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[Display omitted] • We examined lead-free perovskites pure and doped Cs 2 Sn 0.75 Te 0.25 I 6 using density functional theory. • The band structure analysis reveals its semiconducting behavior, with the band gap expanding proportionally to the increased Te concentration. • Optical characteristics were also analyzed. • To expose their potential use of pure and doped Cs 2 Sn 0.75 Te 0.25 I 6 in thermoelectric devices. The global need of energy is raising day by day. To meet this demand double perovskites (DPs) can play a vital role for energy conversion devices. In this letter, we formulated and examined lead-free defect perovskites using a combination of tellurium and tin, denoted as Cs 2 Sn 1-x Te x I 6 (0, 0.25), utilizing density functional theory which include structural, optical and thermal behavior. Both the optimized volume and lattice parameter exhibit a linear increase with the Te content in Cs 2 Sn 1-x Te x I 6 (CsSnTeI). The negative value of formation energy for both pure and doped materials along with their Poisson and Pugh ratio confirm the stability of these materials. The band structure analysis reveals its semiconducting behavior, with the band gap expanding proportionally to the increased Te concentration with band gap value of pure (1.20 eV) and doped 91.43 eV) double perovskites. Optical characteristics, including the dielectric function and absorption coefficient, were also analyzed. To expose their potential use of Cs 2 Sn 1-x Te x I 6 (0, 0.25) in thermoelectric devices, temperature dependent thermoelectric features are investigated reveal that suitability of these materials for energy conversion purposes. [ABSTRACT FROM AUTHOR]

Full potential LAPW + lo method is used for exploring electronic, structural and thermoelectric properties for MgNd 2 X 4 (X = S, Se) spinels that are found to show ferromagnetic-semiconductor behaviour in the spinel structure. The investigated negative value of formation energy and positive value of phonon spectra computed using PBEsol GGA indicates the energetic and dynamical stability of the studied cubic ferromagnetic-semiconductors. We have used TB-mBJ potential functional for electronic and magnetic properties, which lead to a reliable account of electronic structure, demonstrating band occupancy in the spinels along with a clear explanation of density of states. The stability of ferromagnetic state in the studied materials is because of the exchange splitting of Nd cations based on p-d hybridization which is in accordance with the results obtained for electronic band structure and density of states. The exchange splitting of bands can be justified by the spin magnetic moment between anions and cations, and sharing of charge. The computed values of dielectric constant and their associated optical parameters are used to explain the optical active behaviour of the spinels under investigation; indicating that the two spinels studied in the present work are suitable for solar cells device applications. The calculation of thermoelectric properties is very useful for determining a material's potential use in waste energy recovery systems and many other innovative applications. [ABSTRACT FROM AUTHOR]

• Theoretically examined the physical features of DPs Li 2 CuBiZ 6 (Z = Cl, Br, I). • Elastic properties are investigated for structural stability. • Electronic and optical properties for solar applications. • The dispersion of light is explained by ε 1 (ω). • Due to its higher Seebeck coefficient, Li 2 CuBiCl 6 possessed a larger power factor than Li 2 CuBiBr 6 and Li 2 CuBiI 6. Due to their potential applications for optoelectronic and thermoelectric devices, Li-based double perovskites (DPs) have been widely investigated. In current article, we theoretically examined the mechanical, optoelectronic and thermoelectric features of DPs Li 2 CuBiZ 6 (Z = Cl, Br, I). We employ the generalized gradient approximation (PBEsol) for examining the structural and elastic characteristics of these compounds, while the modified Becke-Johnson (mBJ) functional is used for obtaining an improved accord of the thermoelectric and electronic characteristics with experimental observations. For the stability of all DPs, the Born Criteria and formation energy are investigated. The cubic symmetry's elastic constants are examined to determine the difference between ductile and brittle nature, anisotropy, and Debye temperatures. The bandgaps are 2.0 eV, 1.7 eV, and 1.3 eV, for Li 2 CuBiCl 6 , Li 2 CuBiBr 6, and Li 2 CuBiI 6 , respectively, as determined by the mBJ potential. All DPs were also examined regarding optical absorption, refractive index, and dielectric constants for the energy range 0–10 eV, ensuring the absorption among visible regions. Furthermore, all DPs are appropriate candidates for thermoelectric applications due to the lower lattice thermal, higher Seebeck coefficient, thermal conductivity, and Figure of merit (ZT), which are all elucidated by Boltzmann classical theory. [ABSTRACT FROM AUTHOR]

For leading spintronic technology, the significance of rare earth in the spinels chalcogenide MgCe 2 Z 4 (Z = S, Se) has been investigated. Wein2K and BoltzTraP program packages are used to calculate the magnetic and transport characteristics of the spinels. While comparing the energies within the ferromagnetic and nonmagnetic states, the ferromagnetic state stability in the ground state is examined. The formation energy, phonon dispersion curve, and mechanical stability conditions help clarify the issue of stability in the cubic ferromagnetic phase. Poisson's and Pugh's ratios are employed to ensure the brittle characteristics. To explore the electronic properties, modified Becke and Johnson (mBJ) potential are utilized to investigate both spinels' direct narrow bandgap (spin up channel) nature. Chalcogenide's 2p produces the total magnetic moments- and rare-earth metals' f-states, which result in significant hybridization around the Fermi level. The computed total magnetic moment integer values and polarization are used to demonstrate spin polarisation. Finally, the Seebeck coefficient, thermal-to-electrical conductivity ratio, and power factor are used to evaluate thermoelectric properties. [ABSTRACT FROM AUTHOR]

The mechanical, electronic, optical and thermoelectric properties of cubic perovskite BiScO 3 are studied by using density functional theory. The lattice parameter of BiScO 3 calculated at zero pressure indicates good agreement with similar compounds crystallizing in the cubic perovskite structure. The exchange-correlation functional based on Perdew-Burke-Ernzerhof GGA has been used for calculating structural and mechanical properties, while the functional proposed by Tran and Blaha in the form of modified Becke-Johnson (mBJ) exchange potential has been employed to calculate the electronic, optical and thermoelectric properties. The elastic constants and bulk modulus are calculated and their pressure dependence upto 50 GPa has been investigated. Cubic BiScO 3 is found to be an indirect bandgap semiconductor at ambient pressure, while a direct bandgap appears under the influence of pressure. In addition to the electronic properties, the dielectric function, refractive index, reflectivity, extinction coefficient and absorption spectrum are also presented. Moreover, important thermoelectric properties of the compounds are explained in terms of electrical conductivity, thermal conductivity, Seebeck coefficient and figure of merit. [ABSTRACT FROM AUTHOR]

To probe the applications in spintronics and sustainable energy devices of ZnMn 2 X 4 (X=S, Se, Te) spinels, their structural, elastic, electronic and thermoelectric properties have been studied in the present work. Structural properties reveal stability of ferromagnetic (FM) phase in these spinels which is further confirmed by computing the heat of formation for these compounds. The mechanical properties of the ZnMn 2 X 4 spinels have been investigated by computing their elastic constants, which show that all these spinels exhibit a brittle character. Moreover, electronic band structure and density of states reveal a half-metallic FM structure in all these spinels. Analysis of the band structure of these materials reveals a semiconducting nature in the spin down channel. Exchange constants (N 0 α and N 0 β) have been computed to directly probe the state splitting and our results large splitting of Mn 3d-states by N 0 β owing to its larger negative value as compared to N 0 α. The strong p-d hybridization is found to make exchange field dominant to crystal field which consequently induces ferromagnetism. In addition, the p-d hybridization reduces the magnetic moment of Mn ions by inducing traces of magnetic moments at non-magnetic sites. The observation of thermoelectric behavior within temperature range 200K–800K reveals positive Seeback coefficient indicating holes as majority charge carriers. Although the power factor is found to increase on going from ZnMn 2 S 4 to ZnMn 2 Te 4 , our results clearly show improvement of power factor with increasing temperature. Image 1 • Density functional theory calculations are performed for ZnMn 2 X 4 (X = S, Se, Te). • Structural analysis depict FM stability of ZnMn 2 X 4 (X = S, Se, Te). • The band structures analysis show their half-metallic nature of ZnMn 2 X 4 (X = S, Se, Te). • The computed magnetic parameters indicate potential spintronic devices applications. • The temperature effect on thermoelectric properties indicate that the material can be used even at elevated temperatures. [ABSTRACT FROM AUTHOR]

• Density functional theory calculations under varying pressure are performed for ZnZrO 3. • Structural and elastic properties depict stability of ZnZrO 3. • A shift from indirect to direct band gap is observed due to employed pressure. • The computed optical parameters indicate potential opto-electronic devices applications. • The temperature effect on thermoelectric properties indicate that the material can be used even at elevated temperatures. The zinc zirconate ZnZrO 3 perovskite have been studied with respect to their physical properties by inducing pressure upto20 GPa. The predicted value of lattice constant for ZnZrO 3 determined using PBEsol-GGA is reasonable agreement with experimental value. Our calculations showed that Born mechanical stability criteria, confirmed the mechanical stability in cubic phase. Further, through Poisson and Pugh's ratios critical limits, the findings of the ductile strength have been computed. To explore the pressure induced band structure modification, a varying external pressure from 0 GPa to 20 GPa has been applied with a step size of 5 GPa. The change in band structure significantly affected the optical properties of the material under study. It was observed that the band gap of ZnZrO 3 shifted from indirect to direct at applied pressure of 15 GPa. The effect of this shifting on the dielectric constant, optical loss factor, reflection, refraction and absorption has been carried out in this work. To probe the potential of this composition for thermoelectric applications, its electrical conductivity, thermal conductivity, See-beck coefficient and power factor were also calculated. [ABSTRACT FROM AUTHOR]

The simultaneous existence of magnetic order and semiconducting nature in ferromagnetic semiconductors fascinate the spintronics technology to enhance the quantum computing and spin transistors. Therefore, electrons spin dependent ferromagnetism and thermoelectric properties of MgCr 2 X 4 (X ​= ​S, Se) spinels are scrutinized by density functional theory (DFT) based Wien2k code. The negative formation energy ensures thermodynamic stability. The band structures (BS) and density of states (DOS) ensure the ferromagnetic semiconductors nature of the studied spinel's. The insulating behavior in down spin and magnetic moment (Integer value) is the response of 100% spin polarization. The fulfillment of the condition Δ (d) > (Δ C F) and negative Δ (p d) have showed the dominant role of electrons spin to induce ferromagnetism. Moreover, influence of electrons spin on thermodynamic and thermoelectric characteristics are explored by specific heat capacity (C v), electrical conductivity (σ/τ), thermal conductivity ((κ/τ)), Seebeck coefficient (S) and power factor (σS2) by classical Boltzmann transport theory. The Ferromagnetic Semiconducting behavior of MgCr 2 X 4 (X ​= ​S, Se) in which up spin channel is semiconducting and down spin channel is insulating. Image 1 • The MgCr 2 X 4 (X ​= ​S, Se) spinels are ferromagnetic semiconductors with 100% spin polarization. • The exchange energies are exactly according to double exchange mechanism. • The above room temperature ferromagnetism enhance the potential for spintronics. • The thermal conductivity and electrical conductivity ratio is of the order of 10−5. [ABSTRACT FROM AUTHOR]

• DFT calculations are executed for halides double perovskites Cs 2 ScAgX 6 (X = I, Cl, Br). • Structural and elastic investigations represent stability of Cs 2 ScAgX 6 (X = I, Cl, Br) in cubic phase. • The band structures analysis show their indirect bandgap nature of Cs 2 ScAgX 6 (X = I, Cl, Br). • The computed band structures and optical parameters indicate potential solar cells devices applications. • Electronic thermal coefficients are probed and suggested studied halides as promising thermoelectric materials. As a possible suitor for application of solar cells and thermoelectric, halide based double perovskites has been developed due to their ecosystem stability, non-toxicity and noticeable performance. In current study, we have explored structural stability and elastic properties of Cs 2 ScAgX 6 (X = I, Cl, Br) in the cubic phase through tolerance factor and Born stability criteria calculations. Further, we present an extensive analysis of optical, electronic and electronic transport characteristics. An indirect semiconducting bandgap in the range of 1.9 eV and 1.55 eV is observed while analyzing electronic band structure and play vital role in solar cells applications. According to their bandgap values, maximal absorption in visible region is perceived, which reduces the bandgap when chlorine is substituted with bromine and iodine. Dielectric constants and other relevant parameters were produced by studying optical characteristics of Cs 2 ScAgX 6. Within the visible region, the maximum absorption of light has been recorded by investigating dielectric constant. Finally, thermoelectric properties are computed using the BoltzTraP package. The value of figure of merit, which is around 0.74 at 300 K, clearly suggests that these materials are also used as potential candidate for thermoelectric devices. [ABSTRACT FROM AUTHOR]

Intense research work is underway for identifying materials with potential applications in energy storage and energy harvesting systems. The magnesium based scandium chalcogenides have recently emerged as potential candidates for Mg batteries owing to their high Mg ionic conductivity and low electron conduction. At the same time, their band gaps are capable of absorbing electromagnetic radiations in visible to UV range; making them suitable for solar cell applications. In order to analyze the application of MgSc 2 X 4 (X = S, Se) compounds in energy devices, in this work we employ density functional theory calculations using the full potential linear augmented plane-wave method for examining their optoelectronic and thermoelectric properties. For the structural properties, the generalized gradient approximation functional designed for solids (PBEsol-GGA) has been used, while modified Becke and Johnson (mBJ) potential functional is used for computing the optoelectronic and transport properties. Our calculated optical properties indicate that these materials can find applications in solar cells. Moreover, the electronic transport properties computed using Boltzmann transport equation suggest carrier concentrations in MgSc 2 S 4 to MgSc 2 Se 4 spinels can be tuned for making them suitable for metal ion batteries. [ABSTRACT FROM AUTHOR]

Spintronics is an emerging field that has the potential to replace conventional electronics due to their comparatively high speed, low power consumption, and infinite endurance. The phenomena of ferromagnetism with high spin polarization in double perovskites make them the desired materials for spintronics. In the present work, the structure of Cs 2 CuCrX 6 (X = Cl and Br) and their magnetic and optoelectronic properties were studied by utilizing density functional theory (DFT). For the calculations of exchange-correlation potential, PBE-sol approximation was utilized while for the accurate measurement of electronic band structure and density of states (DOS), we employed mBJ potential. Both materials exhibit cubic structure and are thermodynamically stable as confirmed by volume optimization and negative formation energy respectively. Spin-based energy-volume optimization and values of exchange constants reveal the ferromagnetic nature of materials. It has been observed that 3-d states of Cr are responsible for ferromagnetism and have the major contribution to the net magnetic moment caused by exchange splitting. Furthermore, investigations of band structure and electronic density of states showed that both Cs 2 CuCrCl 6 and Cs 2 CuCrBr 6 were indirect bandgap (E g) semiconductors with the E g values of 1.2 eV and 0.33 eV respectively. The optical spectra of materials showed strong absorption in the ultraviolet region. Lastly, the transport and thermoelectric properties (TE) of materials were investigated in the range of temperature 300 K–800 K by using the BoltzTrap code. The transport parameter which included the electrical conductivity (σ/τ) and thermal conductivity (κ e /τ) of the materials showed a decreasing trend with temperature whereas the Seebeck coefficient (S) and Power factor (P.F) showed an increasing trend for Cs 2 CuCrCl 6 while decreases in case of Cs 2 CuCrBr 6. Furthermore, a high figure of merit (ZT) with values of 0.75 and 0.64 was obtained for Cs 2 CuCrCl 6 and Cs 2 CuCrBr 6 respectively. The results of this work are encouraging and show the capabilities of the discussed materials in the fields of spintronics, thermoelectric, and optoelectronics. [Display omitted] • This manuscript presents a comprehensive theoretical investigation into the magnetic, optoelectronic, and thermoelectric properties of Cs 2 CuCrX 6 (X = Cl and Br) double perovskites. • Through rigorous theoretical analysis, the manuscript unveils the spintronic potential of Cs 2 CuCrX 6 double perovskites, shedding light on their intrinsic magnetic properties and their suitability for spin-based electronic applications. This insight opens avenues for innovative spintronics device designs. • Delving into the optoelectronic characteristics, the manuscript elucidates the optical properties of Cs 2 CuCrX 6 double perovskites, offering valuable insights into their light-matter interaction mechanisms. • By examining the thermoelectric properties of Cs 2 CuCrX 6 double perovskites, the manuscript assesses their potential for thermoelectric applications, highlighting their ability to efficiently convert heat into electrical energy. This exploration paves the way for dual-functionality devices coupling data storage with energy harvesting capabilities. [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]

• Rb 2 YInX 6 (X = Cl, Br, I) double perovskites have highly structural stability determined from volume-energy optimization and negative formation energy. • Direct bandgap in the range of 3.05–2.20 eV make them more attractive materials. • The Rb 2 YInBr 6 have large value of figure of merit which means it has largest conversion efficiency to convert thermal energy into electrical energy. The double perovskite-based materials have attracted considerable attention of scientists owing to their potential applications in optoelectronic and transport properties. Here, we report the optoelectronic and transport properties of Rb 2 YInX 6 (X = Cl, Br, I) double perovskites by DFT computations. By computing tolerance factor (t G) , enthalpy of formation (ΔH f) and lattice constant (a o), the thermodynamic and structural stabilities are verified. The energy bandgap computations for Rb 2 YInX 6 gives direct bandgap having values 3.05, 2.60 and 2.20 eV for Cl, Br and I based compositions respectively. Optical absorption calculations executed within the energy range of 2–8 eV which validate its use in optoelectronic applications like solar cells. Using semi classical Boltzmann theory computed values of ZT illustrates that Rb 2 YInBr 6 is fairly good candidate for transport applications. These compounds may attain consideration in optoelectronic and thermoelectric properties. [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]