Study on correlation of thicknesses of transparent electrodes and performance of silicon heterojunction solar cells

Abstract

We investigated the effects of the thicknesses of indium tin oxide (ITO) transparent conducting oxide films on the device performance of silicon heterojunction solar cells. It was observed that the fill factor of the solar cells significantly decreased from 70.9 to 59.4% with increasing ITO thicknesses from 66 to 93 nm, leading to a decrease in solar conversion efficiency. As the thickness of ITO films increased, the Voc × FF products of solar cells decreased, even though the FOM (Figure-Of-Merit) of the ITO films monotonically increased. The degradation effects could not be fully recovered, even after annealing, which overwhelmed the effect of improved FOM on thicker ITO films. This effect will be discussed based upon the role of sputter induced damage for the deteriorated MCLT (minority carrier lifetime) and implied Voc of the p-a-Si:H/i-a-Si:H/n-c-Si/i-a-Si:H/n-a-Si:H structures.