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Hsu YH, Lin YH, Wu MH, Kuo HC, Horng RH. Current Confinement Effect on the Performance of Blue Light Micro-LEDs with 10 μm Dimension. ACS OMEGA 2023; 8:35351-35358. [PMID: 37779943 PMCID: PMC10536243 DOI: 10.1021/acsomega.3c05265] [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: 07/21/2023] [Accepted: 08/30/2023] [Indexed: 10/03/2023]
Abstract
The current confinement effect on the micro-LED (μLED) with a 10 μm dimension was simulated using SpeCLED software. In this study, three p-contact sizes were considered: 2 μm × 2 μm, 5 μm × 5 μm, and 8 μm × 8 μm dimensions for μLEDs with a 10 μm dimension. According to the simulation data, the highest external quantum efficiency (EQE) of 13.24% was obtained with a 5 μm × 5 μm contact size. The simulation data also showed that the μLEDs with narrow contact sizes experienced higher operating temperatures due to the current crowding effect. The experimental data revealed a red-shift effect in narrow contact sizes, indicating higher heat generation in those devices. As the contact sizes increased from 2 to 8 μm, the turn-on voltage decreased due to lower equivalent resistance. Additionally, the leakage current increased from 44 pA to 1.6 nA at a reverse voltage of -5 V. The study found that the best performance was achieved with a contact ratio of 0.5, which resulted in the highest EQE at 9.95%. This superior performance can be attributed to the better current confinement of the μLED compared to the μLED with a contact ratio of 0.8, resulting in lower leakage current and improved current spreading when compared to the μLED with a contact ratio of 0.2.
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Affiliation(s)
- Yu-Hsuan Hsu
- Department
of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan, ROC
| | - Yi-Hsin Lin
- Department
of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan, ROC
| | - Ming-Hsien Wu
- Electronic
and Optoelectronic System Research Laboratories, Industrial Technology Research Institute, Hsinchu 310401, Taiwan, ROC
| | - Hao Chung Kuo
- Department
of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan, ROC
| | - Ray-Hua Horng
- Institute
of Electronics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan, ROC
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Chen W, Hao J. Editorial for the Special Issue on Quantum Dots Frontiers. MICROMACHINES 2023; 14:mi14051026. [PMID: 37241648 DOI: 10.3390/mi14051026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023]
Abstract
Thanks to state-of-the-art chemical and device engineering in past decades, we have witnessed more and more novel applications based on semiconductor nanocrystals: quantum dots (QDs) [...].
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Affiliation(s)
- Wei Chen
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, China
| | - Junjie Hao
- College of Integrated Circuits and Optoelectronic Chips, Shenzhen Technology University, Shenzhen 518118, China
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Liang KL, Kuo WH, Lin CC, Fang YH. The Size-Dependent Photonic Characteristics of Colloidal-Quantum-Dot-Enhanced Micro-LEDs. MICROMACHINES 2023; 14:589. [PMID: 36984995 PMCID: PMC10058900 DOI: 10.3390/mi14030589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 02/25/2023] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
Colloidal CdSe/ZnS quantum dots (QD) enhanced micro-LEDs with sizes varying from 10 to 100 μm were fabricated and measured. The direct photolithography of quantum-dot-contained photoresists can place this color conversion layer on the top of an InGaN-based micro-LED and have a high throughput and semiconductor-grade precision. Both the uncoated and coated devices were characterized, and we determined that much higher brightness of a QD-enhanced micro-LED under the same current level was observed when compared to its AlGaInP counterpart. The color stability across the device sizes and injection currents were also examined. QD LEDs show low redshift of emission wavelength, which was recorded within 1 nm in some devices, with increasing current density from 1 to 300 A/cm2. On the other hand, the light conversion efficiency (LCE) of QD-enhanced micro-LEDs was detected to decrease under the high current density or when the device is small. The angular intensities of QD-enhanced micro-LEDs were measured and compared with blue devices. With the help of the black matrix and omnidirectional light emission of colloidal QD, we observed that the angular intensities of the red and blue colors are close to Lambertian distribution, which can lead to a low color shift in all angles. From our study, the QD-enhanced micro-LEDs can effectively increase the brightness, the color stability, and the angular color match, and thus play a promising role in future micro-display technology.
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Affiliation(s)
- Kai-Ling Liang
- Electronic and Optoelectronic System Research Laboratories, Industrial Technology Research Institute, Hsinchu 31057, Taiwan
- Graduate Institute of Polymer Science and Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Wei-Hung Kuo
- Electronic and Optoelectronic System Research Laboratories, Industrial Technology Research Institute, Hsinchu 31057, Taiwan
| | - Chien-Chung Lin
- Electronic and Optoelectronic System Research Laboratories, Industrial Technology Research Institute, Hsinchu 31057, Taiwan
- Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Yen-Hsiang Fang
- Electronic and Optoelectronic System Research Laboratories, Industrial Technology Research Institute, Hsinchu 31057, Taiwan
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Bae JH, Kim S, Ahn J, Shin C, Jung BK, Lee YM, Hong YK, Kim W, Ha DH, Ng TN, Kim J, Oh SJ. Acid-Base Reaction-Assisted Quantum Dot Patterning via Ligand Engineering and Photolithography. ACS APPLIED MATERIALS & INTERFACES 2022; 14:47831-47840. [PMID: 36255043 DOI: 10.1021/acsami.2c10297] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The integration of quantum dots (QDs) into device arrays for high-resolution display and imaging sensor systems remains a significant challenge in research and industry because of issues associated with the QD patterning process. It is difficult for conventional patterning processes such as stamping, inkjet printing, and photolithography to employ QDs and fabricate high-resolution patterns without degrading the properties of QDs. Here, we introduce a novel strategy for the QD patterning process by treating QDs with a bifunctional ligand for acid-base reaction-assisted photolithography. Bifunctional ligands, such as MPA (mercaptopropionic acid) or TGA (thioglycolic acid), have a carboxyl group on one side that allows the QDs to be etched along with the photoresist (PR) by the base developer, while on the opposite side the ligands have a thiol group that passivates the QD surface. Passivating MPA ligands on QDs facilitates patterning of QD films and makes them compatible with harsh photolithography processes. We successfully achieved the patterning of QDs down to 5 μm. We also fabricated high-resolution patterned QD light-emitting diodes (LEDs) and QD photodetector arrays. Our patterning process provides precise control for the fabrication of highly integrated QD-based optoelectronic devices.
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Affiliation(s)
- Jung Ho Bae
- Department of Materials Science and Engineering, Korea University, Seoul02841, Republic of Korea
| | - Suhyeon Kim
- Department of Advanced Materials Engineering, Kyonggi University, Suwon-si, Gyeonggi-do16227, Republic of Korea
| | - Junhyuk Ahn
- Department of Materials Science and Engineering, Korea University, Seoul02841, Republic of Korea
| | - Chanho Shin
- Materials Science Engineering Program and Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California92093,United States
| | - Byung Ku Jung
- Department of Materials Science and Engineering, Korea University, Seoul02841, Republic of Korea
| | - Yong Min Lee
- Department of Semiconductor Systems Engineering, Korea University, Seoul02841, Republic of Korea
| | - Yun Kun Hong
- School of Integrative Engineering, Chung-Ang University, Seoul06974, Republic of Korea
| | - Woosik Kim
- Department of Materials Science and Engineering, Korea University, Seoul02841, Republic of Korea
| | - Don Hyung Ha
- School of Integrative Engineering, Chung-Ang University, Seoul06974, Republic of Korea
| | - Tse Nga Ng
- Materials Science Engineering Program and Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California92093,United States
| | - Jiwan Kim
- Department of Advanced Materials Engineering, Kyonggi University, Suwon-si, Gyeonggi-do16227, Republic of Korea
| | - Soong Ju Oh
- Department of Materials Science and Engineering, Korea University, Seoul02841, Republic of Korea
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Ren X, Zhang X, Xie H, Cai J, Wang C, Chen E, Xu S, Ye Y, Sun J, Yan Q, Guo T. Perovskite Quantum Dots for Emerging Displays: Recent Progress and Perspectives. NANOMATERIALS 2022; 12:nano12132243. [PMID: 35808081 PMCID: PMC9268187 DOI: 10.3390/nano12132243] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 06/23/2022] [Accepted: 06/27/2022] [Indexed: 02/04/2023]
Abstract
The excellent luminescence properties of perovskite quantum dots (PQDs), including wide excitation wavelength range, adjustable emission wavelength, narrow full width at half maximum (FWHM), and high photoluminescence quantum yield (PLQY), highly match the application requirements in emerging displays. Starting from the fundamental structure and the related optical properties, this paper first introduces the existing synthesis approaches of PQDs that have been and will potentially be used for display devices, and then summarizes the stability improving approaches with high retention of PQDs’ optical performance. Based on the above, the recent research progress of PQDs in displays is further elaborated. For photoluminescent display applications, the PQDs can be embedded in the backlighting device or color filter for liquid crystal displays (LCD), or they may function as the color conversion layer for blue organic light-emitting diodes (OLED) and blue micro-scale light-emitting diodes (μLED). In terms of next-generation electroluminescent displays, notable progress in perovskite quantum-dot light emitting diodes (PeQLED) has been achieved within the past decade, especially the maximum external quantum efficiency (EQE). To conclude, the key directions for future PQD development are summarized for promising prospects and widespread applications in display fields.
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Affiliation(s)
- Xinxin Ren
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
| | - Xiang Zhang
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
| | - Hongxing Xie
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, 2 Xueyuan Road, Fuzhou 350108, China
| | - Junhu Cai
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
| | - Chenhui Wang
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
| | - Enguo Chen
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, 2 Xueyuan Road, Fuzhou 350108, China
- Correspondence: ; Tel.: +86-13599399819
| | - Sheng Xu
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, 2 Xueyuan Road, Fuzhou 350108, China
| | - Yun Ye
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, 2 Xueyuan Road, Fuzhou 350108, China
| | - Jie Sun
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, 2 Xueyuan Road, Fuzhou 350108, China
| | - Qun Yan
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, 2 Xueyuan Road, Fuzhou 350108, China
| | - Tailiang Guo
- National & Local United Engineering Laboratory of Flat Panel Display Technology, College of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China; (X.R.); (X.Z.); (H.X.); (J.C.); (C.W.); (S.X.); (Y.Y.); (J.S.); (Q.Y.); (T.G.)
- Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China, 2 Xueyuan Road, Fuzhou 350108, China
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