Highly luminescent cadmium telluride (CdTe) nanocrystals were synthesized using Li2[Cd4(SPh)10] as a reactive Cd cluster compound at relatively low temperature, making it a safe precursor for the large scale synthesis of CdTe nanocrystals. Transmission electron microscopy (TEM) showed that the shape of the CdTe nanocrystals changes from nanorods to branched structures with increasing reaction time. The nanocrystals show high luminescent quantum yields up to 37% for CdTe branched nanostructures, and as high as 52% for CdTe/CdS core–shell heterostructures. CdTe/CdS nanocrystals were used to make light-emitting diodes in combination with organic layers for electron and hole injection. The devices show a maximum luminance efficiency of 0.35 cd A-1.