PolyU team advances tandem solar cell efficiency and reliability targets

by Riko Seibo

Tokyo, Japan (SPX) Nov 12, 2025

Third-generation solar cell technology is seeing rapid development at The Hong Kong Polytechnic University. Researchers at PolyU have identified breakthrough approaches in perovskite/silicon tandem solar cells, targeting advances in efficiency, stability, and scalability. Their performance analysis and recommendations aim to drive energy conversion efficiency from around 34 percent to 40 percent. The group is accelerating commercialization by fostering collaborations between industry, academia, and research, supporting carbon neutrality plans and the adoption of renewable energy for innovation including artificial intelligence.

The team, led by Prof. Li Gang and Prof. Yang Guang of PolyU’s Department of Electrical and Electronic Engineering, critically reviewed technical challenges for tandem solar cells. Their paper, published in Nature Photonics, highlights instability issues under environmental stresses like moisture, oxygen, ultraviolet light, and temperature fluctuations. Scaling up from small laboratory devices to commercial modules requires overcoming obstacles in uniformity, defect management, and large-scale fabrication.

“While lab-scale devices have shown impressive efficiency advancement, further efforts are needed to improve their reliability, including minimising efficiency losses from small-area devices to large-area modules,” said Prof. Li Gang. “Special focus should also be given to ensuring that the manufacturability of materials and methods aligns with industrial standards.”

Prof. Yang Guang and colleagues advocate extensive stability testing aligned to International Electrotechnical Commission standards in order to better measure product lifetime and commercial viability. Although initial outdoor tests are under way, reliable long-term results are still limited.

Economic and regulatory issues arise from the use of rare elements and lead in perovskite materials. The team calls for the development of safer alternatives and for efficient recycling or containment strategies to make large-scale commercialization both technically and environmentally feasible.

Research Report:Towards efficient, scalable and stable perovskite/silicon tandem solar cells