In summary, we demonstrate a pre-pattern substrate on a-Si thin film solar cells, to serve both anti-reflectance and light trapping. The fabrication of the PSS is based on the colloidal lithography and the reactive-ion etching technique, which is applicable for large area production. The pre-patterned structure embedded in the amorphous materials demonstrates sufficient light coupling at normal incidence, enhancing the photon absorption. The power conversion efficiency of the pre-patterned cell was measured 8.38%, which showed 56.34%
and 8.83% enhancement compared to the reference cell with a flat substrate and the commercialized Asahi U-type substrate, respectively. Angle-resolved absorption spectroscopy measurements also show enhanced light coupling to the cells at oblique angle of incidence.
This result can directly impact the attainment of scalable renewable energy from a-Si thin-film solar cells. Finally, we obtained the optimized pattern by rigorous coupled wave analysis method. The best structure on our pre-patterned substrate is 500 nm bottom width and 400~450 nm height of SiNx nipple pattern. The resulting light management effects directly enable high-efficiency a-Si:H solar cells and are also broadly applicable to other common thin film solar cells such as poly- and micro-crystalline Si, CdSe, and organic solar cells.
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