The electron affinity difference in CdS/CuInSe2 solar cells

The electron affinity difference Delta E-c = chi(1) - chi(2), in CdS/CuInSe2 solar cells fabricated by four different processes has been measured from observations of the variations of open-circuit voltages with temperature. For CdS/CuInSe2 cells the values of Delta E-c lie between 0.20 and 0.30 eV and are found to be independent of the process of cell fabrication. The use of CdZnS in place of CdS reduces the value of Delta E-c to slightly less than 0.1 eV. The method used for the measurement of Delta E-c is very simple. The values of the saturation current I-o for the different types of cells have been estimated from the slopes of qV(oc) versus kT characteristics and compared with those obtained from In I versus V curves. The values of I-o found for each cell by the two methods are in fair agreement. (C) 1998 Elsevier Science B.V. All rights reserved.