Computational analysis of hybrid double perovskite materials and their potential in photovoltaic and thermoelectric applications

Abstract

Hybrid double perovskites are promising for use in next-generation solar cells. The priority is to address their critical problems and gain insight into their operation. The density functional theory is employed to obtain the mechanical, electronic, and optical properties of organic–inorganic double perovskites based on aluminum and gallium. The results revealed that the double perovskite materials are stable, as confirmed by calculating the formation energy and the elastic constant. Moreover, when using the TB-mBJ functional, the electronic properties obtained indicate that the direct band gap values are 1.39 eV and 2.72 eV for (NH4)2AgGaBr6 and (NH4)2AgAlBr6, respectively. Additionally, because of the direct band nature of (NH4)2Ag(Al/Ga)Br6, they exhibit excellent optical properties, including a high order absorption coefficient of 105 cm−1 and low reflectivity, making them useful for multiple optoelectronic applications outside of photovoltaics. Calculations of SLME revealed that (NH4)2AgGaBr6 and (NH4)2AgAlBr6 achieve single-layer efficiency of 32.87% and 8.36% respectively, emphasizing their viability for future applications. The results of the thermoelectric analysis suggest that these compounds have a promising potential for use in transport applications, as they demonstrate a higher figure of merit (ZT) compared to other compounds. Specifically, (NH4)2AgAlBr6 has a ZT value of 0.734, while (NH4)2AgGaBr6 has a ZT value of 0.737.