Wideband nanocomposite antireflective coating based on aluminium dry powder nanoparticles embedded into a photopolymer matrix for solar cells application.

We present a low-cost method to implement a single-layer antireflective coating (ARC) including metallic nanoparticles embedded into a polymer matrix. This ARC shows an almost flat behaviour in the whole visible spectral range (400-750 nm). The metamaterial is formed by a 1% in weight of Aluminium nanoparticles (NPs) randomly dispersed into a transparent UV curable photopolymer matrix that can be deposited on different substrates, which extends its application not only to solar cells but also to the protective glass covers. The NPs dispersion method strongly affects the optical properties, being the reflectance reduction more efficient when the cluster density in the metamaterial is low enough. Our results show an average reflectance reduction up to 50% in the whole VIS spectral range when the substrate is a soda-lime glass slide. The deposition method, based on the doctor-blade technique, is simple and inexpensive, since does not require clean-room nor vacuum equipment, being able to roll out the ARC layer even on already existing devices. The NPs were also deposited on top of a fully operative InN on Si thin-film solar cell. Optical measurements showed an average surface reflectance reduction of a 24% when incorporating the NPs. Furthermore, the photovoltaic performance increased under 1 sun of standard AM1.5G solar illumination when adding the ARC layer, pointing to a relative 9.0% increment in the conversion efficiency.