Post-Treated Polycrystalline SnO2 in Perovskite Solar Cells for High Efficiency and Quasi-Steady-State-IV Stability

Abstract

The prominent chemical bath deposition (CBD) method leverages tin dioxide (SnO₂) as an electron transport layer (ETL) in perovskite solar cells (PSCs), achieving exceptional efficiency. The deposition of SnO₂, however, can lead to the formation of oxygen vacancies and surface defects, which subsequently contribute to performance challenges such as hysteresis and instability under light-soaking conditions. To alleviate these issues, it is crucial to address heterointerface defects and ensure the uniform coverage of SnO₂ on fluorine-doped tin oxide substrates. Herein, the efficacy of tin(IV) chloride (SnCl₄) post-treatment in enhancing the properties of the SnO₂-ETL and the performances of PSCs are presented. The treatment with SnCl₄ not only removes undesired agglomerated SnO₂ nanoparticles from the surface of CBD SnO₂ but also improves its crystallinity through a recrystallization process. This leads to an optimized interface between the SnO₂-ETL and perovskite, effectively minimizing defects while promoting efficient electron transport. The resultant PSCs demonstrate improved performance, achieving an efficiency of 25.56% (certified with 24.92%), while retaining 95.84% of the initial PCE under ambient storage conditions. Additionally, PSCs treated with SnCl₄ endure prolonged light-soaking tests, particularly when subjected to quasi-steady-state-IV measurements. This highlights the potential of SnCl₄ treatment as a promising strategy for advancing PSC technology.