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While solution‐processable colloidal quantum dots (QDs) offer cost‐effective and large‐scale manufacturing, they can be susceptible to subsequent solution processes, making continuous processing challenging. To enable complex and integrated device architectures, robust QD films with subsequent patterning are necessary. Here, we report a facile ligand‐crosslinking strategy based on thiol‐ene click chemistry. Thiol molecules added to QD films react with UV light to form radicals that crosslink with QD ligands containing carbon double bonds, enabling microscale photo‐patterning of QD films and enhancing their solvent resistance. This strategy can also be extended to other ligand‐capped nanocrystals. It is found that the swelling of QD films during the process of binding with the thiol molecules placed between the ligands contributes to the improvement of photoluminescence and electroluminescence properties. These results suggest that the thiol‐ene crosslinking modifies the optoelectronic properties and enables direct optical patterning, expanding the potential applications of QDs.

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Colloidal InAs quantum dots (QDs) are emerging candidates for NIR-SWIR optoelectronic applications because of their excellent electrical and optical properties. However, the syntheses of InAs QDs, which demand strongly reducing atmospheres or highly reactive precursors, are difficult because of their highly covalent bonding and lack of Group 15 precursors. While the coreduction method with commercially available arsenic precursors enables facile syntheses of InAs QDs, it results in broad size distributions requiring subsequent size-selection processes. In this study, we introduced zinc ions in the form of coordination complexes during coreduction of the indium and arsenic precursors. The Zn ions chemically passivated the surfaces of the InAs QDs, narrowed the size distribution and removed surface defects. When the InAs QDs were integrated into infrared photodiodes as IR absorbers, the surface-attached Zn ions electrically modulated the energy level and carrier concentration. Infrared photodiodes with the InAs:Zn QD layers exhibited dark currents and photoresponses that were two orders of magnitude lower and approximately twice as fast, respectively, as those seen for bare InAs QDs.

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