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

• Published in: Solar energy materials and solar cells 2013-09, Vol.116, p.126-134
• Main Authors: Hamadani, B.H., Roller, J., Kounavis, P., Zhitenev, N.B., Gundlach, D.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cadmium tellurides; Charge carriers; Energy; Exact sciences and technology; Mathematical models; Natural energy; Photocurrent; Photoelectric effect; Photovoltaic conversion; Semiconductors; Solar cells; Solar cells. Photoelectrochemical cells; Solar energy; Spectroscopy
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2013.04.011

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. •Modulated photocurrent spectroscopy was used to study charge dynamic response in solar cells.•The impact of light bias and temperature over a broad frequency range was studied.•Data revealed important photocurrent signatures regarding carrier recombination in the device.•A very simple equivalent circuit model explains the data very well at higher temperatures.•Charge carrier recombination at the back contact is the main source of photocurrent loss.