The fundamental physical properties of perovskite materials are crucial for technological applications in a variety of disciplines. Therefore, this study explores the pressure effects on various ...physical properties of perovskite halides TlPbX
3
(X = Cl, Br) via density functional theory and investigate the compounds’ optoelectronic performance. The lattice parameters are reduced for enhancing interaction among the constituent atoms upon pressure. The semiconducting nature of both compounds is revealed by band structure and density of states. The band gap is also reduced under pressure, which improves the optical functions. Moreover, the bonding between Tl–Cl(Br) and Pb–Cl(Br) becomes stronger as pressure is applied than that observed at zero pressure systems. All the optical functions become favorable for using both compounds in several interesting optoelectronic applications under pressure. The mechanical properties are also significantly affected by induced pressure. The applied pressure significantly enhances the ductility, machinability, and anisotropic nature of the studied compounds.
Graphical abstract
Inorganic, non-toxic metal halide perovskites are the benchmark for optoelectronic device commercialization. Due to their significant importance, the density functional theory-based ab initio method ...was engaged to study the fundamental physical properties of metal halide perovskites TlBX3 (B = Ge, Sn; X = Cl, Br, I). The studied lattice constants and volume are different from the chosen systems, and the crystal stability is also justified in particular. Among six studied compounds, Sn-based compounds show lower band gaps than Ge-based compounds, where I at site X shows the lowest band gaps. The illustration of the density of states and the specific projection of the electronic contribution of atomic orbitals were added to verify the actual semiconducting electronic behavior. The presence of dual chemical bonds is confirmed by bond length statistics and charge density distribution. The optical properties vary among the compounds, and there is an opposite behavior between low and high-energy regions. TlGeX3 has a higher Young modulus, bulk modulus, and shear modulus than TlSnX3, whereas the hardness and anisotropic behavior are lower than TlSnX3. In this investigation, three-dimensional diagrams of elastic moduli have been depicted using the ELATE tool, which facilitates the easy identification of anisotropic elastic properties. Furthermore, this study will shed light on how to fabricate lead-free inorganic perovskites for use in optoelectronics.
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•Employing density functional theory, an investigation was conducted into the diverse physical properties of MSnI3 (M = K, Rb) perovskites under different hydrostatic pressures.•This ...exploration revealed a noteworthy semiconductor-to-metallic transition under applied pressures, resulting in the reduction of band gaps.•The pressure-induced red shift in the absorption edge enhances optical functions, making MSnI3 perovskites more versatile for optoelectronic applications.•External pressure also influences the ductile and anisotropic nature of MSnI3, impacting mechanical qualities and performance in different conditions.
In optoelectronic device applications, perovskite materials have overtaken other compounds because of their exceptional power conversion efficiencies. Lead-based perovskites have found extensive use; however, their widespread adoption is hindered by the inherent toxicity associated with lead content. In contrast, lead-free metal halide perovskites have taken the dominant position in the commercialization of optoelectronic devices by offering high efficiency, affordability, flexibility, tunability, and environmental benefits. To better understand the structural, electronic, bonding, optical, elastic, and mechanical properties of the non-toxic MSnI3 (M = K, Rb) metal halides under different hydrostatic pressures, a first-principles simulation has been carried out with the use of density functional theory (DFT). Lattice parameters and electronic band structures have been computed using both the Generalized Gradient Approximation (GGA) and the non-local hybrid sX (Hartree-Fock screened exchange) functional. Utilizing the sX method results in enhanced band gap values for MSnI3 (M = K, Rb) perovskite compounds. The application of pressure has led to a decrease in both lattice parameters and band gaps, marking a transition from a semiconductor to a metallic state. The projection of the density of states and their electronic orbital contributions are also explored to evaluate the band structure tuning of MSnI3 (M = K, Rb) under pressure. The bond length calculation and the charge density mapping confirm the existence of both the ionic and covalent bonds in MSnI3 (M = K, Rb). Additionally, the pressure-induced calculation suggests that the bonds between both compounds will be stronger at high pressure. Increasing hydrostatic pressure causes a dramatic movement of the absorption edge of MSnI3 (M = K, Rb) perovskites into the low energy region (a red shift), which is revealed by the analysis of optical functions. The optical functions’ investigation indicates that the hydrostatic pressure allows the compounds even better for a number of possible uses. The mechanical qualities are a direct reflection of the ductile and anisotropic nature of the compounds, both of which are significantly influenced by the external pressure.
