Improve conversion efficiency! RFH nanosecond solid-state laser for PERC cell laser grooving

How to use solar energy efficiently is the focus of current market research. Conventional all-aluminum back-field solar cells are currently a very mature process for mass production of solar cells, but the high back surface recombination rate limits the improvement of conversion efficiency. Therefore, reducing the back surface recombination rate has gradually become an effective way to improve the conversion efficiency of solar cells. one of the ways.

PERC solar cells are becoming a new generation of conventional technology for solar cells due to their high conversion efficiency and low cost, and have become a new favorite in the market.

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PERC technology, that is, passivated emitter and back cell technology, compared with ordinary cells, adds back passivation, laser grooving and other processes to enhance the reflection of the inner plate and reduce the optical loss of long wavelengths. At the same time, the open circuit voltage of PERC cells Compared with conventional batteries, the short-circuit current and short-circuit current are greatly improved, and the conversion efficiency is effectively improved. The technical implementation is mainly that a backside passivation layer film is first deposited, and then grooves or holes are made on the passivation stack of the PERC cell to open a path for the contact between the silicon substrate and the metal aluminum. This process is mainly completed by laser. . After the laser grooving exposes the silicon substrate, since there is no film barrier in the laser grooving area, the aluminum back field is in contact with the silicon substrate through the holes or grooves in the film. Resistors are connected in series, and the current can be smoothly derived.

The industrial-grade nanosecond solid-state laser produced by RFH can be applied to the back-grooving process of PERC cells through an industrial integrated optical system. After selecting appropriate process parameters, the output 532nm laser is irradiated to the object through a high-speed scanning galvanometer and a condenser lens. On the surface, conduction band electrons are generated by thermal excitation or photoexcitation. The conduction band electrons absorb energy through avalanche ionization and Joule heating to form plasma. The plasma transfers energy to the material through electron-phonon coupling, so that the heated material is melted and sublimated. , and then ablate or break through a portion of the silicon nitride layer in selected areas on the back surface, a process known as a laser grooving process.

The researchers found that the smaller the area of ​​the laser grooving area, the smaller the damage to the passivation layer, the higher the minority carrier lifetime, and the higher the open circuit current. Therefore, the laser grooving pattern can also be set. The combination of (point), line segment and long straight line can retain more area of ​​the passivation film and reduce the damage to the passivation layer. RFH industrial grade nanosecond solid-state laser has excellent beam quality (M2 < 1.2), after focusing, the spot diameter is small, the slotting area is finer, and the flexibility is high, and it can be performed 7*24 hours. Laser slotting pattern circuit is easier , fast speed, while improving the quality of grooving, improve the efficiency of work.

Since there is still a lot of room for efficiency improvement in PERC cells, which means its broad application market, RFH will continue to precipitate technology to improve the efficiency of PERC cells and even the efficiency of the entire solar cell industry and photovoltaic industry. ” and “carbon neutrality” contribute wisdom and strength.