Direct Optical Lithography of Colloidal InP-Based Quantum Dots with Ligand Pair Treatment

Direct optical lithography presents a promising patterning method for colloidal quantum dots (QDs). However, additional care needs to be taken to prevent deterioration of the optical properties of QDs upon patterning, especially for InP-based QDs. This study proposes an efficient method for high-resolution patterning of InP-based QDs using a photoacid generator while preserving their optical properties. Specifically, our solid-state ligand exchange strategy, replacing chloride ligands with long-chain amine/carboxylate pair ligands, successfully recovered the photoluminescence quantum yield (PLQY) of the patterned InP-based QD films to ∼67% of the original PLQY. Upon examination of the origins of the PLQY reduction during patterning, we concluded that the formation of deep traps caused by the exchanged chloride ligands was the primary cause. Finally, we fabricated high-resolution (feature size: 1 μm), multicolored patterns of InP-based QDs, thereby demonstrating the potential of the proposed patterning method for next-generation high-resolution displays and optoelectronic devices.