Chemical Vapour Etching For Double-sided Buried Metallic Contacts In Polycrystalline Silicon Solar Cells Processing

摘要

In this paper, we investigate the effect of double-sided buried metallicontacts (BMCs) on the photovoltaic performances of polycrystalline-silicon (pc-Si) solar cells. Prior to junction formation, groove patterns were achieved on both surface sides of the pc-Si wafers using a chemical vapour etching-based technique. The BMCs were realized onto the grooved areas using the screen printing technique. Once the BMCs were formed, we point out a significant increase of the spectral response in the 400-1100 nm wavelength range, particularly at short and long wavelengths. These results were attributed to an enlargement of the contact areas in both emitter and base regions of the cells, leading to a reduction of their effective thickness and to an enhancement of the minority carrier collection. The dark I-V characteristics of BMCs-based pc-Si cells show a significant reduction of the reverse current together with an improvement of the rectifying behaviour. The I-V characteristic under AM 1.5 illumination shows that the introduction of BMCs in polycrystalline silicon solar cells processing improves the conversion efficiency by about 2.5-3.5%.