Progress in P-type Tunnel Oxide-Passivated Contact Solar Cells with Screen-Printed Contacts

Herein, an update on the work on high-efficiency p-type solar cells with p-type-passivating rear contacts formed by low-pressure chemical vapor deposition andscreen-printed contacts is given. It is shown that thin polysilicon layers enable ahigh level of surface passivation but do show increased contact resistivity andespecially contact recombination. Commercially available pastes and dependenceof contact resistivity and contact recombination on polylayer thickness andfiringset temperature are investigated. For 240 nm-thick poly-Si layers, the values downto 4 mΩcm2and 60 fA cm 2are observed. For the presented process sequence,improved hydrogenation as one possibility to increase the passivation quality of thepassivating contact structure is identified. Implementing allfindings into afinalsolar cell, a maximum total area conversion efficiency of 21.2% is reported.