Extended quantitative characterization of solar cell from calibrated voltage-dependent electroluminescence imaging

Abstract

In this paper, we derived a new method to map various optoelectronic parameters of solar cells from voltage-dependent electroluminescence imaging. To get quantitative data, we show how the voltage dependence of electroluminescence mimics a local diode current-voltage behavior, and we propose a way to measure the absolute electroluminescence flux. We therefore introduce a calibration factor generally left unknown in the literature. Example is shown on the Al-BSF silicon solar cell for which we map several parameters: diffusion lengths, dark saturation current, local voltages, and lumped series resistances with good accuracy. Comparison with other electroluminescence imaging methods is also shown. Preliminary knowledge about the sample are the spectral reflection coefficient, average dopant concentration, and back surface recombination. This method can also be derived for other kinds of solar cells by using an appropriate carrier collection model depending on their structure.