Novel Ag-Paste for Simultaneous Contacting of n+ and p+ Emitters through Contact-Supportive Well-Passivating Doped APCVD Layers for PERT and IBC Solar Cells

Abstract

The European SolarEraNet project HEAVENLY has the goal to jointly develop simultaneously contacting novel silver pastes and chemical vapor deposited (CVD) layers which are used for both, surface passivation and formation of emitter and back surface field regions. Within the project, pastes have been produced that contact n + and p+ doped regions simultaneously over a wide f iring-temperature range, achieving contact resistivities below 0.01 mΩcm2 on a 100 Ω/sq n+ emitter. The doped regions are formed by using the high -throughput, cost efficient atmospheric pressure chemical vapor deposition (APCVD) technique which enables the single-sided deposition of doped glass layers, to allow for an efficient co -diffusion step for the formation of both, emitter and back surface field regions. The glass layers remain on the wafer surface after the diffusion process, providing very good sur face passivation (Seff ≤ 2.5 cms-1) and also supporting the contact formation during the subsequent firing process of the Ag pastes. As pastes and passivation layers are developed together, the production of high -efficiency low-cost PERT (Passivated Emitter and Rear Totally diffused) and IBC (interdigitated back contact) solar cells can benefit in three ways from the project’s results: by low contact resistivities, high quality surface passivation, and an efficient processing sequence.