Evonik launches new processing aids for improving the performance of photovoltaic wafer cutting


With many countries, including China, pledging their commitment to achieving carbon neutrality, better and more cost-effective utilization of renewable energy is vital. In China, solar power continues to be the main source of ecological energy supply. Since the introduction of government incentives in 2011, China plays an important role globally in both solar power deployment and solar system/component manufacturing.

However, the economic competitiveness of current PV systems compared to other energy options remains to be a key metric for the future development of the industry. Solar module manufacturers are looking for any opportunity to reduce production costs while improving the conversion efficiency of solar cells to electricity.

Cutting silicon ingots with diamond wire saws (DWS) is a crucial step in the production of PV cells based on crystalline silicon. Cutting fluids with standard surfactants do not meet the requirements of the latest high-performance cutting process: Deep cut lines and divots caused by ineffective swarf transport and degradation of the wire's diamond coating not only lower wafer quality but can also lead to the formation of large crystals during the subsequent diffusion step, reducing the surface area for photon capture resulting in lower cell efficiency.

“The newly launched product series TEGO Surten E for the PV industry expands our comprehensive additives portfolio for renewable energy manufacturing,” said Benjamin Brehmer, Global Segment Manager Energy & Storage at Evonik’s Interface & Performance business line, “These low-dose additives can significantly improve the quality and speed of PV wafer cutting, contributing to a further step forward on the road to a climate-neutral future.”

TEGO Surten E wetting agents and defoamers contain the right balance of extremely low dynamic surface tensions and adhesion tendency to effectively remove cutting swarf. Cutting fluid formulations containing a low dosage of TEGO Surten E can achieve a much better cut quality ratio (more A+ vs. A) at higher cutting speeds using smaller wire diameters, on ever larger wafers (M12). This leads to an improved economic balance with less costly post-treatment remedial work required for cut wafers. The optimized formulation ensures a consistent cut quality on larger wafers leading to a significant increase in overall PV energy output.

In addition, the ideal wetting behavior of TEGO Surten E products can be modified to specifically operate under extreme operation conditions, such as in circular systems, by refining the overall cooling performance of the fluid. This helps to maintain the durability and performance of the diamond wire, improving the efficiency and sustainability of the whole process.

Evonik’s TEGO Surten E surfactant portfolio can also be useful as a process additive in many related and emerging PV applications, such as supporting more uniform and improved anti-reflective and reflective coatings, as well as other engineered surface modifications that improve overall energy yield.

Evonik is committed to solving the individual formulation needs together with its partners and customers in local markets to evolve as the industry transforms and places more requirements on the cutting process.

For more information, please visit Evonik’s tradeshow stand #550 during December 27-29 at SNEC PV POWER EXPO in Shanghai (postponed from May 24-26) or­­ visit http://www.evonik.com/pv.