Traditional solar cells contain two layers of silicon, commonly called “n-type” and “p-type” for their negative and positive charge behavior. The difference between N-type and P-type semiconductors is the primary material used to create the chemical reaction during doping.

An N-type solar cell consists of a thin p-type silicon (doped with boron) layer over a much thicker n-type silicon (doped with phosphorus) layer. Electrical contacts are applied to both sides. N-Type solar cells offer lower temperature coefficients, better operating temperatures, and better LID degradation, leading to all around improved power generation.

Tunnel oxide passivated contact (TOPCon) solar cell technology is a new development with the eventually to replace passivated emitter and rear contact (PERC) and high-efficiency passivated emitter, rear totally diffused (PERT) solar panels.

TOPCON has an N-Type Silicon substrate and a thin tunneling oxide is applied, followed by a layer of highly doped with n or p poly silicon that contacts the metal at the ends. These tunneling oxide blocks one type of carrier and thus they are called passivating contacts.

The processes and existing equipment that are commonly used in the manufacturing of PERC cells may be easily adapted to TOPCon cell production by adding two process steps:

1. The formation of tunnel oxide.
2. The deposition of intrinsic/doped polysilicon.

To manufacture TOPCon cells, tunnel oxide, and polysilicon layers are added to the rear side of the cell. It helps the cell handle higher voltages, which increases power production.