Search

This article introduces and examines a new type of lead-free double perovskites, K2InSbX6 (X = Cl, Br) for their potential use in optoelectronic and thermoelectric devices. The investigation is conducted through theoretical exploration. The physical features of the materials were investigated using density functional theory. Both compounds are found stable in their cubic structure. Elastic constants and negative formation energies computed for K2InSbX6 demonstrate its mechanical and thermodynamic stability. According to the computed Poisson, Pugh's ratio, and anisotropy, both materials are brittle and show anisotropic behavior. Furthermore, the calculated findings show that K2InSbCl6 and K2InSbBr6 have direct bandgap values of 1.31 and 1.22 eV, respectively. Optical analysis reveals a notable ability to absorb visible and near-UV radiation. Perovskite K2InSbX6's excellent light absorption capabilities and narrow band gap make it a great choice for utilization in solar cell applications and other optoelectronic devices. Furthermore, the findings of transport characteristics indicate that the materials possess exceptional electrical and thermal conductivity and are projected to exhibit optimal thermoelectric capabilities at a temperature of 300 K. [ABSTRACT FROM AUTHOR]

In this work, first-principles DFT calculations were performed to investigate the geometric, electronic, and magnetic properties of double perovskite Ba 2 NaIO 6 (BNIO) in the bulk, and thin film form. The results showed that bulk BNIO in cubic phase (Fm-3m, #225) has a lattice constant of 8.43 Å, and is a non-magnetic direct band gap (E g) semiconductor with E g of 2.22 eV. Three types of cleaved surfaces namely (001), (011), and (111) oriented surfaces were considered here. The stability of the surfaces was examined with surface energy (E s). The E s is found to be 0.06, 0.09, 0.14 eV/Å2 respectively, for (001), (011), and (111) surface, indicating (001) as the energetically most favorable surface. All three surfaces exhibited metallic character, dominated by the splitting of O-p states of the top layer O-atoms. The (001) and (111) surfaces exhibited a magnetic character with magnetic moments of 0.1 and 2.23 μ B per formula unit, whereas the (011) surface remained non-magnetic. • DFT calculations were used to study the electronic properties of Ba 2 NaIO 6 in bulk and thin film.. • The (001) surface was found more stable than (011), and (111) surface. • All the selected surfaces exhibited metallic characteristics. • The (001) and (111) surfaces exhibited a magnetic character, whereas (011) remained non-magnetic. [ABSTRACT FROM AUTHOR]

The lift side represents the absorption coefficient with a large absorption band in the visible region, and the lif side shows the polyhedral crystal structure of studied double perovskites. [Display omitted] • Stable, cheap, and significant for solar cells. • The absorption bands lie in the visible region. • Ultralow lattice thermal conductivity. • Minimal reflection and optical loss. The double perovskites are emerging candidates for renewable energy applications. This work uses the extensive density functional theory (DFT) method to investigate the structural, optoelectronic, transport, and mechanical properties of Rb 2 AgTlX 6 (X = Cl, Br). The thermal and structural stabilities of Rb 2 AgTlX 6 (X = Cl, Br) are investigated through formation energy and tolerance factor evaluation. The Rb 2 AgTlCl 6 and Rb 2 AgTlBr 6 have direct band gaps of 1.61 eV and 1.08 eV. The reported band gap reduction is associated with the p-d hybridization of cations and anions. Investigating optical characteristics yields important insights via the dielectric constant ε(ω), refractive index n(ω), absorption α(ω), and reflectivity R(ω). The ability to absorb light in visible and ultraviolet spectra as demonstrated by optical characteristics highlights the potential of Rb 2 AgTlX 6 for solar cell technology. In addition, the significant electrical conductivity and Seebeck coefficient led to a notable reduction in heat conductivity and figure of merit values of 0.68 and 0.67 at higher temperatures. Elastic parameters, Pugh's, and Passion's ratios are studied to confirm materials' mechanical stability and nature. The studied materials have been found mechanically stable and brittle. Together, our findings demonstrate the distinctive and intriguing features of Rb 2 AgTlX 6 (X = Cl, Br) are suitable for cost-effective energy conversion applications. [ABSTRACT FROM AUTHOR]

• Na 2 CuAsX 6 (X = F, Cl, Br, and I) double perovskites (DPs) are stable in the cubic phase. • They have indirect band gaps of 1.28, 1.14, 0.85, and 0.52 eV, respectively. • These materials are appropriate for solar cell applications exhibiting a significant absorption in the visible region. • Na 2 CuAsX 6 (X = F, Cl, Br, and I) exhibit p-type semiconductor characteristics. • These perovskites possess exceptional physical features to serve as sustainable green energy alternatives. The current research is intended to investigate the physical properties of the Na 2 CuAsX 6 (X = F, Cl, Br, and I) double perovskites using the density functional theory (DFT) framework implemented in the WIEN2k code. Herein, the structural configuration, electronic, optical, thermoelectric, and thermodynamic features are thoroughly discussed. The structural investigation utilized the Murnaghan equation of state (EOS) and the generalized gradient approximation (GGA). The thermal and phase stability has been verified by the formation enthalpy and tolerance factor. The perovskites Na 2 CuAsF 6 , Na 2 CuAsCl 6 , Na 2 CuAsBr 6 , and Na 2 CuAsI 6 exhibit semiconductor properties characterized by indirect band gaps of 1.28, 1.14, 0.85, and 0.52 eV, respectively. An extensive examination of the optical characteristics suggests the possible appropriateness of these materials for photovoltaic applications. Double perovskites exhibit a significant absorption in the visible spectrum. Thermodynamic properties have demonstrated the thermal stability of analyzed perovskites even at high temperatures. Additionally, the thermoelectric properties have been determined at specific temperatures and chemical potentials, indicating the p-type nature of studied perovskites. The figure of merit (ZT) values at 300 K are determined to be 0.79, 0.76, 0.77, and 0.80, suggesting Na 2 CuAsX 6 may be sustainable thermoelectric materials with excellent performance. Consequently, the examined materials can serve as sustainable candidates for solar energy and wasted heat recovery applications. [ABSTRACT FROM AUTHOR]

This article comprehensively explores the structure, stability, mechanical, optoelectronic, and thermoelectric aspects of the emerging double perovskites A2YCuZ6 (A = Rb, Cs and Z = Cl, Br). The structural and mechanical characteristics are estimated using the PBE-GGA functional, whereas the optoelectronic and thermoelectric characteristics are computed using the modified Becke and Johnson potential. Tolerance factor, formation energies, and Gibbs free energies have validated the cubic phase and thermodynamic stability. The anticipated elastic values indicated that all the materials exhibited mechanical stability, ductility, and anisotropic behavior. The computed electronic features verified that Rb2YCuCl6, Rb2YCuBr6, Cs2YCuCl6, and Cs2YCuBr6 have indirect band gaps of 1.95, 1.30, 1.55, and 1.2 eV, respectively. This work also explores the optical response in the energy range 0 to 6 eV in terms of polarization, refractive index, absorption, and optical conduction. The visible and ultraviolet ranges of light are both significantly absorbed, making these materials optimal for use in solar systems. The BoltzTraP code has been used to calculate the transport parameters, demonstrating the p-type semiconductors nature of these materials. Further, the significant merit values of 0.77, 0.83, 0.82, and 0.81 at room temperature for analyzed materials suggest their potential applicability in thermoelectric devices. Hence, the investigated double perovskites, which are not empirically validated, have been recommended as extremely suitable alternatives for creating various energy conversion applications. [ABSTRACT FROM AUTHOR]