Carrier Transport in Polycrystalline Silicon Thin Film Solar Cells Grown on a Highly Textured Structure

Abstract

Photovoltaic performance of polycrystalline silicon (poly-Si) thin film solar cells deposited by plasma enhanced chemical vapor deposition at a low temperature of ∼200°C have been investigated as a function of surface structures of textured substrates, which are needed for enhancing the light trapping effect. With increasing surface roughness of the substrate, the light trapping effect is increased, while the photovoltaic performance is decreased because the carrier transport in the poly-Si photovoltaic layer depends on the poly-Si microstructures which are significantly deteriorated by the surface texture. To quantify the effect of the surface roughness, a simple one-dimensional simulation model consisting of two regions, i.e., the initial growth region near the substrate with poor crystallinity and the postgrowth region, is proposed for the photovoltaic performance of the poly-Si thin film solar cells with different poly-Si layer thicknesses. The simulation result reveals that the carrier transport in the initial growth region more strongly depends on the surface roughness compared with that in the postgrowth region.