CsPb_0.9Sn_0.1IBr₂ Based All-Inorganic Perovskite Solar Cells with Exceptional Efficiency and Stability

Abstract

The emergence of perovskite solar cells (PSCs) has generated enormous interest in the photovoltaic research community. Recently, cesium metal halides (CsMX₃, M = Pb or Sn; X = I, Br, Cl or mixed halides) as a class of inorganic perovskites showed great promise for PSCs and other optoelectronic devices. However, CsMX₃-based PSCs usually exhibit lower power conversion efficiencies (PCEs) than organic-inorganic hybrid PSCs, due to the unfavorable band gaps. Herein, a novel mixed-Pb/Sn mixed-halide inorganic perovskite, CsPb_0.9Sn_0.1IBr₂, with a suitable band gap of 1.79 eV and an appropriate level of valence band maximum, was prepared in ambient atmosphere without a glovebox. After thoroughly eliminating labile organic components and noble metals, the all-inorganic PSCs based on CsPb_0.9Sn_0.1IBr₂ and carbon counter electrodes exhibit a high open-circuit voltage of 1.26 V and a remarkable PCE up to 11.33%, which is record-breaking among the existing CsMX₃-based PSCs. Moreover, the all-inorganic PSCs show good long-term stability and improved endurance against heat and moisture. This study indicates a feasible way to design inorganic halide perovskites through energy-band engineering for the construction of high-performance all-inorganic PSCs.