Partial replacement of B-site cation to stabilize the optically active cubic phase of FAPbI3 for optoelectronic applications

Due to the unique and indispensable electronic, physical and chemical properties, halide perovskites are being widely used in optoelectronic applications like solar cells and LEDs. However, the stability of halide perovskites has always been an alarming issue towards the development of these devices on an industrial scale. Specifically, Formamidinium Lead Iodide (FAPbI3), the most suitable organic halide perovskite for solar cells is very unstable due to environmental factors like humidity, temperature and ultraviolet radiation which led to poor-performing devices. Moreover, FAPbI3 is more stable in its photo-inactive hexagonal (δ-FAPbI3) phase. For photovoltaic devices, only the optically active cubic phase (α-FAPbI3) is suitable due to its proper band gap (∼1.45 eV). In this communication, we have partially substituted the Pb2+ cation in FAPbI3 with Tin (Sn2+) and Manganese (Mn2+). The structural and optical properties are analyzed using X-Ray Diffraction, Ultra-violet Diffuse Reflectance Spectroscopy and Photoluminescence (PL) spectroscopy. The results show that the α-FAPbI3 phase can be retained with successful incorporation of Sn2+ and Mn2+ at the B-site of FAPbI3 structure.