<p>In this study, we engineered SiPGaS/SnC heterostructures with atomically sharp interfaces, confirming their thermal and dynamical stabilities through first-principles analysis. Depending on the specific stacking configurations, these heterostructures exhibit a type-II band alignment with band gap ranging from 0.73&#xa0;eV to 1.23&#xa0;eV and spatially segregated electrons and holes within the SiPGaS and SnC layers. Furthermore, these heterostructures exhibit a substantial potential drop of 10.60–11.68&#xa0;eV and a robust built-in electric field of 3.07–3.46 eVÅ⁻¹, which minimized recombination rate of photoinduced charge carriers and extended lifetimes. Specifically, they could be employed for efficient solar energy harvesting owing to their high absorption coefficient for the ultraviolet and visible light regions. The electron and hole carrier mobilities of these heterostructures are estimated to be within the range of 10² cm²V^-1S^-1. In addition, we demonstrate strongly modulated electronic and optical properties through biaxial strain, achieving an indirect-to-direct band gap transition and an enhanced power conversion efficiency up to 20%. The various marked features hosted by the SiPGaS/SnC-based heterostructures make them suitable for nanoelectronic and optoelectronic devices.</p> Graphical abstract <p></p>