A novel modest synthesis of device applicable flakes based stable BiOI film by the oxidation of BiI3 film

Abstract This paper reports a novel and simple synthesis method of BiOI film preparation. In our experiment, the synthesis process of BiOI was conducted in a typical room temperature environment by the oxidation of spin-coated BiI3 film. This investigation confirms the firm BiOI film's existence at 300–350 °C for 10 mins of post-annealing treatment. This study highlights the structure by X-Ray Diffraction (XRD) and morphology by scanning electron microscope (SEM) of newly prepared BiOI thin films. Moreover, the stability of BiOI over the BiI3 film has been discussed systemically by Raman and film color study with the comprehensive structural and optical behavioral variation in this article. However, once the post-annealing temperature reaches around 400 °C, some structural defects appeared and BiOI was converted into Bi7O9I3. Simultaneously, as days go, BiI3 film gradually transformed into the BiOI film while BiOI stays in its own structure under atmospheric conditions. Lastly, BiOI film has been employed in the solid-state photovoltaic device, and the maximum 0.28 V open-circuit voltage has been observed at ten spin cycles condition. Meanwhile, we have observed a 670 μA/cm2 short-circuit current at three spin cycles condition. We strongly believe that this newly proposed modest synthesis technique of BiOI thin film will encourage the research world to consider it for photovoltaic and optical applications.