p-i-n Structured Semitransparent Perovskite Solar Cells with Solution-Processed Electron Transport Layer

p-i-n structured semitransparent perovskite solar cells have already been established as promising energy harvesting devices for building-integrated photovoltaics and flexible solar cells due to high transparency and low-cost fabrication. In this study, solution based p-i-n structured semitransparent perovskite solar cells (PSCs) have been developed using thin silver (Ag), zinc oxide (ZnO), and aluminium (Al)-doped ZnO nanoparticles (AZO) as buffer layers in addition to PCBM as an electron transport layer (ETL). The thickness of the ZnO and AZO layers are around ~100 nm. In the case of the thin Ag layer, poor interfacial band alignment and less transparency yield device performance with an inferior PCE of 2.53% when illuminated from the top electrode side. On the contrary, Al-doped ZnO possesses excellent optoelectronic performance as a buffer layer for their better electronic conductivity and interfacial band alignment and yield a photovoltaic device characteristic with a power conversion efficiency (PCE) of 5.87% when illuminated from the top electrode side, whereas the standard device with a metal electrode shows a PCE of 6.4%. The semitransparent device also has an average transparency of 21.8% in the visible region.