2, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, , Germany
3, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, , Germany
After 60 years of research, the power conversion efficiency of silicon solar cells is slowly approaching the Auger-recombination-constrained Shockley−Queisser limit close to 30%. Conventional silicon solar cells lose a major part of incident sunlight energy via thermalization of excited charge carriers. Using singlet exciton fission, a process in which converts one high-energy photon into two charge carriers with half the energy, is a promising way to reduce such thermalization losses. Combining highly-optimized silicon solar cells with singlet fission has the possibility to further increase the power conversion efficiency of conventional silicon solar cells while simultaneously reducing the cost per kWh. Here we study the implementation of a singlet fission material on top of conventional silicon solar cell. We investigate the charge transfer behavior of triplet excitons from the singlet fission layer to the silicon solar cell by introducing intermediate molecular acceptors at the hybrid interface of silicon and singlet fission materials. We find that the energetics are unfavorable for charge transfer directly from tetracene, even with a C60 interlayer. We further investigate means to optimize the energy level alignment between the singlet fission layer, the intermediate acceptor and silicon.