Large area co-plated bifacial n-PERT cells with polysilicon passivating contacts on both sides

In this work, we show the integration of polysilicon-based passivating contacts in plated bifacial n-type PERT (passivated emitter and rear totally diffused) solar cells. We show the viability of n-PERT cells using two-side passivating contacts with two-side plated nickel/silver metallization. Compared with commercially available TOPCon cells with rear side passivated contacts only, n-PERT cells with both side passivated contacts should enable the exploitation of the full potential of passivated contacts. We show that both n-poly and p-poly were applied and co-plated successfully on both sides of n-PERT solar cells. Considering the potential parasitic absorption losses on the front side of the device originating from p-poly, we applied selective p-poly by patterning. We compared two patterning methods for front side polysilicon: the masking and etch approach using inkjet printing and a simple and cost-effective patterning method using UV laser oxidation. A best efficiency of 22.7% has been achieved with these cells so far on large area (244.3 cm(2)) n-type Cz, with a potential efficiency above 24%. Some of these co-plated bifacial cells have been processed into one-cell laminates using smart wire interconnection (SWCT) technology. These have passed thermal cycling (TC) tests as defined in IEC61215.

Automated summary

This work demonstrates the integration of polysilicon-based passivating contacts in plated bifacial n-type PERT solar cells, showing the potential for full exploitation of passivated contacts. Successful co-plating of n-poly and p-poly on both sides of n-PERT cells was achieved, with selective patterning used to mitigate parasitic absorption losses. Different patterning methods for front side polysilicon were compared, with a best efficiency of 22.7% achieved on large area n-type Cz. These cells have also passed thermal cycling tests and show potential for efficiencies above 24%.