Photo-crosslinkable Hole Transport Material with an Azide Functional Group for Highly Efficient Quantum Dot Light-emitting Diodes

Abstract

Poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt(4,4′-(N-(4-butylphenyl)))] (TFB) has been a widely used as hole transport material (HTM) in quantum dot light-emitting diodes (QLEDs). However, QLEDs using TFB have faced challenges due to interlayer erosions. To solve dissolution of the underlying layer, it is effective to introduce a crosslinkable group into HTM. Herein, we designed and synthesized new HTM, TFB-N3, with azide as a crosslinking functional group. The crosslinked TFB-N3 thin film exhibited high solvent resistance, smooth surface morphology, and improved charge-carrier transport ability compared to pristine TFB. TFB-N3 also showed a fast crosslinking time under UV irradiation. The green QLEDs based on TFB-N3 showed excellent external quantum efficiency, maximum current efficiency, and maximum power efficiency.