Specific features of time-dependent effects of triplet–triplet annihilation on the kinetics of singlet fission in molecular semiconductors

The characteristic properties of the effects of migration-controlled triplet–triplet annihilation on the kinetics of singlet fission (the splitting of an excited singlet state S₁* into a pair of triplet excitons) in molecular semiconductors are thoroughly analyzed. The analysis assumes that the short-time and long-time parts of the kinetics, i.e., the kinetics of fluorescence I(t) from the S₁* state, are governed by the corresponding short-time (geminate) and long-time (bulk) annihilation stages. Within the analysis, a simple formula is proposed that accurately describes the experimental singlet-fission kinetics over a wide range of times.