Antireflection with graphene oxide

Graphene oxide (GO) obtained by chemical exfoliation exhibits a quasi-2D structure. Its refractive index is very close to the theoretically predicted best refractive index for a single antireflection coating layer between air and Si. The robust honeycomb plane structure of GO makes it a promising mask candidate for surface texturizing. Here, we demonstrate different GO distributions on Si, and report the reflection properties before and after etching. For an etched Si substrate with suitable GO coating, the reflectance reached 2.1% at 667 nm. Preliminary 1.5-min-long etching of a p+nn+ solar cell with a GO mask boosted the efficiency from 7.09% to 7.55%.