Oxidized Nickel films as highly transparent HTLs for inverted planar perovskite solar cells

Inverted planar perovskite solar cells (PSCs) with nickel oxide (NiO) as a hole transporting layer were fabricated in an ambient atmosphere. Nickel (Ni) film synthesized at optimized evaporation conditions using low-cost thermal evaporation were transformed from island-like structure to compact porous thin films of NiO after oxidation at 580 ℃. The formation of highly transparent NiO films without any impurity was confirmed from UV–visible...