Does Singlet Fission Enhance the Performance of Organic Solar Cells?

Singlet fission, in which the optical spin-singlet exciton dissociates into two low energy triplet excitons, has been proposed as a viable approach to enhance the quantum efficiency of organic solar cells. We show that even when singlet fission is occurring in the donor molecule, the electronic structure at the donor$-$acceptor interface must satisfy specific requirements for the solar cell performance to be enhanced by this process. We focus on the pentacene$-$C$_{60}$ solar cell, and on the basis of our calculations and available experimental data, we conclude that there is not enough evidence that these requirements are met by the donor$-$acceptor interface here. We propose experiments that can determine whether the minimal requirement for enhanced performance driven by singlet fission is met in this and other solar cells.