Third-generation solar cell technology is advancing rapidly. An engineering research team at The Hong Kong Polytechnic University (PolyU) has achieved a breakthrough in the field of perovskite/silicon tandem solar cells (TSCs), focusing on addressing challenges that include improving efficiency, stability and scalability. The team has conducted a comprehensive analysis of TSC performance and provided strategic recommendations, which aim to raise the energy conversion efficiency of this new type of solar cell from the current maximum of approximately 34% to around 40%. The team hopes to accelerate the commercialisation of perovskite/silicon TSCs through industry-academia-research collaboration, while aligning with the Nation's strategic plan of carbon peaking and neutrality and promoting the development of innovative technologies such as artificial intelligence through renewable energy.
The research team comprises leading scholars including Prof. LI Gang, Chair Professor of Energy Conversion Technology and Sir Sze-yuen Chung Endowed Professor in Renewable Energy, and Prof. YANG Guang, Assistant Professor, both of the PolyU Department of Electrical and Electronic Engineering. They conducted a critical review of the challenges and future prospects of perovskite/silicon TSCs. Their research paper, "Towards efficient, scalable and stable perovskite/silicon tandem solar cells", has been published in the international journal Nature Photonics.
Tackling stability and manufacturing challenges
"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."
To address these issues, Prof. Yang Guang and the team has highlighted several critical technical challenges. First, the intrinsic instability of perovskite materials under environmental stresses such as moisture, oxygen, ultraviolet light and thermal fluctuation remain a major challenge. Secondly, translating tandem devices to commercial-scale modules requires overcoming hurdles related to uniformity, defect control and large-area fabrication. Although preliminary outdoor testing of perovskite/silicon TSCs has been conducted, certified data on their long-term reliability remain scarce. To better assess the actual lifetime and commercial potential of these cells, the researchers recommend rigorous accelerated stability testing based on standardised procedures outlined by the International Electrotechnical Commission.
Additionally, while perovskite raw materials are relatively low-cost, the use of rare elements and heavy metal lead in most cell designs raises significant environmental and regulatory concerns. The research therefore advocates for the development of sustainable alternatives, along with efficient recycling or lead sequestration strategies to enable viable commercialisation.
Promoting industry-academia-research collaboration to accelerate deployment and drive cost reduction and efficiency gains
The PolyU team advocates for industry-academia-research collaboration through a multidisciplinary approach that integrates material science, device engineering and economic modelling to advance this promising photovoltaic technology. "The development of efficient and reliable perovskite/silicon TSCs must address these remaining scientific challenges to achieve lower levelised electricity costs," said Prof. Yang Guang. "The team hopes this research will facilitate the transition of the technology from laboratory studies to commercial fabrication, while closely aligning with the Nation's strategic plan of carbon peaking and neutrality. By providing a stable supply of high-efficiency renewable energy, we aim to deliver green and reliable power support for high-energy-consuming industries such as artificial intelligence, thereby helping to achieve a low-carbon transformation of the energy structure."
