Perovskite Thin Film Synthesised from Sputtered Lead Sulphide

In the last few years, research on dye-sensitised devices has been focused on the development of solar cells, based on CH₃NH₃PbX₃ (X = I^-, Br^-, Cl^-) composites with perovskite structure. The deposition of perovskite thin films is usually carried out by solution-based processes using spin-coating techniques that result in the production of high quality films. Solar cells made by this method exceed 20% efficiency, with the potential for use in large scale production through ink print or screen printing techniques. As an alternative route, perovskite thin films can be deposited through thermal evaporation. A new method is proposed to produce CH₃NH₃PbI₃, based on a radio-frequency (rf) -sputtering technique that results in a high reproducibility of the films and is compatible with roll-to-roll processes. We deposited thin films of lead-sulphide (PbS) and converted them into perovskite by placing the films in an iodine atmosphere, followed by dipping in a solution of methylammonium iodide (CH₃NH₃I). The conversions to PbI₂ and CH₃NH₃PbI₃ were confirmed by elemental analyses, absorption, and photoluminescence spectroscopy. Structural properties were revealed by X-ray diffraction and infrared and Raman spectroscopy.