PbS, CdSe Mixed Differential Photovoltaic Cell

The differential photovoltaic characteristics of PbS-CdSe mixed vapour deposited layers have been observed experimentally. The photoelectromotiveforce of the mixed layers which two tungsten lamps light simultaneously is obtained as an algebraical sum of each photoelectromotiveforce due to the individual light source. Equal amounts of PbS and CdSe are mixed and evaporated from a molybdenum boat onto a roughened surface of a frosted glass plate in a vacuum of about 5 × 10<-5> mmHg. After evaporation, the mixed layer is heated at 340℃ for about ten minutes in an air atmosphere and then the photoelectromotiveforce of the layer appears. Comparing the spectral response of mixed layers with that of photovoltaic PbS layers, the sensitivity in a near infrared region is more or less inferior but the sensitivity in the visible region is much superior, the spectral response of mixed layers shows no incident direction dependence. The decrease in the photoelectromotiveforce of mixed layers due to the lapse of time is seen scarcely, the photovoltaic characteristics of mixed layers are seen to be much more stable than those of PbS photovoltaic layers. From the data of X ray diffraction, the existence of PbS, CdSe, PbSe and PbSO_4 are found in mixed layers after heat treatment.The temperature dependence of the photoelectromotiveforce of mixed layers and the value of the activation energy are obtained experimentally, the mechanism of photoelectromotive-force generation is discussed and the model of the layer is proposed.