The electron affinity difference in CdS-Cu₂S thin film solar cells

Abstract

The electron affinity difference Delta Ec= chi 2- chi 1, in CdS-Cu2S solar cells fabricated by four different processes has been measured from observations of the variations of open-circuit voltages with temperature. For CdS-Cu2S cells, the values of Delta Ec lie between 0.25 and 0.35 eV and are found to be independent of the process of cell fabrication. The use of ZnxCd1-xS in place of CdS reduces the value of Delta Ec to somewhat less than 0.1 eV. The method used for the measurement of Delta Ec is very simple. The values of the saturation current I0 for the different type of cells have been estimated from the slopes of qVoc versus kT plots and compared with those obtained from ln I versus V curves. The values of Io found for each cell by the two methods are in substantial agreement.