With the rapid growth of global demand for renewable energy, solar photovoltaic technology has become a key solution to addressing energy crises and environmental pollution. Perovskite solar cells, in particular, have attracted significant attention in the solar photovoltaic field due to their high photoelectric conversion efficiency, low material cost, and lightweight structure. Compared to traditional formal structures, inverse perovskite solar cells offer simpler processing, relatively low-temperature fabrication, and improved weather resistance, thus attracting widespread attention from both academia and industry.
In recent years, through optimization strategies such as interface engineering, the efficiency of inverse perovskite solar cells has exceeded 26%. However, existing interfacial self-assembled monolayers (SAMs) are primarily chemically adsorbed onto the surface of the transparent conductive layer (TCO). When devices are exposed to high temperatures or undergo thermal cycling, the molecular layer can desorb or aggregate, leading to degraded interfacial contact and hindered carrier (hole) transport, ultimately significantly impairing device performance and stability. Therefore, developing new, more stable and efficient hole-selective contact material systems is crucial to further improve the thermal stability of devices and promote their industrial application.
To address these issues, Liu Yuhang and Ma Wei from Xi'an Jiaotong University, Michael Graetzel from the Swiss Federal Institute of Technology in Lausanne, Wei Mingyang from Nanyang Technological University, Li Xiong and You Shuai from Huazhong University of Science and Technology, and others published a new paper in Nature Energy titled "Assembled bilayer for perovskite solar cells with improved tolerance against thermal stresses." They designed a self-assembled bilayer structure connected by covalent bonds. Based on a traditional small-molecule SAM material system, a covalently linked polymer network system was formed through a Friedel-Crafts alkylation reaction. This covalent connection effectively "anchors" the small-molecule SAM layer adsorbed on the transparent conductive substrate, significantly improving its resistance to high temperatures and thermal shock. Furthermore, the unique face-oriented molecular arrangement of the upper layer exhibits excellent adhesion to the perovskite material, thereby enhancing the mechanical strength of the perovskite/hole transport layer interface. Using this strategy, the research team achieved device performance exceeding 26% in photoelectric conversion efficiency, as certified by a third-party organization. The laboratory-grade perovskite solar cell devices they fabricated passed the industry standards set by the International Electrotechnical Commission IEC61215:2016 and the International Society for Organic Photovoltaic Stability (ISOS). After 2,000 hours of damp-heat stability testing, the top-performing device based on the self-assembled bilayer exhibited only a 4% loss in efficiency compared to its original performance. Furthermore, after 1,200 cycles of thermal cycling from -40°C to 85°C, its efficiency decreased by only 3% compared to its original performance.
Corresponding Affiliates: Xi'an Jiaotong University, Zhongmao Green Energy Thin Film Photovoltaic Research Institute
Source: Bitao Dong #, Mingyang Wei #, Yuheng Li#, Yingguo Yang#, Wei Ma*, Yueshuai Zhang, Yanbiao Ran, Meijie Cui, Ziru Su, Qunping Fan, Zhaozhao Bi, Tomas Edvinsson, Zhiqin Ding, Huanxin Ju, Shuai You*, Shaik Mohammed Zakeeruddin, Xiong Li*, Anders Hagfeldt, Michael Graetzel*, Yuhang Liu*. Self-Assembled Bilayer for Perovskite Solar Cells with Improved Tolerance Against Thermal Stresses. Nature Energy, 2025
DOI: 10.1038/s41560-024-01689-2
https://www.nature.com/articles/s41560-024-01689-2
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