Chalcogen-Bridged Metal-Free Organic Room Temperature Phosphorescence Materials

Recent development in the field of organic luminescent materials has gained tremendous attention, particularly due to the materials which exhibit efficient room temperature phosphorescence (RTP). The extensive research in the field has led to variety of metal-free pure organic systems exhibiting excellent performance such as high quantum yield, longer lifetime, and afterglow at ambient conditions. A wide range of strategies were developed to enhance the RTP efficiency, among which the incorporation of chalcogen atoms such as O, S, Se, and Te at bridging position in pure organic system has emerged as a promising strategy. The bridging of the chalcogens atoms not only facilitates the strong spin orbit coupling (SOC) and efficient intersystem crossing (ISC), but also provide more rigid molecular framework to reduce the nonradiative decay pathways and stabilizes the triplet excitons, resulting in RTP with higher quantum yield and longer lifetime. This review focuses on the development of bridged chalcogen-containing pure organic RTP materials with various strategies to achieve more efficient RTP and their applications. In particular, we discuss and compare a broad range of chalcogen containing organic phosphors, highlighting their structural differences and design strategies that affect the phosphorescence under ambient condition.