1.6‐Inch Transparent Micro‐Display with Pixel Circuit Integrated microLED Chip Array by Misalignment‐Free Transfer
Kyungwook Hwang, Junsik Hwang, Yongchan Kim, Sanghoon Song, Kiho Kong, Youngtek Oh, Deukseok Chung, Min‐Chul Yu, Dongho Kim, Joon‐Yong Park, Jinho Moon, Sungi Kim, Tae‐Gon Kim, Gyuhyung Lee, Min Jae Yeom, Joosung Kim, Dong‐Chul Shin, Dong Kyun Kim, Seog Woo Hong, Hyun‐Joon Kim‐Lee, Jaewook Jeong, Hojin Lee, Geonwook YooAbstract
Recent advances in mass transfer technology are expected to bring next‐generation micro light‐emitting diodes (µLED) displays into reality, although reliable integration of the active‐matrix backplane with the transferred µLEDs remains as a challenge. Here, the µLED display technology is innovated by demonstrating pixel circuit‐integrated micro‐LEDs (PIMLEDs) and integrating them onto a transparent glass substrate. The PIMLED comprises of low‐temperature poly‐silicon transistors and GaN µLED. The square‐shaped PIMLED is designed to secure a larger process margin but to reduce misalignment in the subsequent bonding process. Its unique four‐fold rotational symmetric design together with concentric circular pixel electrodes of the substrate makes their massive transfer compatible with intrinsic randomness of fluidic‐based transfer and free from angular misalignment during wafer bonding. The vertically integrated pixels show similar optical and electrical properties regardless of four possible arrangements. It is demonstrated that a 96 × 96 PIMLED display on a transparent glass substrate, which is expected to open a door to novel form‐factor free and transparent µLED displays.