Ternary-structured thiospinels have attracted great attention in recent years for energy applications due to their attractive characteristics such as simple production, earth-abundant components and non-toxic nature. In this work, copper cobalt sulfide (CuCo2S4 or carrollite) thiospinel nanocrystals were synthesized by a hot-injection method, and detailed electrical and optoelectronic characterizations were performed in a Schottky device. The synthesized nanocrystals were used as an interfacial layer between the Au metal and p-Si semiconductor to obtain an Au/CuCo2S4/p-Si device. The structural and morphological characterizations confirmed the crystallinity, nanostructure and composition of the CuCo2S4 nanocrystals. The I–V and C–V measurements were employed to characterize the Au/CuCo2S4/p-Si device for various illumination intensities. The obtained device exhibited good rectifying and photodiode properties as well as good photocapacitance. The Au/CuCo2S4/p-Si device can be used and improved for optoelectronic applications.