Li Jianfeng, Wang Lian, Liu Jun, Evmenenko Guennadi, Dutta Pulak, Marks Tobin J
Department of Chemistry, Northwestern University, Evanston, IL 60208, USA.
Langmuir. 2008 Jun 3;24(11):5755-65. doi: 10.1021/la704038g. Epub 2008 May 6.
The electronic properties of various transparent conducting oxide (TCO) surfaces are probed electrochemically via self-assembled monolayers (SAMs). A novel graftable probe molecule having a tethered trichlorosilyl group and a redox-active ferrocenyl functionality (Fc(CH2) 4SiCl3) is synthesized for this purpose. This molecule can be self-assembled via covalent bonds to form monolayers on various TCO surfaces. On as-received ITO, saturation coverage of 6.6 x 10(-10) mol/cm2 by a close-packed monolayer and an electron-transfer rate of 6.65 s(-1) is achieved after 9 h of chemisorption, as determined by cyclic voltammetry (CV) and synchrotron X-ray reflectivity. With this molecular probe, it is found that O2 plasma-treated ITO has a significantly greater electroactive coverage of 7.9 x 10 (-10) mol/cm2 than as-received ITO. CV studies of this redox SAM on five different TCO surfaces reveal that MOCVD-derived CdO exhibits the greatest electroactive coverage (8.1 x 10(-10) mol/cm2) and MOCVD-derived ZITO (ZnIn2.0Sn1.5O) exhibits the highest electron transfer rate (7.12 s(-1)).
通过自组装单分子层（SAMs）对各种透明导电氧化物（TCO）表面的电子性质进行电化学探测。为此合成了一种新型的可接枝探针分子，其具有连接的三氯甲硅烷基和氧化还原活性二茂铁官能团（Fc(CH2)4SiCl3）。该分子可通过共价键自组装，在各种TCO表面形成单分子层。在刚收到的ITO上，通过循环伏安法（CV）和同步加速器X射线反射率测定，化学吸附9小时后，紧密堆积单分子层的饱和覆盖率为6.6×10(-10) mol/cm2，电子转移速率为6.65 s(-1)。使用这种分子探针发现，经O2等离子体处理的ITO的电活性覆盖率显著更高，为7.9×10(-10) mol/cm2，高于刚收到的ITO。对五种不同TCO表面上这种氧化还原SAM的CV研究表明，MOCVD法制备的CdO表现出最大的电活性覆盖率（8.1×10(-10) mol/cm2），而MOCVD法制备的ZITO（ZnIn2.0Sn1.5O）表现出最高的电子转移速率（7.12 s(-1)）。
