Synthesis of SnO₂ nanofibers and nanobelts electron transporting layer for efficient perovskite solar cells

The implementation of positive alternative electron transporting layers (ETLs) with excellent electronic properties is a most promising method to up-scale low-cost highly efficient perovskite solar cell (PSC) technology. The present work demonstrates the preparation of tin oxide (SnO2) nanofibers (NF) and nanobelts (NB) as an electron transporting layer (ETL) for PSCs. The smooth and uniform nanofibers and nanobelts have been prepared using an electrospinning technique followed by calcination at 600 °C. Thermogravimetric analysis (TGA) analysis performed on the as-spun polyvinylpyrrolidone-tin oxide (PVP-SnO2) composite suggests that a calcination temperature of 600 °C is required to obtain pure SnO2 and to ensure complete removal of PVP along with other organic solvents. The structural analysis confirmed the presence of the pure tetragonal rutile phase of SnO2 nanofibers and nanobelts. The prepared nanofibers and nanobelts were further used as ETLs for PSCs. Our optimized experimental parameters yielded a JSC of 22.46 mA cm-2, a VOC of 1.081 V and FF of 66%, leading to >16% power conversion efficiency (PCE) for SnO2 nanobelts using an (FAPbI3)0.85(MAPbI3)0.15 perovskite absorber layer with good stability. The obtained PCE is much higher than that of the SnO2 NF (12.893%) morphology. Nevertheless, the synthesis of SnO2 NF/NB ETLs provides a simple, low-cost and large-scale method for PSCs.