Red shift of lead-free halide perovskite RbCaCl₃ under pressure for enhancing optoelectronic performance

Abstract

This study focuses on the exploration of pressure effects on the structural, electronic, optical, and mechanical properties of a cubic halide perovskite RbCaCl3 using density functional theory. The calculated values of lattice constant and unit cell volume at zero pressure are justified by the previous experimental and theoretical studies. As pressure is applied both the lattice constant and unit cell volume decrease steadily because of bond length reduction inside the material. The indirect band gap nature of the studied perovskite transforms into direct under applied pressure of 40 GPa and more. Moreover, the band gap value significantly reduces under pressure effect from ultraviolet to visible energy region. Though the bonding nature of both Rb−Cl and Ca−Cl is initially ionic, the induced pressure slightly reduces the ionicity of Rb−Cl and makes the Ca−Cl bond covalent. The optical absorption reveals a red shift in the visible energy region advantageous for using RbCaCl3 in solar cell applications. In addition, the overall optical analysis reveals that the pressure-induced compound is more suitable for optoelectronic device applications than that of zero pressure system. The external hydrostatic pressure significantly affects the mechanical properties of titled compound, making it more ductile and anisotropic.

Computational study of stability, photovoltaic, and thermoelectric properties of new inorganic lead-free halide perovskites

“…Similar values have been reported in the case of the cubic NaGeX 3 (X = Cl, Br, I) and CsSnX 3 (X = I, Br, Cl) [60,61]. Finally, all predicted mechanical properties are in good agreement when compared to other alkane-based inorganic perovskite halides [62][63][64].…”

Responses Toward Structural, Electrical, Optical, and Mechanical Properties of RbGeF3 Under Pressure: DFT Insights

“…Figure 5b provides a clear illustration of the absorption that occurs in the visible light region. [ 22 ] When compared to the results obtained at 0 GPa, the absorption of this compound in the visible range is demonstrably greater when measured at 50 GPa. Accordingly, it is anticipated that the researched perovskites will be able to use visible light energy for photovoltaic energy transformation at a pressure of 50 GPa, which might increase the efficiency of solar cells as well as in optoelectronic devices and PV devices.…”

“…The formula from the literature was applied to compute the elastic modulus of polycrystalline materials. In the Cambridge Serial Total Energy Package (CASTEP) [18,22] program code the plane wave pseudopotential density functional theory (DFT) [22,23] based firstprinciples method was devoted to carrying out calculations of the present state. Geometry optimization was used to find the crystal's minimal energy (stable) position.…”

Band gap tuning of perovskite solar cells for enhancing the efficiency and stability: issues and prospects

“…[152][153][154] Different research groups theoretically investigated how indirect band-gaps are transformed into direct band-gaps. 43,[155][156][157] For example, M. A. Haq et al conducted a theoretical study on KCaCl 3 perovskite materials, revealing that under 120 GPa, the indirect bandgap was transformed into a direct one by reducing its band-gap from 4.75 eV to 2.17 eV. 43 Although the hybrid perovskite MAPbI 3 is typically considered a direct bandgap semiconductor, it has been conrmed to retain a slightly indirect bandgap nearly 60 meV below the direct gap.…”