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Liu RJ, Dong JY, Wang MW, Yuan QL, Ji WY, Xu JC, Liu WW, Su SC, Ng KW, Tang ZK, Wang SP. Efficiency Improvement of Quantum Dot Light-Emitting Diodes via Thermal Damage Suppression with HATCN. ACS APPLIED MATERIALS & INTERFACES 2021; 13:49058-49065. [PMID: 34633792 DOI: 10.1021/acsami.1c16034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
With many advantages including superior color saturation and efficiency, quantum dot light-emitting diodes (QLEDs) are considered a promising candidate for the next-generation displays. Emission uniformity over the entire device area is a critical factor to the overall performance and reliability of QLEDs. In this work, we performed a thorough study on the origin of dark spots commonly observed in operating QLEDs and developed a strategy to eliminate these defects. Using advanced cross section fabrication and imaging techniques, we discovered the occurrence of voids in the organic hole transport layer and directly correlated them to the observed emission nonuniformity. Further investigations revealed that these voids are thermal damages induced during the subsequent thermal deposition of other functional layers and can act as leakage paths in the device. By inserting a thermo-tolerant 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HATCN) interlayer with an optimized thickness, the thermally induced dark spots can be completely suppressed, leading to a current efficiency increase by 18%. We further demonstrated that such a thermal passivation strategy can work universally for various types of organic layers with low thermal stability. Our findings here provide important guidance in enhancing the performances and reliability of QLEDs and also other sandwich-structured devices via the passivation of heat-sensitive layers.
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Affiliation(s)
- Ren-Jun Liu
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
| | - Jia-Yi Dong
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
| | - Meng-Wei Wang
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
| | - Qi-Lin Yuan
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
- Key Lab of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, 2699 Qianjin Street, Changchun 130012, China
| | - Wen-Yu Ji
- Key Lab of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics, Jilin University, 2699 Qianjin Street, Changchun 130012, China
| | - Jin-Cheng Xu
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
| | - Wei-Wei Liu
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
- Department of Physics and Electronic Engineering, Yancheng Teachers University, Yancheng 224002, China
| | - Shi-Chen Su
- Institute of Semiconductor Science and Technology, South China Normal University, Guangzhou 510631, China
- SCNU Qingyuan Institute of Science and Technology Innovation Co., Ltd., Qingyuan 511517, China
| | - Kar-Wei Ng
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
| | - Zi-Kang Tang
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
| | - Shuang-Peng Wang
- Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macao SAR 999078, China
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Xiang Y, Xie G, Li Q, Xue L, Xu Q, Zhu J, Tang Y, Gong S, Yin X, Yang C. Feasible Modification of PEDOT:PSS by Poly(4-styrenesulfonic acid): A Universal Method to Double the Efficiencies for Solution-Processed Organic Light-Emitting Devices. ACS APPLIED MATERIALS & INTERFACES 2019; 11:29105-29112. [PMID: 31321974 DOI: 10.1021/acsami.9b09346] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A feasible, universal, and low-cost strategy for solution-processed organic light-emitting diodes (OLEDs) was provided to significantly enhance the electroluminescent performances. The commercially available poly(4-styrenesulfonic acid) (PSSA) aqueous solution was mixed into poly(styrene sulfonic acid)-doped poly(3,4-ethylenedioxythiphene) (PEDOT:PSS) to modify its chemical and physical properties. The corresponding work function can be easily elevated from 5.04 to 5.63 eV. The modification of PEDOT:PSS by PSSA is found to be a universal method to demonstrate highly efficient OLEDs with different solution-processed host/emitter combinations, covering phosphorescent and thermally activated delayed fluorescence devices. The benchmarking solution-processed OLEDs based on 2,4,5,6-tetrakis(carbazol-9-yl)-1,3-dicyanobenzene and bis[2-(4,6-difluorophenyl)pyridinato-C2,N](picolinato)iridium(III) achieved the maximum external quantum efficiencies of 26.6 and 22.4%, respectively, simply by modifying PEDOT:PSS with PSSA, corresponding to the improvement factors of 2.7 and 2.2. It is confirmed that such performances originate simultaneously from reduced interfacial fluorescence quenching, elevated work function, and reduced lateral conduction of the commonly used PEDOT:PSS (Clevios P VP Al 4083).
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Affiliation(s)
- Yepeng Xiang
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry , Wuhan University , Wuhan 430072 , China
- Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering , Shenzhen University , Shenzhen 518060 , China
| | - Guohua Xie
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry , Wuhan University , Wuhan 430072 , China
| | - Qian Li
- School of Power and Mechanical Engineering & The Institute of Technological Science , Wuhan University , South Donghu Road 8 , Wuhan 430072 , China
| | - Longjian Xue
- School of Power and Mechanical Engineering & The Institute of Technological Science , Wuhan University , South Donghu Road 8 , Wuhan 430072 , China
| | - Qian Xu
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , Anhui , China
| | - Junfa Zhu
- National Synchrotron Radiation Laboratory , University of Science and Technology of China , Hefei 230029 , Anhui , China
| | - Yang Tang
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry , Wuhan University , Wuhan 430072 , China
| | - Shaolong Gong
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry , Wuhan University , Wuhan 430072 , China
| | - Xiaojun Yin
- Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering , Shenzhen University , Shenzhen 518060 , China
| | - Chuluo Yang
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry , Wuhan University , Wuhan 430072 , China
- Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering , Shenzhen University , Shenzhen 518060 , China
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Tagare J, Dubey DK, Jou J, Vaidyanathan S. Near UV/Deep‐Blue Phenanthroimidazole‐Based Luminophores for Organic Light‐Emitting Diodes: Experimental and Theoretical Investigation. ChemistrySelect 2019. [DOI: 10.1002/slct.201900383] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Jairam Tagare
- Optoelectronics laboratoryDepartment of ChemistryNational Institute of Technology Rourkela India
| | - Deepak Kumar Dubey
- Department of Materials Science and EngineeringNational Tsing Hua University Hsinchu Taiwan- 30013
| | - Jwo‐Huei Jou
- Department of Materials Science and EngineeringNational Tsing Hua University Hsinchu Taiwan- 30013
| | - Sivakumar Vaidyanathan
- Optoelectronics laboratoryDepartment of ChemistryNational Institute of Technology Rourkela India
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Jayabharathi J, Thanikachalam V, Ramya R, Panimozhi S. Strategic tuning of excited-state properties of electroluminescent materials with enhanced hot exciton mixing. RSC Adv 2019; 9:33693-33709. [PMID: 35528924 PMCID: PMC9073535 DOI: 10.1039/c9ra07509g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 10/14/2019] [Indexed: 12/30/2022] Open
Abstract
Deep blue emitters with excellent stability, high quantum yield and multifunctionality are the major issues for full-color displays. In line with this, new multifunctional, thermally stable blue emitters viz., N-(4-(10-(1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-1H-phenanthro[9,10-d]imidazol-2-yl)anthracen-9-yl)phenyl)-N-phenylbenzenamine (DPIAPPB) and 2-(10-(9H-carbazol-9-yl)anthracen-9-yl)-1-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)-1H-phenanthro[9,10-d]imidazole (CADPPI) with hybridized local charge transfer state (HLCT) and hot exciton properties have been synthesized. These molecules show high photoluminescence quantum yield (Φs/f): (DPIAPPB – 0.82/0.70 and CADPPI – 0.91/0.83). The CADPPI based device (EL – 467 nm) shows high efficiencies [ηc – 9.85 cd A−1; ηp – 10.84 lm W−1; ηex – 4.78% at 2.8 V; CIE (0.15, 0.10)] compared to the DPIAPPB device (EL − 472 nm) [ηc – 6.56 cd A−1; ηp – 6.16 lm W−1; ηex – 4.15% at 2.8 V with CIE (0.15, 0.12)]. The green device with CADPPI:Ir(ppy)3 exhibits a maximum L – 59 012 cd m−2; ηex – 16.8%; ηc – 37.3 cd A−1; ηp – 39.8 lm W−1 with CIE (0.30, 0.60) and the red device with CADPPI:Ir(MDQ)2(acac) shows a maximum L – 43 456 cd m−2; ηex – 21.9%; ηc – 36.0 cd A−1; ηp – 39.6 lm W−1 with CIE (0.64, 0.35). The CADPPI:Ir(ppy)3 device exhibits L – 90 12 cd m−2; ηex – 18.8%; ηc − 27.3 cd A−1; ηp – 29.8 lm W−1; CIE (0.30, 0.60).![]()
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Wen LL, Zang CX, Gao Y, Shan GG, Sun HZ, Wang T, Xie WF, Su ZM. Molecular Engineering of Phenylbenzimidazole-Based Orange Ir(III) Phosphors toward High-Performance White OLEDs. Inorg Chem 2018; 57:6029-6037. [PMID: 29741881 DOI: 10.1021/acs.inorgchem.8b00527] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To develop B-O complementary-color white organic light-emitting diodes (WOLEDs) exhibiting high efficiency and low roll-off as well as color stability simultaneously, we have designed two orange iridium(III) complexes by simply controlling the position of the methoxyl group on the cyclometalated ligand. The obtained emitters mOMe-Ir-BQ and pOMe-Ir-BQ show good photophysical and electrochemical stabilities with a broadened full width at half-maximum close to 100 nm. The corresponding devices realize highly efficient electrophosphorescence with a maximum current efficiency (CE) and power efficiency (PE) of 24.4 cd A-1 and 15.3 lm W-1 at a high doping concentration of 15 wt %. Furthermore, the complementary-color all-phosphor WOLEDs based on these phosphors exhibit good performance with a maximum CE of 31.8 cd A-1, PE of 25.0 lm W-1, and external quantum efficiency of 15.5%. Particularly, the efficiency of this device is still as high as 29.3 cd A-1 and 14.2% at the practical brightness level of 1000 cd m-2, giving a small roll-off. Meanwhile, extremely high color stability is achieved by these devices with insignificant chromaticity variation.
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Affiliation(s)
- Li-Li Wen
- Institute of Functional Material Chemistry and National & Local United Engineering Lab for Power Battery, Faculty of Chemistry , Northeast Normal University , Changchun 130024 , People's Republic of China
| | - Chun-Xiu Zang
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering , Jilin University , Changchun , Jilin 130012 , People's Republic of China
| | - Ying Gao
- Institute of Functional Material Chemistry and National & Local United Engineering Lab for Power Battery, Faculty of Chemistry , Northeast Normal University , Changchun 130024 , People's Republic of China
| | - Guo-Gang Shan
- Institute of Functional Material Chemistry and National & Local United Engineering Lab for Power Battery, Faculty of Chemistry , Northeast Normal University , Changchun 130024 , People's Republic of China
| | - Hai-Zhu Sun
- Institute of Functional Material Chemistry and National & Local United Engineering Lab for Power Battery, Faculty of Chemistry , Northeast Normal University , Changchun 130024 , People's Republic of China
| | - Tong Wang
- Army Armor Academy NCO Institute , Changchun 130017 , People's Republic of China
| | - Wen-Fa Xie
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering , Jilin University , Changchun , Jilin 130012 , People's Republic of China
| | - Zhong-Min Su
- Institute of Functional Material Chemistry and National & Local United Engineering Lab for Power Battery, Faculty of Chemistry , Northeast Normal University , Changchun 130024 , People's Republic of China
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6
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Wang S, Lee CW, Lee JY, Hwang SH. Synthesis and green phosphorescent OLED device performance of cyanofluorene-linked phenylcarbazoles as host material. NEW J CHEM 2018. [DOI: 10.1039/c7nj03748a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A series of three isomeric bipolar host materials for green phosphorescent organic light-emitting diodes (PhOLEDs) was synthesized from a combination of cyanofluorene and N-phenylcarbazole moieties.
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Affiliation(s)
- Shuxin Wang
- Department of Polymer Science & Engineering
- Materials Chemistry & Engineering Laboratory
- Dankook University
- Yongin
- Korea
| | - Chil Won Lee
- Department of Chemistry
- Dankook University
- Chonan
- Korea
| | - Jun Yeob Lee
- School of Chemical Engineering
- Sungkyunkwan University
- Suwon
- Korea
| | - Seok-Ho Hwang
- Department of Polymer Science & Engineering
- Materials Chemistry & Engineering Laboratory
- Dankook University
- Yongin
- Korea
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7
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Chen Z, Zhang T, Zhang Y, Ren Z, Zhang J, Yan S. Main chain copolysiloxanes with terthiophene and perylenediimide units: synthesis, characterization and electrical memory. Polym Chem 2017. [DOI: 10.1039/c7py00418d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
A main chain donor–acceptor copolysiloxane PBIClSi-alt-PTSi for resistor type memory has been designed and synthesized. The PBIClSi-alt-PTSi possesses high thermal stability and shows nonvolatile write-once-read many times (WORM) memory characteristics.
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Affiliation(s)
- Zhen Chen
- State Key Laboratory of Chemical Resource Engineering
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Tingjie Zhang
- State Key Laboratory of Chemical Resource Engineering
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Yi Zhang
- State Key Laboratory of Chemical Resource Engineering
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Zhongjie Ren
- State Key Laboratory of Chemical Resource Engineering
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Jianming Zhang
- Key Laboratory of Rubber-Plastics
- Qingdao University of Science & Technology
- Qingdao
- China
| | - Shouke Yan
- State Key Laboratory of Chemical Resource Engineering
- Beijing University of Chemical Technology
- Beijing 100029
- China
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8
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Ban X, Lin B, Jiang W, Sun Y. Constructing a Novel Dendron for a Self-Host Blue Emitter with Thermally Activated Delayed Fluorescence: Solution-Processed Nondoped Organic Light-Emitting Diodes with Bipolar Charge Transfer and Stable Color Purity. Chem Asian J 2016; 12:216-223. [DOI: 10.1002/asia.201601384] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 11/10/2016] [Indexed: 11/06/2022]
Affiliation(s)
- Xinxin Ban
- School of Chemical Engineering; Huaihai Institute of Technology; Cang Wu Road 59 China) Lianyungang 222005
| | - Baoping Lin
- School of Chemistry and Chemical Engineering; Southeast University; Si Pai Lou 2 China) Nanjing 211189
| | - Wei Jiang
- School of Chemistry and Chemical Engineering; Southeast University; Si Pai Lou 2 China) Nanjing 211189
| | - Yueming Sun
- School of Chemistry and Chemical Engineering; Southeast University; Si Pai Lou 2 China) Nanjing 211189
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Li W, Li J, Liu D, Jin Q. Simple Bipolar Host Materials for High-Efficiency Blue, Green, and White Phosphorescence OLEDs. ACS APPLIED MATERIALS & INTERFACES 2016; 8:22382-22391. [PMID: 27517473 DOI: 10.1021/acsami.6b05355] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
3-(1H-Pyrazol-1-yl)pyridine is used as electron-transporting unit to construct bipolar host materials o-CzPyPz, m-CzPyPz, and p-CzPyPz for application in phosphorescent organic light-emitting diodes (PhOLEDs). By varying the ortho-, meta-, or para-linking mode between the n-type 3-(1H-pyrazol-1-yl)pyridine and the p-type carbazole on phenylene bridge, the optoelectronic parameters are tuned to large extent. The highly twisted o-CzPyPz has high triplet energy of 2.95 eV, while the isomer p-CzPyPz with more coplanar conformation has smaller triplet energy of 2.67 eV. The m-CzPyPz-hosted blue PhOLED exhibits a peak current efficiency of 49.1 cd A(-1) (corresponding to an external quantum efficiency of 24.5%) and low-efficiency roll-off, while the p-CzPyPz-hosted green PhOLEDs turns on at 2.8 V and exhibits high efficiencies of 91.8 cd A(-1) (96.1 lm W(-1) and 27.3%). Furthermore, two-emitting-layer white OLEDs are fabricated with m-CzPyPz or p-CzPyPz as common hosts for both blue and orange phosphors, which realize high efficiencies of 57.8 cd A(-1) (45.4 lm W(-1) and 23.6%) and 60.7 cd A(-1) (38.1 lm W(-1) and 23.1%). The optimization of host structure for good matching of host and dopant and finally for the ideal performance is discussed.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology , 2 Linggong Road, Dalian 116024, China
| | - Jiuyan Li
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology , 2 Linggong Road, Dalian 116024, China
| | - Di Liu
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology , 2 Linggong Road, Dalian 116024, China
| | - Qian Jin
- State Key Laboratory of Fine Chemicals, College of Chemical Engineering, Dalian University of Technology , 2 Linggong Road, Dalian 116024, China
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Ban X, Sun K, Sun Y, Huang B, Jiang W. Enhanced Electron Affinity and Exciton Confinement in Exciplex-Type Host: Power Efficient Solution-Processed Blue Phosphorescent OLEDs with Low Turn-on Voltage. ACS APPLIED MATERIALS & INTERFACES 2016; 8:2010-2016. [PMID: 26726923 DOI: 10.1021/acsami.5b10335] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A benzimidazole/phosphine oxide hybrid 1,3,5-tris(1-(4-(diphenylphosphoryl)phenyl)-1H-benzo[d]imidazol-2-yl)benzene (TPOB) was newly designed and synthesized as the electron-transporting component to form an exciplex-type host with the conventional hole-transporting material tris(4-carbazoyl-9-ylphenyl)amine (TCTA). Because of the enhanced triplet energy and electron affinity of TPOB, the energy leakage from exciplex-state to the constituting molecule was eliminated. Using energy transfer from exciplex-state, solution-processed blue phosphorescent organic light-emitting diodes (PHOLEDs) achieved an extremely low turn-on voltage of 2.8 V and impressively high power efficiency of 22 lm W(-1). In addition, the efficiency roll-off was very small even at luminance up to 10 000 cd m(-2), which suggested the balanced charge transfer in the emission layer. This study demonstrated that molecular modulation was an effective way to develop efficient exciplex-type host for high performanced PHOLEDs.
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Affiliation(s)
- Xinxin Ban
- School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu 211189, People's Republic of China
| | - Kaiyong Sun
- School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu 211189, People's Republic of China
| | - Yueming Sun
- School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu 211189, People's Republic of China
| | - Bin Huang
- School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu 211189, People's Republic of China
| | - Wei Jiang
- School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu 211189, People's Republic of China
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Ban X, Sun K, Sun Y, Huang B, Ye S, Yang M, Jiang W. High Power Efficiency Solution-Processed Blue Phosphorescent Organic Light-Emitting Diodes Using Exciplex-Type Host with a Turn-on Voltage Approaching the Theoretical Limit. ACS APPLIED MATERIALS & INTERFACES 2015; 7:25129-25138. [PMID: 26502064 DOI: 10.1021/acsami.5b06424] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Three solution-processable exciplex-type host materials were successfully designed and characterized by equal molar blending hole transporting molecules with a newly synthesized electron transporting material, which possesses high thermal stability and good film-forming ability through a spin-coating technique. The excited-state dynamics and the structure-property relationships were systematically investigated. By gradually deepening the highest occupied molecular orbital (HOMO) level of electron-donating components, the triplet energy of exciplex hosts were increased from 2.64 to 3.10 eV. Low temperature phosphorescence spectra demonstrated that the excessively high triplet energy of exciplex would induce a serious energy leakage from the complex state to the constituting molecule. Furthermore, the low energy electromer state, which only exists under the electroexcitation, was found as another possible channel for energy loss in exciplex-based phosphorescent organic light-emitting diodes (OLEDs). In particular, as quenching of the exciplex-state and the triplet exciton were largely eliminated, solution-processed blue phosphorescence OLEDs using the exciplex-type host achieved an extremely low turn-on voltage of 2.7 eV and record-high power efficiency of 22.5 lm W(-1), which were among the highest values in the devices with identical structure.
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Affiliation(s)
- Xinxin Ban
- School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu, P. R. China , 211189
| | - Kaiyong Sun
- School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu, P. R. China , 211189
| | - Yueming Sun
- School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu, P. R. China , 211189
| | - Bin Huang
- School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu, P. R. China , 211189
| | - Shanghui Ye
- National Synergistic Innovation Center for Advanced Materials, Nanjing University of Posts and Telecommunications , Nanjing, Jiangsu, P. R. China , 210023
| | - Min Yang
- National Synergistic Innovation Center for Advanced Materials, Nanjing University of Posts and Telecommunications , Nanjing, Jiangsu, P. R. China , 210023
| | - Wei Jiang
- School of Chemistry and Chemical Engineering, Southeast University , Nanjing, Jiangsu, P. R. China , 211189
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Sun D, Zhou X, Li H, Sun X, Ren Z, Ma D, Yan S. Multi-3,3'-Bicarbazole-Substituted Arylsilane Host Materials with Balanced Charge Transport for Highly Efficient Solution-Processed Blue Phosphorescent Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2015; 7:17802-17810. [PMID: 26252613 DOI: 10.1021/acsami.5b04112] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A series of 3,3'-bicarbazole (mCP)-functionalized tetraphenylsilane derivatives (SimCPx), including bis(3,5-di(9H-carbazol-9-yl)phenyl)diphenylsilane (SimCP2), tris(3,5-di(9H-carbazol-9-yl)phenyl)methylsilane (SimCP3-CH3), tris(3,5-di(9H-carbazol-9-yl)phenyl)phenylsilane (SimCP3-Ph), and tetrakis(3,5-di(9H-carbazol-9-yl)phenyl)silane (SimCP4), serving as bipolar blue hosts for bis[2-(4,6-difluorophenyl)pyridyl-N,C2']iridium(III) (FIrpic), have been synthesized by incorporating different ratios of mCP subunits into a central silicon atom. All of the SimCPx derivatives have wide bandgaps and high triplet energies because of the indirect linkage by silicon between each mCP subunit. The good solubility and high thermal and morphological stability of SimCPx are beneficial for forming amorphous and homogeneous films through solution processing. Density functional theory simulations manifest the better bipolar characteristics for SimCPx using three and four mCP units rather than the represented bipolar host SimCP2. As a result, SimCP4 presents the best electron-transporting ability for charge balance. Consequently, the lowest driving voltage of 4.8 eV, and the favorable maximum efficiencies of 14.2% for external quantum efficiency (28.4 cd A(-1), 13.5 lm W(-1)), are achieved by solution-processed, SimCP4-based blue phosphorescent organic light-emitting diodes as the highest performance among SimCPx, in which 32% improved device efficiencies compared to that of SimCP2 are obtained. It is inspiring to develop efficient bipolar hosts for blue phosphors by just incorporating monopolar carbazole into arylsilanes in two steps.
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Affiliation(s)
- Dianming Sun
- †State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xiaokang Zhou
- ‡State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Huihui Li
- †State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xiaoli Sun
- †State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Zhongjie Ren
- †State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Dongge Ma
- ‡State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Shouke Yan
- †State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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Cui LS, Liu Y, Liu XY, Jiang ZQ, Liao LS. Design and Synthesis of Pyrimidine-Based Iridium(III) Complexes with Horizontal Orientation for Orange and White Phosphorescent OLEDs. ACS APPLIED MATERIALS & INTERFACES 2015; 7:11007-11014. [PMID: 25943159 DOI: 10.1021/acsami.5b02541] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Two phosphorescent Ir(III) complexes Ir(ppm)2(acac) and Ir(dmppm)2(acac) were synthesized and characterized with emission ranged at 584/600 nm and high photoluminescence quantum yields (PLQYs) of 0.90/0.92, respectively. The angle-dependent PL spectra analysis reveals that the two orange iridium(III) complexes embodied horizontal orientation property. The high photoluminescence quantum yield and high horizontal dipoles ratio determine their excellent device performance. The devices based on Ir(ppm)2(acac) and Ir(dmppm)2(acac) achieved efficiencies of 26.8% and 28.2%, respectively, which can be comparable to the best orange phosphorescent devices reported in the literature. Furthermore, with the introduction of FIrpic as sky-blue emitter, phosphorescent two-element white organic light-emitting devices (OLEDs) have been realized with external quantum efficiencies (EQEs) as high as 25%, which are the highest values among the reported two-element white OLEDs.
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