Nanotube enhanced carbon grids as top electrodes for fully printable mesoscopic semitransparent perovskite solar cells

Semitransparent solar cells have attracted significant attention for their potential applications, though obtaining high average visible transmittance (AVT) while maintaining good conversion efficiency is a challenge. Here, we report a method to fabricate fully printable semitransparent perovskite solar cells with a (5-AVA)(0.05)(MA)(0.95)PbI3 infiltrated mesoporous TiO2/Al2O3/carbon architecture. Carbon grids were printed as top electrodes, and the effects of the grid spacing on device performance were systematically investigated. Under the smallest grid spacing, the highest power conversion efficiency (PCE) of 11.31% was achieved, though the AVT was low. By adjusting the grid spacing, the highest AVT of 26.4% was obtained, though the PCE dropped to 5.36%. A thin layer of multi-walled carbon nanotubes (MWCNTs) was then introduced on the top electrode, which improved both the conductivity and charge transfer characteristic of the electrode, resulting in a high PCE of 8.21% while maintaining a good AVT of 24.0%.