First-principles study of lead-free double perovskites Ga₂PdX₆ (X = Cl, Br, and I) for solar cells and renewable energy

The double perovskites are promising for solar cells and other optoelectronic applications. In this article, the optoelectronic, transport characteristics of new double perovskites Ga₂PdCl₆, Ga₂PdBr₆, and Ga₂PdI₆ are addressed. The structural and thermodynamic stabilities have been addressed by tolerance factor, and positive frequency of phonon dispersion. The reported band gaps are 2.05 eV, 1.60 eV and 0.80 eV which increases their performance for solar cells. The Ga₂PdBr₆ is ideal for visible light solar cells with absorption band 400 nm–620 nm. The optical properties analyzed by dielectric constants, polarization, absorption of light, and optical losses. Thermoelectric characteristics has been explained by figure of merit (ZT) in terms of chemical potential, and kelvin temperature. The room temperature ZT (0.77, 0.76, 0.75) for Ga₂PdX₆ (X = Cl, Br, I) make them potential for thermoelectric applications.