Influences of Precursor Solution Concentration and Temperature on CH3NH3PbI3 Perovskite Layer Morphology and the Unconverted PbI2 Proportion to their Perovskite Solar Cell Characteristics

Abstract

The formation of organometal-halide perovskite crystal is simply based on stoichiometry reaction. However, the formation process seems to be sensitively affected by some process parameters such as concentration and temperature of precursor solution. In this work, we studied the formation of CH3NH3PbI3 (MAPbI3) crystal in mesoporous TiO2 layer deposited by spin coating technique. Perovskite layers were characterized by X-Ray Diffraction (XRD) and its surface morphology were investigated by Scanning Electron Microscope (SEM). Perovskite layers obtained from precursor solution at 40°C and 60°C show a mesh-like structure. Meanwhile, for higher precursor solution temperature (80°C), it shows a flake-like structure. However, precursor solution at 60°C produced the best conversion of precursor solution with the smallest percentage of the remaining unconverted PbI2 inside the produced crystal layer. These experimental results also showed that the best crystallization degree is obtained from 1.0 M precursor solution. The photovoltaic characteristics of their solar cells seem to have a correlation with the quantity of unconverted PbI2. High PbI2 content significantly decreased the Filling Factor of the solar cell.