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Thermally evaporated perovskite/silicon tandems via formamidinium eutectic
Nature
(2026) Cite this article
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Solution processing remains the dominant route to high-performance perovskite/silicon tandems, but it remains challenging to simultaneously achieve industrial scalability and long-term reliability.1-3 Thermal evaporation is more industrially viable, yet it has not been successfully demonstrated for large-area perovskite/Si tandems, largely due to the thermal degradation of formamidinium iodide (FAI) during high-temperature evaporation. Here, we synthesize a formamidinium-based eutectic (Eu) that lowers the effective evaporation temperature of FAI by an average of 36 °C - below its degradation threshold - thereby enabling stable FAI evaporation without thermal degradation. As a result, the evaporated perovskite films exhibit enhanced crystallinity and atomic-scale compositional homogeneity. Sequentially evaporated perovskite/Si tandems achieve a steady-state efficiency of 31.5% (1 cm2). Benefiting from the uniformity of evaporation, we further demonstrate the first thermally evaporated large-area perovskite/Si tandem on a commercial half-cut G12 wafer, delivering a steady-state efficiency of 30.0% (200 cm2). Scaling the device area from 1 to 200 cm2 incurs only a 3.99% relative efficiency loss, representing the lowest reported efficiency penalty for area scaling in perovskite-based tandems. The Eu-based tandem retains 95% of its initial efficiency after 2000 hours of damp-heat aging (85 °C/85% RH) and exhibits negligible power loss after two months of real-world outdoor operation.
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These authors contributed equally: Chao Luo, Rui He, Luo Ran, Jingcong Hu, Yuduan Wang
Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, Singapore, Singapore
Chao Luo, Luo Ran, Jingcong Hu, Yuduan Wang, Yuxin Yao, Zihao Zhu, Chenxia Kan, Xinyi Du, Ling Kai Lee, Qilin Zhou, Nengxu Li, Xiuxiu Niu, Fengtao Pei, Xi Wang, Jinxi Chen, Zhenrong Jia, Tao Wang, Zijing Dong, Xiao Guo, Meng Xin, Xinyu Zhang, Yuhui Jiang & Yi Hou