CdTe thin-film solar cells are usually composed of n-CdS/p-CdTe. The treatment of CdS in the magnetron chamber prior to radio-frequency magnetron sputtering of CdTe had a significant effect on the properties of CdTe solar cells. We found that a CdS cooling and reheating process prior to CdTe deposition had a significant effect on the energy conversion efficiency and open circuit voltage of CdTe solar cells. Without cooling and reheating CdS before CdTe deposition, the energy conversion efficiency and open circuit voltage of the CdTe solar cell only reached 12.0 +/- 0.5% and 759 +/- 1 mV, respectively. However, the energy conversion efficiency and open circuit voltage of the CdTe solar cell with a CdS cooling and reheating process before CdTe deposition were 13.3 +/- 0.3% and 828 +/- 1 mV, respectively. CdS films after the cooling and reheating process had larger grains, superior crystalline quality, and a higher S/Cd atomic ratio compared with films that did not undergo a CdS cooling and reheating process. CdTe grown on CdS with a cooling and reheating process had the largest grain size after chloride treatment. (C) 2015 Elsevier Ltd. All rights reserved.