Antireflection Coatings Based on Randomly Oriented ZnO Nanowires

Glass is the most widely used transparent material for photovoltaic (PV) panels. Unfortunately, the glass introduces an additional interface and therefore optical losses, which can be mitigated using antireflection (AR) coatings. This article reports a scalable method to prepare AR coatings from ZnO nanowires (NWs) sorted by their size. The measured AR performance depends on the coating coverage and ZnO NW size, which is explained by scattering and absorption cross section simulations. Randomly oriented and size fractioned ZnO NWs with an average diameter of 19-30 nm and lengths of 121-273 nm demonstrate increased transmittance and decreased reflectance compared to a glass substrate in case of low coverage. The experimental PV modules with ZnO NW coatings show an 1.2% increase of the short circuit current. A strategy to decouple ZnO NW synthesis from AR coating preparation allows to tune NW reflectance and other optical properties by varying the length, diameter, and orientation of the constituent NWs. The proposed AR coating made from size-sorted nanomaterials is not limited to ZnO and the method could be adapted to other materials and nanostructures.

Automated summary

This article presents a scalable method to prepare antireflection coatings from size-sorted ZnO nanowires, which can reduce the optical losses in photovoltaic panels. The experimental results show that the ZnO NW coatings can increase transmittance, decrease reflectance, and improve the short circuit current of PV modules. The reflectance and other optical properties of the coatings can be tuned by varying the length, diameter, and orientation of the nanowires.