Self-Host Blue Dendrimer Comprised of Thermally Activated Delayed Fluorescence Core and Bipolar Dendrons for Efficient Solution-Processable Nondoped Electroluminescence.

Abstract

A self-host thermally activated delayed fluorescence (TADF) dendrimer POCz-DPS for solution-processed nondoped blue organic light-emitting diodes (OLEDs) was designed and synthesized, in which the bipolar phosphine oxide carbazole moiety was introduced by alkyl chain to ensure balanced charge transfer. The investigation of physical properties showed that the bipolar dendrons not only improve the morphological stability but also restrain the concentration quenching effect of the TADF emissive core. The spin-coated OLEDs featuring POCz-DPS as the host-free blue emitter achieved the highest external quantum efficiency (7.3%) and color purity compared with those of doped or nondoped devices based on the parent molecule DMOC-DPS, which indicates that incorporating the merits of encapsulation and bipolar dendron is an effective way to improve the electroluminescent performance of the TADF emitter used for a solution-processed nondoped device.