High-resolution Direct Optical Patterning of Perovskite Nanocrystals Using Photo-induced Ligand Exchange

Metal halide perovskite (MHP) nanocrystals have been recognized as a promising material class for next-generation realistic displays, owing to their excellent color purity. To adopt MHP nanocrystals to the next-generation displays (<i>e.g.</i>, augmented reality displays) with high-resolution, precise patterning method should be developed to fabricate RGB pixel arrays. However, the traditional photolithography is not suitable for patterning colloidal MHP nanocrystals since the solvent in photoresist often results in the degradation of the emissive properties of MHP nanocrystals. Direct optical patterning is a photoresist-fee method to pattern MHP nanocrystals, which uses the change in solubility due to a chemical reaction upon light source irradiation. However, the photo-induced chemical reaction often affects the passivation of MHP nanocrystals which is critical in maintaining the photoluminescence quantum yield throughout the patterning process. Herein, we propose a nondestructive photo-induced in-situ ligand exchange mechanism for direct optical patterning of colloidal MHP nanocrystals. The MHP nanocrystals became photosensitive with thiol additives; high-resolution 2-µm line patterns of MHP nanocrystals were achieved without compensating the emissive properties, which is due to the effective passivation of in-situ-exchanged thiolate ligands. The patterning mechanism was in-depth investigated by analyzing the surface properties of MHP nanocrystals at each patterning step.