Enhancing vertical assembly of Dot-LEDs for display application using metal chelate coordination chemical linkers

• Published in: Applied surface science 2025-02, Vol.681, p.161446, Article 161446
• Main Authors: Ko, Minji, Kim, Soyeon, Jeong, Yujeong, Oh, Yeongbeen, Jeong, Seonghyun, Lee, Keyong Nam, Park, Younghoon, Song, Jae Kyu, Do, Young Rag
• Format: Article
• Language: English
• Subjects: Chemical linker; Display; Dot-LED; GaN LED; Metal chelate coordination; Self-assembly
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2024.161446

[Display omitted] •InGaN/GaN dot-LEDs were vertically assembled with a chemical linker enabling metal chelate coordination in Zn complexes.•Face-selective vertical assembly of Au@dot-LEDs using a gly-thiol linker with Zn precursors achieved a 61.8% yield for 750 nm Au@dot- LEDs.•The vertically assembled Au@dot-LED EL devices demonstrated enhanced brightness and uniformity. The chemical linker assembly technique for dot-LEDs described in this study offers practical solutions to critical challenges in micro-LED display production, such as high costs, low yield in mass transfer processes, and high cost of micro-LED chips. Dot-LEDs feature a cylindrical structure with a diameter ranging from 0.75 to 1.35 μm and an aspect ratio of 1.1∼1.2 for height to diameter. We introduce a viable approach using N-(carboxymethyl)-N-(11-mercaptoundecyl)glycine (gly-thiol) chemical linkers for the face-selective vertical assembly of dot-LEDs. The size scale of dot-LED enables solution assembly processes when manufacturing pixels. By bonding the Au surface of the p-GaN face to the bottom Au electrodes using the chelate bond of Au-gly-thiol-Zn2+-gly-thiol-Au, we intend to enhance the face-selective vertical assembly. The process involves forming two chelate coordination bonds of Zn2+ ion surrounded by a gly-thiol-treated dot and bottom electrodes, achieving over 60 % efficiency in face-selective vertical assembly. We achieved bright and uniform dot-LED electroluminescence devices, with a peak external quantum efficiency (EQE) of 8.1 % at 3.4 V and a luminance of 22,387 cd/m2 at 9.0 V. Our findings suggest substantial improvements in the assembly and efficiency of micro-nano-scale dot-LED displays, providing a display platform technology for their application in future display systems.