Gold nanoparticle/organic networks as chemiresistor coatings: The effect of film morphology on vapor sensitivity
Gold nanoparticle/organic networks as chemiresistor coatings: The effect of film morphology on vapor sensitivity
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DOI：
10.1021/jp8013546
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发表时间：
2008-08-14
影响因子：
3.7
通讯作者：
Yasuda, Akio
中科院分区：
文献类型：
--
作者：
Joseph, Yvonne;Guse, Berit;Yasuda, Akio
通过逐层自组装沉积包含金纳米颗粒（4 nm芯直径）和十二烷二硫醇的网络化膜。膜厚度由沉积循环的数量控制，并且范围从亚单层到多层覆盖，厚度高达60 nm。FE-SEM和XPS显示岛生长在前四到五个沉积周期。在室温下，基于岛的膜显示出轻微的非线性电流-电压曲线，而较厚的膜欧姆行为。在100和300 K之间，电导的温度依赖性与活化电荷传输的Arrhenius模型一致。的化学敏感性的膜的特征在于通过给他们与甲苯，4-甲基-2-戊酮，1-丙醇，和水的蒸气，同时监测它们的相对微分电阻。薄膜响应与电阻的降低，而较厚的膜响应与电阻的增加。结果表明，溶胀沿着正常的膜可能是重要的均匀多层膜的基本传感机制。介电常数的变化和/或溶胀引起的介电距离的减小可以是所观察到的较薄的膜的电阻减小的原因。
Networked films comprising gold nanoparticles (4 nm core diameter) and dodecanedithiol were deposited via layer-by-layer self-assembly. The film thickness was controlled by the number of deposition cycles and ranged from submonolayer to multilayer coverage with up to 60 nm thickness. FE-SEM and XPS revealed island growth during the first four to five deposition cycles. At room temperature, films based on islands showed slightly nonlinear current-voltage curves, whereas thicker films gave Ohmic behavior. Between 100 and 300 K, the temperature dependence of conductance was consistent with an Arrhenius model for activated charge transport. The chemical sensitivity of the films was characterized by dosing them with vapors of toluene, 4-methyl-2-pentanone, 1-propanol, and water while monitoring their relative differential resistances. Thin films responded with a decrease in the resistance, whereas thicker films responded with a resistance increase. The results indicate that swelling along the film normal may be important for the underlying sensing mechanism of homogeneous multilayer films. Changes in permittivity and/or swelling-induced decrease of the interisland distance can be responsible for the observed decrease in resistance of the thinner films.