ABSTRACT
In general, ternary organic solar cells are composed of three components in the photoactive layer. The two main ternary configurations are the donor:donor:acceptor and the donor:acceptor:acceptor, where the third component can be a polymer, a small molecule, a dye, or an inorganic/hybrid quantum dot/nanoparticle. For an energy transfer to occur, one of the compounds needs to have an absorption spectrum that overlaps with the emission spectrum of the other one. This mechanism can become a relevant relaxation pathway for the primary photo-excited states in the ternary blends, depending on the domain sizes of the individual components. The alloy model was introduced for the first time by Thompson et al. as a mechanism describing morphology and charge transport in ternary systems, either for host donor:sensitizer or host acceptor:sensitizer. Geminate recombination is a monomolecular process and scales linearly with the number of absorbed photons, but it is worth noting that the recombination probability for each geminate pair remains unchanged.
