Nonadiabatic dynamical simulations to the radiative recombination of nonfullerene acceptor molecular excited states

Improving the radiative recombination rate of nonfullerene acceptor (NFA) molecular excited states can help to promote their photoluminescence quantum yield and thus reduce the nonradiative energy loss in NFA-based organic solar cells. In this Letter, by developing a nonadiabatic dynamical simulation method, we clarify quantitative correlations of some typical characteristics of NFA molecules with their radiative recombination rates. For a single NFA molecule, the weakening of electron-phonon coupling and the strengthening of electron-push-pull potential can each improve the radiative recombination rate. For different NFA molecular aggregates, their radiative recombination rates are all reduced compared with a single molecule, where the A-to-A and A-to-D type J-aggregates have higher rates than D-to-D type H-aggregate. To further improve the radiative recombination rate of NFA molecular J-aggregates, we should increase the intermolecular distance, such as extending the side chain length.