Improving the Air Resistance of the Precursor Solution for Ambient-Air Coating of an Sn–Pb Perovskite Film with Superior Photovoltaic Performance
Owing to narrow band gap and low toxicity, tin–lead (Sn–Pb) hybrid perovskites have shown great potential in photovoltaic applications, and the highest power conversion efficiency (PCE) of Sn–Pb perovskite solar cells (PSCs) has recently reached 23.6%. However, it is still challenging to prepare Sn–Pb films in open-air condition due to the Sn2+ oxidation of the precursor solution under this condition. In this work, we report the stabilizing of the Sn–Pb perovskite precursor solution by using ionic liquid methylammonium acetate (MAAc) as the solvent, which enables the fabrication of Sn–Pb films in air. MAAc is found to coordinate with the Sn–Pb precursor via abundant hydrogen bonding, which stabilizes the colloids and protects the Sn2+ stability in the precursor solution in air. Therefore, the durability of the Sn–Pb precursor solution based on the MAAc solvent is greatly improved, which enables the fabrication of efficient PSCs and achieves a champion PCE of ∼16% with robust device stability. Moreover, due to the chemical interactions of MAAc with Sn–Pb perovskites, the Pb leakage is also suppressed in the MAAc-based Sn–Pb PSCs. This work demonstrates a feasible strategy for reliable fabrication of Sn–Pb PSCs, which could also be applied in many other optoelectronic devices.
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