Meanwhile, there are considerable spin-orbital coupling (SOC) matrix elements between T4-T6 and S1 states (Fig. and Supplementary Fig. ). Taking these factors into consideration, hRISC process is very likely to happen. The theoretical simulation of S-BNPCN-o-CP in solid state by QM/MM 43 method is further performed. As shown in Fig. , the energy levels are similar to those in gas phase, with the energy gaps between T4-T6 and S1 states as small as 0.01-0.07 eV, while that between T1 and S1 states is increased to 0.83 eV. Moreover, the SOC matrix elements between S1 and T5-T6 states are enhanced in solid state. The calculated radiative decay rate of S-BNPCN-o-CP in solid state (3.87 × 10 8 S -1 ) is close to that in gas phase (5.31 × 10 8 S -1 ), but the non-radiative decay rate in solid state (2.62 × 10 7 S -1 ) is much smaller than that in gas phase (2.06 × 10 8 S -1 ). These results indicate that hRISC process can be promoted in solid state .