness. High device efficiencies were also obtained for a wide range of doping concentrations of up to 20 wt % thanks to the steric shielding of the B-N core. A good operational stability with LT95 of 85.2 h has also been revealed. The dual steric and electronic effects resulting from the introduction of a TSCT state offer an effective molecular design to address the critical challenges of MR-TADF emitters.
Collapse
Affiliation(s)
- Sai Luo
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, 518055, Shenzhen, P. R. China
| | - Junjie Wang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, 518055, Shenzhen, P. R. China
| | - Nengquan Li
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, 518055, Shenzhen, P. R. China
| | - Xiu-Fang Song
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, 518055, Shenzhen, P. R. China
| | - Xintong Wan
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, 518055, Shenzhen, P. R. China
| | - Kai Li
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, 518055, Shenzhen, P. R. China
| | - Chuluo Yang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, 518055, Shenzhen, P. R. China
| |
Collapse
|
14
|
Meng G, Zhou J, Huang T, Dai H, Li X, Jia X, Wang L, Zhang D, Duan L. B-N/B-O Contained Heterocycles as Fusion Locker in Multi-Resonance Frameworks towards Highly-efficient and Stable Ultra-Narrowband Emission. Angew Chem Int Ed Engl 2023; 62:e202309923. [PMID: 37584379 DOI: 10.1002/anie.202309923] [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: 07/12/2023] [Revised: 08/10/2023] [Accepted: 08/11/2023] [Indexed: 08/17/2023]
Abstract
Fusing condensed aromatics into multi-resonance (MR) frameworks has been an exquisite strategy to modulate the optoelectronic properties, which, however, always sacrifices the small full width at half maxima (FWHM). Herein, we strategically embed B-N/B-O contained heterocycles as fusion locker into classical MR prototypes, which could enlarge the π-extension and alleviate the steric repulsion for an enhanced planar skeleton to suppress the high-frequency stretching/ scissoring vibrations for ultra-narrowband emissions. Sky-blue emitters with extremely small FWHMs of 17-18 nm are thereafter obtained for the targeted emitters, decreased by (1.4-1.9)-fold compared with the prototypes. Benefiting from their high photoluminescence quantum yields of >90 % and fast radiative decay rates of >108 s-1 , one of those emitters shows a high maximum external quantum efficiency of 31.9 % in sensitized devices, which remains 25.8 % at a practical luminance of 1,000 cd m-2 with a small FWHM of merely 19 nm. Notably a long operation half-lifetime of 1,278 h is also recorded for the same device, representing one of the longest lifetimes among sky-blue devices based on MR emitters.
Collapse
Affiliation(s)
- Guoyun Meng
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Jianping Zhou
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Tianyu Huang
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Hengyi Dai
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Xiao Li
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Xiaoqin Jia
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Lu Wang
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Dongdong Zhang
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
| | - Lian Duan
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China
- Center for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, P. R. China
| |
Collapse
|
15
|
Wu C, Tong K, Shi K, Jin Z, Wu Y, Mu Y, Huo Y, Tang M, Yang C, Meng H, Kang F, Wei G. New [3+2+1] Iridium Complexes as Effective Phosphorescent Sensitizers for Efficient Narrowband Saturated-Blue Hyper-OLEDs. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2301112. [PMID: 37653609 PMCID: PMC10582407 DOI: 10.1002/advs.202301112] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/23/2023] [Indexed: 09/02/2023]
Abstract
Two newly designed and synthesized [3+2+1] iridium complexes through introducing bulky trimethylsiliyl (TMS) groups are doped with a terminal emitter of v-DABNA to form an coincident overlapping spectra between the emission of these two phosphors and the absorption of v-DABNA, creating cascade resonant energy transfer for efficient triplet harvesting. To boost the color quality and efficiency, the fabricated hyper-OLEDs have been optimized to achieve a high external quantum efficiency of 31.06%, which has been among the highest efficiency results reported for phosphor sensitized saturated-blue hyper-OLEDs, and pure blue emission peak at 467 nm with the full width at half maxima (FWHM) as narrow as 18 nm and the CIEy values down to 0.097, satisfying the National Institute of Standards and Technology (NIST) requirement for saturated blue OLEDs display. Surprisingly, such hyper-OLEDs have obtained the converted lifetime (LT50 ) up to 4552 h at the brightness of 100 cd m-2 , demonstrating effective Förster resonance energy transfer (FRET) process. Therefore, employing these new bulky TMS substituent [3+2+1] iridium(III) complexes for effective sensitizers can greatly pave the way for further development of high efficiency and stable blue OLEDs in display and lighting applications.
Collapse
Affiliation(s)
- Chengcheng Wu
- Tsinghua–Berkeley Shenzhen Institute (TBSI)Tsinghua UniversityShenzhen518055China
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Kai‐Ning Tong
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Kefei Shi
- Tsinghua–Berkeley Shenzhen Institute (TBSI)Tsinghua UniversityShenzhen518055China
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Zhaoyun Jin
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Yuan Wu
- PURI Materials, IncShenzhen518133China
| | - Yingxiao Mu
- School of Chemical Engineering and Light IndustryGuangdong University of TechnologyGuangzhou510006China
| | - Yanping Huo
- School of Chemical Engineering and Light IndustryGuangdong University of TechnologyGuangzhou510006China
| | - Man‐Chung Tang
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Chen Yang
- PURI Materials, IncShenzhen518133China
| | - Hong Meng
- School of Advanced MaterialsShenzhen Graduate SchoolPeking UniversityShenzhen518055China
| | - Feiyu Kang
- Tsinghua–Berkeley Shenzhen Institute (TBSI)Tsinghua UniversityShenzhen518055China
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| | - Guodan Wei
- Tsinghua–Berkeley Shenzhen Institute (TBSI)Tsinghua UniversityShenzhen518055China
- Institute of Materials ResearchTsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China
| |
Collapse
|
16
|
Fan X, Hao X, Huang F, Yu J, Wang K, Zhang X. RGB Thermally Activated Delayed Fluorescence Emitters for Organic Light-Emitting Diodes toward Realizing the BT.2020 Standard. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2303504. [PMID: 37587784 PMCID: PMC10558656 DOI: 10.1002/advs.202303504] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/25/2023] [Indexed: 08/18/2023]
Abstract
With the surging demand for ultra-high-resolution displays, the International Telecommunication Union (ITU) announce the next-generation color gamut standard, named ITU-R Recommendation BT.2020, which not only sets a seductive but challenging milestone for display technologies but also urges researchers to recognize the importance of color coordinates. Organic light-emitting diodes (OLEDs) are an important display technology in current daily life, but they face challenges in approaching the BT.2020 standard. Thermally activated delayed fluorescence (TADF) emitters have bright prospects in OLEDs because they possess 100% theoretical exciton utilization. Thus, the development of TADF emitters emitting primary red (R), green (R), and blue (B) emission is of great significance. Here, a comprehensive overview of the latest advancements in TADF emitters that exhibit Commission Internationale de l'Éclairage (CIE) coordinates surpassing the National Television System Committee (NTSC) and approaching BT.2020 standards is presented. Rational strategies for molecular designs, as well as the resulting photophysical properties and OLED performances, are discussed to elucidate the underlying mechanisms for shifting the CIE coordinates of both donor-acceptor and multiple resonance (MR) typed TADF emitters toward the BT.2020 standard. Finally, the challenges in realization of the wide-color-gamut BT.2020 standard and the prospects for this research area are provided.
Collapse
Affiliation(s)
- Xiaochun Fan
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhouJiangsu215123P. R. China
| | - Xiaoyao Hao
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhouJiangsu215123P. R. China
| | - Feng Huang
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhouJiangsu215123P. R. China
| | - Jia Yu
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhouJiangsu215123P. R. China
- Jiangsu Key Laboratory of Advanced Negative Carbon TechnologiesSoochow UniversitySuzhouJiangsu215123P. R. China
| | - Kai Wang
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhouJiangsu215123P. R. China
- Jiangsu Key Laboratory of Carbon‐Based Functional Materials and DevicesSoochow UniversitySuzhouJiangsu215123P. R. China
| | - Xiaohong Zhang
- Institute of Functional Nano & Soft Materials (FUNSOM)Soochow UniversitySuzhouJiangsu215123P. R. China
- Jiangsu Key Laboratory of Advanced Negative Carbon TechnologiesSoochow UniversitySuzhouJiangsu215123P. R. China
| |
Collapse
|
17
|
Huang Z, Xie H, Miao J, Wei Y, Zou Y, Hua T, Cao X, Yang C. Charge Transfer Excited State Promoted Multiple Resonance Delayed Fluorescence Emitter for High-Performance Narrowband Electroluminescence. J Am Chem Soc 2023. [PMID: 37276361 DOI: 10.1021/jacs.3c01267] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters are promising candidates for narrowband organic light-emitting diodes, but their electroluminescent performance is typically hindered by the slow reverse intersystem crossing rate (kRISC). Herein, we present an effective strategy to introduce a multichannel reverse intersystem crossing (RISC) pathway with large spin-orbit coupling by orthogonally linking an electron-donating unit to the MR framework. Through delicate manipulation of the excited-state energy levels, an additional intersegmental charge transfer triplet state could be "silently" induced without perturbing the MR character of the lowest excited singlet state. The proof-of-concept emitter CzBN3 not only affords 23-fold increase of kRISC compared with its prototypical MR skeleton but also realizes close-to-unity photoluminescence quantum yield, large radiative rate constant, and very narrow emission spectrum. These merits enable high maximum external quantum efficiency (EQEmax) of up to 37.1% and alleviated efficiency roll-off in the sensitizer-free device (EQE1000 = 30.4%), and a further boost of efficiency (EQEmax/1000 = 42.3/34.1%) is realized in the hyperfluorescent device. The state-of-the-art electroluminescent performance validates the superiority of our molecular design strategy.
Collapse
Affiliation(s)
- Zhongyan Huang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China
| | - Honghui Xie
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China
| | - Jingsheng Miao
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China
| | - Yaxiong Wei
- Anhui Province Key Laboratory of Optoelectric Materials Science and Technology, School of Physics and Electronic Information, Anhui Normal University, Wuhu 241000, China
| | - Yang Zou
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China
| | - Tao Hua
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China
| | - Xiaosong Cao
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China
| | - Chuluo Yang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China
| |
Collapse
|
18
|
Xiaofeng L, Dongdong Z, Lian D, Yuewei Z. Sterically wrapping of multi-resonant fluorophores: an effective strategy to suppress concentration quenching and spectral broadening. Front Chem 2023; 11:1198404. [PMID: 37214480 PMCID: PMC10196060 DOI: 10.3389/fchem.2023.1198404] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 04/24/2023] [Indexed: 05/24/2023] Open
Abstract
Multiple resonance (MR) emitters are promising for the next-generation wide color gamut organic light-emitting diodes (OLEDs) with narrowband emissions; however, they still face intractable challenges such as concentration-induced emission quenching, exciton annihilation, and spectral broadening. In this concept, we focus on an advanced molecular design strategy called "sterically wrapping of MR fluorophores" to address the above issues. By isolating the MR emission core using bulky substituents, intermolecular interactions can be significantly suppressed to eliminate the formation of unfavorable species. Consequently, using the newly designed emitters, optimized MR-OLEDs can achieve high external quantum efficiencies of >40% while maintaining extremely small full width at half maxima (FWHMs) of <25 nm over a wide range of concentrations (1-20 wt%). This strategy may shed light on the design of efficient MR emitters, which provides more room for tuning the dopant concentrations under the premise of high-efficiencies and small FWHMs, accelerating the practical application of MR-OLEDs.
Collapse
Affiliation(s)
- Luo Xiaofeng
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, China
| | - Zhang Dongdong
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, China
| | - Duan Lian
- Key Lab of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, China
- Center for Flexible Electronics Technology, Tsinghua University, Beijing, China
| | - Zhang Yuewei
- Center for Flexible Electronics Technology, Tsinghua University, Beijing, China
| |
Collapse
|
19
|
Nguyen TB, Nakanotani H, Chan CY, Kakumachi S, Adachi C. Enhancing Triplet-Triplet Upconversion Efficiency and Operational Lifetime in Blue Organic Light-Emitting Diodes by Utilizing Thermally Activated Delayed Fluorescence Materials. ACS APPLIED MATERIALS & INTERFACES 2023; 15:23557-23563. [PMID: 37146232 DOI: 10.1021/acsami.3c02855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In the process of triplet-triplet upconversion (TTU), a bright excited singlet can be generated because of the collision of two dark excited triplets. In particular, the efficiency of TTU is crucial for achieving a high exciton production yield in blue fluorescence organic light-emitting diodes (OLEDs) beyond the theoretical limit. While the theoretical upper limit of TTU contribution yield is expected to be 60%, blue OLEDs with the maximum TTU contribution are still scarce. Herein, we present a proof of concept for realizing the maximum TTU contribution yield in blue OLEDs, achieved through the doping of thermally activated delayed fluorescence (TADF) molecules in the carrier recombination zone. The bipolar carrier transport ability of TADF materials enables direct carrier recombination on the molecules, resulting in the expansion of the recombination zone. Although the external electroluminescence quantum efficiency of OLEDs is slightly lower than that of conventional TTU-OLEDs due to the low photoluminescence quantum yield of the doped layer, the TTU efficiency approaches the upper limit. Furthermore, the operational device lifetime of OLEDs employing TADF molecules increased by five times compared to the conventional ones, highlighting the expansion of the recombination zone as a crucial factor for enhancing overall OLED performance in TTU-OLEDs.
Collapse
Affiliation(s)
- Thanh B Nguyen
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Hajime Nakanotani
- Center for Organic Photonics and Electronics Research (OPERA), 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
| | - Chin-Yiu Chan
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Shunta Kakumachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), 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
| |
Collapse
|
20
|
Lou Q, Chen N, Zhu J, Liu K, Li C, Zhu Y, Xu W, Chen X, Song Z, Liang C, Shan CX, Hu J. Thermally Enhanced and Long Lifetime Red TADF Carbon Dots via Multi-Confinement and Phosphorescence Assisted Energy Transfer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2211858. [PMID: 36893767 DOI: 10.1002/adma.202211858] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Revised: 02/28/2023] [Indexed: 05/19/2023]
Abstract
Thermally activated delayed fluorescence (TADF) materials, which can harvest both singlet and triplet excitons for high-efficiency emission, have attracted widespread concern for their enormous applications. Nevertheless, luminescence thermal quenching severely limits the efficiency and operating stability in TADF materials and devices at high temperature. Herein, a surface engineering strategy is adopted to obtain unique carbon dots (CDs)-based thermally enhanced TADF materials with ≈250% enhancement from 273 to 343 K via incorporating seed CDs into ionic crystal network. The rigid crystal network can simultaneously boost reverse intersystem crossing process via enhancing spin-orbit coupling between singlet and triplet states and suppressing non-radiative transition rate, contributing to the thermally enhanced TADF character. Benefiting from efficient energy transfer from triplet states of phosphorescence center to singlet states of CDs, TADF emission at ≈600 nm in CDs displays a long lifetime up to 109.6 ms, outperforming other red organic TADF materials. Thanks to variable decay rates of the delayed emission centers, time and temperature-dependent delayed emission color has been first realized in CDs-based delayed emission materials. The CDs with thermally enhanced and time-/temperature-dependent emission in one material system can offer new opportunities in information protection and processing.
Collapse
Affiliation(s)
- Qing Lou
- State Centre for International Cooperation on Designer Low-Carbon & Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
- Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, 450052, P. R. China
| | - Niu Chen
- State Centre for International Cooperation on Designer Low-Carbon & Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
- Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou, 450002, P. R. China
| | - Jinyang Zhu
- State Centre for International Cooperation on Designer Low-Carbon & Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Kaikai Liu
- Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, 450052, P. R. China
| | - Chao Li
- College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang, 473061, P. R. China
| | - Yongsheng Zhu
- College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang, 473061, P. R. China
| | - Wen Xu
- Key Laboratory of New Energy and Rare Earth Resource Utilization of State Ethnic Affairs Commission, Key Laboratory of Photosensitive Materials & Devices of Liaoning Province, School of Physics and Materials Engineering, Dalian Minzu University, Dalian, 116600, P. R. China
| | - Xu Chen
- Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, 450052, P. R. China
| | - Zhijiang Song
- Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou, 450002, P. R. China
| | - Changhao Liang
- Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou, 450002, P. R. China
| | - Chong-Xin Shan
- Key Laboratory of Material Physics, Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou, 450052, P. R. China
| | - Junhua Hu
- State Centre for International Cooperation on Designer Low-Carbon & Environmental Materials, School of Materials Science and Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
- Longzihu New Energy Laboratory, Zhengzhou University, Zhengzhou, 450001, P. R. China
| |
Collapse
|
21
|
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.
Collapse
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.
| |
Collapse
|
22
|
Incorporation of a Boron-Nitrogen Covalent Bond Improves the Charge-Transport and Charge-Transfer Characteristics of Organoboron Small-Molecule Acceptors for Organic Solar Cells. Molecules 2023; 28:molecules28020811. [PMID: 36677871 PMCID: PMC9861936 DOI: 10.3390/molecules28020811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/09/2023] [Accepted: 01/11/2023] [Indexed: 01/15/2023] Open
Abstract
An organoboron small-molecular acceptor (OSMA) MB←N containing a boron-nitrogen coordination bond (B←N) exhibits good light absorption in organic solar cells (OSCs). In this work, based on MB←N, OSMA MB-N, with the incorporation of a boron-nitrogen covalent bond (B-N), was designed. We have systematically investigated the charge-transport properties and interfacial charge-transfer characteristics of MB-N, along with MB←N, using the density functional theory (DFT) and the time-dependent density functional theory (TD-DFT). Theoretical calculations show that MB-N can simultaneously boost the open-circuit voltage (from 0.78 V to 0.85 V) and the short-circuit current due to its high-lying lowest unoccupied molecular orbital and the reduced energy gap. Moreover, its large dipole shortens stacking and greatly enhances electron mobility by up to 5.91 × 10-3 cm2·V-1·s-1. Notably, the excellent interfacial properties of PTB7-Th/MB-N, owing to more charge transfer states generated through the direct excitation process and the intermolecular electric field mechanism, are expected to improve OSCs performance. Together with the excellent properties of MB-N, we demonstrate a new OSMA and develop a new organoboron building block with B-N units. The computations also shed light on the structure-property relationships and provide in-depth theoretical guidance for the application of organoboron photovoltaic materials.
Collapse
|