Concepts and prospects of passivating contacts for crystalline silicon solar cells

To further increase the conversion efficiency of crystalline silicon solar cells it is vital to reduce the recombination losses between the photoactive part of the solar cell and the metal contacts. This is ideally achieved by fabricating contacts which passivate defects at the silicon surface while being simultaneously selective for only a single type of charge carrier, i.e. either electrons or holes. Despite the extensive research effort aimed at realizing such contacts, no clear overview of the fundamental physics of passivating contacts has appeared yet. Therefore, we present such an overview, introduce a clear classification of passivating contacts, and discuss their design guidelines and future prospects.