LARGE-AREA HONEYCOMB TEXTURING OF SI-SOLAR CELLS VIA NANOIMPRINT LITHOGRAPHY

摘要

The highest solar cell efficiencies on mc-Si were realized using photolithographically defined texturing processes. The feasibility of fabricating honeycomb textures using Nanoimprint Lithography (NIL) was already demonstrated and excellent short-circuit current densities of up to 40.7 mA/cm~2 were achieved on small-area monocrystalline silicon (c-Si) solar cells. In the present work, large-area honeycomb texturing of multicrystalline silicon (mc-Si) substrates based on Roller-NIL and in-line-capable multi-wafer plasma etching using a modified Roth&Rau SiNA system is demonstrated. The realized honeycomb texture shows superior optical properties compared to isotextured mc-Si reference samples and even random pyramids on c-Si substrates, while surface passivation is comparably good. The fabricated 156 × 156 mm~2 mc-Si solar cells with A1-BSF show an efficiency of 17.8% compared to 17.3% of the isotextured reference. As V_(oc) remains constant for both textures, the efficiency gain of 0.5% absolute results from a J_(sc) increase of up to 1.3 mA/cm~2 (on cut 50 × 50 mm~2 cells even 2.5 mA/cm~2), which confirms the superior optical quality of the honeycomb texture.