This unit results in a 49.8% overlap and demonstrates a typical HLCT feature. In contrast, the fluorene exhibits a main hole composition of 70.9%, an electron composition of 13.5%, and an overlap of 30.9%, which can be considered to show CT feature. These results illustrate that the HLCT features of BTD-HeBr mainly come from the BTD acceptors. In addition, the S1 states of BTD-FL and BTD-FLBr show similar HLCT features (Supplementary Fig. ). The HLCT characteristics are beneficial for the luminescence transition and utilization of excited excitons. Specifically, the LE character of 1 HLCT state of the three HLCT emitters renders a high oscillator strength (f = 0.554-0.679) from S1 to S0. Due to the higher Tn of the emitters are LE-dominated states (Supplementary Fig. ) according to EI-Sayed rule , the CT character of HLCT states results in a high SOC constant (0.53-0.74 cm -1 ) between S1 and Tn, which is beneficial for a fast radiative transition and efficient (R)ISC processes.