Persistent Room-Temperature Phosphorescence from Purely Organic Molecules and Multi-Component Systems

Recently, luminophores showing efficient room-temperature phosphorescence (RTP) have gained tremendous interest due to their numerous applications. However, most phosphors are derived from transition metal complexes because of their intrinsic fast intersystem crossing (ISC) induced by strong spin-orbit coupling (SOC) constants of the heavy metal. Metal-free RTP materials are rare and have become a promising field because they are inexpensive and environmentally friendly. This review summarizes organic molecular materials with long triplet lifetimes at room temperature from the perspective of whether they stem from a molecular or multi-component system. Among purely organic phosphors, heteroatoms are usually introduced into the backbone in order to boost the singlet-triplet ISC rate constant. In multi-component systems, useful strategies such as host-guest, polymer matrix, copolymerization, and supramolecular assembly provide a rigid matrix to restrict nonradiative pathways thus realizing ultralong RTP.

Automated summary

This review discusses organic molecular materials that exhibit long triplet lifetimes at room temperature, examining whether they originate from a molecular or multi-component system. In purely organic phosphors, heteroatoms are typically introduced into the backbone to enhance the singlet-triplet ISC rate constant. In multi-component systems, the implementation of strategies such as host-guest interactions, polymer matrix, copolymerization, and supramolecular assembly create a rigid matrix that restricts nonradiative pathways, resulting in ultralong RTP.