We have developed an efficient strategy to improve the brightness and stability of CuInS2 quantum dots via Ga3+ doping combined with the overgrowth of a ZnS shell. The incorporation of Ga3+ into crystal lattices greatly suppresses the diffusion of Cu+ and reduces the formation of Cu-related defects, leading to a photoluminescence quantum yield as high as 92%. These nanocrystals can be integrated into luminescent solar concentrators and the devices exhibit a power conversion efficiency reaching 3.87%.