DKEM's Advanced Metallization Solutions for TOPCon & TBC Solar Cells

DKEM's Metallization Solutions Overview

• 💡 DKEM offers a comprehensive product portfolio covering various solar cell architectures, including PERC, TOPCon, TBC, and HJT, alongside module interconnection and encapsulation materials.
• 💰 A primary focus is on cost reduction through the introduction of silver-lean and silver-free products, aiming to decrease silver consumption in the industry.

Advancements in TOPCon Cells

• 🚀 The LECO process has significantly boosted TOPCon cell efficiency, with new technologies like EPD, poly-finger, and zero BB integrated into mass production, achieving module power outputs over 670 watts.
• 📈 DKEM helps customers enhance VOC performance by adopting low-etching systems and optimizing emitters for high sheet resistance, though this can introduce challenges like over-etching or reliability issues.
• 🎯 Fine-line printing is advancing, with finger line openings reducing to below 10 microns, and stencil printing offering improved morphology, narrower finger width, and up to 0.1% efficiency gain in mass production.
• 🛠️ For the TOPCon rear side, LECO improves contact, and DKEM's paste weakens etching capability, reduces depth, and improves silver nanocrystallite density, while the poly-finger process addresses contact for thinner poly thickness.

TBC Cell Metallization & Cost Reduction

• ✅ TBC cell processing is relatively stable, with efforts focused on paste development to further improve efficiency, particularly for forming good contacts at the poly-silicon interface.
• 📉 Cost reduction in TBC cells involves reducing poly-silicon thickness (e.g., to 80 nm for N-type, 200 nm for P-type), which demands optimized pastes to maintain contact and minimize damage.
• 💰 Adopting stencil screens for TBC not only saves paste but also enhances efficiency due to improved uniformity and narrower finger morphology.

Copper as a Silver Alternative

• ⚡ Copper is identified as a promising, cost-effective alternative to silver for metallization due to its similar resistivity and widespread use in electronics.
• ⚠️ Key challenges for copper adoption include oxidation (requiring anti-oxidation concepts in paste and firing), high firing sensitivity to oxygen, and concerns about copper diffusion into silicon, which affects cell reliability.

DKEM's Copper-Based Solution

• 🧪 DKEM's solution for TOPCon and TBC involves an ultra-low silver seed layer for silicon contact, followed by a high-copper-content paste for current transportation.
• 🏭 This two-layer approach is already in mass production for TOPCon rear sides, with proven cell and module reliability, marking the first mass production case of high-copper paste in TOPCon.