Electronic band structure and carrier concentration of formamidinium-cesium mixed cation lead mixed halide hybrid perovskites

The electronic structure of hybrid perovskite compositions of FA(0.83) Cs-0.17 PbI3-xBrx (x = 0.0, 0.5, 1.0, 1.5, 2.0, and 2.5) is determined using ultraviolet photoelectron spectroscopy (UPS) and UV-Vis-NIR absorption spectroscopy. With the help of UPS, ionization potential and Fermi energy are determined, and using absorption measurements, bandgap values are obtained. It is observed that for FA(0.83) Cs-0.17 PbI3-xBrx, as the Br content increases, the bandgap increases. The UPS measurements confirm the n-type nature of all compositions. Additionally, the Hall measurements were carried out for the selected compositions and the n-type carrier concentrations were determined. Published by AIP Publishing.