Fracture in electrophoretically deposited CdSe nanocrystal films
Fracture in electrophoretically deposited CdSe nanocrystal films
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DOI：
10.1063/1.3118630
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发表时间：
2009-05-15
影响因子：
3.2
通讯作者：
Herman, Irving P.
中科院分区：
文献类型：
--
作者：
Jia, Shengguo;Banerjee, Sarbajit;Herman, Irving P.
我们研究了电泳法沉积的CdSe纳米晶薄膜的断口、应变和应力随薄膜厚度、纳米晶尺寸和干燥方法的变化。当膜厚超过阈值厚度时，膜的断裂是由于电火花放电后残留溶剂的损失而产生的，对于芯直径从2.3 nm到5.0 nm的纳米晶，膜厚随着纳米晶直径从300 nm到1200 nm而分别增加。干燥后观察到先宽后窄的分层结构，并实时观察到这一世代裂纹的形成和薄膜干燥的优先方向。剥离被认为是从更宽的裂纹开始的，主要是在薄膜的主体和强烈结合在Au涂层的硅衬底上的非常薄的纳米晶层之间。对于通道开裂和分层，给出了薄膜韧性的估算。
We have studied the fracture, strain, and stress of electrophoretically deposited (EPD) films of CdSe nanocrystals as a function of the film thickness, nanocrystal size, and drying method. Fracture results from the film stress that develops with the loss of residual solvent after EPD when the film exceeds a threshold thickness that increases with nanocrystal core diameter from similar to 300 to 1200 nm for core diameters from 2.3 to 5.0 nm, respectively. A hierarchical pattern of wider first generation and then narrower higher-generation cracks is observed after drying and this generational crack formation and a preferred direction for film drying are observed in real time. Delamination is seen to initiate from wider cracks, mostly between the bulk of the film and a very thin layer of nanocrystals strongly bound to the Au-coated silicon substrate. Estimates of the film toughness are made for channel cracking and delamination.