Black surfaces are required for solar absorbers, light traps for optical devices as well as for decorative purposes.
The process can be applied to manifold polymers to produce a black backside absorber.
The subwavelength antireflective structure is generated by the AR-plas® etching process on the backside of transparent polymeric samples. The nanostructure is coated subsequently by a metal layer. Observed directly from the front side a broadband absorption close to 100% appears due to the structured polymer-metal-interface. On the backside a higher reflectance occurs and an enhanced electrical conductivity can be achieved. The front surface can provide a high contrast ratio in reflection if textured with masks.