A novel silver nanoparticle assisted texture as broadband antireflection coating for solar cell applications

To maximise the degree of light incoupling, therefore improving the short circuit current and efficiency of solar cells, a novel subwavelength (SW) structured 'moth-eye' antireflection coating (ARC) is formed on the sun-facing side of the glass superstrate. This moth-eye structure in theory can suppress reflection entirely in the 300-1200 nm wavelength range. It is produced by fabricating a mask, followed by reactive ion etch. In this paper, we present a novel etch mask, a random Ag nanoparticle array on glass with feature size ranging from ∼50 nm to ∼350 nm. The subwavelength features can be adjusted by varying the size, shape and distribution of the Ag nanoparticle array, which in turn is tuned by varying as-deposited Ag thickness. The optimal structures reduce reflection loss by a current equivalent of 1.25 mA/cm² for a 3.3 mm borosilicate glass (BSG) superstrate, by 1.39 mA/cm² for 1.1 mm BSG and enhances J_sc by 3.4% on average for 2.4 μm poly-Si thin-film solar cells on 3.3 mm BSG. On Si film side of the glass surface, a preliminary modulated texture investigation, consisting of growing SW structure on micron sized aluminium induced textured (AIT) glass reduced reflection loss by ∼7% compared to original AIT samples.