Abstract
Differential photovoltaic characteristics of PbS layer deposited chemically on frosted glass and oxidized by heating in an air atmosphere have been determined experimentally. The sign and the magnitude of photovoltage of PbS layer depend on the incident direction and the intensity of light falling on PbS layer.
Two tungsten lamps are used as light sources for measurement of differential photovoltage of PbS layer, and it is confirmed after several experiments that the photovoltage of PbS layer when two tungsten lamps are lighted simultaneously is an algebraical sum of each photovoltage due to the individual light source.
By regulating the incident direction and the intensity of the light of each tungsten lamp adequately, the photovoltage of PbS layer should be reduced to zero, and so the possibility ofnull method photometry is proposed.
In order to illustrate the mechanism of differential photovoltalic effect, a model of “secondary p-n boundary of PbS layer” is proposed.
Temperature dependence of the photovoltage of PbS layer and the value of activation energy are obtained experimentally, spectral response of the photovoltage shows no incident direction dependence.
When this PbS layer is used as photovoltaic cell, the photovoltage must be measured by vacuum tube voltmeter having sufficiently high input impedence because the resistance of the PbS layer used is 3 MΩ/cm2-15MΩ/cm2.
