A Research on Improvement of Hydrogen Generation using CdS/CIGS Photo-Electrode in Photoelectrochemical System

We investigated the photoelectrochemical (PEC) properties of CdS/CIGS thin films as the hydrogen-generating photo-electrode in Na2SO4 electrolyte. The onset potential of CIGS of thin film by itself which is a point of beginning redox reaction for hydrogen generation was -0.6 V under illumination of 200 mW. However, with the deposition of CdS layer on CIGS film, CdS/CIGS structures produced three times enhanced photocurrents at -0.1 V vs compared with only CIGS thin film. CdS layer has ideal band-gap energy and position for redox reaction under visible light irradiation. Also, CdS layer could make P-N junction with CIGS film and form stepwise band-gap structure, which help electrons and holes transfer more easily. From these results, CdS/CIGS thin films could be regarded as a promising photo-electrode cell structure for hydrogen generation.