Fig. 1. (Color online) (a) Traditional design strategy for TADF. Reproduced with permission^[6], Copyright 2016, Wiley-VCH. (b) Design strategy for MR-TADF. Reproduced with permission^[6], Copyright 2016, Wiley-VCH. (c) New MR-TADF skeletons with fused aza-aromatics. Reproduced with permission^[11], Copyright 2020, Wiley-VCH.

Fig. 2. (Color online) (a) Molecular structures of CzBO, CzBS, and CzBSe with different chalcogens, conventional TADF mechanism and ideal superimposed fluorescence (SF) mechanism. Reproduced with permission^[16], Copyright 2022, Wiley-VCH. (b) Double resonance unit superposition strategy. Reproduced with permission^[18], Copyright 2022, Wiley-VCH.