Additive Effects of Copper and Alkali Metal Halides into Methylammonium Lead Iodide Perovskite Solar Cells

Fabrication and characterization of methylammonium lead iodide perovskite solar cells incorporated with formamidinium iodide, copper halides, alkali metal halides and decaphenylcyclopentasilane were performed. Addition of CuCl and KI at 2% into the perovskite layer offered compact morphologies and crystal orientation in the perovskite layer, improving short circuit current densities, series resistance and open-circuit voltages related to conversion efficiencies. The stabilities of conversion efficiencies were improved for the perovskite layer incorporated with 2% CuCl and 2% NaI. The stabilities depended on the state of the surface morphologies and crystal orientation while suppressing decomposition reaction in the perovskite layer. The photovoltaic mechanisms were associated with promotion of carrier generation and diffusion in the crystalline layer. The electronic correlation was based on the charge transfer between 5p orbital of I ion and 3d orbital of Cu ion near valence band, promoting the carrier generation and diffusion related to the short circuit current densities.