A non-Markovian stochastic Schrödinger equation developed in our former work [Y. Ke and Y. Zhao, J. Chem. Phys. 147, 184103 (2017)] is extended to the reciprocal (k-) space to calculate the carrier dynamics in organic semiconductors with both local and nonlocal carrier-phonon interactions taken into account. The validity of this approach is examined by comparing with numerically exact benchmark results. As an application, the carrier mobilities are calculated within a one-dimensional periodic lattice model. The results reveal an inversion in the magnitude of the mobility as the nonlocal carrier-phonon interaction varies from weak to strong strengths, indicating a transition of the transport mechanism. This is also demonstrated by a variation in the temperature dependence of the mobility. In addition, a transient localization diffusive behavior caused by intramolecular vibrations is also found.

Y6 (BTP‐4F) is one of the novel non‐fullerene acceptors and its photo‐physics significantly affects the efficiency of organic solar cells. Here, the photo‐induced energy and charge transfer (CT) dynamics in four typical dimers (Y, C, S1, and S2)‐TYPE from Y6 films are revealed by combining electronic structure theory calculations, rate theories, and quantum dynamics simulations. The rate theories show that in ground‐state CT processes the Y‐TYPE is bipolar with the largest rate among all dimers, and in excitation energy transfer the triplet rates are about 105 smaller than the singlet ones, however, the singlet rates can reach 1013s−1, which may lead to the rate theories invalid. The stochastic Schrödinger equation based on the diabatic Hamiltonian is thus adopted to reveal excited‐state dynamics. The results show that three of the four dimers are H‐aggregate except for S1‐TYPE with J‐aggregate property. However, these J/H‐aggregate properties are excited‐state dependent, for instance, the Y‐TYPE becomes J‐aggregate in the second excited‐state. Furthermore, CT states are strongly mixed with the first two excited states, which can dramatically impact the energy transfer. Indeed, the dynamic simulations clarify that the excited‐state energy relaxation mediated by CT states can be performed in the first 20 fs, and the CT‐state population is even non‐negligible in the quasi‐stationary distribution.