First TOPCon solar cells adapted for space missions

The two main advanced silicon technologies that are currently replacing the standard PERC cell for terrestrial uses are the Silicon HeteroJunction (SHJ) and TOPCon cells. Both feature passivated contacts and usually rely on n-type silicon substrates.

In space, silicon solar cells suffer from electron and proton radiation induced damages. Use of p-type substrates, front emitters and thin wafers can help to limit this effect. Beyond improving the radiation hardness, thin wafers facilitate design of lightweight and flexible photovoltaic arrays. 

In a recent communication1, CEA showed how SHJ cells can be adapted for space applications. Indeed, by using a gallium-doped (p-type) substrate, the cell features a front emitter. Furthermore, both the cell architecture (symmetric structure) and its fabrication process (low temperature, wafers relying on trays) are compliant with very thin (~60 µm) wafers.

The adaptation of TOPCon cells for space raises more challenges. In this case, with p-type wafers, the cell features a rear emitter. Furthermore, the cell fabrication process is less adapted to very thin wafers (high temperature steps, asymmetric structure). In the frame of the CARLAH project2, supported by the European Space Agency (ESA), CEA is developing an alternative TOPCon device which is designed to be better adapted to space missions.

This R&D activity was supported by ESA via a Discovery element contract N° 4000138622. This press release reflects only the authors’ view and not the one of ESA. ESA is not responsible for any use that may be made of the information it contains.