shown in Figure . The S1 energies of 2GtBuCzCO2HDCzB (2.57 eV) and tBuCzCO2HDCzB (2.56 eV) were inferred from the high-energy onset of the steady-state PL at 77 K, while the T1 energies, determined from the onset of the time-gated (1-10 ms) emission at 77 K, are 2.43 and 2.43 eV for 2GtBuCzCO2HDCzB and tBuCzCO2HDCzB, respectively.