ADVANCED LOCAL CONTACT SCHEME FOR HYBRID HETEROJUNCTION SILICON SOLAR CELLS

Abstract

This thesis focuses on the development of rear-side local heterojunction stripe contacts, which shall be used as a rear-side contact system in a novel solar cell architecture, i.e. a hybrid (homojunction/heterojunction) solar cell, using front-side conventionally diffused contacts and rear-side heterojunction stripe contacts. With regards to process optimization, the heterojunction stripe contact system is optimized, i.e. optimizing AlOx/SiNx passivation layer stacks, local laser ablation, and re-passivation of the laser-formed openings by thin-film PECVD deposited heterojunction layers. To provide an experimental basis for contact optimization, a novel methodology for the intensity-dependent characterization of local contacts is developed, using intensity-dependent photoluminescence imaging and intensity dependent transmission line method measurements. Two-dimensional numerical computer simulations of hybrid heterojunction silicon solar cells are performed, which enable to optimize the heterojunction stripe contact geometry and to predict the efficiency potential of hybrid heterojunction silicon solar cells. An advanced power loss analysis method for hybrid heterojunction silicon solar cell and its precursors is developed.