Direct optical lithography of colloidal inp-based qds with ligand pair treatment

Abstract

Quantum dot-based light-emitting diodes have made remarkable progress and have garnered significant attention as next-generation light-emitting devices. However, quantum dot-based light-emitting diodes face limitations in resolution due to the absence of a suitable patterning technology. In this study, we introduce a direct optical lithography technique for indium phosphide core/shell QDs using ligand pair treatment and a photoacid generator. Direct optical lithography relies on the localized generation of hydrochloric acid in the area illuminated by ultraviolet light using a high-absorption photosensitizer, 2-(4-Methoxystyryl)-4,6-bis-1,3,5-triazine (MBT), at I-line (365 nm). This hydrochloric acid induces ligand exchange, replacing the original oleate ligands on the quantum dot surface and reducing solubility in nonpolar solvents, allowing quantum dot patterns to remain on the substrate even after the develop process. However, ligand exchange with hydrochloric acid can lead to a reduction in photoluminescence quantum yield (PLQY) in indium phosphide core/shell QDs. In this study, we recover the PLQY of quantum dot patterns by utilizing the ligand pair treatment. In conclusion, we achieve a 1 μm resolution pattern, resulting in a high PLQY (~67% compared to the PLQY of pristine InP core/shell QDs).