Ligand-Crosslinking Strategy for Efficient Quantum Dot Light-Emitting Diodes via Thiol-Ene Click Chemistry.

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.