High Triplet Energy Polymers Containing Phosphine Oxide as Novel Hosts for Solution-Processable Organic Light-Emitting Diodes

Semiconducting polymers enable the fabrication of low-cost, large-area electronic devices by using low-temperature solution-processing methodologies on flexible substrates. This work presents three novel host materials for the emitting layer (EML) of organic light-emitting diodes (OLEDs). Efficient hosts should possess a number of properties, such as high triplet energy, good and balanced charge-carrier transport, suitable frontier orbital levels that match those of the neighboring layers, and morphological stability. To this end, carbazole-based polymers featuring the electron-withdrawing group (EWG) phenylphosphine oxide at different positions of the chain were designed and synthesized by Suzuki coupling. Chemical and optical characterizations of the polymers were performed prior to the charge-transport property analysis through the fabrication of single-carrier devices. Finally, these materials were incorporated into a green OLED architecture as solution processed EML where tris(2-phenylpyridine)iridium(III) (Ir(ppy)3) acts as phosphorescent emitter dopant.