Boosting organic phosphorescence in pure organics by mixed heavy atoms management

Improved organic phosphorescence in purely organic material was achieved by the combined effect of mixed heavy atoms namely Se and Br. A phenoselenazine core structure was modified with two bromine atoms for strong spin-orbit coupling to accelerate the radiative transition from the triplet excited state to the ground state. The combined heavy atoms effect by the bromine and selenium resulted in a short phosphorescence lifetime of 28 μs from organic crystal. Compared with the phosphorescence lifetime of longer than several hundred μs from pure organic phosphorescent material, dramatic improvement of the phosphorescence lifetime was achieved by mixed heavy atoms of Se and Br along with high photoluminescence quantum yield of 32.9%.