Study of Mis Multicrysraline Silicon Thin-Film Solar Cell

Abstract

State-of-the-art of multicrystalline Silicon (mc-Si) material with minority carrier diffusion lengths exceeding the wafer thickness is commercially available today. It is expected that the diffusion length to wafer thickness ratio will be increasing further due to improved material quality and due to the trend towards thinner wafers to reduce material costs. As a result, the open circuit voltage, V oc decreases with increasing temperature according the ratio V oc /T = 0.00337 mVK-1. The output power decrease with increasing temperature mainly because of a decrease in the photovoltaic and fill factor of the current voltage characteristic. This happens in samples which have P /T =  0.00048 WK-1 , FF / T = 0.002 %K-1 , and R / T =  0.021  K-1. In order to fully exploit the material quality, a solar cell process that includes excellent rear surface passivity is needed. In this paper solar cell results from thin mc-Si solar cells with silicon nitride front and rear surface passivity are presented. Furthermore, the most important loss mechanisms with respect to thin mc-Si cells namely : (i) optical losses, (ii) losses due to rear surface recombination and (iii) losses due to the series resistance caused by local rear contact schemes with dielectric passivity are discussed. The light trapping effect of this structure is also confirmed reflection at the weakly absorbed wavelength.