Affiliation:
1. Department of Physics Thal University Bhakkar Bhakkar 30000 Pakistan
2. Department of Physics University of Sargodha Sargodha 40100 Pakistan
3. Molecular Engineering Laboratory Department of Physics University of Patras Patras 26500 Greece
4. Institute of Physics Khwaja Fareed University of Engineering and Information Technology Rahim Yar Khan 64200 Pakistan
5. Centre for Thermal and Renewable Energy Research Khwaja Fareed University of Engineering and Information Technology Rahim Yar Khan 64200 Pakistan
6. College of Pharmacy Gachon University No. 191, Hambakmeoro Yeonsu‐gu Incheon 21936 Republic of Korea
7. Department of Management College of Business Administration King Saud University Riyadh 11587 Saudi Arabia
Abstract
Lead‐free double perovskites are now assumed to be suitable candidates for green energy harvesting in particular as active materials for solar cells and thermoelectric generators, which can meet future generation energy needs. Therefore, we explore the Au‐based halide double perovskites X2Au+Au3+Br6 (X = Cs, Rb) from the first principles approach. Density functional theory (DFT) is utilized to explore the electronic structure with DFT code Quantum ESPRESSO. The mechanical, thermodynamic, and structural stability is ensured from Burn‐Haun criterion, formation energies, and Goldschmidt factors, respectively. The examined materials have stable structures with direct band gaps i.e. 1.54 and 1.72 eV. The existence of band gaps in the visible region motivates us to explore the optical properties, which give fascinating outcomes. The absorption coefficients and optical conductivity peaks are found to be significant in the visible region i.e., ≈104 cm−1 and ≈1015 s−1, respectively. Additionally, the thermoelectric properties are also investigated using Boltzmann transport theory. There are several good gestures for the usage in the thermoelectric generators since the values of Seebeck coefficients (446.5, and 225.2 μV K−1), power factors (1.75 × 1011 W mk−2 s, and 1.24 × 1011 W mk−2 s), and figure of merits (0.92 and 0.73) are noteworthy for Cs2AuAuBr6 and Rb2AuAuBr6, respectively, at room temperature T = 300 K.