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In this study, the density functional theory (DFT) is employed to investigate the structural, elastic, optoelectronic, and thermoelectric (TE) properties of K2NaSbZ6 (Z = Br, I) halide double perovskites (HDPs). The evaluated second-order elastic constants and formation energy analysis confirm that the studied HDPs are cubic, stable, and ductile. The electronic band structure calculations disclose that both compounds are determined to be p-type semiconductors with indirect band gaps of 3.20 eV and 2.40 eV for K2NaSbZ6 (Z = Br, I), respectively. The optical features demonstrate the prominent role of the present HDPs in photovoltaic conversion and optoelectronic devices. In the visible region, both HDPs exhibit high optical absorption (> 105 cm−1) with excellent refractive index. Furthermore, the studied TE properties show that for both HDPs, n-type doping is more suitable for improving their TE performances. Therefore, the present study would be beneficial for emerging optoelectronic and TE technologies. [ABSTRACT FROM AUTHOR]

In this work, theoretical investigations were performed for the structural, elastic, optoelectronic, thermodynamic, and thermoelectric characteristics of barium ceroplatinate Ba2CePtO6 double perovskite oxide. The direct band gaps 1.518 eV and 1.385 are calculated with TB-mBJ potential, and PBE-GGA approximation. The findings of elastic constants C11, C12 and C44, ensure the mechanical stability, ductile nature, anisotropic, Debye temperature, and ionic bonding. In visible and ultraviolet spectrums, Ba2CePtO6 exhibits a high absorption coefficient (> 105 cm−1), low optical reflectivity, low electron energy loss and excellent refractive index. Finally, the thermoelectric properties are computed using BoltzTraP code. At room temperature the figure of merit has been reported as 0.84 and 0.998. Therefore, the reported results are likely to serve as an inspiration for the forthcoming experimental and theoretical investigations. [ABSTRACT FROM AUTHOR]

Context: Hybrid halide perovskites are gaining prominence as a promising option in the advancement of photovoltaic devices. Ethylammonium-based hybrid halide perovskites have demonstrated impressive characteristics, such as a reduced band gap, enhanced stability, and non-toxic properties. In this study, we have explored the structural, electronic, optical, and thermoelectric characteristics of Ethylammonium tin chloride. We have found that Ethylammonium tin chloride (EASnCl3) is a direct wide band gap semiconductor. Additionally, we conducted calculations for various optical parameters, including the dielectric function, absorption coefficient, and refractive index, across a photon energy spectrum ranging from 0 to 7 eV. The research highlights the exceptional qualities of EASnCl3, which exhibits a high absorption coefficient and an elevated Seeback coefficient, among other favorable attributes. These findings position it as a promising material for cost-effective photovoltaic device applications, addressing concerns related to environmental stability. Methods: Fundamental properties based on the full-potential linearized augmented plane wave (FP-LAPW) method, this computation was performed using the WIEN2k simulation code. We utilized the exchange–correlation potentials PBE-GGA and KTB-mBJ to compute the optimized structure, density of states, and band structure of the material. In order to calculate the thermoelectric properties of the material, the Boltztrap simulation tool has been used. There are several critical absorbance parameters, including the Seeback coefficient, figure of merit, power factor, electrical conductivity, and thermal conductivity, concerning their carrier concentration and chemical potential, that have been taken into consideration. [ABSTRACT FROM AUTHOR]

Context: In this study, the authors have investigated the structural, optoelectronic, thermoelectric, and thermodynamic properties of Ca2NaIO6 and Sr2NaIO6 double perovskite oxides. Both materials exhibit semiconductor behavior with direct band gaps (Eg) of 0.353 eV and 0.263 eV, respectively. Optical parameters like absorption coefficient α(ω), reflectivity R(ω), dielectric constants, and refractive index have been calculated. The most notable absorption peaks are identified at 5.52 eV (equal to 108.33 × 104 cm−1) in the case of Ca2NaIO6 and at 11.16 eV (equivalent to 118.17 × 104 cm−1) for Sr2NaIO6. These findings suggest a promising outlook for applications in optoelectronics. Moreover, their commendably low thermal conductivity and a high figure of merit, particularly at low temperatures (100 K), indicate their effectiveness as thermoelectric materials. This analysis underscores that these materials hold potential as suitable candidates for n-type doping, making them well-suited for use in thermoelectric devices. Studying thermal properties, including thermal expansion, bulk modulus, acoustic Debye temperature, entropy, and heat capacity, contributes to understanding the materials' thermodynamic stability. The titled materials are dynamically stable. The analysis of these double perovskite materials highlights their potential across various technological applications due to their advantageous structural, electronic, optical, and transport properties, offering new possibilities in material science and technology development. Methods: The study utilized the full potential linearized augmented plane wave (FP-LAPW) method in conjunction with density functional theory within the WIEN2k simulation code. This approach is widely recognized as one of the most dependable methods for evaluating the photovoltaic characteristics of semiconducting perovskites. The thermoelectric properties were ascertained using the rigid band approach and the constant scattering time approximation, both implemented in the BoltzTraP computational code. [ABSTRACT FROM AUTHOR]

Distinct types of materials are being explored for usage in thermoelectric (TE) and photovoltaic (PV) systems in order to alleviate the energy problem. In order to create nontoxic, more stable, and best-performance energy convergence devices, the state-of-the-art hybrid halide double perovskites (HHDPs) compound has been identified as a potential TE material and potential replacement for hazardous lead. We have proposed a new HHDP material (CH3NH 3 ) 2 AgInCl6 and performed its theoretical investigation via the full potential linear augmented plane wave (FP-LAPW) method. The computational results show that the studied compound exhibits a direct bandgap of 3.708 eV and has exceptional PV characteristics in the ultraviolet (UV) region. The obtained thermodynamic (TD) characteristics confirm that the titled compound is thermally stable at various temperatures and pressures. At 300 K, the examined HHDP material has the highest ZT (=2.23) in the p-region. Materials with higher ZTe values are substantially more important for generating electrical energy through waste heat. The ZTe result validates the use of these materials in TE devices at ambient temperature. The parameters of this compound have been computed for the first time. This study identifies (CH3NH 3 ) 2 AgInCl6 as a novel HHDP compound. Through an in-depth exploration of its properties, this study offers valuable insight for further research with potential applications in clean energy systems. [ABSTRACT FROM AUTHOR]

Context: Herein, we have studied progressively novel metal lead-free halide double perovskite renewable energy materials. Due to their potential use in electronic devices, researchers have investigated these materials with a lot of interest. From the electronic structure, we have found that these are the indirect band gap semiconductors within the range between 1.273 and 3.986 eV. Optical parameters such as dielectric constant, electrical conductivity, and absorption coefficient have also been investigated, which have shown that these materials have potential use in photovoltaics. We have checked stability issues by thermodynamic parameters and phonon spectra. We have found them thermally stable; however, the phonon spectra show their dynamical instability and except for Na2AgSbF6 and Na2AgSbI6, the remaining compounds are weak in mechanical stability. For another futuristic purpose, thermoelectric parameters such as Seebeck coefficient, power factor, and figure of merit have also been calculated, which again verifies that these materials may be very useful in thermoelectric devices. Most of the parameters have been computed for the first time. Methods: We have performed this computational work using WIEN2k simulation code, which is based on the full-potential linearized augmented plane wave (FP-LAPW) technique. It is one of the most reliable techniques to calculate the photovoltaic properties of semiconducting perovskites. The interaction between ion-core and valence electrons was dealt with within the PAW technique as implemented in Vienna Ab initio Simulation Package (VASP). [ABSTRACT FROM AUTHOR]

Minimal cost, huge area, high throughput, high performance of photovoltaic panels, prolonged lifespan, and less toxicity are vital aspects when transitioning photovoltaic technology from lab‐scale production to industrial implementations. A new class of materials typically known as hybrid halide double perovskites (HHDPs) has emerged as a possible alternative for the replacement of toxic lead in crystal lattice for realizing lead‐free, stable, and high‐performance perovskite solar cells (PSCs). An ab initio analysis of (MA)2AgInBr6 HHDP via the WIEN2K code is conducted. It is found that this material has a direct bandgap of 3.85 eV having excellent optical properties in the UV region. The calculated thermodynamic parameters confirm its thermal stability at different temperatures and pressure. Its figure of merit is more than unity at room temperature as well as higher temperature ranges, so this material will be useful in thermoelectric (TE) devices as a TE material. [ABSTRACT FROM AUTHOR]

To analyze potential alternatives, the fundamental physical properties such as structural, electronic, optical, elastic, thermoelectric, and thermodynamic parameters of tin‐based formamidinium FASnX3 (X = I, Br, Cl) hybrid halide perovskites by using density functional theory are investigated. The calculated results indicate that these compounds exhibit analogous band gap, considerable thermal and elastic stability, and notable optical properties with high dielectric constant and absorption coefficient, significant hole, and electron conductive behavior. The present research work shows as good absorbers for perovskite solar cells, adding to the validity of FP‐LAPW (full‐potential linearized augmented plane wave) methods, simultaneously enhancing the understanding of these practical hybrid perovskite materials. It may be believed that this study will be of a lot of credit for experimentalists for synthesis and characterization of these materials and will be done experimentally in future times due to the very good properties of photovoltaic applications. [ABSTRACT FROM AUTHOR]

Summary To address the instability issues arising due to leaching of lead in the extensively explored MPX perovskite, in this study, we suggest replacement of the cation CH3NH3+ (M+) with a larger cation CH3CH2NH3+ (E+). The proposed material EPX (CH3CH2NH3PbX3; X = Br, Cl), due to the larger size of E+ cation, is expected to offer increased hindrance to the movement of lead ions through the lattice and thereby reducing its degradation against heat and moisture. This investigation unfolds that EPBr has a direct energy band gap of 2.045 eV at R with absorption coefficient above 1.8 × 104 cm−1 and SLME parameter as high as 21.5% for a film of thickness of 1 μm at ambient temperature of 300 K, which confirm its aptness as photovoltaic absorber material (PVA). The investigation also shows that n‐type EPCl has a direct energy band gap of 2.668 eV with the figure of merit (ZT) exceeding 0.95 and Seebeck coefficient (S) more than 700 μV/K that reaffirm its suitability as thermoelectric (TE) material. [ABSTRACT FROM AUTHOR]

Summary: Herein, we have discussed the ethyl‐ammonium based hybrid perovskite (viz. CH3CH2NH3PbI3 or EAPbI3) as the potential candidate material for the development of photovoltaic devices having low processing cost and high power conversion efficiency (PCE). To address the stability and environmental issues due to leaching of lead from MAPbI3, we urge to replace cation CH3NH3+ (MA+) with an appropriate cation CH3CH2NH3+ (EA+) and hope that the EAPbI3 perovskite would prove to be a stable and eco‐friendly photovoltaic absorber (PVA) material yielding high PCE. We have investigated physical properties like energy bandgap, electron density distribution and optical coefficients by FP‐LAPW+lo and density functional theory (DFT). The present study reveals that EAPbI3 has a direct energy bandgap of 1.55 eV with absorption coefficient exceeding 2 × 104 per cm, which confirms its suitability as PVA material. The dependence of thermoelectric (TE) coefficients on chemical potential and carrier concentration at various temperatures has also been discussed. We have also carried out the calculations of spectroscopic limited maximum efficiency (SLME) parameter (30.5%), and the thermodynamic (TD) properties in the realm of quasi‐harmonic approximation. A detailed investigation on some of the properties of EAPbI3 perovskite relevant to PVA material is being done for the first time, the present study may motivate researchers for more comprehensive theoretical and experimental investigations in search of stable and economically and environmentally viable PVA materials. [ABSTRACT FROM AUTHOR]

Summary: Recently, Organometallic halide based perovskites have emanated as an auspicious candidate as a solar cell absorber layer. In this article, we have explored the fundamental properties such as structural, electronic, optical, elastic, and thermoelectric parameters of CH3NH3PbBr3 through first‐principles calculations, because it has accomplished the entire criterion to use in photovoltaic and thermoelectric applications. We have used full‐potential linearized augmented plane wave method (FP‐LAPW) within DFT and implemented in Wien2k. The generalized gradient approximation (GGA) parameterized by Wu‐Cohen (WC) has been used to optimize the lattice parameter, while for band gap calculations different exchange‐correlation potentials (LDA/GGA) have been used. The band gap up to 2.26 eV has been achieved by doing some appropriate changes in the parameter of TB‐mBJ exchange‐correlation potential. The nature of band gap is direct and exist at R (0.5 0.5 0.5) symmetry point of the Brillouin zone. All the optical spectral response between 2 and 5 eV is due to the transition of Br 5p with little contribution Pb 5s orbital electrons of VBM to Pb 6p orbitals in CBM and a minor contribution of second band gap components also incorporate. As well as, a high absorption coefficient shows that it may be strongly applied in photovoltaic devices. The orientation of organic cations (CH3NH3)+ has no considerable impact on the band structure formation. To render a solid foundation about the application in the thermoelectric device up to the high‐temperature region, the thermoelectric parameters have been discussed at optimal carrier concentration and definite temperature range. The measurement of elastic constants, B/G and Poisson's ratio indicates the ductile nature of CH3NH3PbBr3. To the best of my knowledge, most of the investigations have been discussed first time for this material. [ABSTRACT FROM AUTHOR]

Here in, we present the extensive analysis of the parameters associated with structural, electronic, optical and mechanical properties of HC(NH2)2PbI3 or FAPbI3 (FA = Formamidinium) by using full potential linearized augmented plane wave method (FP-LAPW) within framework on the density functional theory. The band structure shows that FAPbI3 has a direct band gap (1.44 eV) at the symmetry point R (0.5, 0.5, 0.5) and are in best agreement with experimental data. The strong hybridization of s orbitals of Pb and p orbitals of I in valance band plays an important role in the structural stability. From the mechanical constants, we have observed that this is ductile in nature and perfect use for photovoltaic applications. Further, FAPbI3 photovoltaic device has been prepared and device parameters have discussed for ZnO, ZnS, ZnSe, ZnTe and CdS buffer layers. The calculated results for FAPbI3 thin layer solar cell show maximum efficiency (20.48% and 20.77%) with ZnS and CdS buffer layers respectively. The proposed results further validate the prospects of methylammonium (MA) free perovskites and it would be persistent and consistent with the flexible substratum. These are the main features of commercialization perovskite solar cells. Thus, promoting the evolution of cubic FAPbI3, for achieving high performance-based optoelectronic devices and will pave a new path in solar cell industry. [ABSTRACT FROM AUTHOR]

Herein, we have measured the mobility of Hole's for the configuration FTO/TiO2/CH3NH3PbBr3/PEDOT:PSS/Al by the SCLC regime. The current–voltage (I–V) characteristics of the CH3NH3PbBr3 perovskite based device shows the rectifying behavior as Schottky diode. Different parameters of the proposed device such as saturation current, ideality factor, barrier height have been taken out from I–V characteristics. The highest Hole's mobility from TiO2 thin film through the perovskite and PEDOT:PSS film to the top aluminum electrode has of order 1.59 × 10–4 cm2 V–1 s–1. Moreover, the proposed device shows the TFSCLC regime at lower voltage while, at higher voltages it shows the TCLC regime. In addition to this, some important parameters like junction resistance, capacitance and carrier lifetime of device can be measured by the spectroscopy analysis of impedance. [ABSTRACT FROM AUTHOR]

Herein, we propose that the commonly used methylammonium cation (CH 3 NH 3 +) in CH 3 NH 3 PbI 3 (MAPbI 3) be replaced with ethyl-phosphonium cation CH 3 CH 2 PH 3 + (EP+), allowing stronger electronic coupling between the PbI 6 octahedra and the organic cation and thereby increasing its stability. This paper will examine EP + based hybrid perovskite (CH 3 CH 2 PH 3 PbI 3 or EPPbI 3) as an alternative absorber material for photovoltaic cells of high efficiency and that too at affordable processing costs. By using FP-LAPW + lo methodology as used in density functional theory (DFT), we have examined physical features such as the bandgap energy, distribution of valence electron density, DOS, and optical and thermodynamical coefficients. We also simulated the performance of solar cells by employing EPPbI 3 as PVA material using SCAPS-1D. The findings of the current study viz. an absorption coefficient surpassing 10 4 cm−1, a direct forbidden energy gap of 1.388 eV and simulated PCE of 31.8%, is enough to support applicability EPPbI 3 perovskite as a PVA material. [ABSTRACT FROM AUTHOR]

In this paper, we have conducted theoretical work on rare earth-based double perovskites namely, La 2 NiMnO 6 and Gd 2 NiMnO 6 , using generalized gradient approximation (GGA) and GGA + U formulations within the full potential linearized augmented plane wave (FP-LAPW) method. It is revealed that using GGA + U computations instead of the conventional GGA method results in a reasonable widening of the band gaps and best fit with the previously explored experimental data with U = 1.5 eV. Further, the band gap values are increased with increasing the U values for the 3d states of Ni and Mn. Moreover, we found that these materials show high magnetic moment, high absorption in the visible and ultraviolet region, and high figure of merit (nearly one for Gd 2 NiMnO 6 at room temperature), hence show their potential in multiple applications such as magneto-caloric, photo-catalytic, solar energy, and thermoelectric devices. [ABSTRACT FROM AUTHOR]

Cs 2 ZSbX 6 (Z ​= ​Ag, Cu, and X ​= ​Cl, Br, I) are promising materials for photovoltaic applications based on their electronic and optical properties, whereas their suitable bandgap inspires us to move towards other substitutions. In the present investigation, when substitute Z with Ag and Cu, and X with Cl, Br, and I; the results suggested that these types of double perovskites have low bandgap and high absorption. The massive density of states and optical properties such as high dielectric constant of about 5.33 and 6.30 for Cs 2 AgSbI 6 and Cs 2 CuSbI 6 respectively, accepted these materials as a highly applicable double perovskite compounds. The large bulk modulus and maximum tolerance factor of Cs 2 CuSbCl 6 among all six compounds make it an extremely reliable compound from structural stability standards. The obtained result shows that these materials are optically active in the visible and ultraviolet regions inclusive of ductile therefore they can be productively utilized for optoelectronic devices. The electronic transport properties have been calculated within the constant relaxation time approximation. Seebeck coefficient is noted to decreasing with increasing temperature and figure of merits are increasing with increasing temperature at a given electron and hole concentration (1018-1021 ​cm−3). The figure of merit signifies that these materials may also be used as thermoelectric devices. These computational observations hereby are of paramount importance for future integrated applications. We present fundamental physical properties by modifying the chemical composition of double perovskite compounds using the first-principles method within the framework of the Wien2k code. The band gap of 2.542 ​eV for Cs 2 AgSbCl 6 is reduced to a significant value of 1.299 ​eV for Cs 2 CuSbCl 6 ; which has persisted with great importance in photovoltaic application due to increment in theoretical photon conversion efficiency, as per Shockley-Queisser limit. These compounds have a high dielectric constant, which leads to low electron-effective mass and high mobility. The calculated value of the elastic parameter shows the ductile nature and elastically isotropic behavior of these compounds. From the results of thermoelectric properties of these materials, strongly doped n -type double perovskites Cs 2 ZSbX 6 with doping on the order of 1018 ​cm−3 should be chosen for thermoelectric applications. As a result, inorganic double perovskites are promising low band gap materials, as a replacement of lead halide perovskites due to their non-toxic properties. [Display omitted] • Switching from lead halide perovskite leads to non-toxic property. • More overlap integral favors the increment in rate of quantum tunneling. • Interband transition corresponding to Van Hove singularity reveals high absorption. • Inorganic double perovskites are stable, low cost and low band gap material. • High dielectric constant decreases the charge carrier recombination rate. [ABSTRACT FROM AUTHOR]

Formamidinium lead iodide [(HC(NH 2) 2 PbI 3 ] material has generated significant interest in their inherent properties and extensive scope of prospective applications. Here, we have successfully computed the structural, electronic, optical, thermal, thermoelectric and elastic properties with the framework of density functional theory over the PBE-sol and WC potential approximations using the WIEN2K code. These explorations show that this material is a direct bandgap semiconductor (1.30 eV), with high absorption coefficients and better thermal stability. The dielectric function and absorption spectra peaks reveal in the IR-visible-UV energy region show the significant future of this material to be used in photovoltaic (PV) devices. Thermal properties have been calculated by GIBBS2 at different temperatures (0–800 K) and pressures (0–8 GPa). Boltztrap with constant relaxation time approximation has been used for computing the thermoelectric parameters at different temperatures (300–800 K). Seebeck coefficient decreases with increasing temperature, electrical conductivity nearly constant in the whole temperature ranges, electrical thermal conductivity increases with increasing temperature, power factor and figure of merit's are also increasing with increasing temperature at a given electron and hole concentration (1018-1019 cm−3). We have also carried out the calculations of spectroscopic limited maximum efficiency (SLME) parameter (39.09%). Moreover, for mechanical stability, we have determined the elastic properties (C 11 , C 12 , C 44), bulk modulus (B), Young's modulus (Y), shear modulus (G) and stability constants B/G ratio, and Poisson's ratio (ν). These computed results show that the FAPbI 3 is a relevant material to be used as an alert substance in photovoltaic device fabrications and proposed outcomes are in good acceptance with the experimental and other theoretical data. • Formamidinium lead iodide hybrid perovskite. • Study of electronic structure and density of states. • Study of dielectric constant, refractive index and absorption. • Thermoelectric and elastic properties have been investigated. [ABSTRACT FROM AUTHOR]

The promising material hybrid Organic-Inorganic Perovskites (HOIP) has been frequently a subject of comprehensive and intensive experimental and theoretical studies. As Because of noxiousness and longtime environmental stability of heavy metal lead, since last few years non-lead based perovskites compounds either organic or inorganic are attracting attention in the solar cell formation. In this work, we have studied the fundamental properties of CH 3 NH 3 SnI 3 and CH 3 NH 3 SnBr 3 like structural, electronic, optical and thermoelectric. We have been used full-potential linearized augmented plane wave method (FP-LAPW) within density functional theory (DFT) and implement it in Wien2k. The generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof (PBE) for the exchange-correlation functional has been used to relax the structural parameters of these materials. The electronic properties have been evaluated by using different GGA and LDA (Local density approximation) exchange correlation potential. We have obtained the values of band gap 1.172 eV and 1.902 eV for CH 3 NH 3 SnI 3 and CH 3 NH 3 SnBr 3 respectively by TB-mBJ exchange-correlation potential. According the optical properties, we have seen that because of high absorption coefficient of CH 3 NH 3 SnI 3 and CH 3 NH 3 SnBr 3 perovskites, they may be strongly applied in photovoltaic device for the visible to ultra-violet wavelength region. Thermoelectric properties have shown that at room temperature they also may be used as thermoelectric device. Based on my knowledge, the investigations on tin based perovskites have been discussed for first time. Sn-based hybrid organic inorganic perovskites have been extensively studied, because of their novel properties and their applications in electronic, photovoltaic and thermoelectric devices. Here, we discuss results from ab initio calculations for CH 3 NH 3 SnI 3 and CH 3 NH 3 SnBr 3 and showing how theory can aid and improve comprehension of the structural, electronic, optical and thermoelectric properties of these systems. Image 1 • Theoretical study of tin-based organomatallic halide perovskites. • Electronic structure based band gap and density of states study. • Dielectric constant, refractive index and absorption study. • Thermoelectric properties have been investigated. [ABSTRACT FROM AUTHOR]