Direct Photolithographic Patterning of Colloidal Quantum Dots Enabled by UV-Crosslinkable and Hole-Transporting Polymer Ligands

Abstract

Quantum dot (QD)-based displays call for nondestructive, high-throughput, and high-resolution patterning techniques with micrometer precision. In particular, self-emissive QD-based displays demand fine patterns of conductive QD films with uniform thickness at the nanometer scale. To meet these requirements, we functionalized QDs with photopatternable and semiconducting poly(vinyltriphenylamine-random-azidostyrene) (PTPA-N-3-SH) ligands in which hole-transporting triphenylamine and UV-crosslinkable azide (-N-3) groups are integrated. The hybridized QD films undergo chemical crosslinking upon UV irradiation without loss in the luminescence efficiency, enabling micrometer-scale QD patterns (pitch size down to similar to 10 mu m) via direct photolithography. In addition, the conjugated moieties in the ligands allow the crosslinked QD films to be used in electrically driven light-emitting diodes (LED). As the ultimate achievement, a patterned QD-LED was prepared with a maximum luminance of 11 720 cd m(-2) and a maximum external quantum efficiency (EQE) of 6.25%. The present study offers a simple platform to fabricate conductive nanoparticle films with micrometer-scale patterns, and thus we anticipate that this system will expedite the realization of QD-based displays and will also be applicable to the manufacture of nanoparticles for other electronic devices.