Abstract
2,2′,7,7′-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9′-spirobifluorene (spiro-OMeTAD), as the most common used hole transport material (HTM), plays a significant role in the normal structured (n-i-p) high-efficiency perovskite solar cells (PSCs). In general, it is prepared by a halogen solvent (chlorobenzene, CBZ) and needs an ion dopant (lithium bis (trifluoromethanesulfonyl)imide, Li-TFSI) to improve its conductivity and hole mobility. However, such a halogen solvent is not environmentally friendly and the widely used Li-TFSI dopant would affect the stability of PSCs. Herein, we develop a non-halogen solvent—tetrahydrofuran (THF)-prepared spiro-OMeTAD solution with a new p-type dopant, potassium bis(fluorosulfonyl)imide (K-FSI), to apply into PSCs. By this strategy, high-hole-mobility spiro-OMeTAD film is achieved. Meanwhile, the potassium ions introduced by diffusion into perovskite surface passivate the interfacial defects. Therefore, a hysteresis-free champion PSC with an efficiency of 21.02% is obtained, along with significantly improved stability against illumination and ambient conditions. This work provides a new strategy for HTMs toward hysteresis-free high-efficiency and stable PSCs by substituting dopants.
摘要
作为最常用的空穴传输材料, spiro-OMeTAD在**式结构的高效钙钛矿太阳能电池(PSCs)中起着重要作用. 一般来说, spiro-OMeTAD是基于卤素溶剂氯苯制备的, 并且需要离子型添加剂(Li-TFSI)来提高其导电性和空穴迁移率. 然而, 这种卤素溶剂并不环保, 而且普遍使用的Li-TFSI会影响PSCs的稳定性. 在此, 我们针对spiro-OMeTAD开发出一种新型的p型添加剂(双氟磺酰亚胺钾, K-FSI)并且以无卤素溶剂四氢呋喃作溶剂将其应用于PSCs器件. 通过该方法制备的spiro-OMeTAD薄膜具有更高的空穴迁移率、 载流子浓度以及导电性. 同时, 由空穴传输层引入的钾离子可以扩散到钙钛矿表面使界面缺陷得到钝化. 因此, 基于K-spiro薄膜的钙钛矿太阳能电池获得了21.02%的最高光电转化效率并且无迟滞现象存在, 而且电池器件的光照稳定性和环境稳定性显著提高. 这项工作为通过替换空穴传输材料的添加剂实现无迟滞、 高效稳定的PSCs提供了新的策略.
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Acknowledgements
This work was financially supported by the National Key Research and Development Plan (2019YFE0107200 and 2017YFE0131900), the National Natural Science Foundation of China (21875178 and 91963209), and Foshan **anhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory (XHD2020-001 and XHT2020-005). The Analytical and Testing Centre of Wuhan University of Technology and Hubei Key Laboratory of Low Dimensional Optoelectronic Material and Devices, Hubei University of Arts and Science is acknowledged for the XPS, XRD and SEM characterizations.
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Huang F and Bu T proposed and supervised the project. Lin Z conducted most of the experiments and analyzed the data as well as wrote the manuscript. Li J contributed to the experimental scheme and materials selection. Li H and Pan J performed the PL measurement. Mo Y and Wang C performed the stability test. Zhang XL, Zhong J, and Cheng YB revised the manuscript. All the authors contributed to the general discussion.
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Zhipeng Lin received his BS degree from Wuhan University of Technology (WUT) in 2019. He is currently a master degree candidate at Wuhan University of Technology. His current research interest is focused on the field of perovskite solar cells.
Tongle Bu received his PhD from WUT in 2019. He joined Okinawa Institute of Science and Technology Graduate University (OIST) as a postdoctoral fellow in 2020. He is currently working on the scalable printing of efficient and stable perovskite solar cells and modules.
Fuzhi Huang received his PhD in chemistry (2009) from The University of Melbourne, Australia. Currently, he is a full professor at the State Key Lab of Advanced Technology for Materials Synthesis and Processing, WUT. His research interest is develo** new materials and techniques for high-efficiency organic-inorganic hybrid perovskite solar cells.
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The authors declare that they have no conflict of interest.
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Lin, Z., Li, J., Li, H. et al. A novel dopant for spiro-OMeTAD towards efficient and stable perovskite solar cells. Sci. China Mater. 64, 2915–2925 (2021). https://doi.org/10.1007/s40843-021-1705-8
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DOI: https://doi.org/10.1007/s40843-021-1705-8