Ab‐initio study of opto‐electronic and thermoelectric properties of direct bandgap double perovskites Rb2XGaBr6 (XNa, K)

• Published in: International journal of energy research Vol. 45; no. 6; pp. 9241 - 9251
• Main Authors: Haq, Anwar Ul, Mustafa, Ghulam M., Amin, Muhammad, Ramay, Shahid M., Mahmood, Asif
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Inc 01.05.2021; Hindawi Limited
• Subjects: Density functional theory; direct band gap double perovskite; Electrical conductivity; Electrical resistivity; Electromagnetic absorption; Electronic devices; Electronic equipment; Electronic properties; Energy; Energy shortages; Environmental management; figure of merit; Free energy; Halides; Heat of formation; Light absorption; Mathematical analysis; mechanical characteristics; Optical properties; opto‐electronic devices; Perovskites; Photonic band gaps; Photovoltaic cells; Plane waves; Renewable energy; Renewable resources; Resource management; Seebeck effect; Solar cells; Structural stability; Thermoelectricity
• ISSN: 0363-907X; 1099-114X
• DOI: 10.1002/er.6455

Summary Double perovskite halides are potential materials for the production of renewable energy that could meet the global demands for resolving energy shortage issues. In this study, we systematically investigate the Rb2XGaBr6 (XNa, K) double perovskites using the full‐potential linearized augmented plane wave (FP‐LAPW+lo) method of density functional theory. The thermodynamic as well as the structural stabilities of the studied materials have been confirmed from the calculated formation energy and Goldsmith tolerance factor (0.89 and 0.92). On the other hand, the calculated Pugh's ratio shows the ductile mechanical nature of the studied materials. The calculated electronic bandgaps of 2.2 eV/1.90 eV for Rb2Na/KGaBr6 lies is in the visible region, which indicated the potential application of these materials in solar cells. The electronic properties of the two compounds are studied using the electronic density of states and the complex dielectric functions are used to evaluate optical properties. Our calculated results clearly indicate the optimum absorption of light in visible regions which depicts the potential of these materials for opto‐electronic devices. The thermoelectric properties of the two Rb2XGaBr6 (XNa, K) double perovskites are also studied in terms of thermal and electrical conductivity and the Seebeck coefficient. Here we report, the thermodynamic and structural stabilities of Rb2NaGaBr6 and Rb2KGaBr6 determined by a tolerance factor, with negative formation energy and ductile behavior of Rb2Na/KGaBr6 by Pugh's (1.82/2.17) and Poisson ratio (0.27/0.30). The larger value of absorption‐coefficient for Rb2NaGaBr6 makes it a potential candidate for solar cell systems. A large value of thermal to electrical conductivity ratio (10−5), n‐type semiconducting nature, and large value of the figure of merit and exposed their potential for thermoelectric generators and refrigerators.