From TFB to PKVA: A Novel Cross-Linkable Hole-Transport Polymer for Enhanced Solvent Resistance and Efficiency in Solution-Processed OLEDs and QLEDs

Abstract

The traditional polymer hole-transport materials (HTMs), TFB, widely employed in solution-processed organic and quantum-dot light-emitting diodes (OLEDs and QLEDs), suffer from limited solvent resistance and fixed energy levels. In this study, a novel polymer HTM (named PKVA) is presented incorporating thermally cross-linkable styryl and high triplet-energy carbazole moieties. Compared to TFB, PKVA exhibits an increased bandgap, higher triplet energy, superior solvent resistance (<1% dissolved), and excellent film-forming properties. The solution-processed green OLED using PKVA demonstrates a remarkable improvement in current efficiency (CE) from 21.0 to 62.5 cd A⁻¹ accompanied by a reduced efficiency roll-off. Further, replacing TFB with PKVA in blue and green QLEDs enhances EQE from 11.9% to 15.2% and 15.1% to 18.5%, respectively, highlighting PKVA's suitability for diverse device applications. The enhanced performance is attributed to PKVA's exceptional solvent resistance and uniform film morphology, which minimize leakage current caused by interfacial mixing. Additionally, PKVA enables balanced charge carrier transport, effectively shifting the recombination zone and preventing charge carrier accumulation at the interface. These findings underscore the versatility and promise of PKVA as a high-performance polymer HTM for various solution-processed light-emitting devices, advancing the design of efficient and stable OLEDs and QLEDs.