as the emitter exhibits an outstanding EQEmax of 31.4%. The orientation of the TDM of TRZ-DI was not investigated, but it is not unreasonable to hypothesize that TRZ-DI possesses a highly horizontally orientated TDM based on the analysis of the FPL and the EQEmax. TRZ-SBA-NAI (∆EST: 0.16 eV; FPL: 87%; 3 wt% in mCPCN), designed by Yang et al., contains an A-D-A' motif, where a spirobiacridine (SBA) donor is used to link the acceptors NAI and TRZ, as shown in Reproduced with permission. Copyright © 2021, Royal Society of Chemistry.