Effect of back-contact barrier on thin-film CdTe solar cells

The presence of a back-contact barrier affects the current-voltage characteristics of thin-film CdS/CdTe/metal solar cells primarily by impeding hole transport, a current-limiting effect commonly referred to as rollover. In this work, the CdS/CdTe solar cell with a CdTe/metal back-contact barrier is modeled by two opposite polarity diodes in series. Analytic simulations are fitted to the measured current-voltage curve, the voltage distribution between the two diodes is shown under different conditions, and the back-contact barrier height is extracted. Room-temperature barrier heights exceeding 0.5 eV will generally result in significant fill-factor reduction. (c) 2006 Elsevier B.V. All rights reserved.