Temperature and frequency dependent dielectric response of C3H7NH3PbI3: A new hybrid perovskite

Abstract

Propylammonium lead iodide (C3H7NH3PbI3), a promising hybrid perovskite, is successfully synthesized by a solgel technique. Structural, optical, and dielectric properties have been studied in detail. The dielectric constant, loss factor, electric modulus, and AC and DC conductivity of this hybrid perovskite exhibit strong temperature dependence over the frequency range of 10 Hz ≤ f ≤ 8 MHz. The Nyquist plot reveals the distinct contributions of grain and grain boundary to the total impedance. The dielectric constant is found to increase with temperature in the high frequency region. The modified Cole–Cole plot shows that the space charge and free charge conductivity increase with the elevation of temperature, whereas the relaxation time decreases with the rise in temperature. From the modified Kohlrausch–Williams–Watts equation, we perceived asymmetrical nature in electric modulus spectra at various temperatures, which corresponds to the non-Debye type nature of perovskite. It has also been found that, with the elevation of temperature, the imaginary part of electric modulus spectra shifts from the non-Debye type toward the Debye type nature, though failing to acquire exact Debye type response, and emerges as a semiconductor material. AC conductivity of PAPbI3 is illustrated on the basis of the correlated barrier hopping (CBH) mechanism. Activation energy estimated from both modulus spectra and DC conductivity matches well, affirming the similarity between relaxation behavior and conduction mechanism. Along with all these, PAPbI3 possesses a high dielectric constant associated with a small dielectric loss, making it a potential candidate for energy harvesting devices.