Formation of organic–inorganic mixed halide perovskite films by thermal evaporation of PbCl2 and CH3NH3I compounds

Abstract

The ratio of PbCl ₂ to CH ₃NH ₃I compounds strongly affect the PCE and stability of perovskite solar cell fabricated by co-evaporation.

Abstract

Organic–inorganic hybrid perovskites were prepared by thermal evaporation from precursor materials PbCl ₂ and CH ₃NH ₃I (MAI). The structures of the perovskite films with various ingredients were characterized by X-ray diffraction (XRD), UV-vis absorption, and scanning electron microscopy (SEM). We found that with the addition of MAI material the evaporated PbCl ₂ films were initially transformed to PbI ₂, then to standard a stoichiometric perovskite and finally to the MAPbI ₃· xMAI phase. The film composition ingredients strongly affect the device performance. An unmatched PbCl ₂ to MAI ratio in the evaporated films resulted in reduced conversion efficiency and higher moisture sensitivity. The planar perovskite solar cells with organic charge layers showed negligible photocurrent hysteresis and delivered a power conversion efficiency of 10.5%.