Molecular Engineering for Metal-Free Amorphous Materials with Room-Temperature Phosphorescence

Materials displaying room-temperature phosphorescence (RTP) have been attracting wide attention in recent years due to their distinctive characteristics including long emissive lifetime and large Stokes shift, and their various applications. Most synthesized RTP materials are metal complexes that display enhanced intersystem crossing and crystallization is a common way to restrict nonradiative transition. Amorphous metal-free RTP materials, which do not rely on expensive and toxic metals and can be prepared in a straightforward fashion, have become an important branch of the field. This Minireview summarizes recent progress in amorphous RTP materials according to the approaches used to immobilize phosphors: host-guest interactions, molecule doping, copolymers, and small-molecule self-assembly. Some existing challenges and insightful perspectives are given at the end of the Minireview, which should benefit the future design and development of amorphous metal-free RTP materials.