Metal and halogen-free purely organic room temperature phosphorescence material using heavy atom effect of phenoselenazine

Development of purely organic room temperature phosphorescent (RTP) emitters is challenging and promising to various applications. However, it is very difficult to observe phosphorescence from common organic emitters. Herein, we introduced phenoselenazine (PSeZ) as a moiety to induce phosphorescence and evaluated the emission properties of (10 H -phenoselenazin-10-yl)(phenyl)methanone (BzylPSeZ) and demonstrated effects of PSeZ on room temperature phosphorescent properties in comparison with (10 H -phenothiazin-10-yl)(phenyl)methanone (BzylPTZ) which contains a phenothiazine. As a result, selenium in the PSeZ enhanced spin-orbit coupling by heavy atom effect and BzylPSeZ showed phosphorescence in crystalline state. The BzylPSeZ exhibited phosphorescence quantum yield of 7.7% and phosphorescence lifetime of 670 μs＀ This work proved the possibility of the PSeZ as a unit of pure organic RTP emitters. • Room temperature phosphorescence using selenium based organic units. • Strong spin-orbit coupling by heavy atom effect of selenium. • Short triplet exciton lifetime in pure organic phosphorescent emitter.