Highly Efficient Full‐Color Inorganic LEDs on a Single Wafer by Using Multiple Adhesive Bonding

Monolithic integration is a promising way to realize full‐color high‐resolution displays. However, it is still a challenge to realize a highly efficient full‐color light‐emitting diode (LED) adopting color conversion layer. In this work, red, green, and blue inorganic LED thin films grown on respective substrates for high‐quality epitaxial layers are integrated on a single substrate using a multiple adhesive bonding technique. It is verified that the stacked thin films are structurally stable. After the multiple bonding, respective subpixels are formed by using standard photolithography only without a mass transfer process, showing the possibility of applying them to a high‐resolution micro‐LED display. Even after the bonding, the device still maintains high efficiency without deteriorating performance. The integrated subpixels are not only independently operated by controlling input power, but the light emission can also cover a wide range of the color space, about 83% compared to Rec.2020 color space. Although it is demanded for full‐color micro‐light‐emitting diodes (micro‐LEDs) to have high resolution, it is difficult to apply them to displays due to limited mass transfer and yield problem. A full‐color micro‐LED applicable to high‐resolution displays is demonstrated by using adhesive bonding only. The full‐color LEDs can cover the color space about 83% compared to Rec.2020 color space.