Compact continuous BiOI film for solid-state solar cell via faster lifting speed of the dip-SILAR technique at room temperature

Abstract

This research paper reports for the first time room temperature deposited, and 100 °C annealed, successive ionic layer adsorption and reaction (SILAR) prepared bismuth oxyiodide (BiOI) continuous film to produce a stable solid-state solar cell. After the successful deposition of continuous BiOI film on the TiO2 electron transport layer (ETL), the hole transport layer (HTL) colloidal graphite has been introduced. Our investigation confirms the continuous growth of the BiOI film at faster lifting speed (e.g., 30 mm/s) of the SILAR technique, while separated flaky structure was observed at slower lifting speed (e.g., 4 mm/s). The BiOI material structure converted into a continuous flower shape at a faster lifting speed, preventing the HTL layer penetration and short circuit with ETL. After ensuring the continuous film, we have observed the short-circuit current density (JSC = 4.7 mA/cm2), open-circuit voltage (VOC = 0.35 V), and power conversion efficiency (η = 0.39%) of the cell at 30 cycles condition. This synthesis technique will encourage the research world to think more interestingly about environmentally friendly BiOI solid-state solar cells.