Understanding charge transport and dielectric relaxation properties in lead-free Cs2ZrCl6 nanoparticles

Abstract

In the exploration of perovskite materials devoid of lead and appropriate for capturing solar energy, a recent finding has surfaced concerning Cs₂ZrCl₆. This compound has attracted interest as a potential candidate, displaying advantageous optical and electrical features, coupled with remarkable durability under environmental stresses. This research outlines the effective production of non-toxic metal halide nanoparticles of Cs₂ZrCl₆ using the gradual cooling technique. Thorough examinations have been conducted to explore the structural, optical, and dielectric traits. Over the frequency range of 10¹–10⁶ Hz, the dielectric constant, loss factor, electric modulus, and electrical conductivity of Cs₂ZrCl₆ exhibit a strong dependence on temperature. The Nyquist plot confirms the distinct contributions of grains and grain boundaries to the total impedance. In the high-frequency region, the dielectric constant tends to increase with temperature. In accordance with the modified Kohlrausch–Williams–Watts (KWW) equation, an asymmetric nature corresponding to the non-Debye type is observed in the electric modulus spectra at different temperatures. Furthermore, the imaginary part of the electric modulus spectrum shifts from the non-Debye type towards the Debye type with increasing temperature, despite not obtaining an exact Debye response. The frequency-dependent behavior of AC conductivity has been modeled using Joncher's universal law. The conduction mechanism within the Cs₂ZrCl₆ compound is attributed to the small polaron tunneling model (NSPT). Furthermore, Cs₂ZrCl₆ has the potential to function as an energy harvesting device due to its elevated dielectric constant combined with minimal dielectric loss.