Effects of guanidinium addition to CH₃NH₃PbI_3−xCl_x perovskite photovoltaic devices

Abstract

CH₃NH₃PbI_3−xCl_x-based photovoltaic devices with guanidinium [C(NH₂)₃, GA] were fabricated and characterized. The additive effects of guanidinium iodide, formamidinium [CH(NH₂)₂, FA] iodide, and guanidinium chloride were compared. Short-circuit current densities, open-circuit voltages, series resistances and shunt resistances were improved by the GA addition. The short-circuit current densities were increased by FA addition with GA. The incident photon-to-current conversion efficiency increased, which results from the suppression of pin-holes in perovskite layers by GA addition. The conversion efficiencies were improved by GA addition. X-ray diffraction showed that the lattice constants of the perovskite crystals increased by GA and FA addition, and that the GA substituted partially at the CH₃NH₃-site.