Longi Breaks New Ground with 34.58% Efficient Tandem Solar Cell

Chinese solar giant Longi has achieved a 34.58% power conversion efficiency with its latest tandem perovskite-silicon solar cell, leveraging an innovative asymmetric self-assembled monolayer (SAM) design. Developed in collaboration with Soochow University, the breakthrough—published in Nature—addresses critical challenges in perovskite defect passivation and charge extraction.

Key Innovations & Performance Metrics

🔬 Breakthrough Technology: HTL201 SAM

✔ Asymmetric molecular structure (unlike conventional symmetric carbazole-based SAMs)
✔ Improves hole transport while reducing non-radiative recombination
✔ Enhances coverage on textured silicon substrates
✔ Optimizes energy level alignment for better charge extraction

⚡ Record Cell Performance

✔ Efficiency: 34.58% (1 cm² lab cell)
✔ Open-circuit voltage (Voc): 2.001 V (industry-leading)
✔ Short-circuit current (Jsc): 20.64 mA/cm²
✔ Fill factor (FF): 83.79%

📊 Comparison to Previous Records

(Note: Longi still holds the absolute world record of 34.85% with another tandem configuration.)

Why This Matters for Solar’s Future

1. Tackling Perovskite’s Biggest Challenges

• Defect passivation at the perovskite-silicon interface

• Stable hole transport layers for long-term reliability

• Scalable deposition on textured silicon (critical for mass production)

2. Pushing Tandem Cells Toward Commercialization

• >34% efficiency brings perovskites closer to real-world viability

• Potential for >30% module efficiency (vs. ~24% for today’s best HJT/TOPCon)

3. Strengthening Longi’s R&D Leadership

• Holds both current (34.85%) and previous (34.6%) world records

• Active collaboration with academia (Soochow University, Nature publications)

Next Steps for Tandem Solar

🚀 Scaling up lab results to larger-area cells
🚀 Improving long-term stability (key for commercialization)
🚀 Reducing manufacturing costs (competing with TOPCon/HJT)

Final Takeaway

Longi’s asymmetric SAM breakthrough proves that tandem perovskite-silicon cells are inching toward viability, with efficiencies far surpassing single-junction silicon. While challenges remain in durability and production scaling, this research accelerates the timeline for next-gen ultra-high-efficiency solar.

Will tandem cells dominate solar by 2030? Share your predictions below!

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