1
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Jin JM, Liu D, Chen WC, Shi C, Chen G, Wang X, Xing L, Ying W, Ji S, Huo Y, Su SJ. Synergetic Modulation of Steric Hindrance and Excited State for Anti-Quenching and Fast Spin-Flip Multi-Resonance Thermally Activated Delayed Fluorophore. Angew Chem Int Ed Engl 2024; 63:e202401120. [PMID: 38326521 DOI: 10.1002/anie.202401120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 02/05/2024] [Accepted: 02/06/2024] [Indexed: 02/09/2024]
Abstract
Multi-resonance thermally activated delayed fluorescence (MR-TADF) materials hold great promise for advanced high-resolution organic light-emitting diode (OLED) displays. However, persistent challenges, such as severe aggregation-caused quenching (ACQ) and slow spin-flip, hinder their optimal performance. We propose a synergetic steric-hindrance and excited-state modulation strategy for MR-TADF emitters, which is demonstrated by two blue MR-TADF emitters, IDAD-BNCz and TIDAD-BNCz, bearing sterically demanding 8,8-diphenyl-8H-indolo[3,2,1-de]acridine (IDAD) and 3,6-di-tert-butyl-8,8-diphenyl-8H-indolo[3,2,1-de]acridine (TIDAD), respectively. These rigid and bulky IDAD/TIDAD moieties, with appropriate electron-donating capabilities, not only effectively mitigate ACQ, ensuring efficient luminescence across a broad range of dopant concentrations, but also induce high-lying charge-transfer excited states that facilitate triplet-to-singlet spin-flip without causing undesired emission redshift or spectral broadening. Consequently, implementation of a high doping level of IDAD-BNCz resulted in highly efficient narrowband electroluminescence, featuring a remarkable full-width at half-maximum of 34 nm and record-setting external quantum efficiencies of 34.3 % and 31.8 % at maximum and 100 cd m-2, respectively. The combined steric and electronic effects arising from the steric-hindered donor introduction offer a compelling molecular design strategy to overcome critical challenges in MR-TADF emitters.
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Affiliation(s)
- Jia-Ming Jin
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, 510006, Guangzhou, P. R. China
| | - Denghui Liu
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, 510640, Guangzhou, P. R. China
| | - Wen-Cheng Chen
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, 510006, Guangzhou, P. R. China
- Guangdong Provincial Laboratory of Chemistry and Fine Chemical Engineering Jieyang Center, 515200, Jieyang, P. R. China
| | - Chengxiang Shi
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, 510006, Guangzhou, P. R. China
| | - Guowei Chen
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, 510006, Guangzhou, P. R. China
| | - Xiaofeng Wang
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, 510006, Guangzhou, P. R. China
| | - Longjiang Xing
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, 510006, Guangzhou, P. R. China
| | - Weidong Ying
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, 510006, Guangzhou, P. R. China
| | - Shaomin Ji
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, 510006, Guangzhou, P. R. China
- Guangdong Provincial Laboratory of Chemistry and Fine Chemical Engineering Jieyang Center, 515200, Jieyang, P. R. China
| | - Yanping Huo
- School of Chemical Engineering and Light Industry, Guangdong University of Technology, 510006, Guangzhou, P. R. China
- Guangdong Provincial Laboratory of Chemistry and Fine Chemical Engineering Jieyang Center, 515200, Jieyang, P. R. China
- Analytical & Testing Center, Guangdong University of Technology, 510006, Guangzhou, P. R. China
| | - Shi-Jian Su
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, 510640, Guangzhou, P. R. China
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2
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Heo Y, Kwon H, Park S, Dae S, Lee H, Lee K, Park J. A High-Efficiency Deep Blue Emitter for OLEDs with a New Dual-Core Structure Incorporating ETL Characteristics. Molecules 2023; 28:7485. [PMID: 38005207 PMCID: PMC10673098 DOI: 10.3390/molecules28227485] [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: 10/17/2023] [Revised: 11/04/2023] [Accepted: 11/07/2023] [Indexed: 11/26/2023] Open
Abstract
In this study, we introduced the weak electron-accepting oxazole derivative 4,5-diphenyl-2-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)oxazole (TPO) into both anthracene and pyrene moieties of a dual core structure. Ultimately, we developed 2-(4-(6-(anthracen-9-yl)pyren-1-yl)phenyl)-4,5-diphenyloxazole (AP-TPO) as the substitution on the second core, pyrene, and 4,5-diphenyl-2-(4-(10-(pyren-1-yl)anthracen-9-yl)phenyl)oxazole (TPO-AP) as the substitution on the first core, anthracene. Both materials exhibited maximum photoluminescence wavelengths at 433 and 443 nm in solution and emitted deep blue light with high photoluminescence quantum yields of 82% and 88%, respectively. When used as the emitting layer in non-doped devices, TPO-AP outperformed AP-TPO, achieving a current efficiency of 5.49 cd/A and an external quantum efficiency of 4.26% in electroluminescence. These materials introduce a new category of deep blue emitters in the organic light-emitting diodes field, combining characteristics related to the electron transport layer.
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Affiliation(s)
| | | | | | | | | | | | - Jongwook Park
- Integrated Engineering, Department of Chemical Engineering, Kyung Hee University, Gyeonggi 17104, Republic of Korea; (Y.H.); (H.K.); (S.P.); (S.D.); (H.L.); (K.L.)
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3
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Zhao H, Kim J, Ding K, Jung M, Li Y, Ade H, Lee JY, Forrest SR. Control of Host-Matrix Morphology Enables Efficient Deep-Blue Organic Light-Emitting Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2210794. [PMID: 36638153 DOI: 10.1002/adma.202210794] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 12/22/2022] [Indexed: 06/17/2023]
Abstract
Mixing a sterically bulky, electron-transporting host material into a conventional single host-guest emissive layer is demonstrated to suppress phase separation of the host matrix while increasing the efficiency and operational lifetime of deep-blue phosphorescent organic light-emitting diodes (PHOLEDs) with chromaticity coordinates of (0.14, 0.15). The bulky host enables homogenous mixing of the molecules comprising the emissive layer while suppressing single host aggregation; a significant loss channel of nonradiative recombination. By controlling the amorphous phase of the host-matrix morphology, the mixed-host device achieves a significant reduction in nonradiative exciton decay, resulting in 120 ± 6% increase in external quantum efficiency relative to an analogous, single-host device. In contrast to single host PHOLEDs where electrons are transported by the host and holes by the dopants, both charge carriers are conducted by the mixed host, reducing the probability of exciton annihilation, thereby doubling of the deep-blue PHOLED operational lifetime. These findings demonstrate that the host matrix morphology affects almost every aspect of PHOLED performance.
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Affiliation(s)
- Haonan Zhao
- Department of Physics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jongchan Kim
- Department of Electrical and Computer Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Kan Ding
- Department of Physics, North Carolina State University, Raleigh, NC, 27695, USA
| | - Mina Jung
- School of Chemical Engineering, Sungkyunkwan University, Suwon, Gyeonggi, 03063, Republic of Korea
| | - Yongxi Li
- Department of Physics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Harald Ade
- Department of Physics, North Carolina State University, Raleigh, NC, 27695, USA
| | - Jun Yeob Lee
- School of Chemical Engineering, Sungkyunkwan University, Suwon, Gyeonggi, 03063, Republic of Korea
| | - Stephen R Forrest
- Department of Physics, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Electrical and Computer Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
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4
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Mahmoudi M, Gudeika D, Kutsiy S, Simokaitiene J, Butkute R, Skhirtladze L, Woon KL, Volyniuk D, Grazulevicius JV. Ornamenting of Blue Thermally Activated Delayed Fluorescence Emitters by Anchor Groups for the Minimization of Solid-State Solvation and Conformation Disorder Corollaries in Non-Doped and Doped Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2022; 14:40158-40172. [PMID: 36000983 PMCID: PMC9460442 DOI: 10.1021/acsami.2c12475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 08/09/2022] [Indexed: 06/15/2023]
Abstract
Motivated to minimize the effects of solid-state solvation and conformation disorder on emission properties of donor-acceptor-type emitters, we developed five new asymmetric multiple donor-acceptor type derivatives of tert-butyl carbazole and trifluoromethyl benzene exploiting different electron-accepting anchoring groups. Using this design strategy, for a compound containing four di-tert-butyl carbazole units as donors as well as 5-methyl pyrimidine and trifluoromethyl acceptor moieties, small singlet-triplet splitting of ca. 0.03 eV, reverse intersystem crossing rate of 1 × 106 s-1, and high photoluminescence quantum yield of neat film of ca. 75% were achieved. This compound was also characterized by the high value of hole and electron mobilities of 8.9 × 10-4 and 5.8 × 10-4 cm2 V-1 s-1 at an electric field of 4.7 × 105 V/cm, showing relatively good hole/electron balance, respectively. Due to the lowest conformational disorder and solid-state solvation effects, this compound demonstrated very similar emission properties (emission colors) in non-doped and differently doped organic light-emitting diodes (OLEDs). The lowest conformational disorder was observed for the compound with the additional accepting moiety inducing steric hindrance, limiting donor-acceptor dihedral rotational freedom. It can be exploited in the multi-donor-acceptor approach, increasing the efficiency. Using an emitter exhibiting the minimized solid-state solvation and conformation disorder effects, the sky blue OLED with the emitting layer of this compound dispersed in host 1,3-bis(N-carbazolyl)benzene displayed an emission peak at 477 nm, high brightness over 39 000 cd/m2, and external quantum efficiency up to 15.9% along with a maximum current efficiency of 42.6 cd/A and a maximum power efficiency of 24.1 lm/W.
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Affiliation(s)
- Malek Mahmoudi
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, Radvilenu pl.19, Kaunas LT-50254, Lithuania
| | - Dalius Gudeika
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, Radvilenu pl.19, Kaunas LT-50254, Lithuania
| | - Stepan Kutsiy
- Department
of Electronic Devices, Lviv Polytechnic
National University, S. Bandera 12, Lviv 79013, Ukraine
| | - Jurate Simokaitiene
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, Radvilenu pl.19, Kaunas LT-50254, Lithuania
| | - Rita Butkute
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, Radvilenu pl.19, Kaunas LT-50254, Lithuania
| | - Levani Skhirtladze
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, Radvilenu pl.19, Kaunas LT-50254, Lithuania
| | - Kai Lin Woon
- Low
Dimensional Material Research Centre, Department of Physics, University Malaya, Kuala Lumpur 50603, Malaysia
| | - Dmytro Volyniuk
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, Radvilenu pl.19, Kaunas LT-50254, Lithuania
| | - Juozas Vidas Grazulevicius
- Department
of Polymer Chemistry and Technology, Kaunas
University of Technology, Radvilenu pl.19, Kaunas LT-50254, Lithuania
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5
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Zhang Z, Zhu Y, Wu Y, Zhao C, Meng H. A Localized Planarization Strategy in Hole Mobility Modulation of Disordered Triphenylamine‐Based Organic Semiconductors. ADVANCED THEORY AND SIMULATIONS 2021. [DOI: 10.1002/adts.202100236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Zewei Zhang
- School of Advanced Materials Peking University Shenzhen Graduated School Peking University Shenzhen 518055 China
| | - Yanan Zhu
- School of Advanced Materials Peking University Shenzhen Graduated School Peking University Shenzhen 518055 China
| | - Yuting Wu
- School of Advanced Materials Peking University Shenzhen Graduated School Peking University Shenzhen 518055 China
| | - Chongguang Zhao
- School of Advanced Materials Peking University Shenzhen Graduated School Peking University Shenzhen 518055 China
- State High‐Tech Industrial Innovation Center Shenzhen 518057 China
| | - Hong Meng
- School of Advanced Materials Peking University Shenzhen Graduated School Peking University Shenzhen 518055 China
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6
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Tang Y, Xie G, Yin X, Gao Y, Ding J, Yang C. Unravelling Electroplex Emission from Long-Range Charge Transfer Based on a Phosphorescent Dendrimer as the Electron Donor. J Phys Chem Lett 2020; 11:5255-5262. [PMID: 32519541 DOI: 10.1021/acs.jpclett.0c01482] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report the exceptionally long-range charge-transfer-induced electroplex between a neat dendrimer emitter and the adjacent electron-transporting layer (ETL). Interestingly, the electroplex exists even in the dilute emitter with a sufficiently low concentration (0.5 wt %) in an inert host. The iridium dendrimer with the carbazole-based dendritic ligands exhibits bright emission, peaking at 536 nm, with a full width at half-maximum (fwhm) of 77 nm in the devices without any ETLs. Unexpectedly, once the ETLs are inserted, a significantly broadened emission (fwhm = 115 nm) is detectable under electroluminescence. Taking advantage of the broad interfacial electroplex emission, a hybrid warm-white device was demonstrated by combining a sky-blue thermally activated delayed fluorescence emitter, exhibiting a maximum external quantum efficiency of 13.7%, which is an order of magnitude higher than that of any other reported works based on the electroplex white organic light-emitting diodes.
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Affiliation(s)
- Yang Tang
- Sauvage Center for Molecular Sciences, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, People's Republic of China
- College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Guohua Xie
- Sauvage Center for Molecular Sciences, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, People's Republic of China
| | - Xiaojun Yin
- College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Yuhan Gao
- Sauvage Center for Molecular Sciences, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, People's Republic of China
| | - Junqiao Ding
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
| | - Chuluo Yang
- Sauvage Center for Molecular Sciences, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, People's Republic of China
- College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
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7
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Role of Molecular Orbital Energy Levels in OLED Performance. Sci Rep 2020; 10:9915. [PMID: 32555238 PMCID: PMC7303122 DOI: 10.1038/s41598-020-66946-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 05/27/2020] [Indexed: 11/08/2022] Open
Abstract
Abundant molecules enable countless combinations of device architecture that might achieve the desirable high efficiency from organic light-emitting diodes (OLEDs). Due to the relatively high cost of OLED materials and facilities, simulation approaches have become a must in further advancing the field faster and saver. We have demonstrated here the use of state-of-art simulation approaches to investigate the effect of molecular orbital energy levels on the recombination of excitons in OLED devices. The devices studied are composed of 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) as hole transporting material (HTM), 4,4'-Bis(9-carbazolyl)-1,1'-biphenyl (CBP) as host, 2,2',2"-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) or bathophenanthroline (Bphen) as electron transporting materials. The outcomes reveal that exciton recombination highly sensitive to the energy-level alignment, injection barriers, and charge mobilities. A low energy-barrier (<0.4 eV) between the layers is the key to yield high recombination. The lowest unoccupied molecular orbital (LUMO) levels of the organic layers have played a more pivotal role in governing the recombination dynamics than the highest occupied molecular orbital (HOMO) level do. Furthermore, the Bphen based device shows high exciton recombination across the emissive layer, which is >106 times greater than that in the TPBi based device. The high carrier mobility of Bphen whose electron mobility is 5.2 × 10-4 cm2 V-1 s-1 may lead to low charge accumulation and hence high exciton dynamics. The current study has successfully projected an in-depth analysis on the suitable energy-level alignments, which would further help to streamline future endeavours in developing efficient organic compounds and designing devices with superior performance.
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8
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Baek SY, Kwak SY, Kim ST, Hwang KY, Koo H, Son WJ, Choi B, Kim S, Choi H, Baik MH. Ancillary ligand increases the efficiency of heteroleptic Ir-based triplet emitters in OLED devices. Nat Commun 2020; 11:2292. [PMID: 32385259 PMCID: PMC7210992 DOI: 10.1038/s41467-020-16091-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 04/01/2020] [Indexed: 11/23/2022] Open
Abstract
The excellent contrast ratio, visibility, and advantages in producing thin and light displays let organic light emitting diodes change the paradigm of the display industry. To improve future display technologies, higher electroluminescence efficiency is needed. Herein, the detailed study of the non-radiative decay mechanism employing density functional theory calculations is carried out and a simple, general strategy for the design of the ancillary ligand is formulated. It is shown that steric bulk properly directed towards the phenylisoquinoline ligands can significantly reduce the non-radiative decay rate. Though Ir-based dopants with ancillary ligands are attractive for realizing efficient organic light-emitting diodes, a strategy for designing these materials remains elusive. Here, the authors report a design strategy for heteroleptic triplet OLED emitters featuring functionalized ancillary ligands.
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Affiliation(s)
- Seung-Yeol Baek
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.,Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
| | - Seung-Yeon Kwak
- Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., Suwon, 16678, Republic of Korea
| | - Seoung-Tae Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.,Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea
| | - Kyu Young Hwang
- Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., Suwon, 16678, Republic of Korea
| | - Hyun Koo
- Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., Suwon, 16678, Republic of Korea
| | - Won-Joon Son
- Data and Information Technology (DIT) Center, Samsung Electronics, Hwaseong, 18448, Republic of Korea
| | - Byoungki Choi
- Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., Suwon, 16678, Republic of Korea
| | - Sunghan Kim
- Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., Suwon, 16678, Republic of Korea
| | - Hyeonho Choi
- Samsung Advanced Institute of Technology (SAIT), Samsung Electronics Co., Ltd., Suwon, 16678, Republic of Korea.
| | - Mu-Hyun Baik
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea. .,Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, Republic of Korea.
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9
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Chandrasekaran N, Li C, Singh S, Kumar A, McNeill CR, Huettner S, Kabra D. Role of Molecular and Interchain Ordering in the Formation of a δ-Hole-Transporting Layer in Organic Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2020; 12:3806-3814. [PMID: 31840485 DOI: 10.1021/acsami.9b17341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Interface engineering, especially the realization of Ohmic contacts at the interface between organic semiconductors and metal contacts, is one of the essential preconditions to achieve high-efficiency organic electronic devices. Here, the interface structures of polymer/fullerene blends are correlated with the charge extraction/injection properties of working organic solar cells. The model system-poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM)-is fabricated using two different degrees of P3HT regioregularity to alter the blend interchain order and molecular packing, resulting in different device performances. Investigations by electroabsorption spectroscopy on these devices indicate a significant reduction (≈1 V) in the built-in potential with an increase in the P3HT regioregularity. This observation is also supported by a change in the work function (WF) of high regioregular polymer blends from photoelectron spectroscopy measurements. These results confirm the presence of a strong dipole layer acting as a δ-hole-transporting layer at the polymer/MoO3/Ag electrode interface. Unipolar hole-only devices show an increase in the magnitude of the hole current in high regioregular P3HT devices, suggesting an increase in the hole injection/extraction efficiency inside the device with a δ-hole-transporting layer. Microscopically, near-edge X-ray absorption fine structure spectroscopy was conducted to probe the surface microstructure in these blends, finding a highly edge-on orientation of P3HT chains in blends made with high regioregular P3HT. This edge-on orientation of P3HT chains at the interface results in a layer of oriented alkyl side chains capping the surface, which favors the formation of a dipole layer at the polymer/MoO3 interface. The increase in the charge extraction efficiency due to the formation of a δ-hole-transporting layer thus results in higher short circuit currents and fill factor values, eventually increasing the device efficiency in high regioregular P3HT devices despite a slight decrease in cell open circuit voltage. These findings emphasize the significance of WF control as a tool for improved device performance and pave the way toward interfacial optimization based on the modulation of fundamental polymer properties, such as polymer regioregularity.
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Affiliation(s)
- Naresh Chandrasekaran
- IITB-Monash Research Academy , IIT Bombay , Mumbai 400076 , India
- Department of Materials Science and Engineering , Monash University , Wellington Road , Clayton , Victoria 3800 , Australia
| | - Cheng Li
- School of Electronic Science and Engineering , Xiamen University , Xiamen 361005 , China
- Department of Chemistry , Universität Bayreuth , Bayreuth 95440 , Germany
| | | | | | - Christopher R McNeill
- Department of Materials Science and Engineering , Monash University , Wellington Road , Clayton , Victoria 3800 , Australia
| | - Sven Huettner
- Department of Chemistry , Universität Bayreuth , Bayreuth 95440 , Germany
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10
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Wei X, Liu Y, Hu T, Li Z, Liu J, Wang R, Gao H, Hu X, Liu G, Wang P, Lee CS, Wang Y. Design of Efficient Exciplex Emitters by Decreasing the Energy Gap Between the Local Excited Triplet ( 3LE) State of the Acceptor and the Charge Transfer (CT) States of the Exciplex. Front Chem 2019; 7:188. [PMID: 31024884 PMCID: PMC6465540 DOI: 10.3389/fchem.2019.00188] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Accepted: 03/11/2019] [Indexed: 11/13/2022] Open
Abstract
A series of thermally activated delayed fluorescence (TADF) exciplex based on the TX-TerPy were constructed. The electronic coupling between the triplet local excited states (3LE) of the donors and acceptor and the charge transfer states had a great influence on the triplet exciton harvesting and ΦPL. Herein, based on this strategy, three donor molecules TAPC, TCTA, and m-MTDATA were selected. The local triplet excited state (3LE) of the three donors are 2.93, 2.72 and 2.52 eV in pure films. And the 3LE of TX-TerPy is 2.69 eV in polystyrene film. The energy gap between the singlet charge transfer (1CT) states of TAPC:TX-TerPy (7:1), TCTA:TX-TerPy (7:1) and the 3LE of TX-TerPy are 0.30 eV and 0.20 eV. Finally, the ΦPL of TAPC:TX-TerPy (7:1) and TCTA:TX-TerPy (7:1) are 65.2 and 69.6%. When we changed the doping concentration of the exciplex from 15% to 50%, the ratio of the triplet decreased, and ΦPL decreased by half, perhaps due to the increased energy gap between 1CT and 3LE. Therefore, optimizing the 1CT, 3CT, and 3LE facilitated the efficient exciplex TADF molecules.
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Affiliation(s)
- Xiaofang Wei
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Yanwei Liu
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, China.,Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Taiping Hu
- School of Future Technology, University of Chinese Academy of Sciences, Beijing, China.,Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Zhiyi Li
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Jianjun Liu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Ruifang Wang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Honglei Gao
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Xiaoxiao Hu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Guanhao Liu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Pengfei Wang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Chun-Sing Lee
- Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong, Hong Kong
| | - Ying Wang
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
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11
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Jurow MJ, Morgenstern T, Eisler C, Kang J, Penzo E, Do M, Engelmayer M, Osowiecki WT, Bekenstein Y, Tassone C, Wang LW, Alivisatos AP, Brütting W, Liu Y. Manipulating the Transition Dipole Moment of CsPbBr 3 Perovskite Nanocrystals for Superior Optical Properties. NANO LETTERS 2019; 19:2489-2496. [PMID: 30848600 DOI: 10.1021/acs.nanolett.9b00122] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Colloidal cesium lead halide perovskite nanocrystals exhibit unique photophysical properties including high quantum yields, tunable emission colors, and narrow photoluminescence spectra that have marked them as promising light emitters for applications in diverse photonic devices. Randomly oriented transition dipole moments have limited the light outcoupling efficiency of all isotropic light sources, including perovskites. In this report we design and synthesize deep blue emitting, quantum confined, perovskite nanoplates and analyze their optical properties by combining angular emission measurements with back focal plane imaging and correlating the results with physical characterization. By reducing the dimensions of the nanocrystals and depositing them face down onto a substrate by spin coating, we orient the average transition dipole moment of films into the plane of the substrate and improve the emission properties for light emitting applications. We then exploit the sensitivity of the perovskite electronic transitions to the dielectric environment at the interface between the crystal and their surroundings to reduce the angle between the average transition dipole moment and the surface to only 14° and maximize potential light emission efficiency. This tunability of the electronic transition that governs light emission in perovskites is unique and, coupled with their excellent photophysical properties, introduces a valuable method to extend the efficiencies and applications of perovskite based photonic devices beyond those based on current materials.
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Affiliation(s)
- Matthew J Jurow
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Thomas Morgenstern
- Institute of Physics , University of Augsburg , 86135 Augsburg , Germany
| | - Carissa Eisler
- Department of Chemistry and Materials Science and Engineering , University of California , Berkeley , California 94720 , United States
| | - Jun Kang
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Erika Penzo
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Mai Do
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Manuel Engelmayer
- Institute of Physics , University of Augsburg , 86135 Augsburg , Germany
| | - Wojciech T Osowiecki
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Department of Chemistry and Materials Science and Engineering , University of California , Berkeley , California 94720 , United States
| | - Yehonadav Bekenstein
- Department of Chemistry and Materials Science and Engineering , University of California , Berkeley , California 94720 , United States
| | - Christopher Tassone
- SSRL Materials Science Division , SLAC National Accelerator Laboratory , 2575 Sand Hill Rd MS 69 , Menlo Park , California 94025 , United States
| | - Lin-Wang Wang
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - A Paul Alivisatos
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Department of Chemistry and Materials Science and Engineering , University of California , Berkeley , California 94720 , United States
- Kavli Energy NanoScience Institute , Berkeley , California 94720 , United States
| | - Wolfgang Brütting
- Institute of Physics , University of Augsburg , 86135 Augsburg , Germany
| | - Yi Liu
- Molecular Foundry , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
- Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
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12
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Wang Z, Li M, Gan L, Cai X, Li B, Chen D, Su S. Predicting Operational Stability for Organic Light-Emitting Diodes with Exciplex Cohosts. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1802246. [PMID: 30989033 PMCID: PMC6446740 DOI: 10.1002/advs.201802246] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/27/2019] [Indexed: 05/06/2023]
Abstract
Organic light-emitting diodes (OLEDs) employing exciplex cohosts have gained attractive interest due to the promising high efficiency, low driving voltage, and potential low cost in future solid-state lighting sources and full-color displays. However, their device lifetime is still the most challenging weakness and rarely studied, which is regarded as a time consuming and complicated work. Therefore, a simplified but effective and comprehensive approach is demonstrated to give prediction for the exciplex cohosts operating lifespan and analyze their possible degradation mechanisms by considering molecular dissociated activation energy with internal exciton dynamics correlations. As a consequence, strong chemical bond stability for the hole transport moieties and rapid reactive exciton relaxation have the intrinsic talent to access potentially long-lived exciplex cohosts, achieving an extended lifetime of 10169 h for the predicted long-lived exciplex cohost OLEDs. Degradation behaviors further confirm that the deteriorated source is attributed to the formation of exciton quenchers and hole traps from excited states and charged-excited states, respectively. The current findings establish a universal technique to screen the stable exciplex cohost candidates with economic time consumption and expenses.
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Affiliation(s)
- Zhiheng Wang
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou510640P. R. China
| | - Mengke Li
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou510640P. R. China
| | - Lin Gan
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou510640P. R. China
| | - Xinyi Cai
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou510640P. R. China
| | - Binbin Li
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou510640P. R. China
| | - Dongcheng Chen
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou510640P. R. China
| | - Shi‐Jian Su
- State Key Laboratory of Luminescent Materials and Devices and Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou510640P. R. China
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13
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Colella M, Pander P, Pereira DDS, Monkman AP. Interfacial TADF Exciplex as a Tool to Localize Excitons, Improve Efficiency, and Increase OLED Lifetime. ACS APPLIED MATERIALS & INTERFACES 2018; 10:40001-40007. [PMID: 30381946 DOI: 10.1021/acsami.8b15942] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this work, we employ a thermally activated delayed fluorescence (TADF) exciplex formed between the emissive layer (EML) host, 26DCzPPy, and the electron transport layer (ETL) 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine at the interface between the EML and the ETL to improve the stability and efficiency of a phosphorescence organic light-emitting diode based on Ir(dmpq)2acac. We show that the presence of the TADF exciplex at the EML-ETL interface induces an efficient localization of the recombination zone, which is confined within the 5 nm thick EML. Furthermore, the TADF exciplex allows harvesting of the holes and electrons that piled up at the EML-ETL interface and transfers the resultant excited state energy to the phosphorescent emitter through Förster and/or Dexter energy transfer. This approach effectively improves the LT90 of devices from <1 min to 6 h by limiting recombination processes outside of the 5 nm EML.
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Affiliation(s)
- Marco Colella
- Physics Department , Durham University , South Road , Durham DH1 3LE , United Kingdom
| | - Piotr Pander
- Physics Department , Durham University , South Road , Durham DH1 3LE , United Kingdom
| | - Daniel de Sa Pereira
- Physics Department , Durham University , South Road , Durham DH1 3LE , United Kingdom
| | - Andrew P Monkman
- Physics Department , Durham University , South Road , Durham DH1 3LE , United Kingdom
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14
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Jayabharathi J, Abirama Sundari G, Thanikachalam V, Panimozhi S. Enhanced internal quantum efficiency of organic light-emitting diodes: A synergistic effect. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2018.06.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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15
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Shih CJ, Lee CC, Yeh TH, Biring S, Kesavan KK, Amin NRA, Chen MH, Tang WC, Liu SW, Wong KT. Versatile Exciplex-Forming Co-Host for Improving Efficiency and Lifetime of Fluorescent and Phosphorescent Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2018; 10:24090-24098. [PMID: 29943574 DOI: 10.1021/acsami.8b08281] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report a new efficient exciplex-forming system consisting of a biscarbazole donor and a triazine-based acceptor. The new exciplex was characterized with a high photoluminescence quantum yield up to 68% and effective thermally activated delayed fluorescence behavior. The BCzPh:3P-T2T (2:1, 30 nm) blend was examined not only as an emitting layer (device D1) but also a reliable co-host of fluorescent and phosphorescent emitters for giving highly efficient exciplex-based organic light-emitting diodes (OLEDs) with a high maximum external quantum efficiency of 15.5 and 29.7% for devices doped with 1 wt % C545T (device D2) and 8 wt % Ir(ppy)2(acac) (device D4), respectively. More strikingly, a strongly enhanced lifetime ( T75 = 16 927 min.) of the C545T-doped device was obtained. The transient electroluminescence measurement as well as capacitance-voltage and impedance-voltage correlations were utilized to explore the factors governing the high efficiency and stability. The obtained results clearly show that the energy transfer and charge transport is highly efficient; they also show the photoelectric semiconducting characteristics of exciplex-based OLEDs, which are significantly different from those of unipolar host-based reference devices D3 (Alq3: 1 wt % C545T) and D5 (CBP: 8 wt % Ir(ppy)2(acac)). Our works have established a systematic protocol to shed light on the mechanisms behind exciplex-based devices. The combined results also confirm the bright prospect of the exciplex-forming system as the co-host for highly efficient and stable OLEDs.
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Affiliation(s)
- Chun-Jen Shih
- Department of Electronic Engineering , National Taiwan University of Science and Technology , Taipei 10617 , Taiwan
| | - Chih-Chien Lee
- Department of Electronic Engineering , National Taiwan University of Science and Technology , Taipei 10617 , Taiwan
| | - Tzu-Hung Yeh
- Department of Electronic Engineering , National Taiwan University of Science and Technology , Taipei 10617 , Taiwan
| | | | | | | | | | - Wei-Chieh Tang
- Department of Chemistry , National Taiwan University , Taipei 10617 , Taiwan
| | | | - Ken-Tsung Wong
- Department of Chemistry , National Taiwan University , Taipei 10617 , Taiwan
- Institute of Atomic and Molecular Science , Academia Sinica , Taipei 10617 , Taiwan
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16
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Jayabharathi J, Ramya R, Thanikachalam V, Nethaji P. Optical and electroluminescent performances of dihydrobenzodioxin phenanthroimidazoles based blue-emitting materials. J Photochem Photobiol A Chem 2018. [DOI: 10.1016/j.jphotochem.2018.02.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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17
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Shih CJ, Lee CC, Chen YH, Biring S, Kumar G, Yeh TH, Sen S, Liu SW, Wong KT. Exciplex-Forming Cohost for High Efficiency and High Stability Phosphorescent Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2018; 10:2151-2157. [PMID: 29265796 DOI: 10.1021/acsami.7b15034] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
An exciplex forming cohost system is employed to achieve a highly efficient organic light-emitting diode (OLED) with good electroluminescent lifetime. The exciplex is formed at the interfacial contact of a conventional star-shaped carbazole hole-transporting material, 4,4',4″-tris(N-carbazolyl)-triphenylamine (TCTA), and a triazine electron-transporting material, 2,4,6-tris[3-(1H-pyrazol-1-yl)phenyl]-1,3,5-triazine (3P-T2T). The excellent combination of TCTA and 3P-T2T is applied as the cohost of a common green phosphorescent emitter with almost zero energy loss. When Ir(ppy)2(acac) is dispersed in such exciplex cohost system, OLED device with maximum external quantum efficiency of 29.6%, the ultrahigh power efficiency of 147.3 lm/W, and current efficiency of 107 cd/A were successfully achieved. More importantly, the OLED device showed a low-efficiency roll-off and an operational lifetime (τ80) of ∼1020 min with the initial brightness of 2000 cd/m2, which is 56 times longer than the reference device. The significant difference of device stability was attributed to the degradation of exciplex system for energy transfer process, which was investigated by the photoluminescence aging measurement at room temperature and 100 K, respectively.
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Affiliation(s)
- Chun-Jen Shih
- Department of Electronic Engineering, National Taiwan University of Science and Technology , Taipei 10617, Taiwan
| | - Chih-Chien Lee
- Department of Electronic Engineering, National Taiwan University of Science and Technology , Taipei 10617, Taiwan
| | - Ying-Hao Chen
- Department of Electronic Engineering, National Taiwan University of Science and Technology , Taipei 10617, Taiwan
| | | | | | - Tzu-Hung Yeh
- Department of Electronic Engineering, National Taiwan University of Science and Technology , Taipei 10617, Taiwan
| | | | | | - Ken-Tsung Wong
- Department of Chemistry, National Taiwan University , Taipei 10617, Taiwan
- Institute of Atomic and Molecular Science, Academia Sinica , Taipei 10617, Taiwan
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