Analysis of Temperature Dependent Surface Recombination Properties

To understand and maximize the annual energy output of silicon based photovoltaic modules beyond standard testing conditions (STC) it is of utmost importance to get insight into the temperature dependent device properties of silicon solar cells. In this study we demonstrate an approach which allows for both a global and a local characterization of effective recombination at the sample/air interface with varying injection and temperature. We investigate with SiNx or Al2O3 symmetrically passivated lifetime samples with temperature dependent lifetime measurements via modulated photoluminescence. Results show a decreasing effective surface recombination velocity with temperature and a significant injection-dependence. The results indicate a laterally varying and injection dependent temperature coefficient of the effective surface recombination. The common assumption of temperature-independent J0/ni2 for device simulations is demonstrated to cause errors of up to 30 percent. Our results can serve to improve temperature dependent device modelling for predicting and optimizing solar cell performance beyond STC as the proposed analysis is applicable to lifetime samples as well as wafers with diffused surfaces.