This study investigates the structural, electronic, optical, and mechanical properties of non-toxic, francium-based halide perovskites FrXCl3 (X = Ge, Sn) under hydrostatic pressure using Density Functional Theory (DFT). The research aims to explore how pressure affects the physical properties of these compounds, which are potential alternatives to lead-based perovskites due to their stability and environmental friendliness. Key findings include: 1. **Structural Properties**: The lattice parameter and unit cell volume decrease with increasing pressure, indicating shorter interatomic distances. Bond lengths between Fr–Cl and X–Cl (X = Ge, Sn) also shorten, leading to compressive strain. 2. **Electronic Properties**: Both compounds exhibit a direct band gap, but under pressure, the band gap reduces to zero, transitioning from semiconductors to metals. The electronic density of states around the Fermi level increases, enhancing optoelectronic performance. 3. **Mechanical Properties**: The compounds exhibit mechanical stability and ductility, with elastic constants and mechanical moduli increasing under pressure. The materials become more ductile, as indicated by higher Pugh's ratio and Poisson's ratio. 4. **Optical Properties**: The static dielectric function (ε1(0)) increases significantly under pressure, suggesting improved charge carrier mobility. Absorption spectra shift towards lower photon energies, indicating enhanced light absorption in the visible and infrared regions. 5. **Conclusion**: The study demonstrates that FrXCl3 (X = Ge, Sn) perovskites under pressure exhibit promising optoelectronic properties, making them suitable for applications in solar cells and other optoelectronic devices. The findings highlight the potential of these compounds for environmentally friendly and efficient optoelectronic devices.This study investigates the structural, electronic, optical, and mechanical properties of non-toxic, francium-based halide perovskites FrXCl3 (X = Ge, Sn) under hydrostatic pressure using Density Functional Theory (DFT). The research aims to explore how pressure affects the physical properties of these compounds, which are potential alternatives to lead-based perovskites due to their stability and environmental friendliness. Key findings include: 1. **Structural Properties**: The lattice parameter and unit cell volume decrease with increasing pressure, indicating shorter interatomic distances. Bond lengths between Fr–Cl and X–Cl (X = Ge, Sn) also shorten, leading to compressive strain. 2. **Electronic Properties**: Both compounds exhibit a direct band gap, but under pressure, the band gap reduces to zero, transitioning from semiconductors to metals. The electronic density of states around the Fermi level increases, enhancing optoelectronic performance. 3. **Mechanical Properties**: The compounds exhibit mechanical stability and ductility, with elastic constants and mechanical moduli increasing under pressure. The materials become more ductile, as indicated by higher Pugh's ratio and Poisson's ratio. 4. **Optical Properties**: The static dielectric function (ε1(0)) increases significantly under pressure, suggesting improved charge carrier mobility. Absorption spectra shift towards lower photon energies, indicating enhanced light absorption in the visible and infrared regions. 5. **Conclusion**: The study demonstrates that FrXCl3 (X = Ge, Sn) perovskites under pressure exhibit promising optoelectronic properties, making them suitable for applications in solar cells and other optoelectronic devices. The findings highlight the potential of these compounds for environmentally friendly and efficient optoelectronic devices.