Lead-free double perovskite Cs2MBiCl6 (M = Ag, Cu): insights into the optical, dielectric, and charge transfer properties

Mohamed Ben Bechir; Mohamed Houcine Dhaou

doi:10.1039/d3ra02731g

Lead-free double perovskite Cs₂MBiCl₆ (M = Ag, Cu): insights into the optical, dielectric, and charge transfer properties

RSC Adv. 2023 Jun 13;13(26):17750-17764. doi: 10.1039/d3ra02731g. eCollection 2023 Jun 9.

Authors

Mohamed Ben Bechir¹, Mohamed Houcine Dhaou²

Affiliations

¹ Laboratory of Spectroscopic and Optical Characterization of Materials (LaSCOM), Faculty of Sciences, University of Sfax BP1171 - 3000 Sfax Tunisia mohamedbenbechir@hotmail.com.
² Department of Physics, College of Science, Qassim University P.O. Box: 6644, Almolaydah: 51452 Buraydah Saudi Arabia.

Abstract

Recently, double perovskites have shown excellent potential considering the instability and toxicity problems of lead halide perovskites in optoelectronic devices. Here, the double perovskites Cs₂MBiCl₆ (M = Ag, Cu) were successfully synthesized via the slow evaporation solution growth technique. The cubic phase of these double perovskite materials was verified through the X-ray diffraction pattern. The investigation of Cs₂CuBiCl₆ and Cs₂AgBiCl₆ utilizing optical analysis showed that their respective indirect band-gap values were 1.31 and 2.92 eV, respectively. These materials, which are double perovskites, were examined using the impedance spectroscopy technique within the 10^-1 to 10⁶ Hz frequency and 300-400 K temperature ranges. Jonncher's power law was utilized to describe AC conductivity. The outcomes of the study on charge transportation in Cs₂MBiCl₆ (where M = Ag, Cu) suggest that the non-overlapping small polaron tunneling mechanism was present in Cs₂CuBiCl₆, whereas the overlapping large polaron tunneling mechanism was present in Cs₂AgBiCl₆.