Modulated photocurrent spectroscopy of CdTe/CdS solar cells-equivalent circuit analysis

Modulated photocurrent spectroscopy was used to investigate the dynamic response of charge carrier transport in thin film CdTe/CdS solar cells. The impact of light bias and temperature over a broad excitation frequency range were measured. The observed features of the data, including a photocurrent 'phase-lead' and a 'phase-lag' over different regions of the frequency spectrum, were explored in the context of an equivalent circuit model. Comparisons between the model's predicted performance and the measured data suggest that charge carrier recombination at the cell's back metal/semiconductor contact is the main source of photocurrent loss in these devices.