The present invention relates to light-converting materials which comprise semiconductor nanoparticles and an unactivated crystalline material, where the semiconductor nanoparticles are located on the surface of the unactivated crystalline material. The present invention furthermore relates to the use of the light-converting material in a light source. The present invention furthermore relates to a light-converting mixture, to a light source, to a lighting unit which contains the light-converting material according to the invention, and to a process for the production of the light source.