This double-side polysilicon (poly-Si)/silicon oxide (SiO_x) TOPCon (tunnel oxide passivated contact) cell concept provides a unique opportunity to meet cost and efficiency targets simultaneously. A novel approach deploys low-cost, manufacturable screen-printed TOPCon on both sides of the solar cell. The key design feature is that TOPCon on the front side is selectively placed under the metal grid with ~5% area coverage, while the remaining 95% area on the front has undiffused Si wafer passivated with silicon oxide/silicon nitride or aluminum oxide (Al₂O₃)/silicon nitride (SiN) dielectric. This provides nearly the same passivation as full-area TOPCon without appreciable absorption of light. It also allows the use of thick TOPCon (~200 nanometer), eliminating the risk of contact punching or shunting due to screen-printed contacts to thin poly.

The innovation also includes a new method of patterning front TOPCon by selective area laser oxidation. This design and process sequence enhances efficiency and reduces cell processing costs by eliminating traditional diffusion technology. Further, the proposed bifacial cell structure offers a much lower temperature coefficient that will further increase energy harvesting and lower costs. Most passive emitter rear contact (PERC) manufacturing lines can be transformed easily into TOPCon lines by adding polysilicon (poly-Si) deposition tools, enabling the rapid and low-cost adoption of this technology.