Understanding the temporal dynamics of thermally activated delayed fluorescence in solid hosts

Thermally activated delayed fluorescence (TADF) emitters are the latest advance in seeking to achieve 100% internal quantum yield and even beat the dominant phosphorescent materials in commercial OLED devices. Though mostly having a rather simple structure, donor-acceptor-based TADF compounds demonstrate rather unexpected emission features solely in solid hosts, namely, temporal dynamics of emission spectra and prolonged delayed fluorescence lifetime. This article presents an overview of different approaches for analysing the untypical solid-state TADF dynamics, its implications in unexpected emission phenomena, as well as methods to mitigate its negative impact. This perspective presents the efforts towards understanding the nature of the temporal instability of thermally activated delayed fluorescence in solid hosts as well as its implications for emission properties.