Abstract
Recently, hybrid halide perovskite solar cells have drawn the researchers' attention, owing to their high-power conversion efficiency. Among the different compounds, MAPbI(3) (MA = Methylammonium CH3NH3) and FAPbI(3) (FA = Formamidinium CH(NH2)(2)) are especially potential candidates since their bandgap suited the energy range of visible light. Here, the hybrid pemvskite FAPbI(3) is successfully synthesized via the inverse temperature crystallization method. Different characterization techniques such as variable-temperature structural analyses, differential scanning calorimetry (DSC), and impedance spectroscopic analysis show that FAPbI(3) presents a phase transition at T = 300 K from the hexagonal to the cubic symmetry. Optical analysis of FAPbI(3) shows the direct band-gap value of similar to 1.4 eV. FAPbI(3) is characterized by impedance spectroscopy technique performed in the 10(-)(1)-10(6) Hz frequency and 210-390 K temperature ranges. The alternating current (AC) conductivity is illustrated in terms of Jonncher' s power law. The study on charge transportation within FAPbI(3) suggests the presence of the NSPT (non-overlapping small polamn tunneling) and OLPT (overlapping large polamn tunneling) models in the hexagonal and cubic phases, respectively.