Insights into the optoelectronic and thermoelectric properties of lead-free Rb2NaIrF6 double perovskite compound: A first-principles study

Publication Type

Journal Article

Name of Author

• Mwende Mbilo, Department of Physics and Sustainable Technology, School of Pure and Applied Sciences, Pwani University, Kilifi, Kenya
• Robinson Musembi, Monolith Research Group, Department of Physics, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
• John Peter Kachira, Monolith Research Group, Department of Physics, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
• Wisley Nyangau Onsate, Department of Physics and Sustainable Technology, School of Pure and Applied Sciences, Pwani University, Kilifi, Kenya
• Fanuel Mugwanga Keheze, Department of Physics and Sustainable Technology, School of Pure and Applied Sciences, Pwani University, Kilifi, Kenya
• Refilwe Edwin Mapasha, Department of Physics, University of Pretoria, Hatfield Campus, Pretoria South Africa

Publication Date (Issue Year)

2025

Journal Name

Results in Physics

Abstract

This study investigated the structural, electronic, elastic, mechanical, thermodynamic, optical, and thermoelectric properties of the Rb2NaIrF6 lead-free double perovskite compound using first-principles methods. The structural stability of the perovskite was confirmed by the Goldschmidt tolerance and octahedral factors. Dynamic stability was confirmed through the negative energy of formation and positive frequency modes of the phonon dispersion curve. The dynamic stability results suggest that the studied compound could be potentially synthesised experimentally. The Rb2NaIrF6 compound is a direct semiconductor with electronic band gaps within the range of 2.14–3.76 eV, computed using different approximations. The mechanical stability was confirmed by the elastic calculation results. The Rb2NaIrF6 compound was found to be ductile, ionic, and anisotropic. The optical properties showed that Rb2NaIrF6 strongly absorbs light in the ultraviolet region, which is desirable for ultraviolet-photosensitive materials in optoelectronic devices. The computed thermoelectric figure of merit of the Rb2NaIrF6 compound is 0.81 at 1000 K, suggesting high thermoelectric efficiency. These findings demonstrate the potential of Rb2NaIrF6 lead-free double perovskite compound for optoelectronic and thermoelectric applications. Therefore, our investigation offers theoretical insights that can lead to the experimental synthesis and study of Rb2NaIrF6 lead-free double perovskites.

Keywords

DFT GGA, Double perovskites, Optoelectronics, Thermoelectric applications

Grantee Name(s)

Robinson Juma Musembi

Project Title

Self-cleaning solar module for enhanced electrical output

Type of Grant

Research Award

Funding Statement

The work was carried out with the financial support of the World Bank under the project “Africa Regional Scholarship and Innovation Fund for Applied Sciences, Engineering and Technology (RSIF)”, financed under P165581 IDA D3470, TF A8639, and TDF B1033. The views expressed herein do not necessarily reflect the official opinions of the donors. The authors acknowledge the University of Nairobi for resources in doing this work and the Centre for High-Performance Computing (CHPC-RSA) for computing resources through the account number MATS1321. REM is grateful to the University of Pretoria for the availability of financial support.

Recommended Citation

Mbilo, M., Musembi, R., Kachira, J. P., Onsate, W. N., Keheze, F. M., & Mapasha, R. E. (2025). Insights into the optoelectronic and thermoelectric properties of lead-free Rb2NaIrF6 double perovskite compound: A first-principles study. Results in Physics https://doi.org/10.1016/j.rinp.2025.108349