Exploring the structural, electronic and optical properties of Rb2InGaCl6 and Rb2InGaF6 double perovskite compounds for high-energy applications: a DFT-based investigation.

Double perovskites have harvested considerable attention in the realm of solar cells and renewable energy applications. Therefore, in this current study, we explored the structural, electronic, and optical properties of Rb2InGaCl6 and Rb2InGaF6 using DFT-based simulations with WIEN2K codes. It is unequivocally established that both compounds demonstrate structural and mechanical stability. Structural stability is further evaluated using Goldsmith's tolerance factor (τG). The τG values of 4.29 and 3.77 are considered acceptable for ensuring the stability of cubic structures for Rb2InGaCl6 and Rb2InGaF6 respectively. It is determined that both compounds are stable elastically and possess ductile characteristics, allowing them to undergo plastic deformation without fracturing. Our investigation reveals indirect band gaps of 1.7 eV (semiconductor) for Rb2InGaCl6 and 4.8 eV (insulator) for Rb2InGaF6. These diverse band structures open up exciting possibilities for optoelectronic applications. Regarding optical properties, the spectral curves of various parameters are examined in the range of 0 eV to 15 eV incident photon energy. The findings reveal the exceptional optical performance of Rb2InGaCl6 and Rb2InGaF6, particularly by their notably high absorption coefficients α(ω). Specifically, Rb2InGaCl6 demonstrates a remarkable absorption of 6.635 at 2.05 eV, while Rb2InGaF6 exhibits a significant absorption of 3.91 at 4.78 eV. The optical conductivity σ(ω) attains peak values, reaching 4.60 for Rb2InGaCl6 and 2.85 for Rb2InGaF6. Furthermore, the optical reflectivity R(ω) peaks at 13.60 eV for Rb2InGaCl6 and 6.30 eV for Rb2InGaF6. Lastly, the energy loss functions L(ω) attain their highest values of 0.57 and 7.58 for Rb2InGaCl6 and Rb2InGaF6, respectively. These results collectively emphasize the impressive optical characteristics of these compounds across a range of energy levels. These findings suggest promising potential energy applications for these materials, particularly in influencing electromagnetic radiation within the ultraviolet (UV) spectrum ranges. [ABSTRACT FROM AUTHOR]