Dielectric relaxation of CH3NH3PbI3 thin film

A film of CH3NH3PbI3 of thickness 1200 nm is fabricated on fluorine doped tin oxide coated glass. The crystal structure of the material has been determined by X-ray diffraction method which shows that CH3NH3PbI3 is crystallized in the tetragonal phase with space group I4/mcm. The dielectric relaxation of the CH3NH3PbI3 thin film is investigated in the frequency range from 42 Hz to 4.8 MHz. The frequency dependent electrical data are analyzed in the framework of conductivity and electric modulus formalisms. Owing to the distribution of relaxation time, the relaxation mechanism in CH3NH3PbI3 is found to follow the Cole-Cole model. A comparison of the impedance with the electric modulus suggests the presence of localized relaxation process. The complex impedance plane plot is analyzed by a parallel electrical circuit consisting of a resistance and a capacitance. The frequency dependent conductivity spectra are found to follow the power law.