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The switch to sustainable power generation sources has gained substantial spotlight due to the essential need to decrease fossil fuels dependence, and alleviate climate change issues. This research aims to explore the first principle calculations for geometrical structure, enthalpy of formation, electronic structure behavior, optical spectra, and photocatalytic performance of the clean new Iodine-based triple perovskite compounds A3B2I9 (A = Rb or Cs, and B = Sb or Bi) using FP-LAPW method based on the density functional theory implemented in Wien2K software. The outcomes prove that these triple perovskite compounds can be formed spontaneously under standard conditions, because they are thermodynamically stable. Moreover, the electronic band structure shows an indirect semiconductor behavior of all studied compounds. Further, the optical spectra highlights that all studied compounds have high visible light absorption due to their suitable forbidden band values [1.8 eV–2.369 eV] which facilitate efficient electron–hole pairs generation maximizing the conversion of light into electrical energy. In addition, all studied compounds are satisfied the limits necessary to split water and then to produce hydrogen. Consequently, these compounds are most likely to be used as Lead-free perovskites in various optoelectronic applications, especially solar cells and hydrogen production from water splitting. [ABSTRACT FROM AUTHOR]

In this study, we investigated the optoelectronic properties of cubic (Pm3m) and orthorhombic (Pnma) CsPbX3 (X = I, Br, and Cl). We utilized the full potential linear augmented plane wave method, which is implemented in the WIEN2k code, to facilitate the investigation. Different exchange potentials were used to analyze the optoelectronic behavior using the available density functional theory methods. Our findings revealed that CsPbX3 perovskites display direct band gaps at the R and Г points for cubic (Pm3m) and orthorhombic (Pnma) structures, respectively. Among the exchange potentials, the mBJ-GGA method provided the most accurate results. These outcomes concurred with the experimental results. In both Pm3m and Pnma structures, interesting changes were observed when iodide (I) was replaced with bromine (Br) and then chlorine (Cl). The direct band gap at the R and Г points shifted to higher energy levels. Similarly, when I was replaced with Br and Cl, there was a noticeable decrease in the absorption coefficient, dielectric constants, refractive index, and reflectivity, in addition to a band gap shift to higher energy levels. [ABSTRACT FROM AUTHOR]

• The structural, elastic, electronic, magnetic, and optical properties of vacancy-ordered Rb 2 TcCl 6 have been thoroughly examined through the use of first-principles calculations. • The stability of Rb 2 TcCl 6 is demonstrated by the formation energy, optimization curves and phonon curves. • The spin-plarized electronic band structure and density of states (DOS) predict the semiconductor nature in both spin states. • The obtained magnetic moments for Rb 2 TcCl 6 reveal the potential of for spintronics. • An optical band gap with maximum absorption reveals that this compound is also useful for the application in optoelectronics. Due to their versatile properties, vacancy-ordered double perovskites offer a wide range of potential uses due to their versatile properties. We have thoroughly examined the physical characteristics of vacancy-ordered Rb 2 TcCl 6 in its cubic phase by employing the spin-polarized computations. The ground state energy and optimum structural parameters are obtained in order to assess the structural stability, which is further validated using the tolerance factor and formation energy values. The ductile character of Rb 2 TcCl 6 is revealed by a comprehensive evaluation of mechanical properties. Vickers hardness factor suggests that Rb 2 TcCl 6 can withstand against pressure-induced disturbance more strongly. A direct bandgap for spin-up is measured up to 2.33 eV, while for spin-dn it is 2.02 eV. According to the magnetic moments of 2.69 μ B , Rb 2 TcCl 6 is an attractive material for spintronic devices. A number of optical parameters are determined. For optoelectronic applications, Rb 2 TcCl 6 is an excellent choice due to its strong polarization in the visible and ultraviolet regions, as shown by its optical characteristics. [ABSTRACT FROM AUTHOR]

Magnetic double perovskites have garnered significant interest due to their unique magnetic properties and are promising candidates for various spintronic applications. Spin-polarized method is used to investigate the physical attributes of magnetic cubic double perovskites Cs 2 XCeI 6 (X = Li, Na) using density functional theory. Elastic constants and mechanical properties are evaluated to assess the mechanical stability of studied perovskites. The confirmation of the structure stability is accomplished via formation and cohesive energies, optimization plots, octahedral tilting and tolerance factor. Electronic properties revealed that Cs 2 LiCeI 6 possess an indirect bandgap of 2.06 eV and 2.43 eV in spin up and down channels, and Cs 2 NaCeI 6 have an indirect bandgap of 2.30eV and 2.64 eV in spin up and down channels, respectively. The computed magnetic moment for both perovskites is reported as 1 μ B. Kramers-Kronig complex equations are used to analyze the optical behavior. The peak absorption in the UV range is revealed with minimal energy loss for both perovskites. The maximum peaks for optical conductivity and extinction coefficient also observed in UV spectrum. According to an analysis of the derived properties, optoelectronics and spintronic are two areas for which these double perovskites are well suited. [ABSTRACT FROM AUTHOR]

Double perovskites based on rubidium have demonstrated potential for obtaining high solar cell power conversion efficiencies. Their distinct crystal structure and electrical characteristics influence these materials’ potential as effective light absorbers. In this present manuscript, a detailed scrutiny of the physical aspects of halide perovskites Rb2TlAsI6 and Rb2TlGaI6 is presented using density functional theory framework implanted in Wien2K code using. Modified Becke Johnson potential is employed to treat the exchange–correlation effects. A computed tolerance factor, octahedral tilting, and formation energy ensure the structural and thermodynamic stability of given structures. Three independent elastic constants and mechanical properties were computed using the Thomas Charpin method. Ductile nature of Rb2TlAsI6 and brittle nature for Rb2TlGaI6 is revealed from computed mechanical attributes. The Debye temperature for Rb2TlGaI6 (171.32 K) is noted higher than Rb2TlAsI6 (144.53 K). Electronic properties revealed a direct bandgap (1.09 eV) for Rb2TlAsI6 and an indirect bandgap (1.2 eV) for Rb2TlGaI6. Optical properties indicate high polarization and absorption of incident light, which is suitable for photovoltaic applications in the visible spectrum. [ABSTRACT FROM AUTHOR]

[Display omitted] • The structural, elastic, electronic, transport, and optical properties of lead-free double perovskites K 2 CuBiX 6 (where X can be I, Br, or Cl) have been thoroughly examined through first-principles calculations. • The electronic band structure shows an increment in the energy gap after the replacement of Iodine with Bromine and Chlorine, which is also endorced by the density of states (DOS). An optical band gap with large absorption in the visible and UV region reveal the potential of K 2 CuBiX 6 (X = I, Br, Cl) for the applications in optoelectronics. • The perovskites exhibit substantial potential for renewable energy applications, as they demonstrate significant ZT values, which suggest their availability for thermoelectric devices. Potassium-based perovskites hold significant potential to revolutionize renewable technology by enabling more cost-effective and sustainable energy devices. The DFT incorporated in the Wein2K interface is used to provide an extensive investigation of the structural, mechanical, electrical, optical, and thermoelectric behavior of double perovskites K 2 CuBiX 6 (X = I, Br, Cl). Structural stability is confirmed through optimization curves, tolerance factor and octahedral tilting. Mechanical properties support the ductile character of K 2 CuBiX 6 (X = I, Br, Cl). Electronic band structures reveal that perovskite K 2 CuBiI 6 initially possesses a bandgap of 0.6 eV. This bandgap is increased to 0.97 eV when (I) atom is replaced with (Br) atom. Furthermore, a prominent shift in the bandgap value occurs when the bromine (Br) atom is replaced with a chlorine (Cl) atom, resulting in a bandgap of 1.3 eV. The Kramer-Kronig equations are used to evaluate the optical characteristic, which shows significant absorption in the visible range for all structures, allowing them to be utilized in optoelectronics. Numerous thermoelectric characteristics are calculated using the Boltzmann semi-classical theory. The perovskites exhibit substantial potential for renewable energy applications, as they demonstrate significant ZT values, along with elevated Seebeck coefficients and electrical conductivities, which enhance their suitability for utilization in clean energy technologies. [ABSTRACT FROM AUTHOR]

The structural, electronic, and optical features of CsPb(I 1-x Br x) 3 (x = 0, 0.25, 0.50, 0.75, and 1.0) compounds were evaluated using first-principles calculations based on the full-potential linear augmented plane wave (FP-LAPW). The ground-state properties were examined, with a focus on the structural, electronic, and optical properties of the compounds. The structural features were computed using the PBE-GGA potential, revealing that both the lattice constant and bulk modulus varied nonlinearly with respect to the bromide concentration. Theoretical X-ray diffraction analyses revealed peak shifts to larger angles when the average fraction of bromide incorporated increased, indicating shrinkage in the lattice. While the E g values were calculated using the PBE-GGA potential and resulted the 1.45, 1.43, 1.53, 1.50, and 1.77 eV values, the mBJ-GGA potential values resulted the 1.90, 1.81, 2.11, 2.12, and 2.50 eV for CsPbI 3 , CsPbI 2.75 Br 0.25 , CsPbI 1.5 Br 1.5 , CsPbI 0.25 Br 2.75 , and CsPbBr 3 respectively. In addition to that, the E g values of CsPbI 1.5 Br 1.5 which were calculated using other potentials: LDA and PBEsol potentials have resulted the 1.43 and 1.49 eV values, respectively. The E g of CsPb(I 1-x Br x) 3 obtained using mBJ-GGA potential has relatively matched with previously reported experimental values. The calculated effective masses are highly correlated with the energies of E g, the valence-band maximum (VBM), and conduction-band minimum (CBM). We observed that there was an increase, with small bowing parameters (b), in E g value as the Br concentration increases in the CsPb(I 1-x Br x) 3 compounds. The semiconductor characteristic was prominent in the observed band profiles when PBE-GGA and mBJ-GGA potentials were applied. Additionally, the optical properties were examined in details. The calculations indicate that the CsPb(I 1-x Br x) 3 compounds are promising candidates for optoelectronics. Image 1 • The structural, electrical and optical properties of CsPb(I 1-x Br x) 3 were investigated using the PBE-GGA and mBJ-GGA. • An increase in the band gap energy (Eg) values of 0.32 eV (PBE-GGA) and 0.60 eV (mBJ-GGA) when substituting I with Br. • The calculated band gap (Eg) values using the mBJ-GGA were better matched with the experimental values. • The effective masses of electron and hole were calculated using PBE-GGA and mBJ-GGA potentials. • All the optical properties of CsPb(I1-xBrx)3 were investigated using PBE-GGA and mBJ-GGA potentials in details. [ABSTRACT FROM AUTHOR]