Low-Dimensional 2-thiopheneethylammonium Lead Halide Capping Layer Enables Efficient Single-Junction Methylamine-Free Wide-Bandgap and Tandem Perovskite Solar Cells |
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Authors: | Hongling Guan Wenjun Zhang Jiwei Liang Chen Wang Xuzhi Hu Dexing Pu Lishuai Huang Yansong Ge Hongsheng Cui Yuanrong Zou Guojia Fang Weijun Ke |
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Affiliation: | Key Lab of Artificial Micro- and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, 430072 China |
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Abstract: | Wide-bandgap (WBG) perovskite solar cells (PSCs) have garnered significant attention for their potential applications in tandem solar cells. However, their large open-circuit voltage (VOC) deficit and serious photo-induced halide segregation remain the main challenges that impede their applications. Herein, a post-treatment strategy without thermal annealing is presented to form a 2D top layer of 2-thiopheneethylammonium lead halide (n = 1) on WBG perovskites. This thermal annealing-free post-treatment method can more effectively passivate the defects of WBG methylamine (MA)-free formamidinium/cesium lead iodide/bromide perovskite films and suppress photo-induced perovskite phase segregation, as compared with the thermal annealing method that yields multi-2D phases. The resulting opaque and semi-transparent 1.66 eV-bandgap perovskite solar cells deliver maximum power conversion efficiencies of 21.47% (a small VOC deficit of 0.43 V) and 19.11%, respectively, both of which are among the highest reports for inverted MA-free WBG PSCs. Consequently, four-terminal all-perovskite tandem cells realize a remarkable efficiency of 26.64%, showing great promise for their applications in efficient multi-junction tandem solar cells. |
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Keywords: | open-circuit voltage deficit perovskite tandem solar cells phase segregation wide-bandgap perovskites |
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