PHOTORESPONSES OF SEMICONDUCTOR POLYCRYSTALLITES SEPARATING TWO AQUEOUS SOLUTIONS

Solar cells using polycarbonate membranes, with CdS deposited on them, were made by a very simple way; the CdS-containing membrane separates a Lucite cell into two compartments. On illumination, about 150 mV photovoltage ( V _op) and 0.5 μA cm^-2 photocurrent ( I _sc) could be produced; one side of the membrane acted as photoanode, and the other side as photocathode. By means of coating Victoria Blue B (VBB) onto the membrane before CdS deposition, the maximum V _op and I _sc of the CdS-deposited membrane could reach 500 mV and 3.0 (μA cm^-2, respectively. A mixture of CdS and CdSe deposited membrane has also been tested and found to have both the advantages of high photovoltage (over 400 mV) and good stability after modification. Even more interesting results were also obtained with CdSe pellets in place of the CdS-deposited membrane, in which V _op and I _sc of the cell were 1.2 V and 6 mA cm^-2, respectively. The essential aspect of the system, modelled after the photosynthetic thylakoid membrane, contains an asymmetrical, ultrathin semiconductor crystallite layer separating two aqueous solutions.