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Nawaz A, Merces L, Ferro LMM, Sonar P, Bufon CCB. Impact of Planar and Vertical Organic Field-Effect Transistors on Flexible Electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2204804. [PMID: 36124375 DOI: 10.1002/adma.202204804] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 09/13/2022] [Indexed: 06/15/2023]
Abstract
The development of flexible and conformable devices, whose performance can be maintained while being continuously deformed, provides a significant step toward the realization of next-generation wearable and e-textile applications. Organic field-effect transistors (OFETs) are particularly interesting for flexible and lightweight products, because of their low-temperature solution processability, and the mechanical flexibility of organic materials that endows OFETs the natural compatibility with plastic and biodegradable substrates. Here, an in-depth review of two competing flexible OFET technologies, planar and vertical OFETs (POFETs and VOFETs, respectively) is provided. The electrical, mechanical, and physical properties of POFETs and VOFETs are critically discussed, with a focus on four pivotal applications (integrated logic circuits, light-emitting devices, memories, and sensors). It is pointed out that the flexible function of the relatively newer VOFET technology, along with its perspective on advancing the applicability of flexible POFETs, has not been reviewed so far, and the direct comparison regarding the performance of POFET- and VOFET-based flexible applications is most likely absent. With discussions spanning printed and wearable electronics, materials science, biotechnology, and environmental monitoring, this contribution is a clear stimulus to researchers working in these fields to engage toward the plentiful possibilities that POFETs and VOFETs offer to flexible electronics.
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Affiliation(s)
- Ali Nawaz
- Center for Sensors and Devices, Bruno Kessler Foundation (FBK), Trento, 38123, Italy
| | - Leandro Merces
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo, 13083-100, Brazil
| | - Letícia M M Ferro
- Research Center for Materials, Architectures and Integration of Nanomembranes (MAIN), Chemnitz University of Technology, 09126, Chemnitz, Germany
- Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, São Paulo, 13083-100, Brazil
- Institute of Chemistry, University of Campinas, Campinas, São Paulo, 13083-970, Brazil
| | - Prashant Sonar
- School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD, 4000, Australia
- Centre for Materials Science, Queensland University of Technology, 2 George Street, Brisbane, QLD, 4000, Australia
| | - Carlos C B Bufon
- MackGraphe - Graphene and Nanomaterials Research Center, Mackenzie Presbyterian Institute, São Paulo, 01302-907, Brazil
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2
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Mallem K, Prodanov MF, Dezhang C, Marus M, Kang C, Shivarudraiah SB, Vashchenko VV, Halpert JE, Srivastava AK. Solution-Processed Red, Green, and Blue Quantum Rod Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2022; 14:18723-18735. [PMID: 35417119 DOI: 10.1021/acsami.2c04466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Solution-processed semiconductor nanocrystals are evolving as potential candidates for future display and lighting applications owing to their size-tunable emission, ultrasaturated colors, and compatibility with large-area flexible substrates. Among them, quantum rods (QRs) are emerging materials for optoelectronic applications, offering polarized emission, high light outcoupling efficiency, color purity, and better stability in solid films. However, synthesizing QRs covering the full visible wavelength region has been a big challenge, particularly in the blue range. Herein, we report for the first time the synthesis of red CdSe/CdS, green CdSe/ZnxCd1-xS/ZnS, and blue CdSe/ZnxCd1-xS/ZnS QRs and their application in red, green, and blue QR-based light-emitting diodes (QR-LEDs). We have improved the charge injection balance into the QRs through embedding a poly(methyl methacrylate) (PMMA) layer between the emissive and electron transport layers. The thin PMMA electron-blocking layer (EBL) suppresses the excessive electron flux and thus promotes charge injection balance and pushes the recombination zone back to the QR layer, resulting in 1.35×, 1.2×, and 1.7× peak external quantum efficiency improvement for red, green, and blue QR-LEDs, respectively. The efficiency roll-off of green and blue QR-LEDs with an EBL is less than 50% at maximum current density. The proposed red, green, and blue QR-LEDs open up an avenue toward further improving the light source efficiency and stability focusing on real device applications.
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Affiliation(s)
- Kumar Mallem
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies and Centre for Display Research, Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Maksym F Prodanov
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies and Centre for Display Research, Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Chen Dezhang
- Department of Chemistry, Hong Kong University of Science and Technology (HKUST), Clear Water Bay Road, Kowloon, Hong Kong 999077, China
| | - Mikita Marus
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies and Centre for Display Research, Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Chengbin Kang
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies and Centre for Display Research, Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Sunil B Shivarudraiah
- Department of Chemistry, Hong Kong University of Science and Technology (HKUST), Clear Water Bay Road, Kowloon, Hong Kong 999077, China
| | - Valeri V Vashchenko
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies and Centre for Display Research, Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Jonathan E Halpert
- Department of Chemistry, Hong Kong University of Science and Technology (HKUST), Clear Water Bay Road, Kowloon, Hong Kong 999077, China
| | - Abhishek K Srivastava
- State Key Laboratory on Advanced Displays and Optoelectronics Technologies and Centre for Display Research, Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
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3
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Kim CW, Lee JH, Cho S, Kim HJ, Hwang J, Kim YW, Choi DH, Cho MJ, Lee K, Choi DH. Novel carbazole-acridine-based hole transport polymer for low turn-on voltage of green quantum dot light-emitting diodes. Polym Chem 2021. [DOI: 10.1039/d1py00497b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We synthesized a novel hole transporting polymer (P-CzAc) for solution-processable green QD-LEDs. Compared to PVK, the P-CzAz-based device showed higher device performance.
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Affiliation(s)
- Chai Won Kim
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Ji Hye Lee
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Seunguk Cho
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Hyung Jong Kim
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Jinhyo Hwang
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Yong Woo Kim
- LT Materials, 113-19, Dangha-Ro, Namsa-Myeon, Cheoin-Gu, Yongin-Si, Gyeonggi-Do 17118, Republic of Korea
| | - Dae Hyuk Choi
- LT Materials, 113-19, Dangha-Ro, Namsa-Myeon, Cheoin-Gu, Yongin-Si, Gyeonggi-Do 17118, Republic of Korea
| | - Min Ju Cho
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Kwangyeol Lee
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Dong Hoon Choi
- Department of Chemistry, Research Institute for Natural Sciences, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
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Sun W, Xie L, Guo X, Su W, Zhang Q. Photocross-Linkable Hole Transport Materials for Inkjet-Printed High-Efficient Quantum Dot Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2020; 12:58369-58377. [PMID: 33331766 DOI: 10.1021/acsami.0c17336] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Efficient approach based on the photochemistry of benzophenone has been developed for the cross-linking of the polymer hole-transporting layer (HTL). The cross-linked poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-butylphenyl) (TFB) thin films showed high solvent stability, smooth surface morphology, and improved charge-carrier mobility. The solution-processed red, green, and blue (RGB) quantum dot light-emitting diodes (QLEDs) based on the cross-linked HTLs showed much better performances than the corresponding devices based on the pristine TFB HTLs. The spin-coated red QLEDs based on the cross-linked HTLs showed the maximum current efficiency (CE), the maximum power efficiency (PE), and the peak external quantum efficiency (EQE) of 32.3 cd A-1, 42.3 lm W-1, and 21.4%, respectively. The inkjet-printed red QLEDs with the cross-linked HTLs exhibited the CE, PE, and EQE of 26.5 cd A-1, 37.8 lm W-1, and 18.1%, respectively. The high-performance HTLs were obtained by significantly reducing the amount of cross-linking agents.
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Affiliation(s)
- Wenjian Sun
- Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, School of Chemistry and Chemical Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Liming Xie
- Printable Electronics Research Center, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 398 Ruoshui Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China
| | - Xiaojun Guo
- National Engineering Laboratory of TFT-LCD Materials and Technologies, Department of Electronic Engineering, Shanghai JiaoTong University, Shanghai 200240, China
| | - Wenming Su
- Printable Electronics Research Center, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 398 Ruoshui Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, China
| | - Qing Zhang
- Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, School of Chemistry and Chemical Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
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5
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Kim HM, Jeong W, Kim JH, Jang J. Stability of Quantum-Dot Light Emitting Diodes with Alkali Metal Carbonates Blending in Mg Doped ZnO Electron Transport Layer. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E2423. [PMID: 33291578 PMCID: PMC7761844 DOI: 10.3390/nano10122423] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 11/30/2022]
Abstract
We report here the fabrication of highly efficient and long-lasting quantum-dot light emitting diodes (QLEDs) by blending various alkali metal carbonate in magnesium (Mg) doped zinc oxide (ZnO) (MZO) electron transport layer (ETL). Alkali metal carbonates blending in MZO, X2CO3:MZO, control the band-gap, electrical properties, and thermal stability. This can therefore enhance the operational lifetime of QLEDs. It is found that the conductivity of X2CO3:MZO film can be controlled and the thermal stability of ETLs could be improved by X2CO3 blending in MZO. The inverted red QLEDs (R-QLEDs) with Cs2CO3:MZO, Rb2CO3:MZO, and K2CO3:MZO ETLs exhibited the operational lifetime of 407 h for the R-QLEDs with Cs2CO3:MZO, 620 h with Rb2CO3:MZO and 94 h with K2CO3:MZO ETLs at T95 with the initial luminance of 1000 cd/m2. Note that all red QLEDs showed the high brightness over 150,000 cd/m2. But the R-QLEDs with Na2CO3:MZO and Li2CO3:MZO ETLs exhibited shorter operational lifetime and poor brightness than the R-QLED with pristine MZO ETL.
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Affiliation(s)
| | | | | | - Jin Jang
- Department of Information Display and Advanced Display Research Center, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Korea; (H.-M.K.); (W.J.); (J.H.K.)
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6
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Cho H, Park S, Shin H, Kim M, Jang H, Park J, Yang JH, Han CW, Baek JH, Jung YS, Jeon DY. Highly Efficient Deep Blue Cd-Free Quantum Dot Light-Emitting Diodes by a p-Type Doped Emissive Layer. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2002109. [PMID: 32930494 DOI: 10.1002/smll.202002109] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Environmentally friendly ZnSe/ZnS core/shell quantum dots (QDs) as an alternative blue emission material to Cd-based QDs have shown great potential for use in next-generation displays. However, it remains still challenging to realize a high-efficiency quantum dot light-emitting diode (QLED) based on ZnSe/ZnS QDs due to their insufficient electrical characteristics, such as excessively high electron mobility (compared to the hole mobility) and the deep-lying valence band. In this work, the effects of QDs doped with hole transport materials (hybrid QDs) on the electrical characteristics of a QLED are investigated. These hybrid QDs show a p-type doping effect, which leads to a change in the density of the carriers. Specifically, the hybrid QDs can balance electrons and holes by suppressing the overflow of electrons and improving injection of holes, respectively. These electrical characteristics help to improve device performance. In detail, an external quantum efficiency (EQE) of 6.88% is achieved with the hybrid QDs. This is increased by 180% compared to a device with pure ZnSe/ZnS QDs (EQE of 2.46%). This record is the highest among deep-blue Cd-free QLED devices. These findings provide the importance of p-type doping effect in QD layers and guidance for the study of the electrical properties of QDs.
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Affiliation(s)
- Hyunjin Cho
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Sunjoong Park
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Hongjoo Shin
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Moohyun Kim
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Hanhwi Jang
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Jaehyun Park
- LG Display R&D Center, LG Sciencepark, 30, Magokjungang 10-ro, Gangseo-gu, Seoul, 07796, Republic of Korea
| | - Joong Hwan Yang
- LG Display R&D Center, LG Sciencepark, 30, Magokjungang 10-ro, Gangseo-gu, Seoul, 07796, Republic of Korea
| | - Chang Wook Han
- LG Display R&D Center, LG Sciencepark, 30, Magokjungang 10-ro, Gangseo-gu, Seoul, 07796, Republic of Korea
| | - Ji Ho Baek
- LG Display R&D Center, LG Sciencepark, 30, Magokjungang 10-ro, Gangseo-gu, Seoul, 07796, Republic of Korea
| | - Yeon Sik Jung
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Duk Young Jeon
- Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
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7
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Davidson-Hall T, Aziz H. Significant Enhancement in Quantum Dot Light-Emitting Device Stability via a Cascading Hole Transport Layer. ACS APPLIED MATERIALS & INTERFACES 2020; 12:16782-16791. [PMID: 32181638 DOI: 10.1021/acsami.9b23567] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
This work investigates the effect of the hole transport layer (HTL) on the stability of electroluminescent quantum dot light-emitting devices (QDLEDs). The electroluminescence half-life (LT50) of QDLEDs can be improved by 25× through the utilization of a cascading HTL (CHTL) structure with consecutive steps in the highest occupied molecular orbital energy level. Using this approach, a LT50 of 864,000 h (for an initial luminance of 100 cd m-2) is obtained for red QDLEDs using a conventional core/shell QD emitter. The CHTL primarily improves QDLED stability by shifting excessive hole accumulation away from the QD/HTL interface and toward the interlayer HTL/HTL interfaces. The wider electron-hole recombination zone in the CHTL for electrons that have leaked from the QD layer results in less HTL degradation at the QD/HTL interface. This work highlights the significant influence of the HTL on QDLED stability and represents the longest LT50 for a QDLED based on the conventional core/shell QD structure.
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Affiliation(s)
- Tyler Davidson-Hall
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Hany Aziz
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
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8
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Jiang X, Liu G, Tang L, Wang A, Tian Y, Wang A, Du Z. Quantum dot light-emitting diodes with an Al-doped ZnO anode. NANOTECHNOLOGY 2020; 31:255203. [PMID: 32135523 DOI: 10.1088/1361-6528/ab7ceb] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A study of hybrid ZnCdSeS/ZnS quantum dot light-emitting diodes (QLEDs) device fabricated with indium tin oxide-free transparent electrodes is presented. Al-doped zinc oxide (AZO) prepared by magnetron sputtering is adopted in anode transparent electrodes for green QLEDs with different sputtering pressures. A Kelvin probe force microscopy measurement showed that AZO has a work function of approximately 5.0 eV. The AZO/poly(ethylene-dioxythiophene)/polystyrenesulfonate (PEDOT:PSS) interface can be adjusted by the sputtering pressures, which was confirmed by hole-only devices. AZO films with low surface roughness can form a good AZO/PEDOT:PSS interface, which can increase the holes' injection, and result in an improved charge balance. The maximum current efficiency, luminance, and external quantum efficiency of the optimized QLED devices under a sputtering pressure of 1 mTorr can achieve values of 50.75 cd A-1, 102 500 cd m-2, and 12.94%, respectively.
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Affiliation(s)
- Xiaohong Jiang
- Key Lab for Special Functional Materials, Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, School of Materials Science and Engineering, and Collaborative Innovation Center of Nano Functional Materials and Applications, Henan University, Kaifeng 475004, People's Republic of China
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9
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Lee CY, Kuo YP, Chen PY, Lu HH, Lin MY. Influence of Annealing Temperature on Weak-Cavity Top-Emission Red Quantum Dot Light Emitting Diode. NANOMATERIALS (BASEL, SWITZERLAND) 2019; 9:E1639. [PMID: 31752259 PMCID: PMC6915585 DOI: 10.3390/nano9111639] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 11/15/2019] [Accepted: 11/15/2019] [Indexed: 12/29/2022]
Abstract
In this report, we show that the annealing temperature in QDs/Mg-doped ZnO film plays a very important role in determining QLEDs performance. Measurements of capacitance and single carrier device reveal that the change of the device efficiency with different annealing temperatures is related to the balance of both electron and hole injection. A comparison of annealing temperatures shows that the best performance is demonstrated with 150 °C-annealing temperature. With the improved charge injection and charge balance, a maximum current efficiency of 24.81 cd/A and external quantum efficiency (EQE) of 20.09% are achievable in our red top-emission QLEDs with weak microcavity structure.
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Affiliation(s)
- Chun-Yu Lee
- AU Optronics Corporation, Hsinchu 30078, Taiwan (Y.-P.K.); (P.-Y.C.); (H.-H.L.)
| | - Ya-Pei Kuo
- AU Optronics Corporation, Hsinchu 30078, Taiwan (Y.-P.K.); (P.-Y.C.); (H.-H.L.)
| | - Peng-Yu Chen
- AU Optronics Corporation, Hsinchu 30078, Taiwan (Y.-P.K.); (P.-Y.C.); (H.-H.L.)
| | - Hsieh-Hsing Lu
- AU Optronics Corporation, Hsinchu 30078, Taiwan (Y.-P.K.); (P.-Y.C.); (H.-H.L.)
| | - Ming Yi Lin
- Department of Electrical Engineering, National United University, Miaoli 36003, Taiwan
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10
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Chen Q, Yan Y, Wu X, Lan S, Hu D, Fang Y, Lv D, Zhong J, Chen H, Guo T. High-Performance Quantum-Dot Light-Emitting Transistors Based on Vertical Organic Thin-Film Transistors. ACS APPLIED MATERIALS & INTERFACES 2019; 11:35888-35895. [PMID: 31544456 DOI: 10.1021/acsami.9b11198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this work, a novel vertical quantum-dot light-emitting transistor (VQLET) based on a vertical organic thin-film transistor is successfully fabricated. Benefiting from the new vertical architecture, the VQLET is able to afford an extremely high current density, which allows most of the organic thin film transistors (OTFT) even with low mobility (for instance, poly(3-hexylthiophene)) to drive a quantum-dot light-emitting diode (QLED), which was previously unavailable. Moreover, the hole injection barrier could be modulated by the additional gate electrode, which precisely optimizes the charge balance in the device, a critical issue in QLED, resulting in the precise control of current density and brightness of the VQLET. The VQLET shows a high performance with a maximum current efficiency of 37 cd/A. Furthermore, integrating OTFT and QLED into a single device, the VQLET features drastic advantages by realizing active matrix quantum-dot light-emitting diodes (AMQLEDs), which significantly reduces the number of transistors and frees the large area fraction occupied by transistors. Hence, these results indicate that the VQLET provides a new strategy for realizing a low-cost, solution-processed, high-performance OTFT-AMQLED for the flat panel display technology. Moreover, the novel design offers a unique method to exquisitely control the charge balance and maximize the efficiency the QLED.
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Affiliation(s)
- Qizhen Chen
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Yujie Yan
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Xiaomin Wu
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Shuqiong Lan
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Daobing Hu
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Yuan Fang
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Dongxu Lv
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Jianfeng Zhong
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Huipeng Chen
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
| | - Tailiang Guo
- Institute of Optoelectronic Display, National & Local United Engineering Lab of Flat Panel Display Technology , Fuzhou University , Fuzhou 350002 , China
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11
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Davidson-Hall T, Aziz H. The role of excitons within the hole transporting layer in quantum dot light emitting device degradation. NANOSCALE 2019; 11:8310-8318. [PMID: 30982837 DOI: 10.1039/c8nr09560d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This work investigates the root causes of the limited stability of electroluminescent quantum dot light-emitting devices (QDLEDs). Studies using electrical measurements, continuous UV irradiation, and both steady-state and transient photoluminescence (PL) spectroscopy reveal that exciton-induced degradation of the hole transporting material (HTM) in QDLEDs plays a role in limiting their electroluminescence (EL) stability. The results indicate that there is a correlation between device EL stability and the susceptibility of the HTM to exciton-induced degradation. The presence of quenchers in the HTM layer can lead to a decrease in the luminescence quantum yield of QDs, suggesting that energy transfer between the QD and HTM films may play a role in this behavior. The results uncover a new degradation mechanism where excitons within the HTM limit the EL stability of QDLEDs.
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Affiliation(s)
- Tyler Davidson-Hall
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
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12
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Liu Y, Nell B, Ortstein K, Wu Z, Karpov Y, Beryozkina T, Lenk S, Kiriy A, Leo K, Reineke S. High Electron Affinity Molecular Dopant CN6-CP for Efficient Organic Light-Emitting Diodes. ACS APPLIED MATERIALS & INTERFACES 2019; 11:11660-11666. [PMID: 30810028 DOI: 10.1021/acsami.8b21865] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
p-Type molecular doping of organic materials with high ionization energies (IEs) of above 5.50 eV is still a challenge, limiting the use of doping in high-performance organic light-emitting diodes (OLEDs). Here, we investigate the molecular dopant hexacyano-trimethylene-cyclopropane (CN6-CP) with a high electron affinity of 5.87 eV as p-dopant in OLEDs. We show that CN6-CP can be used not only as a dopant in the traditional hole transport material 4,4'-cyclohexylidenebis[ N, N-bis(4-methylphenyl)benzenamine] (TAPC, IE = 5.50 eV) but also effectively dopes the host material tris(4-carbazoyl-9-ylphenyl)amine (TCTA, IE = 5.85 eV), reaching a conductivity of 1.86 × 10-4 S/cm at a molar ratio of 0.25. Using CN6-CP-doped TAPC as hole injection and transport layer, we achieve a low driving voltage of 2.92 V at the practical brightness of 1000 cd/m2 and 3.18 V at a current density of 10 mA/cm2 for a green phosphorescent OLED based on bis[2-(2-pyridinyl- N)phenyl- C](acetylacetonato)iridium(III) (Ir(ppy)2(acac)), together with a maximum external quantum efficiency of 18% and a luminous efficacy of 78 lm/W. The device also exhibits a very low efficiency roll-off at high luminance. Further, by directly adopting CN6-CP-doped TCTA as the injection/transport layer, the driving voltage drops to 2.78 V at 1000 cd/m2 and 2.93 V at 10 mA/cm2. Moreover, conductivity and absorption measurements suggest that CN6-CP could also dope CBP with an IE as high as 6.05 eV. The results show that CN6-CP is an excellent p-type dopant for efficient OLEDs and possesses great potential for future application in organic optoelectronic devices.
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Affiliation(s)
- Yuan Liu
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics , Technische Universität Dresden , Nöthnitzer Straße 61 , 01187 Dresden , Germany
| | - Bernhard Nell
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics , Technische Universität Dresden , Nöthnitzer Straße 61 , 01187 Dresden , Germany
| | - Katrin Ortstein
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics , Technische Universität Dresden , Nöthnitzer Straße 61 , 01187 Dresden , Germany
| | - Zhongbin Wu
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics , Technische Universität Dresden , Nöthnitzer Straße 61 , 01187 Dresden , Germany
| | - Yevhen Karpov
- Leibniz-Institut für Polymerforschung Dresden , Hohe Straße 6 , 01069 Dresden , Germany
- Center for Advancing Electronics Dresden (cfaed) , Technische Universität Dresden , 01062 Dresden , Germany
| | - Tetyana Beryozkina
- Technology for Organic Synthesis Department Ural Federal University , Mira str., 28 , 620002 Yekaterinburg , Russia
| | - Simone Lenk
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics , Technische Universität Dresden , Nöthnitzer Straße 61 , 01187 Dresden , Germany
| | - Anton Kiriy
- Leibniz-Institut für Polymerforschung Dresden , Hohe Straße 6 , 01069 Dresden , Germany
- Center for Advancing Electronics Dresden (cfaed) , Technische Universität Dresden , 01062 Dresden , Germany
| | - Karl Leo
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics , Technische Universität Dresden , Nöthnitzer Straße 61 , 01187 Dresden , Germany
- Center for Advancing Electronics Dresden (cfaed) , Technische Universität Dresden , 01062 Dresden , Germany
| | - Sebastian Reineke
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics , Technische Universität Dresden , Nöthnitzer Straße 61 , 01187 Dresden , Germany
- Center for Advancing Electronics Dresden (cfaed) , Technische Universität Dresden , 01062 Dresden , Germany
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13
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Sun Y, Jiang Y, Sun XW, Zhang S, Chen S. Beyond OLED: Efficient Quantum Dot Light-Emitting Diodes for Display and Lighting Application. CHEM REC 2019; 19:1729-1752. [PMID: 30698895 DOI: 10.1002/tcr.201800191] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Indexed: 01/25/2023]
Abstract
The unique features of solution-processed quantum dots (QDs) including emission tunability in the visible range, high-quality saturated color and outstanding intrinsic stability in environment are highly desired in various application fields. Especially, for the preparation of wide color gamut displays, QDs with high photoluminescence quantum yield are deemed as the optimal fluorescent emitter that has been utilized in the backlight for liquid crystal display. Nevertheless, the commercialization of electrically driven self-emissive quantum dot light-emitting diode (QLED) display is the ultimate target due to its merits of high contrast, slim configuration and compatibility with flexible substrate. Through the great efforts devoted to material engineering and device configuration, astonishing progresses have been made in device performance, giving the QLED technology a great chance to compete with other counterparts for next-generation displays. In this review, we retrospect the development roadmap of QLED technology and introduce the essential principles in the QLED devices. Moreover, we discuss the key factors that affect the QLED efficiency and lifetime. Finally, the advances in device architectures and pixel patterning are also summarized.
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Affiliation(s)
- Yizhe Sun
- Institute of Microelectronics, Peking University, Beijing, P. R. China, 100871.,Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, P. R. China, 518055
| | - Yibin Jiang
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, P. R. China, 518055.,State Key Lab on Advanced Displays and Optoelectronics, The Hong Kong University of Science and Technology Clear Water Bay, Kowloon, Hong Kong
| | - Xiao Wei Sun
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, P. R. China, 518055
| | - Shengdong Zhang
- Institute of Microelectronics, Peking University, Beijing, P. R. China, 100871
| | - Shuming Chen
- Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, P. R. China, 518055
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14
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Chen L, Wang S, Li D, Fang Y, Shen H, Li L, Du Z. Simultaneous Improvement of Efficiency and Lifetime of Quantum Dot Light-Emitting Diodes with a Bilayer Hole Injection Layer Consisting of PEDOT:PSS and Solution-Processed WO 3. ACS APPLIED MATERIALS & INTERFACES 2018; 10:24232-24241. [PMID: 29943572 DOI: 10.1021/acsami.8b00770] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Even though chemically stable metal oxides (MOs), as substitutes for poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), have been successfully adopted for improving device stability in solution-processed quantum dot light-emitting diodes (QLEDs), the efficiencies of QLEDs are at a relatively low level. In this work, a novel architecture of QLEDs has been introduced, in which inorganic/organic bilayer hole injection layers (HILs) were delicately designed by inserting an amorphous WO3 interlayer between PEDOT:PSS and the indium tin oxide anode. As a result, the efficiency and operational lifetime of QLEDs were improved simultaneously. The results show that the novel architecture QLEDs relative to conventional PEDOT:PSS-based QLEDs have an enhanced external quantum efficiency by a factor of 50%, increasing from 8.31 to 12.47%, meanwhile exhibit a relatively long operational lifetime (12 551 h) and high maximum brightness (>40 000 cd m-2) resulting from a better pathway for hole injection with staircase energy-level alignment of the HILs and reduction of surface roughness. Our results demonstrate that the novel architecture QLEDs using bilayer MO/PEDOT:PSS HILs can achieve long operational lifetime without sacrificing efficiency.
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Affiliation(s)
- Ling Chen
- Key Laboratory for Special Functional Materials, Collaborative Innovation Center of Nano Functional Materials and Applications , Henan University , Kaifeng 475004 , P. R. China
| | - Shujie Wang
- Key Laboratory for Special Functional Materials, Collaborative Innovation Center of Nano Functional Materials and Applications , Henan University , Kaifeng 475004 , P. R. China
| | - Dongdong Li
- Key Laboratory for Special Functional Materials, Collaborative Innovation Center of Nano Functional Materials and Applications , Henan University , Kaifeng 475004 , P. R. China
| | - Yan Fang
- Key Laboratory for Special Functional Materials, Collaborative Innovation Center of Nano Functional Materials and Applications , Henan University , Kaifeng 475004 , P. R. China
| | - Huaibin Shen
- Key Laboratory for Special Functional Materials, Collaborative Innovation Center of Nano Functional Materials and Applications , Henan University , Kaifeng 475004 , P. R. China
| | - Linsong Li
- Key Laboratory for Special Functional Materials, Collaborative Innovation Center of Nano Functional Materials and Applications , Henan University , Kaifeng 475004 , P. R. China
| | - Zuliang Du
- Key Laboratory for Special Functional Materials, Collaborative Innovation Center of Nano Functional Materials and Applications , Henan University , Kaifeng 475004 , P. R. China
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15
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Jin X, Chang C, Zhao W, Huang S, Gu X, Zhang Q, Li F, Zhang Y, Li Q. Balancing the Electron and Hole Transfer for Efficient Quantum Dot Light-Emitting Diodes by Employing a Versatile Organic Electron-Blocking Layer. ACS APPLIED MATERIALS & INTERFACES 2018; 10:15803-15811. [PMID: 29667818 DOI: 10.1021/acsami.8b00729] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The electron-blocking layer (EBL) is important to balance the charge carrier transfer and achieve highly efficient quantum dot light-emitting diodes (QLEDs). Here, we report the utilization of a soluble tert-butyldimethylsilyl chloride-modified poly( p-phenylene benzobisoxazole) (TBS-PBO) as an EBL for simultaneous good charge carrier transfer balance while maintaining a high current density. We show that the versatile TBS-PBO blocks excess electron injection into the quantum dots (QDs), thus leading to better charge carrier transfer balance. It also restricts the undesired QD-to-EBL electron-transfer process, which preserves the superior emission capabilities of the emitter. As a consequence, the TBS-PBO device delivers an external quantum efficiency (EQE) maximum of 16.7% along with a remarkable current density as high as 139 mA/cm2 with a brightness of 5484 cd/m2. The current density of our device is higher than those of insulator EBL-based devices because of the higher conductivity of the TBS-PBO versus insulator EBL, thus helping achieve high luminance values ranging from 1414 to 20 000 cd/cm2 with current densities ranging from 44 to 648 mA/cm2 and EQE > 14%. We believe that these unconventional features of the present TBS-PBO-based QLEDs will expand the wide use of TBS-PBO as buffer layers in other advanced QLED applications.
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Affiliation(s)
- Xiao Jin
- School of Physics Science and Technology , Lingnan Normal University , Zhanjiang 524048 , P. R. China
| | - Chun Chang
- Jiangxi Engineering Laboratory for Optoelectronics Testing Technology , Nanchang Hangkong University , Nanchang 330063 , P. R. China
| | - Weifeng Zhao
- School of Materials and Chemical Engineering , Xi'an Technological University , Xi'an 710021 , P. R. China
| | - Shujuan Huang
- School of Photovoltaic and Renewable Energy Engineering , University of New South Wales , Sydney , New South Wales 2052 , Australia
| | - Xiaobing Gu
- Jiangxi Engineering Laboratory for Optoelectronics Testing Technology , Nanchang Hangkong University , Nanchang 330063 , P. R. China
| | - Qin Zhang
- Jiangxi Engineering Laboratory for Optoelectronics Testing Technology , Nanchang Hangkong University , Nanchang 330063 , P. R. China
| | - Feng Li
- Jiangxi Engineering Laboratory for Optoelectronics Testing Technology , Nanchang Hangkong University , Nanchang 330063 , P. R. China
| | - Yubao Zhang
- Jiangxi Engineering Laboratory for Optoelectronics Testing Technology , Nanchang Hangkong University , Nanchang 330063 , P. R. China
| | - Qinghua Li
- School of Physics Science and Technology , Lingnan Normal University , Zhanjiang 524048 , P. R. China
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16
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Liu Y, Jiang C, Song C, Wang J, Mu L, He Z, Zhong Z, Cun Y, Mai C, Wang J, Peng J, Cao Y. Highly Efficient All-Solution Processed Inverted Quantum Dots Based Light Emitting Diodes. ACS NANO 2018; 12:1564-1570. [PMID: 29365251 DOI: 10.1021/acsnano.7b08129] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In all-solution processed inverted quantum dots based light emitting diodes (QLEDs), the solvent erosion on the quantum dot (QD) layer prevents devices from reaching high performance. By employing an orthogonal solvent 1,4-dioxane for the hole transport layer (HTL) poly(9-vinlycarbazole) (PVK), the external quantum efficiencies (EQE) of red QLED is increased 4-fold, while the luminous efficiencies (LE) of blue QLED is enhanced by 25 times, compared to the previous devices' record. To further improve the device efficiency and reduce the efficiency roll-off, solution processed PVK/poly [(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(p-butylphenyl))diphenylamine)] (TFB) double-layer HTL is introduced to facilitate hole injection with stepwise energy level. By reducing the hole injection barrier, the turn-on voltage of QLEDs decreases from 3.4 to 2.7 V for red, from 5.1 to 2.7 V for green, and from 5.3 to 4.1 V for blue. The peak LE reach 22.1 cd/A, 21.4 cd/A, and 1.99 cd/A, while the maximum EQE reach 12.7%, 5.29%, and 5.99%, for red, green, and blue QLEDs, respectively. To the best of our knowledge, the red and blue QLEDs exhibit the best device performance among all the all-solution processed inverted QLEDs. In addition, the blue QLED is the champion among all the inverted QLEDs, including the devices fabricated by thermal evaporation.
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Affiliation(s)
- Yu Liu
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Congbiao Jiang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Chen Song
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Juanhong Wang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Lan Mu
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Zhiwei He
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Zhenji Zhong
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Yangke Cun
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Chaohuang Mai
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Jian Wang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Junbiao Peng
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
| | - Yong Cao
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology , Guangzhou 510640, China
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