Developing versatile dendrimer host materials for solution-processed phosphorescence, TADF and multi-resonance narrow-band OLEDs

The host material is crucial for significantly enhancing the performance of solution-processed OLEDs. Herein, two diphenyl-sulfone based dendrimers with highly branched spherical geometry are developed as versatile solution-processible hosts for phosphorescence, thermally activated delayed fluorescence (TADF), and multi-resonance narrow-band emitters. The paddle-like twisted configuration endows the host with a small singlet and triplet splitting (Δ E ST ) of 0.20 eV and high triplet energy of up to 2.9 eV, which can be qualified for most of the color gamut of solution-processible emitters. In addition, both hosts also exhibit clear AIE properties in the molecular packaging state, promotes the utilization of excitons and efficient energy transfer to guest materials. By using 4Cz-SO as the host, phosphorescent OLEDs achieved the maximum external quantum efficiency (EQE) of 13.7% and 14.5% for blue and white devices, respectively. Moreover, such dendrimers can also be an efficient good host for TADF and multi-resonance narrow-band emitters, both of which achieved a better device efficiency and a small efficiency roll-off than the classical solution-processed host PVK. This work demonstrates the great potential of dendrimer system for developing efficient host materials for solution-processed optoelectronic applications. The host material is crucial for significantly enhancing the performance of solution-processed OLEDs.