The global PV cell market is dominated by crystalline silicon cells.
Efficiency improvement and cost reduction of crystalline silicon cells is the key to the development of the PV industry, and scale-up, technological advancement and cost reduction promote each other. From the initial mass production of aluminum backfield cells, to PERC (passivated emitter and backside contact), to HJT (heterojunction with intrinsic amorphous layer) and TOPCon (passivated contact cell with tunneled oxide layer), and to the future stacked cells, the efficiency of photovoltaic cells has been constantly approaching the limit, which has led to a breakthrough in cost and scale.
Despite the continuous iteration of photovoltaic cell technology routes, efficiency continues to improve, but based on the basic principles of crystalline silicon cells and the core process has not changed, that is, the four major steps of cleaning fluffing, diffusion junction system, passivation coating, metallization.
1) Cleaning Fluff
Cleaning is mainly used to remove impurities on the surface of the wafer, to remove the damage layer on the surface of the wafer, and flocking is used to form a pyramid structure on the surface of the wafer, thus reducing the reflectivity.
2) Diffusion Junction Making
The core structure of a PV cell is formed by diffusion: the P-N junction. This is usually applied to homogeneous junction cells.
3) Passivation Coating
Through the form of vacuum coating, a passivation film is formed on the surface of the cell, which plays a role in reducing the oligon composite, providing a passivation effect and reducing the reflectivity, which plays a key role in improving the efficiency of the battery, and is also the main starting point for the efficiency improvement of PV cells.
4) Metallization
Used to form the front electrode and back electrode of the photovoltaic cell, usually using screen printing. Metallization process route is closely related to the passivation process, and at the same time to reduce the minority compound, reduce resistance loss plays a key role. In addition, it also includes generalized steps such as etching and testing, which are not very different in different cell technology routes.
