Synchronous Microlens Transfer-Printing Packaging for High-Efficiency Micro-LED Arrays

Microlight-emitting diodes (micro-LEDs) exhibit high brightness, low power consumption, and fast response, making them highly promising for next-generation displays and optical communication. However, conventional planar encapsulation limits the light extraction efficiency (LEE) and emission directionality, constraining overall luminous performance. Here, we propose a mask-free synchronous-alignment microlens transfer-printing technique capable of packaging thousands to tens of thousands of pixels simultaneously. At a drive current density of 100 A cm–2, the forward luminance increases from 6.5 to 9.6 Mcd m–2 (+48%) and the external quantum efficiency (EQE) increases from 19% to 29% (+53%) compared to planar packaging. To reach a target luminance of 10 Mcd m–2, the required drive current density is reduced by ∼45%. Angular measurements show the emission range expanding from 60°–120° to about 30°–150°, with significantly enhanced on-axis output. Overall, this technique combines high alignment precision and yield with significant LEE/EQE gains, tunable directionality, and lower drive currents, making it viable for mass-produced applications such as visible light communication (VLC), copackaged optics (CPO), and high-density microdisplays.