Yang Meifang, Tan Ying, Yang Guo, Chang Xueqing, Tian Tian, Li Wen-Guang, Fang Yuxuan, Shen Jinliang, Yang Shaopeng, Wu Wu-Qiang
Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, LIFM, School of Chemistry, IGCME, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.
Institute of Innovation Materials and Energy, School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, 225002, P. R. China.
Angew Chem Int Ed Engl. 2025 Jan 21;64(4):e202415966. doi: 10.1002/anie.202415966. Epub 2024 Nov 4.
High Br-content lead mixed-halide perovskites with wide-bandgap (WBG) of 1.6-2.0 eV have showcased vast potential to be used in tandem solar cells. However, WBG perovskites often suffer from severe halide segregation, phase separation and ion migration under the stress of light, heat, moisture and electric bias, which would accelerate the decomposition of perovskite films and thus deteriorate the photovoltaic performance and even aggravate the lead leakage from damaged devices. Here, we report a novel chemical synergic interaction strategy to mitigate the abovementioned issues in WBG perovskites. To achieve that, a small amount of cationic β-cyclodextrin, composed of multiple ammonium cations, chlorine ions and abundant hydroxyl functional groups, was introduced into WBG perovskites, which effectively stabilized the halide ions and homogenized the phase distribution, comprehensively passivated the crystallographic defects, as well as efficiently immobilized the Pb ions. Encouragingly, the cationic β-cyclodextrin was universal and useful for different WBG perovskite compositions (i.e. 1.68 eV, 1.79 eV and 1.99 eV), which favorably boosted the efficiencies by 10 %-36 % and extended the operational stability of resultant devices to 2680 h. The four-terminal all-perovskite tandem and six-terminal all-perovskite tandem solar cells integrated with different WBG perovskite sub-cells exhibited efficiencies up to 24.39 % and 22.42 %, respectively. More importantly, we demonstrated the cationic β-cyclodextrin-assisted internal chemical encapsulation effectively prevented the Pb leakage when the devices were severely damaged and immersed in water. Surprisingly, there was only 5.63 ppb Pb leaching out for the single-junction devices, far below than the U.S. standard for safe drinking water (<15 ppb). The target tandem solar cells with cationic β-cyclodextrin modification also realized a Pb sequestration efficiency of 93.4 % under the most adverse environment.
具有1.6 - 2.0电子伏特宽带隙（WBG）的高溴含量混合卤化物铅基钙钛矿在串联太阳能电池中展现出了巨大的应用潜力。然而，宽带隙钙钛矿在光、热、湿气和电偏压的作用下，常常会遭受严重的卤化物偏析、相分离和离子迁移，这会加速钙钛矿薄膜的分解，进而恶化光伏性能，甚至加剧受损器件的铅泄漏。在此，我们报道了一种新颖的化学协同作用策略，以缓解宽带隙钙钛矿中的上述问题。为此，将由多个铵阳离子、氯离子和丰富的羟基官能团组成的少量阳离子β - 环糊精引入宽带隙钙钛矿中，这有效地稳定了卤离子并使相分布均匀化，全面钝化了晶体缺陷，同时有效地固定了铅离子。令人鼓舞的是，阳离子β - 环糊精对不同的宽带隙钙钛矿组成（即1.68电子伏特、1.79电子伏特和1.99电子伏特）具有通用性且效果显著，这有利地将效率提高了10% - 36%，并将所得器件的运行稳定性延长至2680小时。集成不同宽带隙钙钛矿子电池的四端全钙钛矿串联和六端全钙钛矿串联太阳能电池分别展现出高达24.39%和22.42%的效率。更重要的是，我们证明了阳离子β - 环糊精辅助的内部化学封装在器件严重受损并浸入水中时能有效防止铅泄漏。令人惊讶的是，单结器件仅有5.63 ppb的铅浸出，远低于美国安全饮用水标准（<15 ppb）。经过阳离子β - 环糊精改性的目标串联太阳能电池在最不利的环境下也实现了93.4%的铅螯合效率。
