We have used the technique of photocurrent modulated spectroscopy to investigate the dynamic response of charge carrier transport in thin film CdTe/CdS solar cells as a function of light bias and temperature over a broad excitation frequency range. The observed features of the data, including a photocurrent phase-lead and a phase-lag revealed over different regions of the frequency spectrum, were explored in the context of an equivalent circuit model incorporating a back-contact barrier that limits the photocurrent collection at the metal/semiconductor contact. Good agreement was observed between the data and the predictions of the model and point to charge carrier recombination at the back contact as the main source of photocurrent loss observed in these devices.
Citation: Solar Energy Materials and Solar Cells
Pub Type: Journals
solar cells, CdTe, thin films, photovoltaic, modulated photocurrent spectroscopy