Toward Wide‐Angle III‐Nitride Miniaturized LEDs: Device Engineering and Photon Extraction Strategy

Abstract Miniaturized LEDs (mini‐LEDs) constitute a high‐quality light source in the backlight unit (BLU) of liquid crystal displays (LCDs). However, the Lambertian light field distribution of mini‐LEDs leads to limited viewing angles and decreased uniformity in BLU. Here, a high‐performance wide‐angle mini‐LED is demonstrated via device engineering and an innovative photon extraction strategy. By integrating distributed Bragg reflectors (DBRs) on the light emission surface of mini‐LED, propagation behaviors of photons are manipulated and thus altered Lambertian light field distribution into heart‐shaped light field distribution, realizing the construction of wide‐angle mini‐LED. Furthermore, the effects of the reflectivity of various DBRs on the light field distribution and optoelectronic characteristics of wide‐angle mini‐LEDs are systematically investigated. To boost the external quantum efficiency (EQE) of wide‐angle mini‐LEDs, a photon extraction strategy, including optimizing sapphire substrate thickness and employing multiple laser stealth scribing techniques is proposed. As a result, the optimal wide‐angle mini‐LED exhibits a peak light intensity angle of 38°, a full width at half maximum of angular light intensity distribution of 162° and a 21.3% increment in peak EQE, in comparison to the wide‐angle mini‐LED without utilizing photon extraction strategy. It believes these innovations provide a substantial advancement in developing wide‐angle mini‐LEDs, contributing to their application in LCDs.