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Hillebrandt S, Moon CK, Taal AJ, Overhauser H, Shepard KL, Gather MC. High-Density Integration of Ultrabright OLEDs on a Miniaturized Needle-Shaped CMOS Backplane. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2300578. [PMID: 37470219 DOI: 10.1002/adma.202300578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 05/24/2023] [Accepted: 07/03/2023] [Indexed: 07/21/2023]
Abstract
Direct deposition of organic light-emitting diodes (OLEDs) on silicon-based complementary metal-oxide-semiconductor (CMOS) chips has enabled self-emissive microdisplays with high resolution and fill-factor. Emerging applications of OLEDs in augmented and virtual reality (AR/VR) displays and in biomedical applications, e.g., as brain implants for cell-specific light delivery in optogenetics, require light intensities orders of magnitude above those found in traditional displays. Further requirements often include a microscopic device footprint, a specific shape and ultrastable passivation, e.g., to ensure biocompatibility and minimal invasiveness of OLED-based implants. In this work, up to 1024 ultrabright, microscopic OLEDs are deposited directly on needle-shaped CMOS chips. Transmission electron microscopy and energy-dispersive X-ray spectroscopy are performed on the foundry-provided aluminum contact pads of the CMOS chips to guide a systematic optimization of the contacts. Plasma treatment and implementation of silver interlayers lead to ohmic contact conditions and thus facilitate direct vacuum deposition of orange- and blue-emitting OLED stacks leading to micrometer-sized pixels on the chips. The electronics in each needle allow each pixel to switch individually. The OLED pixels generate a mean optical power density of 0.25 mW mm-2, corresponding to >40 000 cd m-2, well above the requirement for daylight AR applications and optogenetic single-unit activation in the brain.
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Affiliation(s)
- Sabina Hillebrandt
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
- Humboldt Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939, Cologne, Germany
| | - Chang-Ki Moon
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
- Humboldt Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939, Cologne, Germany
| | | | | | | | - Malte C Gather
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, UK
- Humboldt Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939, Cologne, Germany
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2
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Han K, Jin J, Zhou X, Duan Y, Kovalenko MV, Xia Z. Narrow-Band Green-Emitting Hybrid Organic-Inorganic Eu (II)-Iodides for Next-Generation Micro-LED Displays. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2313247. [PMID: 38359440 DOI: 10.1002/adma.202313247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 02/08/2024] [Indexed: 02/17/2024]
Abstract
Low-dimensional metal halide perovskites are an emerging class of light-emitting materials for LED-based displays; however, their B-site cations are confined to ns2, d5, and d10 metals. Here, the design of divalent rare earth ions at B-site is presented and a novel Eu(II)-based iodide hybrid is reported with efficient (PLQY ≈98%) narrow-band (FWHM ≈43 nm) green emission and high thermal stability (97%@150 °C). Owing to reduced lattice vibrations and shrunken average distance of Eu(II)-iodide bonds in the face-sharing 1D-structure, photoluminescence from Eu(II) 4f-5d transition appears along with elevated crystal-field splitting of 5d energy level. The Eu(II)-based iodide hybrid is further demonstrated for color-pure green phosphor-converted LEDs with a maximum brightness of ≈396 000 cd m-2 and photoelectric efficiency of 29.2%. High-resolution micrometer-scale light-emitting diode (micro-LED) displays (2540 PPI) via the solution-processed screen is also presented. This work thus showcases a compelling narrow-band green emitter for commercial micro-LED displays.
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Affiliation(s)
- Kai Han
- The State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, Guangdong Engineering Technology Research and Development Centre of Special Optical Fiber Materials and Devices, School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510641, China
| | - Jiance Jin
- The State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, Guangdong Engineering Technology Research and Development Centre of Special Optical Fiber Materials and Devices, School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510641, China
| | - Xinquan Zhou
- The State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, Guangdong Engineering Technology Research and Development Centre of Special Optical Fiber Materials and Devices, School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510641, China
| | - Yan Duan
- Spin-X Institute, South China University of Technology, Guangzhou, 510641, China
| | - Maksym V Kovalenko
- Department of Chemistry and Applied Biosciences, Institute of Inorganic Chemistry, ETH Zürich, Zürich, 8093, Switzerland
- Laboratory for Thin Films and Photovoltaics, Empa-Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, 8600, Switzerland
| | - Zhiguo Xia
- The State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, Guangdong Engineering Technology Research and Development Centre of Special Optical Fiber Materials and Devices, School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510641, China
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong, 510641, China
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3
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Chu EK, Youn EJ, Kim HW, Park BD, Sung HK, Park HH. Wafer-Scale Characterization of 1692-Pixel-Per-Inch Blue Micro-LED Arrays with an Optimized ITO Layer. MICROMACHINES 2024; 15:560. [PMID: 38793133 PMCID: PMC11122828 DOI: 10.3390/mi15050560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/22/2024] [Accepted: 04/23/2024] [Indexed: 05/26/2024]
Abstract
Wafer-scale blue micro-light-emitting diode (micro-LED) arrays were fabricated with a pixel size of 12 μm, a pixel pitch of 15 μm, and a pixel density of 1692 pixels per inch, achieved by optimizing the properties of e-beam-deposited and sputter-deposited indium tin oxide (ITO). Although the sputter-deposited ITO (S-ITO) films exhibited a densely packed morphology and lower resistivity compared to the e-beam-deposited ITO (E-ITO) films, the forward voltage (VF) values of a micro-LED with the S-ITO films were higher than those with the E-ITO films. The VF values for a single pixel and for four pixels with E-ITO films were 2.82 V and 2.83 V, respectively, while the corresponding values for S-ITO films were 3.50 V and 3.52 V. This was attributed to ion bombardment damage and nitrogen vacancies in the p-GaN layer. Surprisingly, the VF variations of a single pixel and of four pixels with the optimized E-ITO spreading layer from five different regions were only 0.09 V and 0.10 V, respectively. This extremely uniform VF variation is suitable for creating micro-LED displays to be used in AR and VR applications, circumventing the bottleneck in the development of long-lifespan and high-brightness organic LED devices for industrial mass production.
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Affiliation(s)
- Eun-Kyung Chu
- Optical Device Laboratory, Korea Advanced Nano Fab Center (KANC), Suwon 443270, Republic of Korea; (E.-K.C.); (E.J.Y.)
| | - Eun Jeong Youn
- Optical Device Laboratory, Korea Advanced Nano Fab Center (KANC), Suwon 443270, Republic of Korea; (E.-K.C.); (E.J.Y.)
| | - Hyun Woong Kim
- Convergence Technology Division, Korea Advanced Nano Fab Center (KANC), Suwon 443270, Republic of Korea; (H.W.K.); (B.D.P.); (H.K.S.)
| | - Bum Doo Park
- Convergence Technology Division, Korea Advanced Nano Fab Center (KANC), Suwon 443270, Republic of Korea; (H.W.K.); (B.D.P.); (H.K.S.)
| | - Ho Kun Sung
- Convergence Technology Division, Korea Advanced Nano Fab Center (KANC), Suwon 443270, Republic of Korea; (H.W.K.); (B.D.P.); (H.K.S.)
| | - Hyeong-Ho Park
- Optical Device Laboratory, Korea Advanced Nano Fab Center (KANC), Suwon 443270, Republic of Korea; (E.-K.C.); (E.J.Y.)
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4
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Sun D, Liu L, Wang G, Yu J, Li Q, Tian G, Wang B, Xu X, Zhang L, Wang S. Research Progress in Liquid Phase Growth of GaN Crystals. Chemistry 2024; 30:e202303710. [PMID: 38140956 DOI: 10.1002/chem.202303710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 12/24/2023]
Abstract
As a wide band gap semiconductor, gallium nitride (GaN) has high breakdown voltage, excellent structural stability and mechanical properties, giving it unique advantages in applications such as high frequency, high power, and high temperature. As a result, it has broad application prospects in optoelectronics and microelectronics. However, the lack of high-quality, large-size GaN crystal substrates severely limit the improvement of electronic device performance. To solve this problem, liquid phase growth of GaN has attracted much attention because it can produce higher quality GaN crystals compared to traditional vapor phase growth methods. This review introduces two main methods of liquid phase growth of GaN: the flux method and ammonothermal method, as well as their advantages and challenges. It reviews the research history and recent advances of these two methods, including the effects of different solvents and mineralizers on the growth quality and performance of GaN crystals, as well as various technical improvements. This review aims to outline the principles, characteristics, and development trends of liquid phase growth of GaN, to provide more inspiration for future research on liquid phase growth, and to achieve further breakthroughs in its development and commercial application.
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Affiliation(s)
- Defu Sun
- Institute of Novel Semiconductors, State Key Lab of Crystal Materials, Shandong University, Jinan, Shandong, 250100, P. R. China
| | - Lei Liu
- Institute of Novel Semiconductors, State Key Lab of Crystal Materials, Shandong University, Jinan, Shandong, 250100, P. R. China
| | - Guodong Wang
- Institute of Novel Semiconductors, State Key Lab of Crystal Materials, Shandong University, Jinan, Shandong, 250100, P. R. China
| | - Jiaoxian Yu
- Key Laboratory of Processing and Testing Technology of Glass & Functional Ceramics of Shandong Province, School of Materials Science and Engineering, Qilu, University of Technology (Shandong Academy of Sciences), Jinan, Shandong, 250353, P. R. China
| | - Qiubo Li
- Institute of Novel Semiconductors, State Key Lab of Crystal Materials, Shandong University, Jinan, Shandong, 250100, P. R. China
| | - Ge Tian
- School of Life Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, Shandong, 271000, P. R. China
| | - Benfa Wang
- Institute of Novel Semiconductors, State Key Lab of Crystal Materials, Shandong University, Jinan, Shandong, 250100, P. R. China
| | - Xiangang Xu
- Institute of Novel Semiconductors, State Key Lab of Crystal Materials, Shandong University, Jinan, Shandong, 250100, P. R. China
| | - Lei Zhang
- Institute of Novel Semiconductors, State Key Lab of Crystal Materials, Shandong University, Jinan, Shandong, 250100, P. R. China
- Shenzhen Research Institute, Shandong University, Shenzhen, Guangdong, 518000, P. R. China
| | - Shouzhi Wang
- Institute of Novel Semiconductors, State Key Lab of Crystal Materials, Shandong University, Jinan, Shandong, 250100, P. R. China
- Shenzhen Research Institute, Shandong University, Shenzhen, Guangdong, 518000, P. R. China
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5
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Li H, Zhao Y, Qiu Y, Gao H, He K, Yang J, Zhao Y, OuYang G, Ma N, Wei X, Du Z, Jiang L, Wu Y. Multi-Interfacial Confined Assembly of Colloidal Quantum Dots Quasisuperlattice Microcavities for High-Resolution Full-Color Microlaser Arrays. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2314061. [PMID: 38350441 DOI: 10.1002/adma.202314061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 02/08/2024] [Indexed: 02/15/2024]
Abstract
Colloidal quantum dots (CQDs) are considered a promising material for the next generation of integrated display devices due to their designable optical bandgap and low energy consumption. Owing to their dispersibility in solvents, CQD micro/nanostructures are generally fabricated by solution-processing methods. However, the random mass transfer in liquid restricts the programmable construction in macroscopy and ordered assembly in microscopy for the integration of CQD optical structures. Herein, a multi-interfacial confined assembly strategy is developed to fabricate CQDs programmable microstructure arrays with a quasisuperlattice configuration through controlling the dynamics of three-phase contact lines (TPCLs). The motion of TPCLs dominates the division of liquid film for precise positioning of CQD microstructures, while pinned TPCLs control the solvent evaporation and concentration gradient to directionally drive the mass transfer and packing of CQDs. Owing to their long-range order and adjustable structural dimensions, CQD microring arrays function as high-quality-factor (high-Q) lasing resonant cavities with low thresholds and tunable lasing emission modes. Through the further surface treatment and liquid dynamics control, the on-chip integration of red (R), green (G), and blue (B) multicomponent CQD microlaser arrays are demonstrated. The technique establishes a new route to fabricate large-area, ultrahigh-definition, and full-color CQD laser displays.
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Affiliation(s)
- Hui Li
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Henan University, Kaifeng, 475004, P. R. China
- Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Yuyan Zhao
- Suzhou Institute for Advanced Research, University of Science and Technology of China, Suzhou, Jiangsu, 215123, China
| | - Yuchen Qiu
- College of Chemistry, Jilin University, Changchun, 130012, P. R. China
| | - Hanfei Gao
- Suzhou Institute for Advanced Research, University of Science and Technology of China, Suzhou, Jiangsu, 215123, China
| | - Ke He
- Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- School of Future Technology, University of Chinese Academy of Sciences (UCAS), Beijing, 100049, P. R. China
| | - Junchuan Yang
- Suzhou Institute for Advanced Research, University of Science and Technology of China, Suzhou, Jiangsu, 215123, China
| | - Yingjie Zhao
- College of Chemistry, Zhengzhou University, Zhengzhou, 450001, P. R. China
| | - Guangwen OuYang
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Henan University, Kaifeng, 475004, P. R. China
| | - Na Ma
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Henan University, Kaifeng, 475004, P. R. China
| | - Xiao Wei
- Ji Hua Laboratory Foshan, Guangdong, 528200, P. R. China
| | - Zuliang Du
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Henan University, Kaifeng, 475004, P. R. China
| | - Lei Jiang
- Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- School of Future Technology, University of Chinese Academy of Sciences (UCAS), Beijing, 100049, P. R. China
| | - Yuchen Wu
- Key Laboratory for Special Functional Materials of Ministry of Education, National & Local Joint Engineering Research Center for High-efficiency Display and Lighting Technology, Henan University, Kaifeng, 475004, P. R. China
- Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- Suzhou Institute for Advanced Research, University of Science and Technology of China, Suzhou, Jiangsu, 215123, China
- School of Future Technology, University of Chinese Academy of Sciences (UCAS), Beijing, 100049, P. R. China
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6
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Takeuchi K, Ogura H, Hasuike N, Kamikawa T. Decomposition of the anisotropic strain in 3D-structure GaN layers using Raman spectroscopy. Sci Rep 2024; 14:3330. [PMID: 38336918 PMCID: PMC10858272 DOI: 10.1038/s41598-024-53478-2] [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: 10/17/2023] [Accepted: 01/31/2024] [Indexed: 02/12/2024] Open
Abstract
Strain engineering for gallium nitride has been studied by many researchers to improve the performance of various devices (i.e., light-emitting diodes, laser diodes, power devices, high electron mobility transistors, and so on). Further miniaturization of gallium nitride devices will clearly continue in the future, and therefore an accurate understanding of the strain state in the devices is essential. However, a measurement technique for axially resolved evaluation of the strain in microareas has not yet been established. In this study, we revealed that the anisotropic strain state induced in c-plane growth gallium nitride is linked to the split state of Raman peaks, which were measured with [Formula: see text] and [Formula: see text] polarized configurations. The anisotropic strain state in c-plane gallium nitride was induced in the 3D-structure by epitaxial lateral overgrowth, which enabled successful performance of our work. This result allowed us to axially decompose the strain in c-plane gallium nitride through Raman spectroscopy and establish a measurement technique for axially resolving the strain. This measurement technique is feasible using a conventional Raman spectrometer. Furthermore, the method was indicated to be applicable to all wurtzite-type crystals, including gallium nitride, silicon carbide, and aluminum nitride. Our work provides a new perspective for understanding the complex strain state in microareas for wurtzite materials. Comprehending the strain state, which strongly affects device performance, will help promote the research and development of III-V semiconductor devices.
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Affiliation(s)
- Kazuma Takeuchi
- Corporate R&D Group, Keihanna Research Center, Kyocera Corporation, 3-5-3 Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan.
| | - Hiroyuki Ogura
- Corporate R&D Group, Keihanna Research Center, Kyocera Corporation, 3-5-3 Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan
| | - Noriyuki Hasuike
- Faculty of Electrical Engineering and Electronics, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Takeshi Kamikawa
- Corporate R&D Group, Keihanna Research Center, Kyocera Corporation, 3-5-3 Hikaridai, Seika-cho, Soraku-gun, Kyoto, Japan
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Wan S, Li Z, Dai C, Shi Y, Li Z. Multi-Dimensional Light-Emitting Meta-Display: Photoluminescence and Pumping Light Multiplexing. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2310294. [PMID: 38088224 DOI: 10.1002/adma.202310294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/03/2023] [Indexed: 12/20/2023]
Abstract
The advent of intelligent display devices has given rise to diverse and complex demands for miniature light-emitting devices. Light-emitting metasurfaces have emerged as a practical and efficient means of achieving precise light modulation. However, their practicality is limited by certain constraints. First, there is a need for further exploration of the ability to manipulate both pumping and emitting light simultaneously. Second, there is currently no encoding freedom in multi-dimensional emitting light. To address these concerns, using meta-atoms is proposed to encode both fluorescence and pumping light independently, and expand the encoding freedom with different incident wavevector directions. A light-emitting metasurface with quad-fold multiplex encoding meta-displays, including dual scattering images and dual fluorescence images, is further demonstrated. This design strategy not only manipulates both pumping and fluorescence light but also broadens encoding freedom for comprehensive multi-functionality. This can pave the way for multiplexing optical displays, information storage, and next-generation wearable displays.
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Affiliation(s)
- Shuai Wan
- Electronic Information School, Wuhan University, Wuhan, 430072, China
| | - Zhe Li
- Electronic Information School, Wuhan University, Wuhan, 430072, China
| | - Chenjie Dai
- Electronic Information School, Wuhan University, Wuhan, 430072, China
| | - Yangyang Shi
- Electronic Information School, Wuhan University, Wuhan, 430072, China
| | - Zhongyang Li
- Electronic Information School, Wuhan University, Wuhan, 430072, China
- Wuhan Institute of Quantum Technology, Wuhan, 430206, China
- School of Microelectronics, Wuhan University, Wuhan, 430072, China
- Suzhou Institute of Wuhan University, Suzhou, 215123, China
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8
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Qi L, Li P, Zhang X, Wong KM, Lau KM. Monolithic full-color active-matrix micro-LED micro-display using InGaN/AlGaInP heterogeneous integration. LIGHT, SCIENCE & APPLICATIONS 2023; 12:258. [PMID: 37899364 PMCID: PMC10613616 DOI: 10.1038/s41377-023-01298-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 09/28/2023] [Accepted: 10/04/2023] [Indexed: 10/31/2023]
Abstract
A prototype of full-color active-matrix micro-light-emitting diode (micro-LED) micro-display with a pixel density of 391 pixel per inch (ppi) using InGaN/AlGaInP heterogeneous integration is demonstrated. InGaN blue/green dual-color micro-LED arrays realized on a single metal organic chemical vapor deposition (MOCVD)-grown GaN-on-Si epiwafer and AlGaInP red micro-LED arrays are both monolithically fabricated, followed by the integration with a common complementary metal oxide semiconductor (CMOS) backplane via flip-chip bonding technology to form a double-layer thin-film display structure. Full-color images with decent color gamut and brightness are successfully displayed through the fine adjustment of driving current densities of RGB subpixels. This full-color display combines the advantages of high quantum efficiency of InGaN material on blue/green light and AlGaInP material on red light through heterogeneous integration and high pixel density through monolithic fabrication approach, demonstrating the feasibility and prospects of high brightness, good color performance, and high-resolution micro-LED micro-displays in future metaverse applications.
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Affiliation(s)
- Longheng Qi
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Peian Li
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xu Zhang
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Ka Ming Wong
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Kei May Lau
- Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
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Ryu JE, Park S, Park Y, Ryu SW, Hwang K, Jang HW. Technological Breakthroughs in Chip Fabrication, Transfer, and Color Conversion for High-Performance Micro-LED Displays. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2204947. [PMID: 35950613 DOI: 10.1002/adma.202204947] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/05/2022] [Indexed: 06/15/2023]
Abstract
The implementation of high-efficiency and high-resolution displays has been the focus of considerable research interest. Recently, micro light-emitting diodes (micro-LEDs), which are inorganic light-emitting diodes of size <100 µm2 , have emerged as a promising display technology owing to their superior features and advantages over other displays like liquid crystal displays and organic light-emitting diodes. Although many companies have introduced micro-LED displays since 2012, obstacles to mass production still exist. Three major challenges, i.e., low quantum efficiency, time-consuming transfer, and complex color conversion, have been overcome with technological breakthroughs to realize cost-effective micro-LED displays. In the review, methods for improving the degraded quantum efficiency of GaN-based micro-LEDs induced by the size effect are examined, including wet chemical treatment, passivation layer adoption, LED structure design, and growing LEDs in self-passivated structures. Novel transfer technologies, including pick-up transfer and self-assembly methods, for developing large-area micro-LED displays with high yield and reliability are discussed in depth. Quantum dots as color conversion materials for high color purity, and deposition methods such as electrohydrodynamic jet printing or contact printing on micro-LEDs are also addressed. This review presents current status and critical challenges of micro-LED technology and promising technical breakthroughs for commercialization of high-performance displays.
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Affiliation(s)
- Jung-El Ryu
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Sohyeon Park
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
| | - Yongjo Park
- Advance Institute of Convergence Technology, Seoul National University, Suwon, 16229, Republic of Korea
| | - Sang-Wan Ryu
- Department of Physics, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Kyungwook Hwang
- Samsung Advanced Institute of Technology, Suwon, 16678, Republic of Korea
| | - Ho Won Jang
- Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul, 08826, Republic of Korea
- Advance Institute of Convergence Technology, Seoul National University, Suwon, 16229, Republic of Korea
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10
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Luo C, Zheng Z, Ding Y, Ren Z, Shi H, Ji H, Zhou X, Chen Y. High-Resolution, Highly Transparent, and Efficient Quantum Dot Light-Emitting Diodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2303329. [PMID: 37335765 DOI: 10.1002/adma.202303329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 06/16/2023] [Indexed: 06/21/2023]
Abstract
Aiming at next-generation displays, high-resolution quantum dot light-emitting diodes (QLEDs) with high efficiency and transparency are highly desired. However, there is limited study involving the improvements of QLED pixel resolution, efficiency, and transparency simultaneously, which undoubtedly restricts the practical applications of QLED for next-generation displays. Here, the strategy of electrostatic force-induced deposition (EF-ID) is proposed by introducing alternating polyethyleneimine (PEI) and fluorosilane patterns to synergistically improve the pixel accuracy and transmittance of QD patterns. More importantly, the leakage current induced by the void spaces between pixels that is usually reported for high-resolution QLEDs is greatly suppressed by substrate-assisted insulating fluorosilane patterns. Finally, high-performance QLEDs with high resolution ranging from 1104 to 3031 pixels per inch (PPI) and a high efficiency of 15.6% are achieved, among the best performances of high resolution QLEDs. Notably, the high resolution QD pixels greatly enhance the transmittance of the QD patterns, thus prompting an impressive transmittance of 90.7% for the transparent QLEDs (2116 PPI), which represents the highest transmittance of transparent QLED devices. Consequently, this work contributes an effective and general approach for high-resolution QLEDs with high efficiency and transparency.
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Affiliation(s)
- Chengzhao Luo
- School of Optoelectronic Science and Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, P. R. China
| | - Zhishuai Zheng
- School of Optoelectronic Science and Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, P. R. China
| | - Yanhui Ding
- School of Optoelectronic Science and Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, P. R. China
| | - Zhenwei Ren
- School of Optoelectronic Science and Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, P. R. China
| | - Hengfei Shi
- School of Optoelectronic Science and Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, P. R. China
| | - Huifeng Ji
- School of Optoelectronic Science and Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, P. R. China
| | - Xin Zhou
- School of Optoelectronic Science and Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, P. R. China
| | - Yu Chen
- School of Optoelectronic Science and Engineering, Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou, 215006, P. R. China
- National University of Singapore Suzhou Research Institute, Dushu Lake Science and Education Innovation District, Suzhou, 215123, P. R. China
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11
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Yang L, Huang J, Tan Y, Lu W, Li Z, Pan A. All-inorganic lead halide perovskite nanocrystals applied in advanced display devices. MATERIALS HORIZONS 2023; 10:1969-1989. [PMID: 37039776 DOI: 10.1039/d3mh00062a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Advanced display devices are in greater demand due to their large color gamut, high color purity, ultrahigh visual resolution, and small size pixels. All-inorganic lead halide perovskite (AILHP) nanocrystals (NCs) possess inherent advantages such as narrow emission width, saturated color, and flexible integration, and have been developed as functional films, light sources, backlight components, and display panels. However, some drawbacks still restrict the practical application of advanced display devices based on AILHP NCs, including working stability, large-scale synthesis, and cost. In this review, we focus on AILHP NCs, review the recent progress in materials synthesis, stability improvement, patterning techniques, and device application. We also highlight the important role of materials systems in creating advanced display devices, followed by the challenges and opportunities in industrial processes. This review provides beneficial inspiration for the future development of AILHP NCs in colorful and white backlight, as well as high resolution full-color displays.
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Affiliation(s)
- Liuli Yang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, Hunan Institute of Optoelectronic Integration, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, P. R. China.
| | - Jianhua Huang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, Hunan Institute of Optoelectronic Integration, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, P. R. China.
| | - Yike Tan
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, Hunan Institute of Optoelectronic Integration, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, P. R. China.
| | - Wei Lu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, Hunan Institute of Optoelectronic Integration, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, P. R. China.
| | - Ziwei Li
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, Hunan Institute of Optoelectronic Integration, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, P. R. China.
- Wuhan National Laboratory for Optoelectronics and School of Physics, Huazhong University of Science and Technology, Wuhan, China
| | - Anlian Pan
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, Hunan Institute of Optoelectronic Integration, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, P. R. China.
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12
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Kumar V, Kymissis I. MicroLED/LED electro-optical integration techniques for non-display applications. APPLIED PHYSICS REVIEWS 2023; 10:021306. [PMID: 37265477 PMCID: PMC10155219 DOI: 10.1063/5.0125103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 03/20/2023] [Indexed: 06/03/2023]
Abstract
MicroLEDs offer an extraordinary combination of high luminance, high energy efficiency, low cost, and long lifetime. These characteristics are highly desirable in various applications, but their usage has, to date, been primarily focused toward next-generation display technologies. Applications of microLEDs in other technologies, such as projector systems, computational imaging, communication systems, or neural stimulation, have been limited. In non-display applications which use microLEDs as light sources, modifications in key electrical and optical characteristics such as external efficiency, output beam shape, modulation bandwidth, light output power, and emission wavelengths are often needed for optimum performance. A number of advanced fabrication and processing techniques have been used to achieve these electro-optical characteristics in microLEDs. In this article, we review the non-display application areas of the microLEDs, the distinct opto-electrical characteristics required for these applications, and techniques that integrate the optical and electrical components on the microLEDs to improve system-level efficacy and performance.
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Affiliation(s)
- V. Kumar
- Department of Electrical Engineering, Columbia University, New York, New York 10027, USA
| | - I. Kymissis
- Department of Electrical Engineering, Columbia University, New York, New York 10027, USA
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13
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Zhu L, Tao J, Li P, Sun W, Li J, Fan K, Lv J, Qin Y, Zheng K, Zhao B, Zhao Y, Chen Y, Tang Y, Wang W, Liang J. Microfluidic static droplet generated quantum dot arrays as color conversion layers for full-color micro-LED displays. NANOSCALE ADVANCES 2023; 5:2743-2747. [PMID: 37205280 PMCID: PMC10186985 DOI: 10.1039/d2na00765g] [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: 10/31/2022] [Accepted: 03/21/2023] [Indexed: 05/21/2023]
Abstract
This paper presents an easy and intact process based on microfluidics static droplet array (SDA) technology to fabricate quantum dot (QD) arrays for full-color micro-LED displays. A minimal sub-pixel size of 20 μm was achieved, and the fluorescence-converted red and green arrays provide good light uniformity of 98.58% and 98.72%, respectively.
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Affiliation(s)
- Licai Zhu
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jin Tao
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Panyuan Li
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Wenchao Sun
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jiwei Li
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - KaiLi Fan
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jinguang Lv
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Yuxin Qin
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Kaifeng Zheng
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Baixuan Zhao
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Yingze Zhao
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Yupeng Chen
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Yingwen Tang
- College of Physics and Information Engineering, Minnan Normal University Zhangzhou 363000 China
| | - Weibiao Wang
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
| | - Jingqiu Liang
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences Changchun Jilin 130033 China
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14
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Quesnel E, Poncet S, Altazin S, Lin YP, D'Amico M. Lifetime prediction of encapsulated CdSe xS 1-x quantum platelets for color conversion in high luminance LED microdisplays. OPTICS EXPRESS 2023; 31:10955-10964. [PMID: 37155742 DOI: 10.1364/oe.480567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The LED technology is seen today as the most promising approach to manufacture high luminance color microdisplays for augmented reality application. So far, it mostly involves blue micro-LED technology and quantum dots-based layers for green and red color generation by light down-conversion. Despite significant progress, the viability of this technology still raises many questions. Among them, the stability of the color conversion layer under nominal display operating conditions is still an issue which has not been thoroughly addressed yet. This paper provides experimental data on the aging behavior of CdSexS1-x quantum platelets (QP) for blue-to-red conversion, under a wide range of blue irradiation power. A modeling of the photoluminescence (PL) decrease versus aging time is proposed, that enables to reliably predict the lifetime of a color LED microdisplay in real operating conditions. At room temperature, the alumina encapsulated CdSexS1-x QPs exhibit a lifetime (t70) of 35,000 h under operating conditions representative of a microdisplay emitting 100,000 nits white light, in video mode. With an average daily use of 3 hours, it would represent for a microdisplay more than 30 years. In addition, the study highlights that display heating induces a lifetime decrease related to a thermally activated enhancement of the annihilation rate of PL emission centers. As a result, a display operated at 100,000 nits and 45°C would see its lifetime t70 reduced by a factor 4 (∼8 years), which remains acceptable for most micro-display applications.
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15
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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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16
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Wang Z, Shi X, Peng H. Alternating current electroluminescent fibers for textile displays. Natl Sci Rev 2022; 10:nwac113. [PMID: 36684510 PMCID: PMC9843127 DOI: 10.1093/nsr/nwac113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 05/25/2022] [Accepted: 06/09/2022] [Indexed: 01/25/2023] Open
Abstract
This perspective summarizes the research status of textile displays based on fiber-shaped and interwoven light-emitting devices with remaining challenges and future directions.
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Affiliation(s)
- Zhen Wang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, and Laboratory of Advanced Materials, Fudan University, China
| | - Xiang Shi
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, and Laboratory of Advanced Materials, Fudan University, China
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