Browsing by Author "ZIKEM Afifa"

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    Contribution to the study of the physical properties of some double perovskite crystals via first principles methods
    (University of M'Sila, 2024-10-10) ZIKEM Afifa
    Currently, there is significant interest in finding efficient materials with favorable optoelectronic and thermoelectric properties for power generation. This study employs first-principles computations to investigate the structural, thermodynamic, optoelectronic, and thermoelectric characteristics of potassium tin halide vacancy-ordered double perovskites K2SnX6 (X = Cl, Br, I). Using the density functional theory (DFT) method and Boltzmann transport theory, we conduct a thorough analysis. We utilize the Perdew-Burke-Ernzerhof functional for bulk solids and their surface for generalized gradient approximation (PBESol- GGA) with and without the mBJ correction, employing a LAPW base-set. Our electronic analysis indicates that the electronic band structures depicts direct band gaps for K2SnCl6 and K2SnBr6, while K2SnI6 exhibits an indirect band gap., with band gaps ranging from 1.70 eV to 4.126 eV (utilizing PBESol-mBJGGA), suggesting their potential for solar cells and optoelectronic applications. Analysis of dielectric functions, absorption coefficients, and refractive indices calculations of the investigated compounds show excellent agreement with theoretical band gaps, validating their precise prediction. K2SnI6 demonstrates superior light absorption in the visible range compared to K2SnCl6, owing to its narrower band gap, rendering it suitable for solar cells. Refractive index analysis further confirms their applicability for solar applications. Thermoelectric properties, including electronic and lattice thermal conductivities, Seebeck coefficients, and power factors, are evaluated. The studied compounds exhibit p-type conductivity, and their power factor values indicate promise as efficient thermoelectric materials. At 500 K, maximum ZT values of 0.58, 0.69, and 0.65 are achieved for K2SnCl6, K2SnBr6, and K2SnI6, respectively. These results underscore the promise of these materials for use in solar cells and thermoelectric devices, particularly noting their efficacy even under high-temperature conditions.