Dibenzothiophene-Based Phosphine Oxide Host and Electron-Transporting Materials for Efficient Blue Thermally Activated Delayed Fluorescence Diodes through Compatibility Optimization

Abstract

Thermally activated delayed fluorescence (TADF) organic light-emitting diodes arise from the development of high-performance host materials and carrier transporting materials fitting for TADF dyes with optimized respective properties and interplays, making simultaneous performance improvement and device structure simplification feasible. In this work, a highly efficient blue TADF diode with simplified four-layer structure was successfully achieved by utilizing bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (DMAC-DPS) as blue emitter, 4,6-bis(diphenylphosphoryl)dibenzothiophene (DBTDPO) as host, and 4,6-bis(diphenylphosphoryl)dibenzothiophene sulfone (46DBSODPO) as electron-transporting layer. The compatibilities between DBTDPO and DMAC-DPS and DBTDPO and 46DBSODPO were optimized with respect to configuration, polarity, energy level, and interfacial interaction, resulting in the unchanged roughness of ∼0.25 nm before and after doping, high photoluminescence quantum yield over 85%, and reduced inte...