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

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

Toward a Diagnostic Method for Efficient Perovskite Solar Cells Based on Equivalent Circuit Parameters

The equivalent circuit model is one of the essential tools for revealing information about the material characteristics, working mechanisms, and operation state of perovskite solar cells. However, it is still challenging to accurately obtain the equivalent circuit parameters of the highly efficient solar cells with a power conversion efficiency more than 22%. In this work, we proposed a new scheme to estimate all the parameters of the high-performance solar cells only from their current–voltage curves by reasonably combining the traditional analytical method and the parameter optimization method. Then, we applied the proposed method to analyze the equivalent circuit parameters of a typical efficient perovskite solar cell under different light intensities and aging times. Through the parameters, we succeeded in bridging photovoltaic parameters and the structural, morphological, and optoelectronic changes of the solar cells. In particular, the proposed method is compatible with the notorious current–voltage hysteresis. To test the method further, it is compared with two typical approximate methods commonly used recently. By comparison, the proposed approach is simple, reliable, and insensitive to the initial values. Moreover, limitations and precautions for the traditional methods are given to ensure their effectiveness. Finally, we note that the proposed approach of this work provides a feasible solution to conduct real-time monitoring and analysis of the high-performance solar cells