Temperature Dependence of Dark Current-Voltage Characteristics of Hydrogenated Amorphous and Nanocrystalline Silicon Based Solar Cells

Abstract

AbstractSystematic measurements of dark current density versus voltage (J-V) characteristics were carried out on a-Si:H, a-SiGe:H, and nc-Si:H solar cells at different temperatures from 23°C to 150°C. In a first order approximation, the dark J-V characteristics follow the standard diode characteristic formula for most high quality solar cells. The temperature dependence of the reverse saturation current can be used for deducing the intrinsic layer bandgap for the three types of solar cells. From a detailed analysis using the derivative of the measured dark J-V characteristics, we obtain different features in the plot of ideality factor versus bias voltage for the three types of solar cells. We also deduce the distribution of density of states using a recently proposed procedure [1]. In general, a peak near the middle of the bandgap appears for the three types of solar cells; below the middle of the bandgap, there is an exponential-like broad distribution of gap states. However, the calculated gap state distribution shows a temperature dependence, which may be caused by the simplification of the calculation procedure.