Dual-Strategy Direct Photocatalytic Patterning for Efficient Perovskite Nanocrystal LED Displays

Achieving nondestructive, high-resolution patterning of perovskite nanocrystals (PeNCs) is essential for next-generation near-eye displays. However, the intrinsic instability of PeNCs renders conventional patterning methods detrimental to their optical and electrical properties. Herein, a dual strategy is reported that enables both high-resolution patterning and the fabrication of efficient light-emitting diodes (LEDs). The first strategy involves an advanced direct photocatalytic patterning method. Thiol crosslinkers are systematically investigated and identified 1,8-octanedithiol and 1,10-decanedithiol as optimal candidates due to their solvent compatibility, colloidal stability, and ability to achieve nondestructive patterning with high resolution and fidelity. The second strategy introduces a film-state ligand exchange (FLE) process to enhance the optical and electrical properties of patterned PeNC films. Replacing long-chain ligands with short-chain ammonium halides results in denser surface passivation and enhanced charge transport capability. Dual strategy enabled high-performance crosslinked PeNC-LEDs, including a maximum external quantum efficiency of 14.7% and luminance of ≈25,400 cd m^-2 for green CsPbBr₃ LEDs, representing the highest values reported for green CsPbBr₃ PeNC-LEDs obtained via direct optical patterning. Furthermore, FLE enabled post-patterning halide exchange, representing the first demonstration of a red crosslinked CsPbBr_xI_3-x PeNC-LED via direct optical patterning. This study establishes molecular and lithographic design principles for integrating colloidal nanocrystals into next-generation displays and optoelectronics.