1.6-Inch Transparent Micro-Display with Pixel Circuit Integrated microLED Chip Array by Misalignment-Free Transfer

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.