Zhang Xinwen, Fei Chengbin, Shen Lening, Baral Pramod, Vijayaraghavan Sankaranarayanan Nair, Yan Feng, Gong Xiong, Wang He
Department of Physics, University of Miami, Coral Gables, Florida 33146, United States.
School of Polymer Science and Polymer Engineering, College of Engineering and Polymer Science, The University of Akron, Akron, Ohio 44325, United States.
ACS Appl Mater Interfaces. 2023 Aug 16;15(32):38522-38529. doi: 10.1021/acsami.3c08746. Epub 2023 Aug 7.
Inorganic metal halide perovskite materials as sunlight absorbers for solar cells exhibit better thermal stability than organic-inorganic hybrid counterparts. Pure cesium lead triiodide (CsPbI), with the most suitable band gap, suffers phase instability under an ambient environment. Nucleation and crystal growth are two crucial steps in fabricating a solution-processed perovskite film. A high-quality perovskite film with good morphology makes a significant impact on the efficiency and stability of perovskite solar cells. Dimethylformamide (DMF) is a commonly used aprotic solvent. However, it is difficult to obtain a high-quality inorganic perovskite film using DMF as a single solvent due to its slow evaporation and strong coordination with Pb. Here, we investigate dimethylacetamide (DMAc)/DMF as a cosolvent to prompt nucleation during the spin-coating process, leading to higher nucleation density and better surface coverage. In addition, we introduce CsBr in dimethylammonium lead triiodide (DMAPbI)/CsI precursors to slow down the crystal growth process. CsBr does not increase the film band gap but leads to a pinhole-free film with better crystallinity. Through nucleation and crystal growth engineering, the power conversion efficiency of inorganic perovskite devices is improved to 17.67%, and ambient environment stability is significantly enhanced.
作为太阳能电池阳光吸收剂的无机金属卤化物钙钛矿材料，比有机-无机杂化同类材料表现出更好的热稳定性。具有最合适带隙的纯铯铅三碘化物（CsPbI）在环境条件下会发生相不稳定。成核和晶体生长是制备溶液法钙钛矿薄膜的两个关键步骤。具有良好形貌的高质量钙钛矿薄膜对钙钛矿太阳能电池的效率和稳定性有重大影响。二甲基甲酰胺（DMF）是一种常用的非质子溶剂。然而，由于其蒸发缓慢且与Pb的强配位作用，使用DMF作为单一溶剂很难获得高质量的无机钙钛矿薄膜。在此，我们研究了二甲基乙酰胺（DMAc）/DMF作为共溶剂，以在旋涂过程中促进成核，从而导致更高的成核密度和更好的表面覆盖率。此外，我们在二甲基铵铅三碘化物（DMAPbI）/CsI前驱体中引入CsBr以减缓晶体生长过程。CsBr不会增加薄膜带隙，但会导致形成无针孔且结晶度更好的薄膜。通过成核和晶体生长工程，无机钙钛矿器件的功率转换效率提高到了17.67%，并且环境稳定性得到了显著增强。
