Direct Photolithography of Colloidal InP-Based Quantum Dots Utilizing the Photoligation Method

High-resolution quantum dot (QD) pixelation technologies are essential for advancing QD-based light-emitting diodes (QLEDs) in next-generation display systems. Here, we present a ligand with dual functionality for ligand exchange and direct patterning of InP-based QDs. This ligand incorporates a multidentate lipoic acid group and an azide group, enabling simultaneous photoligation and photo-cross-linking. Upon ultraviolet (UV) light exposure (365 nm), in situ ligand exchange occurs in the solvent-dispersed state via photoligation, significantly reducing ligand exchange time and enhancing QD solution stability by securely anchoring ligands to the QD surface. Under 254 nm UV light, the functional azide groups enable selective cross-linking with neighboring QD ligands, achieving high-resolution patterns down to 5 μm while preserving the optical properties of the QDs. Furthermore, QLEDs employing the cross-linked QDs demonstrate improved current efficiency, increasing from 2.8 to 4.3 cd/A, and operational lifetime, extending from 100 to 940 h, at an initial luminance of 150 cd/m2. These improvements are attributed to the upshifted energy level, enhanced QD stability, and improved charge balance within the device. This approach provides an efficient and scalable strategy for direct QD patterning, paving the way for next-generation display technologies through innovative ligand design and simplified processing.