Singlet Fission Enables Triplet Sensitization of Narrow Gap Hybrid Perovskites

Materials that exhibit singlet fission, where a high-energy photon generates two lower energy triplet excitons, open interesting opportunities to surpass the Shockley-Queisser limit in single-junction solar cells. Although existing candidates such as TIPS-Pentacene achieve high triplet exciton yields, the low energy of these triplets (1eV) limits their application to modern thin-film solar cell applications, such as hybrid perovskites, where band gaps remain >1.25 eV. In this study, we investigate and report triplet energy transfer from a high-energy singlet fission material, 9,10-dicyanoanthracene (DCA), to the low bandgap FA0.5MA0.5Pb0.5Sn0.5I3. Photoluminescence measurements reveal triplet transfer from DCA to the perovskite resulting in one order magnitude increased emission intensity. This claim is validated by correlating the energy threshold for this process with the singlet fission generation threshold in DCA (3eV). Carrier lifetime is extended by an order of magnitude in DCA/perovskite systems as revealed by transient absorption spectroscopy. This study provides an important first step towards the successful sensitization of hybrid perovskites with wide bandgap singlet fission molecules.