1
|
Kim HS, Lee SH, Yoo S, Adachi C. Understanding of complex spin up-conversion processes in charge-transfer-type organic molecules. Nat Commun 2024; 15:2267. [PMID: 38480706 PMCID: PMC10937997 DOI: 10.1038/s41467-024-46406-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 02/13/2024] [Indexed: 03/17/2024] Open
Abstract
Despite significant progress made over the past decade in thermally activated delayed fluorescence (TADF) molecules as a material paradigm for enhancing the performance of organic light-emitting diodes, the underlying spin-flip mechanism in these charge-transfer (CT)-type molecular systems remains an enigma, even since its initial report in 2012. While the initial and final electronic states involved in spin-flip between the lowest singlet and lowest triplet excited states are well understood, the exact dynamic processes and the role of intermediate high-lying triplet (T) states are still not fully comprehended. In this context, we propose a comprehensive model to describe the spin-flip processes applicable for a typical CT-type molecule, revealing the origin of the high-lying T state in a partial molecular framework in CT-type molecules. This work provides experimental and theoretical insights into the understanding of intersystem crossing for CT-type molecules, facilitating more precise control over spin-flip rates and thus advancing toward developing the next-generation platform for purely organic luminescent candidates.
Collapse
Affiliation(s)
- 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
| | - Sang Hoon Lee
- Department of Applied Chemistry, Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Seunghyup Yoo
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
| | - 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.
| |
Collapse
|
2
|
Kim HS, Cheon HJ, Lee D, Lee W, Kim J, Kim YH, Yoo S. Toward highly efficient deep-blue OLEDs: Tailoring the multiresonance-induced TADF molecules for suppressed excimer formation and near-unity horizontal dipole ratio. SCIENCE ADVANCES 2023; 9:eadf1388. [PMID: 37256963 PMCID: PMC10413681 DOI: 10.1126/sciadv.adf1388] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 04/24/2023] [Indexed: 06/02/2023]
Abstract
Boron-based compounds exhibiting a multiresonance thermally activated delayed fluorescence are regarded promising as a narrowband blue emitter desired for efficient displays with wide color gamut. However, their planar nature makes them prone to concentration-induced excimer formation that broadens the emission spectrum, making it hard to increase the emitter concentration without raising CIE y coordinate. To overcome this bottleneck, we here propose o-Tol-ν-DABNA-Me, wherein sterically hindered peripheral phenyl groups are introduced to reduce intermolecular interactions, leading to excimer formation and thus making the pure narrowband emission character far less sensitive to concentration. With this approach, we demonstrate deep-blue OLEDs with y of 0.12 and full width at half maximum of 18 nm, with maximum external quantum efficiency (EQE) of ca. 33%. Adopting a hyperfluorescent architecture, the OLED performance is further enhanced to EQE of 35.4%, with mitigated efficiency roll-off, illustrating the immense potential of the proposed method for energy-efficient deep-blue OLEDs.
Collapse
Affiliation(s)
- Hyung Suk Kim
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Hyung Jin Cheon
- Department of Chemistry and RIGET, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Donggyun Lee
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Woochan Lee
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Junho Kim
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Yun-Hi Kim
- Department of Chemistry and RIGET, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Seunghyup Yoo
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| |
Collapse
|
3
|
Gao C, Zeng J, Zhang X, Liu Y, Zhan ZP. A Photosensitizer for N-O Bond Activation: 2,7-Br-4CzIPN-Catalyzed Difunctionalization of Alkenes with Oxime Esters. Org Lett 2023; 25:3146-3151. [PMID: 37083314 DOI: 10.1021/acs.orglett.3c01073] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
We developed 2,4,5,6-tetrakis(2,7-dibromo-9H-carbazol-9-yl)isophthalonitrile (2,7-Br-4CzIPN) as a new photosensitizer for the energy-transfer-driven N-O bond dissociation of oxime esters. In the presence of 2,7-Br-4CzIPN, difunctionalization of alkenes with oxime esters, including oxyimination, aminocarboxylation, and amidylimination, could afford a variety of versatile molecules in good yields with excellent regioselectivity, which widely occur in natural products and drugs. Our theoretical investigations and experiments have demonstrated that 2,7-Br-4CzIPN has unique photophysical properties, favorable triplet energy, and excellent photocatalytic activity.
Collapse
Affiliation(s)
- Cai Gao
- Department of Chemistry and Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People's Republic of China
| | - Jiahao Zeng
- Department of Chemistry and Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People's Republic of China
| | - Xianming Zhang
- Department of Chemistry and Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People's Republic of China
| | - Yanzhi Liu
- Department of Chemistry and Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People's Republic of China
| | - Zhuang-Ping Zhan
- Department of Chemistry and Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, People's Republic of China
| |
Collapse
|
4
|
Singlet and triplet to doublet energy transfer: improving organic light-emitting diodes with radicals. Nat Commun 2022; 13:2744. [PMID: 35585063 PMCID: PMC9117228 DOI: 10.1038/s41467-022-29759-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 03/02/2022] [Indexed: 11/30/2022] Open
Abstract
Organic light-emitting diodes (OLEDs) must be engineered to circumvent the efficiency limit imposed by the 3:1 ratio of triplet to singlet exciton formation following electron-hole capture. Here we show the spin nature of luminescent radicals such as TTM-3PCz allows direct energy harvesting from both singlet and triplet excitons through energy transfer, with subsequent rapid and efficient light emission from the doublet excitons. This is demonstrated with a model Thermally-Activated Delayed Fluorescence (TADF) organic semiconductor, 4CzIPN, where reverse intersystem crossing from triplets is characteristically slow (50% emission by 1 µs). The radical:TADF combination shows much faster emission via the doublet channel (80% emission by 100 ns) than the comparable TADF-only system, and sustains higher electroluminescent efficiency with increasing current density than a radical-only device. By unlocking energy transfer channels between singlet, triplet and doublet excitons, further technology opportunities are enabled for optoelectronics using organic radicals. Organic light-emitting diodes must be engineered to circumvent efficiency limits imposed by the ratio of triplet to singlet exciton formation, following electron-hole capture. Here, authors unlock energy transfer channels between singlet, triplet and doublet excitons using thermally activated delayed fluorescence and radical emitters towards more efficient light-emitting devices.
Collapse
|
5
|
Yurash B, Dixon A, Espinoza C, Mikhailovsky A, Chae S, Nakanotani H, Adachi C, Nguyen TQ. Efficiency of Thermally Activated Delayed Fluorescence Sensitized Triplet Upconversion Doubled in Three-Component System. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2103976. [PMID: 34793602 DOI: 10.1002/adma.202103976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/01/2021] [Indexed: 06/13/2023]
Abstract
As in many fields, the most exciting endeavors in photon upconversion research focus on increasing the efficiency (upconversion quantum yield) and performance (anti-Stokes shift) while diminishing the cost of production. In this vein, studies employing metal-free thermally activated delayed fluorescence (TADF) sensitizers have garnered increased interest. Here, for the first time, the strategy of ternary photon upconversion is utilized with the TADF sensitizer 2,4,5,6-tetrakis(carbazol-9-yl)isophthalonitrile (4CzIPN), resulting in a doubling of the upconversion quantum yield in comparison to the binary system employing p-terphenyl as the emitter. In this ternary blend, the sensitizer 4CzIPN is paired with an intermediate acceptor, 1-methylnaphthalene, in addition to the emitter molecule, p-terphenyl, yielding a normalized upconversion quantum yield of 7.6% while maintaining the 0.83 eV anti-Stokes shift. These results illustrate the potential benefits of utilizing this strategy of energy-funneling, previously used only with heavy-metal based sensitizers, to increase the performance of these photon upconversion systems.
Collapse
Affiliation(s)
- Brett Yurash
- Center for Polymers and Organic Solids (CPOS) and Department of Chemistry & Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| | - Alana Dixon
- Center for Polymers and Organic Solids (CPOS) and Department of Chemistry & Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| | - Carolina Espinoza
- Center for Polymers and Organic Solids (CPOS) and Department of Chemistry & Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| | - Alexander Mikhailovsky
- Center for Polymers and Organic Solids (CPOS) and Department of Chemistry & Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| | - Sangmin Chae
- Center for Polymers and Organic Solids (CPOS) and Department of Chemistry & Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| | - Hajime Nakanotani
- 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
| | - Thuc-Quyen Nguyen
- Center for Polymers and Organic Solids (CPOS) and Department of Chemistry & Biochemistry, University of California, Santa Barbara, CA, 93106, USA
| |
Collapse
|
6
|
Hasan M, Saggar S, Shukla A, Bencheikh F, Sobus J, McGregor SKM, Adachi C, Lo SC, Namdas EB. Probing polaron-induced exciton quenching in TADF based organic light-emitting diodes. Nat Commun 2022; 13:254. [PMID: 35017481 PMCID: PMC8752634 DOI: 10.1038/s41467-021-27739-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 12/06/2021] [Indexed: 11/10/2022] Open
Abstract
Polaron-induced exciton quenching in thermally activated delayed fluorescence (TADF)-based organic light-emitting diodes (OLEDs) can lead to external quantum efficiency (EQE) roll-off and device degradation. In this study, singlet-polaron annihilation (SPA) and triplet-polaron annihilation (TPA) were investigated under steady-state conditions and their relative contributions to EQE roll-off were quantified, using experimentally obtained parameters. It is observed that both TPA and SPA can lead to efficiency roll-off in 2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN) doped OLEDs. Charge imbalance and singlet-triplet annihilation (STA) were found to be the main contributing factors, whereas the device degradation process is mainly dominated by TPA. It is also shown that the impact of electric field-induced exciton dissociation is negligible under the DC operation regime (electric field < 0.5 MV cm-1). Through theoretical simulation, it is demonstrated that improvement to the charge recombination rate may reduce the effect of polaron-induced quenching, and thus significantly decrease the EQE roll-off.
Collapse
Affiliation(s)
- Monirul Hasan
- School of Mathematics and Physics, The University of Queensland, Brisbane, QLD, 4072, Australia
- Centre for Organic Photonics & Electronics, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Siddhartha Saggar
- School of Mathematics and Physics, The University of Queensland, Brisbane, QLD, 4072, Australia
- Centre for Organic Photonics & Electronics, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Atul Shukla
- School of Mathematics and Physics, The University of Queensland, Brisbane, QLD, 4072, Australia
- Centre for Organic Photonics & Electronics, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Fatima Bencheikh
- Center for Organic Photonics and Electronics Research, Kyushu University, Fukuoka, 819-0395, Japan
| | - Jan Sobus
- School of Mathematics and Physics, The University of Queensland, Brisbane, QLD, 4072, Australia
- Centre for Organic Photonics & Electronics, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Sarah K M McGregor
- Centre for Organic Photonics & Electronics, The University of Queensland, Brisbane, QLD, 4072, Australia
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research, Kyushu University, Fukuoka, 819-0395, Japan.
| | - Shih-Chun Lo
- Centre for Organic Photonics & Electronics, The University of Queensland, Brisbane, QLD, 4072, Australia.
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia.
| | - Ebinazar B Namdas
- School of Mathematics and Physics, The University of Queensland, Brisbane, QLD, 4072, Australia.
- Centre for Organic Photonics & Electronics, The University of Queensland, Brisbane, QLD, 4072, Australia.
| |
Collapse
|
7
|
Su R, Huang Z. "H-Type" Like Constructed Dimer: Another Way to Enhance the Thermally Activated Delayed Fluorescence Effect. J Phys Chem Lett 2021; 12:11497-11502. [PMID: 34797082 DOI: 10.1021/acs.jpclett.1c03044] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Thermally activated delayed fluorescence (TADF) materials are an essential part of TADF-based organic light-emitting diodes (OLEDs). All the reported methods to improve the performance of TADF materials were focused on achieving a high reverse intersystem crossing rate (kRISC) and oscillator strength (f), but most of them were studies on single molecular states. In this paper, we have discovered a new dimer architecture called the "H-type" like dimer and proved that the "H-type" like dimer is another way to improve the performance of TADF materials by calculation and experiment. The calculated energy levels of excited states only provided 1.72-5.46% relative errors (RE) compare with the measured values, which indicated that the methods we chose were suitable for predicting the properties. The intermolecular interactions of the "H-type" like dimer endow it with much larger f and kRISC properties than monomer states, proving that the "H-type" like dimer could improve the performance of TADF emitters.
Collapse
Affiliation(s)
- Rongchuan Su
- Department of Pharmacology, North Sichuan Medical College, Nanchong 637100, China
| | - Zhenmei Huang
- College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, China
| |
Collapse
|
8
|
Tsuchiya Y, Diesing S, Bencheikh F, Wada Y, Dos Santos PL, Kaji H, Zysman-Colman E, Samuel IDW, Adachi C. Exact Solution of Kinetic Analysis for Thermally Activated Delayed Fluorescence Materials. J Phys Chem A 2021; 125:8074-8089. [PMID: 34473511 DOI: 10.1021/acs.jpca.1c04056] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photophysical analysis of thermally activated delayed fluorescence (TADF) materials has become instrumental for providing insights into their stability and performance, which is not only relevant for organic light-emitting diodes but also for other applications such as sensing, imaging, and photocatalysis. Thus, a deeper understanding of the photophysics underpinning the TADF mechanism is required to push materials design further. Previously reported analyses in the literature of the kinetics of the various processes occurring in a TADF material rely on several a priori assumptions to estimate the rate constants for forward and reverse intersystem crossing. In this report, we demonstrate a method to determine these rate constants using a three-state model together with a steady-state approximation and, importantly, no additional assumptions. Further, we derive the exact rate equations, greatly facilitating a comparison of the TADF properties of structurally diverse emitters and providing a comprehensive understanding of the photophysics of these systems.
Collapse
Affiliation(s)
- Youichi Tsuchiya
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Stefan Diesing
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, Fife, St Andrews KY16 9ST, U.K.,Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, Fife, St Andrews KY16 9ST, U.K
| | - Fatima Bencheikh
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Yoshimasa Wada
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Paloma L Dos Santos
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, Fife, St Andrews KY16 9ST, U.K
| | - Hironori Kaji
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, Fife, St Andrews KY16 9ST, U.K
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, Fife, St Andrews KY16 9ST, U.K
| | - 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 (WPI-I2CNER), Kyushu University, 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| |
Collapse
|
9
|
Liu Y, Hua L, Zhao Z, Ying S, Ren Z, Yan S. High-Efficiency Solution-Processable OLEDs by Employing Thermally Activated Delayed Fluorescence Emitters with Multiple Conversion Channels of Triplet Excitons. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2101326. [PMID: 34313017 PMCID: PMC8456236 DOI: 10.1002/advs.202101326] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/30/2021] [Indexed: 05/29/2023]
Abstract
The state-of-the-art luminescent materials are gained widely by utilizing thermally activated delayed fluorescence (TADF) mechanism. However, the feasible molecular designing strategy of fully exploiting triplet excitons to enhance TADF properties is still in demand. Herein, TADF emitters with multiple conversion channels of triplet excitons are designed by concisely halogenating the electron acceptors containing carbonyl moiety. Compared with the chlorinated and brominated analogues, the fluorinated emitter exhibits distinguishing molecular stacking structures, participating in the formation of trimers through integrating CH···F and C═O···H hydrogen bonds together. It is also demonstrated that the multiple channels can be involved synergistically to accelerate the spin-flip of triplet excitons, and to take charge of the relatively superior reverse intersystem crossing constant rate of 6.20 × 105 s-1 , and thus excellent photoluminescence quantum yields over 90% can easily be achieved. Then the solution-processable organic light emitting diode based on fluorinated emitter can achieve a record-high external quantum efficiency value of 27.13% and relatively low efficiency roll-off with remaining 24.74% at 1000 cd m-2 . This result manifests the significance of enhancing photophysical properties through constructing multiple conversion channels of triplets excitons for high-efficiency TADF emitters and provides a guideline for the future study.
Collapse
Affiliation(s)
- Yuchao Liu
- State Key Laboratory of Chemical Resource EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China
- Key Laboratory of Rubber‐PlasticsMinistry of EducationQingdao University of Science & TechnologyQingdao266042P.R. China
| | - Lei Hua
- State Key Laboratory of Chemical Resource EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China
| | - Zhennan Zhao
- State Key Laboratory of Chemical Resource EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China
| | - Shian Ying
- Key Laboratory of Rubber‐PlasticsMinistry of EducationQingdao University of Science & TechnologyQingdao266042P.R. China
| | - Zhongjie Ren
- State Key Laboratory of Chemical Resource EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China
| | - Shouke Yan
- State Key Laboratory of Chemical Resource EngineeringCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China
- Key Laboratory of Rubber‐PlasticsMinistry of EducationQingdao University of Science & TechnologyQingdao266042P.R. China
| |
Collapse
|
10
|
Jung YH, Karthik D, Lee H, Maeng JH, Yang KJ, Hwang S, Kwon JH. A New BODIPY Material for Pure Color and Long Lifetime Red Hyperfluorescence Organic Light-Emitting Diode. ACS APPLIED MATERIALS & INTERFACES 2021; 13:17882-17891. [PMID: 33826283 DOI: 10.1021/acsami.1c03175] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A red fluorescent material, 1,3,7,9-tetrakis(4-(tert-butyl)phenyl)-5,5-difluoro-10-(2-methoxyphenyl)-5H-4l4,5l4-dipyrrolo[1,2-c:2',1'-f][1,3,2]diazaborinine (4tBuMB), as an emitting dopant in a thermally activated delayed fluorescence (TADF) sensitized hyperfluorescence organic light-emitting diode (HFOLED) is reported. The 4tBuMB shows a high photoluminescence quantum yield (PLQY) of 99% with an emission maximum at 620 nm and a full width at half-maximum (fwhm) of 31 nm in solution. Further, it shows a deep lowest unoccupied molecular orbital (LUMO) of 3.83 eV. Thus, two TADF materials, 4CzIPN and 4CzTPN, as sensitizing hosts, are selected on the basis of a suitable LUMO level and spectrum overlap with 4tBuMB. The fabricated HFOLED device with 4CzTPN as a sensitizing host and 4tBuMB as an emitting dopant shows a maximum external quantum efficiency (EQE), an emission maximum, an fwhm, and CIE coordinates of 19.4%, 617 nm, 44 nm, and (0.64, 0.36), respectively. The electroluminance performances of the 4CzTPN sensitized device are higher than those of the 4CzIPN-based device, which is attributed to a higher Förster resonance energy transfer (FRET) rate and reduced intersystem crossing/reverse intersystem crossing (ISC/RISC) cycles of the former. Also, the 4CzTPN-based HF device shows a longer device lifetime (LT90) of 954 h than the 4CzIPN-baed device (LT90 of 57 h) at 3000 cd m-2. The higher device stability is due to the higher bond dissociation energies (BDEs) of 4CzTPN and 4tBuMB than that of 4CzIPN.
Collapse
Affiliation(s)
- Young Hun Jung
- Organic Optoelectronic Device Laboratory, Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Durai Karthik
- Organic Optoelectronic Device Laboratory, Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Hyuna Lee
- Organic Optoelectronic Device Laboratory, Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Jee Hyun Maeng
- Organic Optoelectronic Device Laboratory, Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Ki Joon Yang
- Organic Optoelectronic Device Laboratory, Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Soonjae Hwang
- Organic Optoelectronic Device Laboratory, Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| | - Jang Hyuk Kwon
- Organic Optoelectronic Device Laboratory, Department of Information Display, Kyung Hee University, 26, Kyungheedae-ro, Dongdaemun-gu, Seoul, 02447, Republic of Korea
| |
Collapse
|
11
|
Jakoby M, Heidrich S, Graf von Reventlow L, Degitz C, Suresh SM, Zysman-Colman E, Wenzel W, Richards BS, Howard IA. Method for accurate experimental determination of singlet and triplet exciton diffusion between thermally activated delayed fluorescence molecules. Chem Sci 2020; 12:1121-1125. [PMID: 34163879 PMCID: PMC8179038 DOI: 10.1039/d0sc05190j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Understanding triplet exciton diffusion between organic thermally activated delayed fluorescence (TADF) molecules is a challenge due to the unique cycling between singlet and triplet states in these molecules. Although prompt emission quenching allows the singlet exciton diffusion properties to be determined, analogous analysis of the delayed emission quenching does not yield accurate estimations of the triplet diffusion length (because the diffusion of singlet excitons regenerated after reverse-intersystem crossing needs to be accounted for). Herein, we demonstrate how singlet and triplet diffusion lengths can be accurately determined from accessible experimental data, namely the integral prompt and delayed fluorescence. In the benchmark materials 4CzIPN and 4TCzBN, we show that the singlet diffusion lengths are (9.1 ± 0.2) and (12.8 ± 0.3) nm, whereas the triplet diffusion lengths are negligible, and certainly less than 1.0 and 1.2 nm, respectively. Theory confirms that the lack of overlap between the shielded lowest unoccupied molecular orbitals (LUMOs) hinders triplet motion between TADF chromophores in such molecular architectures. Although this cause for the suppression of triplet motion does not occur in molecular architectures that rely on electron resonance effects (e.g. DiKTa), we find that triplet diffusion is still negligible when such molecules are dispersed in a matrix material at a concentration sufficiently low to suppress aggregation. The novel and accurate method of understanding triplet diffusion in TADF molecules will allow accurate physical modeling of OLED emitter layers (especially those based on TADF donors and fluorescent acceptors). A method for measuring triplet diffusion between TADF molecules is presented, and implications of limited triplet diffusion for OLEDs discussed.![]()
Collapse
Affiliation(s)
- Marius Jakoby
- Institute of Microstructure Technology, Karlsruhe Institute of Technology Hermann-von-Helmholtz-Platz 1 D-76344 Eggenstein-Leopoldshafen Germany
| | - Shahriar Heidrich
- Institute of Nanotechnology Technology, Karlsruhe Institute of Technology Hermann-von-Helmholtz-Platz 1 D-76344 Eggenstein-Leopoldshafen Germany
| | - Lorenz Graf von Reventlow
- Light Technology Institute, Karlsruhe Institute of Technology Engesserstrasse 13 D-76131 Karlsruhe Germany
| | - Carl Degitz
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews St Andrews KY16 9ST UK
| | - Subeesh Madayanad Suresh
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews St Andrews KY16 9ST UK
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews St Andrews KY16 9ST UK
| | - Wolfgang Wenzel
- Institute of Nanotechnology Technology, Karlsruhe Institute of Technology Hermann-von-Helmholtz-Platz 1 D-76344 Eggenstein-Leopoldshafen Germany
| | - Bryce S Richards
- Institute of Microstructure Technology, Karlsruhe Institute of Technology Hermann-von-Helmholtz-Platz 1 D-76344 Eggenstein-Leopoldshafen Germany .,Light Technology Institute, Karlsruhe Institute of Technology Engesserstrasse 13 D-76131 Karlsruhe Germany
| | - Ian A Howard
- Institute of Microstructure Technology, Karlsruhe Institute of Technology Hermann-von-Helmholtz-Platz 1 D-76344 Eggenstein-Leopoldshafen Germany .,Light Technology Institute, Karlsruhe Institute of Technology Engesserstrasse 13 D-76131 Karlsruhe Germany
| |
Collapse
|
12
|
Nyga A, Izumi S, Higginbotham HF, Stachelek P, Pluczyk S, Silva P, Minakata S, Takeda Y, Data P. Electrochemical and Spectroelectrochemical Comparative Study of Macrocyclic Thermally Activated Delayed Fluorescent Compounds: Molecular Charge Stability vs OLED EQE Roll‐Off. ASIAN J ORG CHEM 2020. [DOI: 10.1002/ajoc.202000475] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Aleksandra Nyga
- Faculty of Chemistry Silesian University of Technology M. Strzody 9 44–100 Gliwice Poland
| | - Saika Izumi
- Department of Applied Chemistry Graduate School of Engineering Osaka University Yamadaoka 2–1, Suita Osaka 5650871 Japan
| | | | - Patrycja Stachelek
- Physics Department Durham University South Road Durham DH1 3LE United Kingdom
| | - Sandra Pluczyk
- Faculty of Chemistry Silesian University of Technology M. Strzody 9 44–100 Gliwice Poland
| | - Piotr Silva
- Department of Energy Conversion and Storage Technical University of Denmark Anker Engelunds Vej 301 2800 Kgs. Lyngby Denmark
| | - Satoshi Minakata
- Department of Applied Chemistry Graduate School of Engineering Osaka University Yamadaoka 2–1, Suita Osaka 5650871 Japan
| | - Youhei Takeda
- Department of Applied Chemistry Graduate School of Engineering Osaka University Yamadaoka 2–1, Suita Osaka 5650871 Japan
| | - Przemyslaw Data
- Faculty of Chemistry Silesian University of Technology M. Strzody 9 44–100 Gliwice Poland
- Centre of Polymer and Carbon Materials Polish Academy of Science M. Curie-Sklodowskiej 34 41–819 Zabrze Poland
| |
Collapse
|
13
|
Tian H, Yang H, Tian C, An G, Li G. Cross-Dehydrogenative Coupling of Strong C(sp3)–H with N-Heteroarenes through Visible-Light-Induced Energy Transfer. Org Lett 2020; 22:7709-7715. [DOI: 10.1021/acs.orglett.0c02912] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Haitao Tian
- Key Laboratory of Functional Inorganic Material Chemistry (MOE), School of Chemistry and Materials Science, Heilongjiang University, No. 74, Xuefu Road, Nangang District, Harbin 150080, People’s Republic of China
| | - Hui Yang
- Key Laboratory of Functional Inorganic Material Chemistry (MOE), School of Chemistry and Materials Science, Heilongjiang University, No. 74, Xuefu Road, Nangang District, Harbin 150080, People’s Republic of China
| | - Chao Tian
- Key Laboratory of Functional Inorganic Material Chemistry (MOE), School of Chemistry and Materials Science, Heilongjiang University, No. 74, Xuefu Road, Nangang District, Harbin 150080, People’s Republic of China
| | - Guanghui An
- Key Laboratory of Functional Inorganic Material Chemistry (MOE), School of Chemistry and Materials Science, Heilongjiang University, No. 74, Xuefu Road, Nangang District, Harbin 150080, People’s Republic of China
- College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin, Heilongjiang 150001, China
| | - Guangming Li
- Key Laboratory of Functional Inorganic Material Chemistry (MOE), School of Chemistry and Materials Science, Heilongjiang University, No. 74, Xuefu Road, Nangang District, Harbin 150080, People’s Republic of China
| |
Collapse
|
14
|
Franco O, Jakoby M, Schneider RV, Hundemer F, Hahn D, Richards BS, Bräse S, Meier MAR, Lemmer U, Howard IA. Sensitizing TADF Absorption Using Variable Length Oligo(phenylene ethynylene) Antennae. Front Chem 2020; 8:126. [PMID: 32175310 PMCID: PMC7054278 DOI: 10.3389/fchem.2020.00126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 02/12/2020] [Indexed: 12/23/2022] Open
Abstract
Beyond their applications in organic light-emitting diodes (OLEDs), thermally activated delayed fluorescence (TADF) materials can also make good photonic markers. Time-gated measurement of their delayed emission enables “background-free” imaging in, for example, biological systems, because no naturally-occurring compounds exhibit such long-lived emission. Attaching a strongly-absorbing antenna, such as a phenylene ethynylene oligomer, to the TADF core would be of interest to increase their brightness as photonic markers. With this motivation, we study a sequence of TADF-oligomer conjugates with oligomers of varying length and show that, even when the absorption of the oligomer is almost resonant with the charge-transfer absorption of the TADF core, the antenna transfers energy to the TADF core. We study this series of compounds with time resolved emission and transient absorption spectroscopy and find that the delayed fluorescence is essentially turned-off for the longer antennae. Interestingly, we find that the turn-off of the delayed fluorescence is not caused by quenching of the TADF charge-transfer triplet state due to triplet energy transfer of the lower-lying triplet state to the antenna, but must be associated with a decrease in the reverse intersystem crossing rate. These results are of relevance for the further development of TADF “dyes” and also, in the broader context, for understanding the dynamics of TADF molecules in the vicinity of energy donors/acceptors (i.e., in fluorescent OLEDs wherein TADF molecules are used as an assistant dopant).
Collapse
Affiliation(s)
- Olga Franco
- Department of Electrical Engineering and Information Technology, Light Technology Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Marius Jakoby
- Department of Electrical Engineering and Information Technology, Institute of Microstructure Technology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Rebekka V Schneider
- Laboratory of Applied Chemistry, Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Fabian Hundemer
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Daniel Hahn
- Laboratory of Applied Chemistry, Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Bryce S Richards
- Department of Electrical Engineering and Information Technology, Light Technology Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Department of Electrical Engineering and Information Technology, Institute of Microstructure Technology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Stefan Bräse
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Biological and Chemical Systems - Functional Molecular Systems, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Michael A R Meier
- Laboratory of Applied Chemistry, Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Biological and Chemical Systems - Functional Molecular Systems, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Uli Lemmer
- Department of Electrical Engineering and Information Technology, Light Technology Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Department of Electrical Engineering and Information Technology, Institute of Microstructure Technology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Ian A Howard
- Department of Electrical Engineering and Information Technology, Light Technology Institute, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Department of Electrical Engineering and Information Technology, Institute of Microstructure Technology, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| |
Collapse
|