Singlet fission is a process in which singlet excitation is converted to two triplet excitations. Although it promises to improve the efficiency of solar cells, it is not currently used, because only very few truly efficient materials are known, and they do not fulfill other necessary requirements. A discussion of ways in which quantum chemistry could help find additional suitable materials is provided.
Michil, Josef, "How Quantum Chemistry of Singlet Fission Helps to Improve the Efficiency of Solar Cells" (2016). Chemistry & Biochemistry Faculty Contributions (1986-2018). 61.