Quantum-size silicon (Si) nanorods bridge the gap in understanding between Si nanocrystals and nanowires.To produce Si nanorods with precise lengths and diameters requires a hybrid approach that combines colloidal chemistry with metal-seeded solution-liquid-solid (SLS) growth.As such, capping ligands play a key role in limiting the Si nanorod diameter to about 5 nm—the size at which quantum confinement effects emerge for Si—while maintaining uniform nanorod length.The choice of metal growth seed also dramatically affects the nanorod optical properties—tin-seeded nanorods exhibit bright near-infrared photoluminescence after tip removal, while gold seeds quench photoluminescence.