Silicon-tin alloy nanocrystals with quantum confinement effect for photovoltaics. Synthetized nanoparticles with average of 3 nm in diameter and optical bandgap of 0.81 eV at room temperature were obtained with a Si (0.88)/Sn (0.12) alloyed composition that corresponds to a ratio of about eight Si atoms for every Sn atom. The potential of silicon-tin nanocrystals as a photovoltaic material is assessed and an enhancement of the solar cells performance is demonstrated due to the extended spectral range and increased absorption. (Materials Today Energy 7, 2018, 87).