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Li S, Xu X, Lin Q, Sun J, Zhang H, Shen H, Li LS, Wang L. Bright and Stable Yellow Quantum Dot Light-Emitting Diodes Through Core-Shell Nanostructure Engineering. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2306859. [PMID: 38155356 DOI: 10.1002/smll.202306859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 12/15/2023] [Indexed: 12/30/2023]
Abstract
Solution-processed and efficient yellow quantum dot light-emitting diodes (QLEDs) are considered key optoelectronic devices for lighting, display, and signal indication. However, limited synthesis routes for yellow quantum dots (QDs), combined with inferior stress-relaxation of the core-shell interface, pose challenges to their commercialization. Herein, a nanostructure tailoring strategy for high-quality yellow CdZnSe/ZnSe/ZnS core/shell QDs using a "stepwise high-temperature nucleation-shell growth" method is introduced. The synthesized CdZnSe-based QDs effectively smoothed the release stress of the core-shell interface and revealed a near-unit photoluminescence quantum yield, with nonblinking behavior and matched energy level, which accelerated radiative recombination and charge injection balance for device operation. Consequently, the yellow CdZnSe-based QLEDs exhibited a peak external quantum efficiency of 23.7%, a maximum luminance of 686 050 cd m-2, and a current efficiency of 103.2 cd A-1, along with an operating half-lifetime of 428 523 h at 100 cd m-2. To the best of the knowledge, the luminance and operational stability of the device are found to be the highest values reported for yellow LEDs. Moreover, devices with electroluminescence (EL) peaks at 570-605 nm exhibited excellent EQEs, surpassing 20%. The work is expected to significantly push the development of RGBY-based display panels and white LEDs.
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Affiliation(s)
- Saifei Li
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, 475004, China
| | - Xiongping Xu
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, 475004, China
| | - Qingli Lin
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, 475004, China
| | - Jiahui Sun
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, 475004, China
| | - Han Zhang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, 475004, China
| | - Huaibin Shen
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, 475004, China
| | - Lin Song Li
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, 475004, China
| | - Lei Wang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Centre for High-efficiency Display and Lighting Technology, School of Materials, Henan University, Kaifeng, 475004, China
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Tan X, Dou D, Chua LL, Png RQ, Congrave DG, Bronstein H, Baumgarten M, Li Y, Blom PWM, Wetzelaer GJAH. Inverted device architecture for high efficiency single-layer organic light-emitting diodes with imbalanced charge transport. Nat Commun 2024; 15:4107. [PMID: 38750042 PMCID: PMC11096390 DOI: 10.1038/s41467-024-48553-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 05/04/2024] [Indexed: 05/18/2024] Open
Abstract
Many wide-gap organic semiconductors exhibit imbalanced electron and hole transport, therefore efficient organic light-emitting diodes require a multilayer architecture of electron- and hole-transport materials to confine charge recombination to the emissive layer. Here, we show that even for emitters with imbalanced charge transport, it is possible to obtain highly efficient single-layer organic light emitting diodes (OLEDs), without the need for additional charge-transport and blocking layers. For hole-dominated emitters, an inverted single-layer device architecture with ohmic bottom-electron and top-hole contacts moves the emission zone away from the metal top electrode, thereby more than doubling the optical outcoupling efficiency. Finally, a blue-emitting inverted single-layer OLED based on thermally activated delayed fluorescence is achieved, exhibiting a high external quantum efficiency of 19% with little roll-off at high brightness, demonstrating that balanced charge transport is not a prerequisite for highly efficient single-layer OLEDs.
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Affiliation(s)
- Xiao Tan
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Dehai Dou
- Max Planck Institute for Polymer Research, Mainz, Germany
| | - Lay-Lay Chua
- Department of Physics, National University of Singapore, Singapore, Singapore
- National University of Singapore, Department of Chemistry, Singapore, Singapore
| | - Rui-Qi Png
- Department of Physics, National University of Singapore, Singapore, Singapore
| | | | - Hugo Bronstein
- Department of Chemistry, University of Cambridge, Cambridge, UK
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | | | - Yungui Li
- Max Planck Institute for Polymer Research, Mainz, Germany.
| | - Paul W M Blom
- Max Planck Institute for Polymer Research, Mainz, Germany
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Maduwanthi C, Jong CA, Mohammed WS, Hsu SH. Stability and photocurrent enhancement of photodetectors by using core/shell structured CsPbBr 3/TiO 2 quantum dots and 2D materials. NANOSCALE ADVANCES 2024; 6:2328-2336. [PMID: 38694456 PMCID: PMC11059547 DOI: 10.1039/d3na01129a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 03/18/2024] [Indexed: 05/04/2024]
Abstract
Ultra-stable CsPbBr3 perovskite quantum dots (QDs) were prepared, and the performance of the photodetector fabricated from them was enhanced by 2D material incorporation. This multi-component photodetector appears to have good stability in the ambient utilization environment. All inorganic CsPbBr3 QDs are potential candidates for application in photodetection devices. However, QDs have several issues such as defects on the QD surface, degradation under environmental conditions, and unfavorable carrier mobility limiting the high performance of the photodetectors. This work addresses these issues by fabricating a core/shell structure and introducing 2D materials (MXenes, Ti3C2Tx) into the device. Here, three types of photodetectors with QDs only, QDs with a core/shell structure, and QDs with a core/shell structure and MXenes are fabricated for systematic study. The CsPbBr3/TiO2 photodetector demonstrated a two times photocurrent enhancement compared to bare QDs and had good device stability after TiO2 shell coating. After introducing Ti3C2Tx into CsPbBr3/TiO2, a significant photocurrent enhancement from nanoampere (nA) to microampere (μA) was observed, revealing that MXenes can improve the photoelectric response of perovskite materials significantly. Higher photocurrent can avoid signal interference from environmental noise for better practical feasibility. This study provides a systematic understanding of the photocurrent conversion of perovskite quantum dots that is beneficial in advancing optoelectronic device integration, especially for flexible wearable device applications.
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Affiliation(s)
- Chathurika Maduwanthi
- School of Integrated Science and Innovation, Sirindhorn International Institute of Technology, Thammasat University Pathum Thani 12120 Thailand
| | - Chao-An Jong
- Taiwan Semiconductor Research Institute, National Applied Research Laboratories Hsinchu 300091 Taiwan ROC
| | - Waleed S Mohammed
- Center of Research in Optoelectronics, Communication and Control Systems (BU-CROCCS), Bangkok University Pathum Thani 12120 Thailand
| | - Shu-Han Hsu
- School of Integrated Science and Innovation, Sirindhorn International Institute of Technology, Thammasat University Pathum Thani 12120 Thailand
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Azadinia M, Davidson-Hall T, Chung DS, Ghorbani A, Samaeifar F, Chen J, Chun P, Lyu Q, Cotella G, Aziz H. Inverted Solution-Processed Quantum Dot Light-Emitting Devices with Wide Band Gap Quantum Dot Interlayers. ACS APPLIED MATERIALS & INTERFACES 2023; 15:23631-23641. [PMID: 37141421 DOI: 10.1021/acsami.3c02356] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Despite its benefits for facilitating device fabrication, utilization of a polymeric hole transport layer (HTL) in inverted quantum dots (QDs) light-emitting devices (IQLEDs) often leads to poor device performance. In this work, we find that the poor performance arises primarily from electron leakage, inefficient charge injection, and significant exciton quenching at the HTL interface in the inverted architecture and not due to solvent damage effects as is widely believed. We also find that using a layer of wider band gap QDs as an interlayer (IL) in between the HTL and the main QDs' emission material layer (EML) can facilitate hole injection, suppress electron leakage, and reduce exciton quenching, effectively mitigating the poor interface effects and resulting in high electroluminescence performance. Using an IL in IQLEDs with a solution-processed poly(9,9-dioctylfluorene-alt-N-(4-sec-butylphenyl)-diphenylamine) (TFB), HTL improves the efficiency by 2.85× (from 3 to 8.56%) and prolongs the lifetime by 9.4× (from 1266 to 11,950 h at 100 cd/m2), which, to the best of our knowledge, is the longest lifetime for an R-IQLED with a solution-coated HTL. Measurements on single-carrier devices reveal that while electron injection becomes easier as the band gap of the QDs decreases, hole injection surprisingly becomes more difficult, indicating that EMLs of QLEDs are more electron-rich in the case of red devices and more hole-rich in the case of blue devices. Ultraviolet photoelectron spectroscopy measurements verify that blue QDs have a shallower valence band energy than their red counterparts, corroborating these conclusions. The findings in this work, therefore, provide not only a simple approach for achieving high performance in IQLEDs with solution-coated HTLs but also novel insights into charge injection and its dependence on QDs' band gap as well as into different HTL interface properties of the inverted versus upright architecture.
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Affiliation(s)
- Mohsen Azadinia
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - 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
| | - Dong Seob Chung
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Atefeh Ghorbani
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Fatemeh Samaeifar
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Junfei Chen
- Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Peter Chun
- Ottawa IC Laboratory, Huawei Canada, 19 Allstate Parkway, Markham, Ontario L3R 5B4, Canada
| | - Quan Lyu
- Cambridge Research Centre, Huawei Technologies Research & Development (UK) Ltd., Cambridge CB4 0FY, U.K
| | - Giovanni Cotella
- Ipswich Research Centre, Huawei Technologies Research & Development (UK) Ltd., Phoenix House (B55), Adastral Park, Ipswich IP5 3RE, U.K
| | - 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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