Analysis of thin film polycrystalline cadmium telluride-based solar cell devices

We have conducted extensive experimental measurements on optimized high efficiency polycrystalline thin film CdTe/CdS heterojunction solar cell devices fabricated at the Institute of Energy Conversion, University of Delaware.;Detailed analysis of the experimental results strongly suggest that carrier recombination through a nearly exponential distribution of states within the band gap of the CdTe absorber layer is the dominant current transport mechanism in these devices. Temperature dependent current voltage measurements consistently show that diode A factors have values between 1 and 2 and are temperature dependent. Low temperature non-ohmic behaviors are observed in all measured devices. Open circuit voltage analysis under various light illumination is in good agreement with the theoretical model of recombination through an exponential density of states within the CdTe absorber layer.