Solution Processed CuCl treatment for efficient CdS/CdTe Solar Cells

Copper (Cu) doping is a crucial process to improve the hole concentration in CdTe absorber layer and reduce the back-barrier height for efficient CdTe solar cells. However, excess Cu creates detrimental defects and deteriorates device stability due to its high diffusivity. Here, we introduce a wet chemical method to incorporate Cu in CdTe using a CuCl solution. This approach allows a better control of Cu doping than the conventional method using evaporated Cu. Our investigation shows that the CuCl treatment can significantly improve the overall device performances due to an increased carrier concentration in the CuCl treated CdTe absorber layer. Furthermore, the CuCl treated devices show a longer minority carrier lifetime than the conventional Cu treated devices.