Multilayer solution‐processed phosphorescent organic light‐emitting diodes based on a crosslinkable and solvent‐resistant hole transport material

Abstract

Phosphorescent organic light-emitting diodes (PhOLEDs) with multiple functional layers are favorable for high device performance. However, due to the erosion between functional layers, it is still a great challenge to prepare multilayer devices with a low-cost solution process. In this manuscript, 4,4′-bis (4-vinylphenyl) triphenylamine (VBTPA) can be in-situ polymerized as the thermally crosslinkable hole transport layer and successfully applied to solution-processed green light PhOLEDs by spin-coating method. It had the styryl groups as the thermally crosslinking position and can be crosslinked at 175°C with short crosslinking time (20 min). The high thermal stability (446.0°C), good photoelectric property and excellent solvent resistance and so forth, made the crosslinked VBTPA achieve a good device performance in solution-processed PhOLEDs. The turn-on voltage was 6.1 V, the maximum luminance was 8271 cd m−2 and the maximum current efficiency was 12.4 cd A−1. It indicated that the hole transport material with styryl groups as the thermally crosslinking position can be crosslinked under lower temperature (<200°C) for shorter time and applied to the preparation of multilayer solution-processed stacked PhOLEDs.