Synthesis and Characterization of BiOI Films for Photo-Electrochemical Cell via Simple Heating Process of BiI₃

Abstract

This work aims to prepare BiOI films via simple heating of BiI3 materials and study their characters from structural, optical, and morphology perspectives. In the heating process, we varied the heating treatment time. In addition, the solar cell performance of prepared BiOI films was tested. In BiOI preparation, we deposited BiI3 films first onto FTO substrates via BiI3 heating in the air using a closed chamber at the temperature of 360 °C for 30, 45, and 120 minutes. The deposited BiI3 films were then rinsed with water/ethanol and re-heated at 350 °C for 30 minutes. As a result, by increasing the heating treatment time, it could form thicker BiOI films. All the resulting films confirmed the BiOI characters. A longer BiI3 heating time could direct the growth of BiOI crystal, wavelength red-shift, and flake structure. In the electrochemical solar cell study, it was known that BiOI films had a lower performance compared to the reported results. After a certain thickness (~1.3 μm), the device's open-circuit voltage and current decreased.