Insights into the pressure-dependent physical properties of cubic Ca3MF3 (M = As and Sb): First-principles calculations

Abstract

Here, first-principles calculations have been employed to make a comparative study on structural, mechanical, electronic, and optical properties of new Ca₃MF₃ (M = As and Sb) photovoltaic compounds under pressure. The findings disclose that these two systems possess a direct band gap, showcasing a large tunable range under pressure, effectively encompassing the visible light spectrum. Adjusting various levels of hydrostatic pressure has effectively tuned both the band alignment and the effective masses of electrons and holes. Both compounds were initially identified as brittle materials at 0 GPa pressure; however, as the pressure increases, they transform, becoming highly anisotropic and ductile. Due to the material's mechanical robustness and enhanced ductility, as evidenced by its stress-induced mechanical properties, the Ca₃MF₃ (M = As and Sb) material shows potential for use in solar energy applications. Furthermore, as the influence of external pressure increases, the absorption edge seems to move slightly towards lower energy region. Optical properties show that the materials studied might be used from several optoelectronic devices in the visible and ultraviolet range area. Our findings show that pressure considerably influences the physicochemical properties of Ca₃MF₃ (M = As and Sb) compounds, which is a promising feature that can be useful for optoelectronic and photonic applications, for instance, light-emitting diodes, photodetectors, and solar cells.

Keywords: A3BX3 photovoltaic compound; First-principles study; Mechanical properties; Optoelectronic properties; Pressure effect.

Graphical abstract

Fig. 1

Constructed (a) 2D and (b) 3D crystal structure of Ca₃MF₃ (M = As and Sb) compounds.

Fig. 2

Volume optimization of (a) Ca₃AsF₃ and (b) Ca₃SbF_3.

Fig. 3

Pressure-induced reduction of lattice constant and unit cell volume of Ca₃MF₃ (M = As and Sb).

Fig. 4

Obtained band structure profile of Ca₃AsF₃ via TB-mBJ functional at various pressures: (a) 0 GPa, (b) 10 GPa, (c) 20 GPa, (d) 30 GPa, (e) 40 GPa, and (f) 50 GPa.

Fig. 5

Obtained band structure profile of Ca₃AsF₃ via GGA-PBE functional at various pressures: (a) 0 GPa, (b) 10 GPa, (c) 20 GPa, (d) 30 GPa, (e) 40 GPa, and (f) 50 GPa.

Fig. 6

Obtained band structure profile of Ca₃SbF₃ via TB-mBJ at different pressures: (a) 0 GPa, (b) 10 GPa, (c) 20 GPa, (d) 30 GPa, (e) 40 GPa, and (f) 50 GPa.

Fig. 7

Obtained band structure profile of Ca₃SbF₃ via GGA-PBE functional at different pressures: (a) 0 GPa, (b) 10 GPa, (c) 20 GPa, (d) 30 GPa, (e) 40 GPa, and (f) 50 GPa.

Fig. 8

The pressure-induced band gap narrowing of Ca₃AsF₃ and Ca₃SbF₃.

Fig. 9

Calculated PDOS profile of novel Ca₃AsF₃ perovskite under pressure.

Fig. 10

Calculated PDOS profile of novel Ca₃SbF₃ cubic perovskite under pressure.

Fig. 11

TDOS of (a) Ca₃AsF₃ and (b) Ca₃SbF₃ at different applied pressures.

Fig. 12

Charge density distribution of Ca₃MF₃ (M = As and Sb) along (100) crystallographic plane at 0 and 50 GPa pressure.

Fig. 13

Calculated effective masses of holes (m_h) and electrons (m_e) of Ca₃MF₃ (M = As and Sb) under all applied pressure (0–50 GPa).

Fig. 14

Variation of (a) Poisson's ratio and (b) Pugh's ratio of Ca₃MF₃ (M = As and Sb) compounds at different pressures.

Fig. 15

The anisotropic 3D illustration of (a) Young's modulus, (b) shear modulus, and (c) Poisson's ratio of Ca₃MF₃ (M = As and Sb) at 0 and 50 GPa pressure.

Fig. 16

The pressure-induced (a) real part ε₁(ω), (b) imaginary part ε₂(ω) of dielectric function, (c) absorption α(ω), (d) conductivity σ(ω) of Ca₃MF₃ (M = As and Sb) at pressure = 0, and 50 GPa.

Fig. 17

The pressure-induced (a) Refractive index, (b) Extinction coefficient and (c) Reflectivity spectrum, and (d) loss function of Ca₃MF₃ (M = As and Sb) at pressure = 0, and 50 GPa.