Fullerene based molecular heterojunctions such as the [6,6]-pyrrolidine-C60 donor-acceptor conjugate containing triphenylamine (TPA) are potential materials for high-efficient dye-sensitized solar cells. In this work, we estimate the rate constants for the photoinduced charge separation and charge recombination processes in TPA-C60 using the unrestricted and time-dependent DFT methods. Different schemes are applied to evaluate excited state properties and electron transfer parameters (reorganization energies, electronic couplings, and Gibbs energies). The use of open-shell singlet or triplet states, several density functionals and continuum solvation models is discussed. Strengths and limitations of the computational approaches are highlighted. The present benchmark study provides an overview of the expected performance of DFT-based methodologies in the description of photoinduced charge transfer reactions in fullerene heterojunctions

We are grateful for financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) (Project CTQ2014-54306-P), the Catalan DIUE (Project 2014SGR931, ICREA Academia 2014 Award to MS, and Xarxa de Referència en Química Teòrica i Computacional), and the FEDER fund (UNGI10-4E-801). JPM acknowledges the Mexican National Council of Science and Technology (CONACYT) for his PhD fellowship (register/application number 217067/312543).