Hydrophilicity and Water Contact Angle on Methylammonium Lead Iodide
Hydrophilicity and Water Contact Angle on Methylammonium Lead Iodide
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DOI：
10.1002/admi.201801173
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发表时间：
2019-02-08
影响因子：
5.4
通讯作者：
Mattoni, Alessandro
中科院分区：
文献类型：
--
作者：
Caddeo, Claudia;Marongiu, Daniela;Mattoni, Alessandro
表面特性通常通过测量水滴的接触角来评估。然而，对于非常重要的一类混合钙钛矿材料（广泛用于太阳能电池和光电子研究），该工艺存在缺陷，因为它们是水溶性的，并且在接触角测量过程中其表面会降解。虽然杂化钙钛矿被认为是高度亲水的，但可以测量到与水的接触角为83度，好像它们几乎是疏水的。通过实验和模拟的结合，实际值被解释为水与在亚毫秒时间尺度上在水/钙钛矿界面上形成的退化表面层相互作用的结果。通过对各种基材上的水的接触角测量验证了模型的有效性，并参考了液固结合与接触角之间的Young-Dupre关系。本工作将甲基碘化铅的亲水性与接触角测量中明显的疏水行为相协调，提出了一种研究进化底物接触角的方法。
Surface properties are often assessed with measurements of the contact angle of a water drop. The process is however flawed for the very important class of hybrid perovskite materials, extensively employed in solar cells and optoelectronics research, because they are water soluble and their surface degrades during contact angle measurements. While hybrid perovskites are considered to be highly hydrophilic, a contact angle with water of 83 degrees can be measured, as if they were almost hydrophobic. By combining experiments and simulations, the actual value is explained as the result of the interaction of water with degraded superficial layers that form over sub-millisecond time scale at the water/perovskite interface. The models are validated against contact angle measurements for water on a variety of substrates, and are referenced to with the Young-Dupre relation between liquid-solid adhesion and contact angle. Present work reconciles the hydrophilic nature of methylammonium lead iodide with the apparent hydrophobic behavior in contact angle measurements, proposing a methodology for the study of contact angle on evolving substrates.