SnO₂-in-Polymer Matrix for High-Efficiency Perovskite Solar Cells with Improved Reproducibility and Stability

Understanding interfacial loss and the ways to improving interfacial property is critical to fabricate highly efficient and reproducible perovskite solar cells (PSCs). In SnO₂-based PSCs, nonradiative recombination sites at the SnO₂–perovskite interface lead to a large potential loss and performance variation in the resulting photovoltaic devices. Here, a novel SnO₂-in-polymer matrix (i.e., polyethylene glycol) is devised as the electron transporting layer to improve the film quality of the SnO₂ electron transporting layer. The SnO₂-in-polymer matrix is fabricated through spin-coating a polymer-incorporated SnO₂ colloidal ink. The polymer is uniformly dispersed in SnO₂ colloidal ink and promotes the nanoparticle disaggregation in the ink. Owing to polymer incorporation, the compactness and wetting property of SnO₂ layer is significantly ameliorated. Finally, photovoltaic devices based on Cs_0.05FA_0.81MA_0.14PbI_2.55Br_0.45 perovskite sandwiched between SnO₂ and Spiro-OMeTAD layer are fabricated. Compared with the averaging power conversion efficiency of 16.2% with 1.2% deviation for control devices, the optimized devices exhibit an improved averaging efficiency of 19.5% with 0.25% deviation. The conception of polymer incorporation in the electron transporting layer paves a way to further increase the performance of planar perovskite solar cells.