IMPEDANCE SPECTROSCOPY OF SILICON SOLAR CELLS

Abstract

In this thesis, impedance spectroscopy was performed on both large-area and small-area silicon solar cells to characterize the impedance of the solar cells. Impedance spectroscopy using silicon cells is relatively novel, and the new contribution to knowledge here was that emitter saturation current density effects the shape i.e. height of the semicircular-shape of the Nyquist plots the most. In addition, simplified RC equivalent circuit was fitted to two of the Nyquist plots, and charge transfer resistance plotted against frequency. Saturation current density was also calculated using two methods, and the values compared with one another. In the PERC and Al-BSF cells, the J0 values using both methods were similar. However, in the n-type bifacial cell, the J0 values were had a difference of one order of magnitude, due to lower fill factor of this n-type bifacial sample.