New Tin(II) Fluoride Derivative as a Precursor for Enhancing the Efficiency of Inverted Planar Tin/Lead Perovskite Solar Cells

Hybrid organic-inorganic lead halide perovskite has become one of the most attractive materials for future low-cost and high-efficiency solar technology. However, serious concern about the content of toxic lead in photovoltaic devices emphasizes the mixture of tin/lead. Here, we synthesized and fully characterized tin(II) fluoride with a molecule of dimethyl sulfoxide such as a [SnF2(DMSO)]2 complex to be used as an additive in the Sn–Pb perovskite precursor for photovoltaic applications. Once the concentration of the SnF2 complex has been optimized to be 10 mol %, the highest efficiency achieved in the inverted architecture was 15.93% with an open circuit voltage of 0.77 V, short circuit current of 26.53 mA cm–2, and fill factor (FF) of 0.78. Transient absorption and impedance spectroscopy corroborated that this complex reduces the trap states and improves the transport recombination at the interface compared with solar cells without additives or with the SnF2 additive, in which the latter is widely used. Here, we suggest an alternative method to control the Sn+2 reaction in Sn–Pb perovskite devices.