Non-doped and unsorted single-walled carbon nanotubes as carrier-selective, transparent, and conductive electrode for perovskite solar cells

Lead halide perovskite solar cells (PSCs) with a structure of glass/FTO/TiO2/CH3NH3PbI3 with single-walled carbon nanotubes (SWNT) as the transparent top electrodes, followed by polymethyl methacrylate (PMMA) over-coating were fabricated. The SWNT-based PSCs do not require expensive metal electrodes and hole-transporting materials yet produce a decent power conversion efficiency of 11.8%, owing to the densifying effect of SWNTs by PMMA. The resulting devices demonstrate reduced hysteresis, improved stability, and increased power conversion efficiency.