[6p-A501-1~21] 12.5 Organic solar cells

△ [6p-A501-11] Minute-Scale Evaluation of the Changes in Electronic and Electric Properties
of Sn-based Perovskites Under Atmosphere

〇(M2)Ryosuke Nishikubo¹, Naoki Ishida¹, Atsushi Wakamiya², Akinori Saeki^1,3 (1.Osaka Univ., 2.Kyoto Univ., 3.JST-PRESTO)

Keywords:perovskite, tin, degradation

Recently, tin-based perovskite solar cells is becoming a pervasive topic; however, their inherent instabilities have prevented boost of PCE and deeper understanding of their fundamental properties. By using photoelectron yield spectroscopy (PYS) and flash-photolysis time-resolved microwave conductivity (TRMC) techniques, we investigate the effects of air exposure on the valence band maxima (VBM) and photoconductivities of tin iodide perovskites (methylammonium cation: MASnI3 and formamidinium cation: FASnI3). These perovskites exhibit a shift of VBM (e.g., -5.02 eV at 0 min to -5.17 eV at 18 min), deterioration of the PYS profiles, and progressive decrease of TRMC transients on the minute scale of air exposure. The addition of SnF₂ is found to suppress the initial defect-related density of the filled electronic states and partly mitigate the degradation. A low-dimensional perovskite (MA₂SnI₆) composed of the oxidized form of Sn(IV) is also evaluated to explain an anomalous TRMC behavior of the air-exposed MASnI₃. Our results provide an important basis to correlate with the degradation and energetics of a device.