Interface-Dependent Radiative and Nonradiative Recombination in Perovskite Solar Cells

Interfacial engineering has shown to play an essential role to optimize recombination losses in perovskite solar cells; however, an in-depth understanding of the various loss mechanisms is still underway. Herein, we study the charge transfer process and reveal the primary recombination mechanism at inorganic electron-transporting contacts such as TiO2 and its modified organic rivals. The modifiers are chemically ([6,6]-phenyl C61 butyric acid, PC60BA) or physically ([6,6]-phenyl C61 butyric acid methyl ester, PC60BM and C60) attached fullerene to the TiO2 surface to passivate the density of surface states. We do not observe any change in morphology, crystallinity, and bulk defect density of halide perovskite (CH3NH3PbI3 in this case) upon interface modification. However, we observe compelling results via photoluminescence and electroluminescence studies that the recombination dynamics at both time scales (slow and fast) are largely influenced by the choice of the selective contact. We note a strong correl...