Bing Jueming, Kim Jincheol, Zhang Meng, Zheng Jianghui, Lee Da Seul, Cho Yongyoon, Deng Xiaofan, Lau Cho Fai Jonathan, Li Yong, Green Martin A, Huang Shujuan, Ho-Baillie Anita W Y
Australian Centre for Advanced Photovoltaics (ACAP), School of Photovoltaic and Renewable and Engineering, University of New South Wales, Sydney, 2052, Australia.
Small. 2019 Mar;15(9):e1804858. doi: 10.1002/smll.201804858. Epub 2019 Feb 1.
This paper provides deep understanding of the formation mechanism of perovskite film fabricated by sequential solution-based methods. It compares two sequential spin-coating methods for Cs (MA FA ) PbI perovskite. First is the "static process," with a stoppage between the two spin-coating steps (1st PbI -CsI-dimethyl sulfoxide (DMSO)-dimethylformamide (DMF) and 2nd methylammonium iodide (MAI)-formamidinium iodide (FAI)-isopropyl alcohol). Second is the "dynamic process," where the 2nd precursor is dispensed while the substrate is still spinning from the 1st step. For the first time, such a dynamic process is used for Cs (MA FA ) PbI perovskite. Characterizations reveal improved film formation with the dynamic process due to the "retainment" of DMSO-complex necessary for the intermediate phase which i) promotes intercalation between precursors and ii) slows down perovskite crystallization for full conversion. The comparison on as-deposited perovskite before annealing indicates a more ordered film using this dynamic process. This results in a thicker, more uniform film with higher degree of preferred crystal orientation and higher carrier lifetime after annealing. Therefore, dynamic-processed devices present better performance repeatability, achieving a higher average efficiency of 17.0% compared to static ones (15.0%). The new insights provided by this work are important for perovskite solar cells processed sequentially as the process has greater flexibility in resolving solvent incompatibility, allowing separate optimizations and allowing different deposition methods.
本文深入探讨了基于溶液的连续法制备钙钛矿薄膜的形成机制。比较了两种用于Cs(MA FA )PbI钙钛矿的连续旋涂方法。第一种是“静态过程”，在两次旋涂步骤之间有停顿（第一步是PbI -CsI-二甲基亚砜（DMSO）-二甲基甲酰胺（DMF），第二步是甲基碘化铵（MAI）-甲脒碘化铵（FAI）-异丙醇）。第二种是“动态过程”，即在第一步的衬底仍在旋转时滴加第二种前驱体。首次将这种动态过程用于Cs(MA FA )PbI钙钛矿。表征显示，由于中间相所需的DMSO络合物的“保留”，动态过程改善了薄膜形成，这一保留作用：i）促进前驱体之间的插层，ii）减缓钙钛矿结晶以实现完全转化。对退火前沉积的钙钛矿的比较表明，使用这种动态过程得到的薄膜更有序。这导致退火后薄膜更厚、更均匀，具有更高的择优晶体取向度和更长的载流子寿命。因此，动态处理的器件具有更好的性能重复性，与静态处理的器件（15.0%）相比，平均效率更高，达到17.0%。这项工作提供的新见解对于连续处理的钙钛矿太阳能电池很重要，因为该工艺在解决溶剂不相容性方面具有更大的灵活性，允许单独优化并允许采用不同的沉积方法。
