1. A DFT investigation of Li substitution in CsCaY3 (Y[dbnd]F, Cl, Br) having admirable optoelectronic characteristics as a viable candidate for photocatalytic water splitting.
- Author
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Jawad, Muhammad Ajmal and Gillani, S.S.A.
- Subjects
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POISSON'S ratio , *BULK modulus , *MODULUS of rigidity , *OXYGEN evolution reactions , *ENERGY dissipation , *ELASTIC constants - Abstract
In this study we investigated pristine and Li substituted Cs 1-x Li x CaY 3 (Y F, Cl, Br) lead free halide perovskite with different concentrations x = 0, 0.11, 0.33, 0.55, 0.77, and 1 using CASTEP under Density functional theory (DFT) has been employed under Perdew Burke Ernzerhof generalized gradient approximation (GGA-PBE) and Ultrasoft pseudo potential (USSP) approaches. Understudy pristine materials have a cubic phase Pm3 m space group. At the same time, doped compositions show a tetragonal phase structure except those in which Li completely swaps out Cs, so both end materials own a cubic nature. Li introduced at the Cs site is more effective than Ca because additional gamma points formed, influencing the electronic formation of pristine CsCaF 3 , CsCaCl 3, and CsCaBr 3 minimized band gap from 6.299 to 4.152 eV, 5.261–3.613 eV and 4.338–2.752 eV respectively. All compositions are thermodynamically stable, as suggested by the negative values of the formation energy. For all compositions, the Fermi level resides near the valence band which confirms the p-type behavior of the semiconductors. All of the materials retain the indirect bandgap. The total/partial/elemental density of states calculated has been approximated to provide a full picture of the band structure. Although elastic constants for all compounds, whether cubic or tetragonal, are used to predict mechanical parameters such as bulk modulus, shear modulus, young modulus, Poisson ratio, and Pugh's ratio, materials were first developed to support born stability criteria. From all of the compositions Cs 1-x Li x CaF 3 for x = (0.11, 0.55, 0.77, and 1) and Cs 0.23 Li 0.77 CaCl 3 are found to be mechanically unstable. All other combinations are stable, whether cubic or tetragonal. We evaluated and contrasted many optical properties like absorption spectra, refractive index, dielectric function, reflectivity, and energy loss function of pristine CsCaY 3 (Y F, Cl, Br) in comparison with Li substitution concentrations. For both pristine and Li substituted CsCaY 3 (Y F, Cl, Br) the overall water splitting was explored. All the compositions can be used for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting reactions but Cs 0.23 Li 0.77 CaBr 3 is a good catalyst among all. It is proposed that the aforementioned materials have a bandgap range suitable for solar cell applications in addition to being lead-free for environmentally conscious applications in photocatalytic activity. • Cs 1-x Li x CaY 3 (Y F, Cl, Br) lead-free halide perovskite with x = 0, 0.11, 0.33, 0.55, 0.77, 1 is studied. • Formation enthalpy confirms the thermodynamic stability of the compounds. • Electronic properties show semiconductor nature and have an indirect bandgap. • The absorption edge was shifted into the infrared region for Li-substituted CsCaBr 3. • Cs 0.23 Li 0.77 CaBr 3 is a good catalyst among all. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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