A-site cation engineering of lead-free M2NiCl6 (M = Na, K, Cs) vacancy-ordered double perovskites: first-principles insights into stability, band-gap tuning, excitonic behavior, and optical response
The growing global energy demand and the environmental consequences of fossil-fuel consumption underscore the urgent need to develop sustainable, efficient, and environmentally benign energy materials. Lead-free vacancy-ordered double halide perovskites M2NiCl6 (M = Na, K, Cs) were systematically investigated using fir...