High-efficiency micro-LED displays with indistinguishable color shift

Micro-scale light emitting diode (micro-LED) with a chip size less than 100 mu m has improved light extraction efficiency due to increased sidewall emission. However, it causes mismatched angular distributions between AlGaInP-based red micro-LED and InGaN-based blue/green counterparts because of the epitaxial material difference. As a result, color shift of RGB micro-LED displays may become visually noticeable. To address this issue, the angular distributions of RGB micro-LEDs are analyzed theoretically and experimentally. In addition, a device structure with top black matrix and taper angle in micro-LEDs is proposed, which greatly suppresses the color shift while keeping a reasonably high light extraction efficiency.