Injected current-related distortion of photothermal signals from a photovoltaic cell

When power dissipation in a photovoltaic cell is measured as a function of load resistance via photothermal techniques which sense only part of the photovoltaic cell, significant deviations from previously reported photoacoustic measurements can be obtained. These deviations occur under nonuniform illumination. They are due to the fact that, under these experimental conditions, the measured signal is proportional to only part of the power dissipation by injected carriers, while all of the photogenerated carriers contribute to the signal. Results from photothermal radiometry experiments are presented and explained in this way.