Surface quasi periodic and random structures based on nanomotor lithography for light trapping

We compare the characteristics of two types of patterns obtained with two azopolymer materials: a Gaussian random pattern and a quasi-random grating pattern. The surface structurations have been obtained with a simple bottom-up technique by illuminating azopolymer thin films with a single laser beam. We demonstrate the interesting generated properties of these two surfaces. In particular, the surface with quasi-random gratings can address beam splittings for light coupling in different directions in an ultra-thin film. We use these two surfaces as a mold and replicate them on a transparent elastomeric material and we demonstrate a very good light entrapment. We also show that the efficiency of light trapping is 20% better with the quasi-random gratings than with the Gaussian random surface, and is close to 40%.