A Simple Route to the Synthesis and Deposition of All Inorganic Perovskite CsPbBr₃ Films and Their Photocatalytic Properties

The compounds belonging to the family of perovskites exhibit a wide range of mechanical, magnetic, and optical properties and for these reasons are currently key materials for many technologies, such as piezoelectrics, photocatalytic systems, and photovoltaic solar cells. Among perovskites, the all-inorganic halide perovskites (AIHPs) with the ABX₃ structure (with A = Cs, Rb; B = Pb, Sn and X = F, Br, I) represent an emerging class of materials that have drawn a growing interest due to the combination of the advantages of containing cheap and abundant elements with the excellent stability of these structures by excluding organic species sensitive to the external environment.<br/><br/>Particularly, our attention is devoted to CsPbBr₃ all-inorganic perovskites, which, among other effects, have emerged for photocatalytic degradation processes of different organic dye compounds. In fact, one of the most challenging applications of AIHP materials regards the wastewater purification process of textile effluents from industrial production. In this field, heterogeneous catalysis under light is widely accepted due to its high efficiency, yield of degradation, and cost effectiveness. For these reasons, CsPbBr₃ in the form of films, being immobilized and not used as a dispersed phase, has the advantage of a simple separation and recovery from the solution. Therefore, a smooth, continuous well-covering thin film on a regular substrate is preferred.<br/><br/>Herein, we report a novel method for the synthesis of CsPbBr₃ films on different substrates such as silicon, glass, quartz, and flexible substrates. The present synthetic strategy is a facile, one-step, and low-temperature approach to the synthesis of Cs-Pb halide perovskite and takes advantage of the Cs and Pb β-diketonate compounds as precursors, allowing, reproducibly and selectively, the synthesis of the CsPbBr₃ phase. The as obtained CsPbBr₃ suspension is deposited onto the substrates by spray deposition at room temperature and atmospheric pressure. This approach reveals to be very simple and extremely versatile and makes it possible to deposit the perovskite on a wide range of different kinds of materials.<br/><br/>Structural, morphological, and compositional analyses of the final products, carried out by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and Energy Dispersive X-ray analysis (EDX), show the formation of the pure CsPbBr₃ system. Uv-vis spectrophotometric analyses were performed in order to determine the bandgap energy (E_g) of the system. Preliminary results on photodegradation of an organic dye under both visible or UV light irradiation will be presented.