[100] Tuning the optoelectronic and thermoelectric characteristics of narrow bandgap Rb₂AlInX₆(X= Cl, Br, I) double perovskites: A DFT study

In this paper, the structural, optoelectronic, and thermoelectric characteristics of halide-based double perovskite Rb₂AlInX₆ (Cl, Br, I)compounds are examined by DFT. These compounds belong to the cubic family and their lattice parameter increased when halogens are replaced from Cl to I. The structural stability is confirmed by computing the enthalpy of formation, tolerance factor, and pugh’s ratio. The Pugh’s ratio demonstrates the ductile behavior of the compounds under consideration. A comprehensive study of the optoelectronic charac- teristics indicates that Rb₂AlInX₆ (Cl, Br, I) double perovskites are potential candidates for optoelectronic devices due to their narrow bandgap (1.05, 0.65, and 0.25 eV). The calculated power factor and thermal conductivity lead to the high figure of merit values (0.75–0.77), which show the potential of these compositions for ther- moelectric devices. These investigations provide an insightful understanding of these materials for their future utilization.