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The electronic, optical and thermoelectric analyses of BaGeO 3 perovskite have been done by using density functional theory (DFT) based Trans and Blaha modified Becke and Johnson (TB-mBJ) approach. The applied pressure (up to 30 GPa) has been found tailoring the band gap from indirect to direct bandgap (at 20 GPa), within the visible region, revealing renewable energy applications of the studied perovskite. The applied pressure improves mechanical stability by increasing ductility. Furthermore, optical properties are illustrated by computing dielectric constants, refraction, absorption, optical conductivity and optical loss factor for suggesting optoelectronic applications. The maximum peaks shifting to higher energy, due to increasing pressure indicate a blue shift. Finally, the calculated thermal and electrical conductivities, See-beck coefficient, power factor, Hall coefficient, specific heat capacity, susceptibility and electron densities are also elaborated for thermoelectric applications by using BoltzTraP code. [ABSTRACT FROM AUTHOR]

The density functional theory based full-potential linear-augmented-plane-wave plus local-orbital method has been used to study the physical properties of PbSnO 3 in hypothetical cubic perovskite. An external pressure up to 40 GPa has been applied on PbSnO 3 to realize the variation in its electronic band structure and the subsequent optical properties. The stability of the PbSnO 3 has been investigated by the mechanical properties, the enthalpy of formation and Goldschmidt tolerance factor. Moreover, the Born criteria have been adopted to justify the mechanical stability of the PbSnO 3 perovskite. We show that the electronic bandgap of PbSnO 3 can be tailored from indirect to direct band gap at high symmetry (X-X) direction at an external pressure of magnitude ~ 26 GPa. The effect of pressure on the optical properties has been studied in terms of dielectric function, absorption, refraction, reflection, and optical loss factor. The application of hydrostatic pressure has shifted the maximum absorption toward the visible range, revealing that PbSnO 3 can be used for high- pressure optoelectronic applications. [ABSTRACT FROM AUTHOR]

We present the mechanical, electronic, optical and thermoelectric behaviors for BiBO 3 and BiAlO 3 perovskite crystals, which are investigated by employing density functional theory (DFT). The structural and elastic characteristics are computed by using GGA-PBEsol exchange-correlation functional, while the electronic, optical and thermoelectric properties are derived through modified Becke-Johnson (mBJ) potential. The thermal stability is calculated by using the enthalpy expression and further verified by the elastic properties. Besides the physical properties at the ground state, we also explore the effects of pressure (0–40 GPa) onBiBO 3 and BiAlO 3 , in strides of 10 GPa, on the electronic structure. Both BiBO 3 and BiAlO 3 illustrate indirect band gap (Γ-M) at 0 GPa, however, increase in pressure results in transforming to a direct (Γ-Γ) band gap at 20 GPa and 40 GPa, respectively. Under the application of pressures, complex dielectric constant and some other optical parameters are also inspected. All the computed optical properties have revealed a higher energy shift, as the applied pressure increases proposing potential optoelectronic device applications of BiBO 3 and BiAlO 3 . Finally the thermoelectric characters are elucidated by calculating the electrical conductivity, thermal conductivity and the Seebeck coefficient of BiBO 3 and BiAlO 3 compounds, which are discussed as a function of temperature. These compounds are prospective applicants for the optoelectronics and thermoelectric devices, due to their appropriate direct bandgap nature realized by applying pressure and the optimum exhibited thermoelectric behaviors, respectively. [ABSTRACT FROM AUTHOR]

Double perovskite halides (DPHs) hold great promise for applications in energy conversion. This article provides a comprehensive exploration of the elastic, thermoelectric and optoelectronic characteristics of Cs 2 YCuX 6 (X = Cl, Br, I) DPHs. The examined DPHs indicate low thermal conductivity scales and high Seebeck coefficient significantly increased the figure of merit (ZT). The examined ZT∼1 at room temperature against temperature and chemical potential makes them appropriate for thermoelectric devices. [Display omitted] Double perovskite halides (DPHs) hold great promise for applications in energy conversion. This article provides a comprehensive exploration of the elastic, thermoelectric and optoelectronic characteristics of Cs 2 YCuX 6 (X = Cl, Br, I) DPHs. The elastic constants and phonon dispersion curves reveal ductile nature and mechanical and thermodynamic stability of the examined materials. The Born stability criteria ensures structural stability, while the formation energy ranging from −2.28 to −1.68 eV signifies thermodynamic viability. Furthermore, the thermodynamic stability of investigated double perovskites Cu 2 YCuX 6 (X = Cl, Br, I) have been verified by performing ab-initio finite temperature molecular dynamics (MD) simulation. The examination of mechanical characteristics affirms the ductile nature of the material, and its substantial anisotropic factor enhance its significance for device fabrication. The band gaps calculated at 2.65 eV, 2.55 eV, and 2.45 eV from band structures, highlight the significance of the studied double perovskites (DPs) for optoelectronic applications. Optical parameters yield information on minimal dispersion and expansive absorption band. Additionally, transport characteristics are analyzed through parameters such as Seebeck coefficient, thermal conductivity, electrical conductivity, and the Figure of merit (ZT). [ABSTRACT FROM AUTHOR]

[Display omitted] • Halide based double perovskites Na 2 AgTlZ 6 (Z = Cl, Br, I) have been explored for their optoelectronic and thermoelectric properties. • Lattice parameter, bulk modulus, and mechanical properties varied with substitution at halide side. • Study of optical, electronic and thermoelectric properties highlighted the importance of these materials for optoelectronic and thermoelectric applications. The bandgap engineering and deliberate band edge manipulation of perovskites make them potential candidates for the photovoltaic industry. Here we theoretically investigate the structure, density of states, and photovoltaic and thermoelectric characteristics of Na 2 AgTlZ 6 (Z = Cl, Br, I) using WIEN2k code. The incorporation of Br and I at the Cl site caused the increase in lattice constant which leads to the decrease in bulk modulus and Debye temperature. The computed values of Poisson (<0.26) and Pugh (<1.75) ratio verified their brittle nature. The bandgap analysis reveals direct bandgap nature and bandgap value lie in the visible region for parent composition and infrared and far infrared when Cl is replaced with Br and I. The density of state plots uncovers the shifting of energy states in valence and conduction bands towards the Fermi level with the increasing number of electrons in the halogens. The increase in the value of dielectric constant, refractive index, and shifting of peaks towards lower energy value is witnessed with atomic number of halogen atoms. The viability of these compositions for thermoelectric devices is further confirmed when electrical conductivity and Seebeck coefficient dependent Figure of merit and power factor are evaluated in the temperature range of 200–800 K. In addition, the anisotropic nature of studied compositions is explored through the computation of the modulus of elasticity including Young's modulus, Shear modulus in addition to compressibility, and Poisson's ratio. [ABSTRACT FROM AUTHOR]

• Double perovskites halides K 2 AgBiX 6 (X = Cl, Br) are executed in terms of density functional theory. • Structural and thermodynamic investigation depict structural stability of K 2 AgBiX 6 in cubic phase. • The electronic band structures and optical analysis show both halides are strong candidate for the fabrication of solar cell devices. • Calculated thermoelectric parameters indicate that the both halides can be used even at elevated temperatures. Lead-free double-perovskites (DPs) K 2 AgBiX 6 (X = Cl, Br) has been executed as well as examined by ab-initio computations for solar cell energy sources. Improved and latest Becke and Johnson potential (TB-mBJ) has been suggested to calculate optoelectronics characteristics. The lattice constants reported theoretical and computed values using Perdew-Burke-Ernzerhof's generalized-gradient-approximation (PBEsol-GGA) had been determined in good agreement. The calculated bandgap 2.3 eV (K 2 AgBiCl 6) and 1.5 eV (K 2 AgBiBr 6) disclosed their indirect nature, which showed that these are suitable potential candidates for visible light solar-cell (SC). Optical ranges explain the dielectric-constant, light absorption and reflection, and refractive index. The maximum absorption band has been noted within the wavelength of 620–310 nm. In addition, the BoltzTraP (BT) Code has been determined thermoelectric characteristics that result in higher value Seebeck coefficient and lower thermal conductivity. Hence, executed theoretical calculation proposed that examined material has potential application in renewable energy fields. [ABSTRACT FROM AUTHOR]

The toxicity and instability of lead-based perovskites have been replaced with newly investigated stable lead-free inorganic perovskites. The current study included the comprehensive analysis of electronic behavior, elastic, optical, and transport characteristics of lead-free inorganic double perovskites (DPs) Rb 2 KTlX 6 (X = Cl, Br) halides for possible uses. These physical characteristics were revealed using density functional theory (DFT) based Wien2k code. Using the energy optimization process, we have computed structural parameters comparable to existing data using generalized gradient approximation (PBEsol-GGA). In addition, the elastic parameters, formation energy (−1.94 eV and −1.39 eV), and tolerance factor (0.98 and 0.97) endorsed the cubic stability of both halides. Further, we employed modified Becke-Johnson (mBJ) potential to an accurate value of direct bandgaps of both halides reveal that changing the anions from Cl to Br leads to significant adjustment in the band gap, transitioning from the visible to the IR spectrum, with energy levels ranging from 2.08 to 1.2 eV. Our calculated results of optical parameters indicate that both halides with remarkable optoelectronic working due to low reflectivity, high optical absorption, and conductivity. The study reveals that electronic transport factors are associated with temperature due to small bandgap of the materials. The observed figure of merit near unity indicates the semiconducting behavior of these materials that can be useful in thermoelectric tools. • First-principle calculations of DPs Rb 2 KTlX 6 (X = Cl, Br). • Direct bandgap semiconductor. • Optical characteristics for optoelectronic devices. • Transport characteristics are discussed in details for thermoelectric devices. [ABSTRACT FROM AUTHOR]

Using the full-potential linearized augmented plane wave plus local orbitals method within the frame work of density functional theory, the Sc-based double halide perovskites K 2 ScAgZ 6 (Z = Cl, Br, I) are investigated for determining their physical properties. To investigate the structural and thermodynamic stability of these Sc-based double halide perovskites we calculate tolerance factor, formation energy, and phonon dispersion curve using GGA-PBEsol approximation. The calculated values of lattice parameters using GGA-PBEsol are found to be consistent with the available data. Subsequently, the Tran-Blaha modified Becke-Johnson (mBJ-LDA) potential is used for electronic properties. Implementation of TB-mBJ potential is clearly shows that K 2 ScAgZ 6 have indirect bandgap, which is consistent with the literature. To evaluate these double perovskites and reveal their potential use in optical devices, several optical parameters are computed for an incident photon energy range of 0–8 eV. The BoltzTraP code is also employed to investigate temperature dependent electrical characteristic of these compounds in the temperature range of 200–600 K. Investigated halide double-perovskites have been shown to display excellent physical properties for solar cells and renewable energy device applications. • In the cubic phase double perovskites are structurally and thermodynamically stable. • The calculated indirect bandgaps for K 2 ScAgCl 6 , K 2 ScAgBr 6 , and K 2 ScAgI 6 are 2.0, 1.85, and 1.65 eV. • These are suitable materials for solar cell devices due to their greatest least reflection, absorption, and optical loss in the visible area. [ABSTRACT FROM AUTHOR]

Lead free double perovkistes is an emerging class of optoelectronic material which have a huge potential for futuristic electronic industry. In present communication, we theoretically studied the structural, optoelectronic, and thermoelectric properties of Li 2 AgTlCl 6 and Li 2 AgTlBr 6 using WIEN2k software. The permissible values of tolerance factor and enthalpy of formation ensure the structural and thermodynamic stability of these compositions. The substitution of halides increase the lattice constant from 10.52 to 11.11 Å and reduce the bulk modulus from 33.38 to 26.20 GPa. The calculation of Poisons and Pugh ratios ensures their ductile nature, whereas the examination of band structure indicates exposed the bansgap value of 2.0 and 1.2 eV for Li 2 AgTlCl 6 and Li 2 AgTlBr 6 , respectively. A remarkable increase in optical parameters like static dielectric constant, refractive index, and shifting of peaks towards lower energy values is observed the replacement of Cl with Br. This substitution increased the electrical conductivity, specific heat at constant volume, Seebeck coefficient, and figure of merit that showed the feasibility of these compositions for photovoltaic and thermoelectric applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Halide based double perovskites K 2 ScAuX 6 (X = Br, I) have been theoretically investigated using WEIN2k software. • Structural parameters were optimized using Perdew–Burke–Ernzerhof generized gradient approximation (PBEsol-GGA) • Investgation of mechanical response of these materials revealed their ductile nature. • Indirect band gap nature with bang gap values of 2.20 eV and 1.90 eV were estimated using mBJ potential. • Electronic transport properties in a wide range of temperature has been evaluated. Here we report a theoretical analysis of various technologically important physical properties of double perovskites K 2 ScAuX 6 (X = Cl, Br) including thansport, optoelecronic, and strucutral. The computation of tolerance factor and estimation of entahly of formation remained key indicators to ensure the srucutal and thermodynamic stability of these compositions. The substitution of Br at Cl site increased the lattice parameter and reduced the bulk modulus. The computation of elastic constants-based modulus of elasticity revealed their ductile nature. The analysis of electronic band structure unveiled their indirect bandgap nature. Polarizability of material is accessed by computing the dielectric constant, scattering by extinction coefficient, absorption by refractive index, in addition to electrical and thermal conductivity and the Seebeck coefficient, highlighted their suitability for advanced technologically important applications in optoelectronic and thermoelectric industry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Halide based double perovskites K 2 YAgX 6 (X = Br, I) have been theoretically investigated using WEIN2k software. • Structural parameters were optimized using the Perdew–Burke–Ernzerhof generized gradient approximation (PBEsol-GGA) • Investgation of the mechanical response of these materials revealed their ductile nature. • An indirect band gap nature with bang gap values of 3.4 and 2.6 eV were estimated using mBJ potential. • Electronic transport properties over a wide range of temperatures have been evaluated. The halide based double perovskites K 2 YAgBr 6 and K 2 YAgI 6 have been extensively investigated for their optoelectronic properties using the full-potential linearized augmented plane wave method. Their thermodynamic and structural stabilities were mapped by computing the enthalpy of formation and tolerance factor respectively, which revealed that K 2 YAgBr 6 is more stable. The computed values of the structural parameters in the ground state showed that the unit cell expands upon replacement of Br with I, which is explained based on their relative ionic radii. The Poisson and Pugh ratio were calculated, based on the elastic constants, which argued the ductile nature of these double perovskites. The presence of band edges at two different symmetry points proclaimed their indirect bandgap nature and the bandgap value decreases upon replacement of Br with I. The computation of optical parameters manifested an increasing trend in the dielectric constant, refractive index and reflectivity when Br is substituted with I. Semi-classical Boltzmann theory-based BoltzTraP code is employed to estimate different thermoelectric parameters, including the power factor and figure of merit, which exhibited the potential of these materials for optoelectronic and thermoelectric devices. [ABSTRACT FROM AUTHOR]

Double perovskite halides are a potential candidate for the applications of the solar cell, photovoltaic and thermoelectric, due to their non-toxicity and environmental stability. The density functional theory (DFT) calculation investigates the details physical properties of halides Rb 2 ScAgX 6 (X = Cl, Br, I) that can be useful for applications like thermoelectric and solar cells. The structural and thermodynamics stability is endorsed by the formation energy, tolerance factor, and Born stability criteria. The calculated indirect band gaps of 1.95 eV, 1.85, and 1.60 eV for Rb 2 ScAgCl 6 , Rb 2 ScAgBr 6 , and Rb 2 ScAgI 6 respectively, ensure the light absorption in the region of visible range. Therefore, all studied halides are widely used in optoelectronic devices like solar cells. In addition, thermoelectric properties are examined through thermal conductivity, electrical conductivity, and the Seebeck coefficient. ZT values of 0.74, 0.71, and 0.72 for Rb 2 ScAgI 6 , Rb 2 ScAgBr 6 , and Rb 2 ScAgCl 6 double perovskites are recorded, which spotlight their significance for the applications of thermoelectric. [ABSTRACT FROM AUTHOR]