The use of organic materials for the construction of bulk heterojunction solar cells has indeed developed substantially since the first reports appeared in the literature. The number of carriers at the interface will ultimately determine the efficiency of the solar device. There have been attempts to create more carriers in solar devices. Singlet fission is a spin-allowed process in which two triplets match the energy of one singlet and subsequently lead to the formation of a triplet pair. In general, the most thoroughly investigated singlet exciton fission organic material is pentacene. A factor that has given renewed enthusiasm toward organic photovoltaic (OPV) is the emergence of perovskite-based solar cells. While it is true that these structures were created relatively recently, perovskite solar cells have shown great promise as an affordable alternative to other solar technologies and their performance achieved new and amazing goals.