Novel thermally activated delayed fluorescence materials by high-throughput virtual screening: going beyond donor–acceptor design

A series of candidates of thermally activated delayed fluorescence (TADF) materials, which have important applications in organic light emitting diodes devices, are identified by a high-throughput virtual screening of a database of known molecular materials. The first step of the screening identifies nearly 700 molecules that, in the X-ray geometry, have a sufficiently small gap between excitation energy of the lowest singlet and triplet states and acceptable oscillator strength of the singlet. After geometry optimization, 125 molecules continue to satisfy the energy criteria for potential TADF. Furthermore, the parameters of excited state dynamics including the reorganization energy, adiabatic excitation energy and spin–orbital coupling are calculated for a sample of molecules based on the optimized excited state geometries. The majority of the candidates are not known as TADF materials and could be considered promising lead compounds for the exploration of this materials class. Interestingly, it is found that some novel chromophores deviate from the current design rule for TADF materials, which are invariably based on a donor–acceptor molecular architecture. We also illustrate how to design completely new types of TADF materials using the results of this screening.