Antisolvent-Free Fabrication of Efficient and Stable Sn-Pb Perovskite Solar Cells

Pb-based perovskite solar cells (PSCs) have shown great potential in next-generation photovoltaics. However, the toxicity of Pb remains a big concern. Partial replacement of Pb with Sn is shown to reduce the toxicity of PSCs without considerably compromising the device performance. Currently, Sn-Pb single-junction PSCs have realized a champion power conversion efficiency (PCE) of 21.7%, whereas all perovskite tandem PSCs with a Pb-Sn device as the bottom cell have achieved a PCE of 25.5%. However, the fabrication process of Sn-Pb PSCs is still not ecofriendly due to the use of hazardous organic solvents and antisolvents. Herein, for the first time, a one-step antisolvent-free method is developed to fabricate a high-quality Sn-Pb perovskite film using methylammonium acetate (MAAc) ionic liquid as a green solvent. The crucial effects of multiple organic halides (MOHs) on the crystallization process and characteristics of the Sn-Pb film are comprehensively investigated. After optimizing the film fabrication parameters, PSCs with a champion PCE of 15.42% can be achieved. Moreover, the device exhibits robust stability that shows negligible PCE loss after being stored in N-2 for 720 h. A new avenue to promote the ecofriendly fabrication of efficient Sn-Pb PSCs is opened up.

Automated summary

Pb-based perovskite solar cells have shown potential in next-generation photovoltaics, and partial replacement of Pb with Sn reduces toxicity. A one-step antisolvent-free method using green solvent MAAC to fabricate high-quality Sn-Pb perovskite film achieves a champion PCE of 15.42%. Additionally, the device exhibits robust stability even after being stored in N-2 for 720 hours.