Recently, Maxwell Technologies, together with several universities including Nanchang University, the Hong Kong Polytechnic University, and Henan Normal University, published a research paper on Joule, an authoritative international journal, which introduced the research finding that strained heterojunction enables high-performance, fully textured perovskite/silicon tandem solar cells with an efficiency of up to 31.5%. This is the first paper published by Maxwell on Joule, marking a breakthrough after the two papers published on Nature Energy in 2023.
Joule, is a world-class, globally influential academic journal, known for its uniqueness and forward-thinking approach. It’s a home for research and practice in energy-related fields to address a key global challenge: the need for more sustainable energy. It spans scales of energy research, from fundamental laboratory research into energy conversion and storage up to impactful analysis at the global level.
The paper published by Maxwell is entitled "Strained heterojunction enables high-performance, fully textured perovskite/silicon tandem solar cells", it was jointly published by Shaofei Yang, R&D Manager of Solar Cell Technology Department, as well as the Principal of Solar Cell Technology Department, Professor Kai Yao from Nanchang University, Professor Haitao Huang from the Hong Kong Polytechnic University, and research personnel from other universities and research institutes.
The paper reports an innovative strain regulation strategy by forming a 3D/3D perovskite heterojunction at the buried interface through a vacuum-deposition method applicable to pyramidal texture, which promotes the conformal growth of high-quality perovskite films on fully textured silicon. This strained heterostructure promotes the preferred crystal growth, reduces interfacial defect-induced recombination, and facilitates charge extraction. As a result, the fully textured perovskite/silicon tandem cell achieves a certified steady-state efficiency of 31.5% and retains over 95% of its initial efficiency after 800 h of continuous operation. The above experimental results were achieved on Maxwell’s full set of Perovskite/HJT tandem solar cells R&D platform and related equipment.
At present, Maxwell has established a 4MW perovskite/HJT tandem solar cell experimental line, and conducted the all-around development in terms of tandem process, equipment and materials. Maxwell has achieved a tandem solar cell efficiency of 28.3% on the silicon wafer of 182mm*182mm, which is the maximum wafer size based on published data of perovskite/HJT tandem cell. Additionally, Maxwell not only improves the mass production efficiency of heterojunction cells with technical advancement, but also paves the way for cost reduction, efficiency improvement, technical exploration and application expansion in the future.
Perovskite-Heterojunction Tandem Cells - A Future Trend with Natural Advantages
The surface of the heterojunction cell is the transparent conductive oxide (TCO) film. Its symmetrical structure allows it to be compatible with the positive/inverse perovskite cell technology, and effectively connected with perovskite in series. Additionally, due to its high open-circuit voltage and filling factor, it features great advantages as a material for base cells and perovskite tandems. The theoretical efficiency of perovskite-heterojunction tandem solar cells can be over 42%, showcasing a significant space for improvement on the efficiency of tandem solar cells in mass production in the future. As a result, it could be the optimized solution for the perovskite/silicon tandem solar cells.
Currently, the perovskite/HJT tandem technology is under rapid development. There have been enterprises that achieved the efficiency of 34.6% on a small-sized tandem solar cell, and the efficiency of 30.1% on the 166mm*166mm tandem solar cell.
The efficiency of full-size Perovskite/HJT tandem solar cells is expected to be over 32% in 2025. With high-efficient research, development and innovation, Maxwell will constantly overcome challenges in efficiency, cost, process, and equipment in the mass production of tandem solar cells, which can further promote the cost reduction of photovoltaic power generation and contributes to the photovoltaic industry to achieve the zero-carbon goal.