Efficient perovskite solar cells based on polyoxyethylene bis(amine) and NaPF6 modified SnO2 layer with high open-circuit voltage

The electron transport layer (ETL) of SnO2 with a rough surface, low conductivity, and poor wettability has limited its application in perovskite solar cells (PSCs). To address this issue, we propose a strategy that involves the simultaneous use of bulk dopant NaPF6 and polymer stabilizer NH2-PEG-NH2 in SnO2. NH2-PEG-NH2 is compatible with both SnO2 and NaPF6, resulting in a homogeneous distribution. Additionally, the intrinsic hydrophilicity of the polymer facilitates the formation of a continuous and ordered ETL with improved wettability. The inclusion of NaPF6 as a bulk dopant enhances conductivity and promotes upper perovskite growth. As a result, optimized morphology, aligned energy levels, improved crystallinity, and reduced bottom defects are achieved in the fabricated perovskite layer. The champion device exhibits a power conversion efficiency (PCE) of ∼23.36%, which is ∼11.88% higher than that of the pristine device (PCE=20.88%). Notably, the VOC reaches ∼1.2 V with only ∼0.08 V of VOC loss, which is among the highest report one. Furthermore, the PCE of the modified unpackaged PSC was only attenuated by 25% after 250 h of maximum power point tracking in the environment. These results present an alternative and effective approach for preparing high-quality SnO2 ETL for efficient PSCs.