Photonic crystals as rear-side diffusers and reflectors for high efficiency silicon solar cells

The results in this publication show that it is possible to fabricate photonic crystals through spincoating of nano spheres made of Polymethylmethacrylate (PMMA) or SiO2, a subsequent infiltration with SiyC1-y using plasma enhanced chemical vapour deposition and optional burning out of the PMMA spheres. The structures are highly ordered and show enhanced reflectivity (600 nm spheres). An implementation of such structures into the process chain of high efficiency solar cells was done successfully. After passivating the solar cells rear side with SixC1-x and generating the photonic structure the rear metal contact was established with laser ablation and Al evaporation. Reflectivity measurements show reduced reflection for the solar cells with photonic structures and conductivity measurements proof that the rear contacting was successful.