Passivating and Carrier-selective Contacts - Basic Requirements and Implementation

Effective passivating and carrier-selective contacts are based on the deposition of thin-film systems on the silicon wafer which results in a spatial decoupling of carrier generation and carrier separation in the device. They provide excellent passivation, high carrier selectivity and low contact resistivity. We have performed dedicated experiments to visualize these properties, thus allowing a better understanding of practical passivating and carrier-selective contact systems. Based on this analysis we recommend a measurement procedure to analyze carrier-selective contacts. The proper design of contact systems as the TOPCon structure and its careful implementation in a solar cell process featuring a simple both-sides contacted cell architecture allows to achieve excellent efficiencies of 25.7% and 21.9% on monocrystalline and multicrystalline silicon, respectively.