A comparative study of semiconductor sensitization by micro-crystals of indium sulfide on various porous wide band gap semiconductor substrates

Semiconductor sensitization on various n-type wide band gap semiconductors was studied by micro-crystals of n-type indium sulfide. The generation of an anodic photocurrent on the electrode is explained from the viewpoint of semiconductor sensitization. A very high incident photon-to-current conversion efficiency (IPCE) of more than 80% was achieved on In2S3/In2O3 electrodes in a polysulfide electrolyte. The observed values for the IPCE for In2S3/TiO2 and In2S3/ZnO electrodes were rather low compared to that of In2S3/In2O3 electrodes, in the same electrolyte. The semiconductor sensitization process was not observed on In2S3/ZnS electrodes. Different kinetics at the semiconductor/semiconductor interface are the reasons for the observed difference of the IPCE, for the electrodes.