Synchrotron and optical probing of hybrid organic-inorganic perovskite halides for photovoltaics

The Goldschmidt's Tolerance Factor is a reliable figure of merit or empirical index to forecast the formation of preferred and stable structures and phases with ABX(3) hybrid organic-inorganic perovskite tolerance factors in the range of 0.9 to 1. Here, we probe perovskites of compositional variations ABX(3) with tolerance factors in the range of 0.9 to 1.0, and a large effective ionic radius greater than 200 pm. We report on the structural and optical properties of hybrid perovskite halides for photovoltaic (PV) applications, MAPbI(3), FA(0.8)MA(0.1)Cs(0.1)Pb(I0.86Br0.14)(3), and FA(0.8)Cs(0.2)Pb(I0.86Br0.14)(3), with tolerance factors of 0.91, 0.964 and 0.967 respectively. PV devices were fabricated using these high tolerance factor hybrid perovskite halides. We report we have achieved power conversion efficiencies (PCEs) greater than 21% using the high tolerance factor perovskites investigated. Note, the high PCEs reflect unusually high Jsc's which may be due to lack of equipment calibration and will be further investigated.