Study of Charge Transfer Mechanism and Dielectric Relaxation of CsCuCl3 Perovskite Nanoparticles

ABSTRACT Non-toxic inorganic metal halide perovskites have commercially established dominance over all the other optoelectronic devices. In this paper, a non-toxic CsCuCl3 metal halide is successfully synthesized through the slow evaporation solution growth technique. The hexagonal phase of the material is checked using the X-ray diffraction measurement. The morphological study indicates the spherical shape of nanoparticles with about 20 nm size. CsCuCl3 demonstrates a semiconducting property with a direct band gap value of approximately 2.18 eV. Over the 10−1–107 Hz frequency range, the dielectric constant, the loss factor, the electric modulus and also the electrical conductivity of CsCuCl3 show strong temperature dependence. The Nyquist plot confirms the various contributions of grains and grain boundaries to the total impedance. In the high-frequency region, the dielectric constant tends to increase with temperature. The modified Cole–Cole plot asserts that while the relaxation time decreases with the rise in temperature, the space charge and free charge conductivity increase the moment the temperature climbs. In accordance with the modified Kohlrausch-Williams-Watts (KWW) equation, an asymmetrical nature corresponding to the non-Debye type of the perovskite is noticed in the electric modulus spectra at different temperatures. Moreover, the imaginary part of the electric modulus spectra is found to shift from the non-Debye toward the Debye type with the increase in temperature despite not getting the exact Debye response and emerging as a semi-conductor material. The alternating current (AC) conductivity of CsCuCl3 is shown based on the non-overlapping small-polaron tunneling (NSPT) mechanism. The fact that the direct current (DC) conductivity matches well with the activation energy which is based on the two modulus spectra indicates that the relaxation behavior and the conduction mechanism are remarkably similar. Additionally, CsCuCl3 is likely to be an energy-harvesting device since it has a high dielectric constant related to its low dielectric loss.