Silicon nanowires are considered as a promising architecture for solar energy conversion systems. By metal assisted chemical etching of multi-crystalline upgraded metallurgical silicon (UMG-Si), large areas of silicon nanowires (SiNWs) with high quality can be produced on the mother substrates. These areas show a low reflectance comparable to black silicon. More interestingly, we find that various metal impurities inside UMG-Si are removed due to the etching through element analysis. A prototype cell was built to test the photoelectrochemical (PEC) properties of UMG-SiNWs for water splitting. The on-set potential for hydrogen evolution was much reduced, and the photocurrent density showed an increment of 35% in comparison with a ‘dirty’ UMG-Si wafer.
Photon management is a key component in the development of efficient solar cells. Especially light-trapping concepts
have a high potential to realize enhanced efficiencies. Here, we give an overview over several light trapping concepts for
photon management in solar cells. These include basic as well as advanced light-trapping concepts. The theoretical limits
of light path enhancement of the different concepts are given and experimental work on these topics is presented. The
potential of 3D photonic crystals is discussed in the context of the corresponding approaches as well.