Ab initio study of the structural, electronic, and optical properties of fluoro-double perovskites A2SbAgF6 (A = Li, K, Rb) for photovoltaic and optoelectronic applications
M. Abdellaoui, Rodouan Touti, Abdelghafour El Mekkaouy, El Houcine Akarchaou, L. Talha, Abdellah Tahiri, M. Filali, Samir Chtita
Abstract
Perovskite materials are highly attractive for solar energy applications due to their semiconducting nature, wide light absorption range, and mechanical stability. This study presents the first comprehensive investigation of A 2 SbAgF 6 (A = Li, K, and Rb), combining structural, mechanical, electronic, and optical analyses using CASTEP with the GGA-PBE functional. Structural calculations confirm that these compounds are geometrically and thermodynamically stable. Electronic property analysis reveals that Li 2 SbAgF 6 , K 2 SbAgF 6 , and Rb 2 SbAgF 6 are indirect semiconductors (G–R) with band gaps of 1.562 eV, 2.057 eV, and 2.173 eV, respectively. Mechanical analysis indicates ductile behavior, high B/G ratios of 15.64, 9.09, and 5.95, and elastic anisotropy, while mechanically stable according to the Born criteria. Optical properties show strong absorption spanning the visible to ultraviolet regions, with maximum absorption peaks at 11.12 eV (14.35 × 10 4 cm⁻¹) for Li 2 SbAgF 6 , 13.72 eV (12.02 × 10 4 cm⁻¹) for K 2 SbAgF 6 , and 13.64 eV (10.5 × 10 4 cm⁻¹) for Rb 2 SbAgF 6 . These results indicate that A 2 SbAgF 6 (A = Li, K, and Rb) double fluoro-perovskites combine electronic tunability, optical responsiveness, and mechanical stability, making them promising candidates for photovoltaic and optoelectronic applications.