Study on charge transfer mechanism and dielectric relaxation of cesium lead bromide (CsPbBr3)

In this work, CsPbBr3 has been successfully synthesized via sol-gel technique. The orthorhombic phase of the material has been verified by X-ray diffraction measurement followed by Rietveld refinement analysis. Morphological study has revealed the cubic shape of particles with dimension similar to 3 mu m. Electrical properties are characterized by Complex impedance (Z*), dielectric permittivity (epsilon*), and ac conductivity within the frequency range 10 Hz-5 MHz for different temperatures between 313K and 673 K. The dielectric behavior of CsPbBr3 is found to be thermally activated and frequency dependent. The ascensive nature of epsilon'(w) at lower frequency is assigned to the Maxwell-Wagner type interfacial polarization. epsilon'(w) has been fitted using Kramers-Kronig relation by including the dielectric constant at infinite frequency. Variation of epsilon ''(w) with frequency has been explained by the hopping of charge carrier over a potential barrier between charge defects. AC conductivity has also been fitted by Jonscher's power law to find the real component of conductivity and it has been described by using the Jump relaxation model. Activation energy has been calculated by fitting the dc conductivity using Arrhenius relation and found to have a value of 0.517 eV. Grain resistance (r(g)), grain capacitance (c(g)), grain boundary resistance (r(gb)), and grain boundary capacitance (c(gb)) have been accounted by fitting Z' vs log(f) plot with equivalent circuit and existing theoretical model. Published by AIP Publishing.