Impact of Bridging Units on the Dynamics of Photoinduced Charge Generation and Charge Recombination in Donor–Acceptor Dyads

Abstract We estimate, at a full quantum‐chemical level, the various molecular parameters governing the rate of photoinduced charge generation and charge recombination in model organic structures containing a donor and an acceptor unit in view of the possible use of such systems in organic solar cells. The rate of through‐space excitation dissociation, as predicted in the framework of the Marcus–Levich–Jortner theory, is found to be low in comparison to intramolecular decay processes when the donor and acceptor molecules are lying in a head‐to‐tail arrangement and high when the donor and acceptor molecules are superimposed in a cofacial arrangement. The charge separation rates for side‐by‐side donor–acceptor dyads are significantly increased by promoting through‐bond interactions in covalently linked donor and acceptor units. This has motivated a detailed quantitative analysis of the influence of the nature, size, and conformation of the bridging moiety on the calculated transfer rates.