To produce the combined structure, the team from Tianjin University, China, first fabricates n-type ZnO nanorod arrays on conductive glass substrates and then electrochemically deposits n-type CdS and p-type CdTe nanocrytals sequentially on the ZnO nanorods. The researchers found that the overall conversion efficiency of the ZnO/CdS/CdTe photoelectrode is more than three times the value of the sum of ZnO/CdS and ZnO/CdTe photoelectrodes.

Detailed investigations suggested that the cascade band structure of the ZnO/CdS/CdTe photoelectrode facilitated charge separation and hole transfer, which contributed to the improvement in overall conversion efficiency. A further enhancement in device performance can be anticipated by lengthening the ZnO nanorods and reducing the carrier recombination, such as adding an electron blocking layer outside the CdTe nanocrystals.

Full details can be found in the journal Nanotechnology.