Pressure-driven modification of optoelectronic features of ACaCl3 (A = Cs, Tl) for device applications.

Intending to advance the use of halide-perovskites in technological applications, in this research, we investigate the structural, electronic, optical, and mechanical behavior of metal-halide perovskites ACaCl3 (A = Cs, Tl) through first-principle analysis and assess their potential applications. Due to the applied hydrostatic pressure, the interaction between constituent atoms increases, thereby causing the lattice parameter to decrease. The band structure reveals that band gap nature transits from indirect to direct at elevated pressure. Moreover, at high pressure, the electronic band structure shows a notable band gap contraction from the insulator (>5.0 eV) to the semiconductor region, which makes them promising for electronic applications. The charge density map explores the ionic and covalent characteristics of Cs/Tl-Cl and Ca-Cl under pressured and unpressurized environments. Induced pressure enhances the optical conductivity as well as the optical absorption that moves toward the low-energy region (red shift), making ACaCl3 (A = Cs, Tl) advantageous for optoelectronic applications. Additionally, this study reveals that the mechanical properties of ductility and anisotropy were found to be improved at higher pressures than in ambient conditions. Overall, this study will shed light on the technological applications of lead-free halide perovskites in extreme pressure conditions.

Ultra-violet to visible band gap engineering of cubic halide KCaCl3 perovskite under pressure for optoelectronic applications: insights from DFT.

Density functional theory is utilized to explore the effects of hydrostatic pressure on the structural, electrical, optical, and mechanical properties of cubic halide perovskite KCaCl3 throughout this study. The interatomic distance is decreased due to the pressure effect, which dramatically lowers the lattice constant and unit cell volume of this perovskite. Under pressure, the electronic band gap shrinks from the ultra-violet to visible region, making it easier to move electrons from the valence band to the conduction band, which improves optoelectronic device efficiency. Furthermore, the band gap nature is switched from indirect to direct around 40 GPa pressure, which is more suitable for a material to be exploited in optoelectronic applications. The use of KCaCl3 in microelectronics, integrated circuits, QLED, OLED, solar cells, waveguides, solar heat reduction materials, and surgical instruments has been suggested through deep optical analysis. The use of external hydrostatic pressure has a considerable impact on the mechanical properties of this material, making it more ductile and anisotropic.