Controlling the intersystem crossing/reverse intersystem crossing (ISC/RISC) competition to achieve efficient red metal-free phosphorescent molecules

-carborane as a strong electron acceptor, PhSeDCB can represent an unprecedented red-emitting RTP molecule with a very impressive photoluminescence quantum yield (PLQY) of 0.48 and a short lifetime of 14.7 µs. In addition, the first red organic light-emitting diodes (OLEDs) prepared with PhSeDCB show a high electroluminescence efficiency of 18.9%. All these encouraging results have indicated the great potential of metal-free phosphorescent materials in the field of OLEDs.