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首页> 外文学位 >Porphyrin-Based Molecular Multilayer Films Assembled via Copper(I)-Azide-Alkyne Cycloaddition Coupled Layer-by-Layer Method for Light Harvesting Applications.
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Porphyrin-Based Molecular Multilayer Films Assembled via Copper(I)-Azide-Alkyne Cycloaddition Coupled Layer-by-Layer Method for Light Harvesting Applications.

机译：通过聚（I）-叠氮化物-炔烃环加成偶联层-层方法组装的基于卟啉的分子多层膜，用于光收集应用。

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摘要

We have developed a Layer-by-Layer (LbL) method for the fabrication of thin-film molecular multilayers on electron-beam evaporated Au surfaces. Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) coupling reactions were used for initial surface attachment and subsequent LbL deposition. The molecular multilayer films comprised of porphyrins and multi–azido linkers were assembled and characterized with a multitude of surface techniques. The electrochemical and photophysical properties of the thin-films can be tuned through synthetic modification of the individual building blocks, resulting in new porphyrin multilayers. These films have applications as light-harvesting arrays in Dye-Sensitized Solar Cells (DSSC), molecular electronics, and sensors.;Herein, we demonstrate the reproducible growth trends and optical properties of multilayer films on Au surfaces modified with an azido–terminated alkanethiol self-assembled monolayer. Multilayer growth was followed by UV-Vis absorption and specular reflectance spectroscopy. Film thickness and optical constants were obtained through spectroscopic ellipsometry. The resulting extinction coefficients were consistent with typical porphyrin absorption spectra. The multilayers show consistent linear growth in absorbance and film thickness over tens of layers as well as continuity and moderate ordering in their molecular structure. This flexible molecular LbL technique has the potential to control the nanoscale structure and function of the thin films. Topology and local surface roughness were examined by TM-AFM, and elemental composition found by X-ray Photoelectron Spectroscopy (XPS) was consistent with the expected morphology of the porphyrin based films assembled on Au surfaces. Additionally, the copper content of the resulting films was quantified by XPS, and the utility of ethylenediaminetetraacetic acid disodium salt (Na2EDTA) was examined to remove the adventitious Cu catalyst. The gold supported multilayers were developed as a test-bed of the films’ electrochemical properties were studied by cyclic voltammetry and interfacial electron transfer rate constants were measured using chronoamperometry. It is crucial to examine the electron transport in the films in order to determine the applicability of the films for DSSC.;Additionally, films grown on silicon oxide surfaces were also characterized in a similar manner as those on gold. Specular X-ray Reflectivity (XRR) measurements were done for silicon oxide supported films, and yield an average thickness of the films and confirm highly linear dependence of the film thickness on bilayer number. Macroscopic surface roughness was determined by XRR and data fitting. It was found to increase with the number of layers and generally was around 12% of the film thickness for silicon oxide supported films. Tapping mode AFM measurements confirm the continuous nature of the thin films and the local roughness, which had values slightly larger than those determined from XRR. Spectroscopic ellipsometry analysis yielded film thickness and optical constants. The film thickness correlated well with XRR derived film thickness, although it was slightly higher. The average molecular growth angles were estimated by comparing intramolecular distances from DFT modeling with experimental film thicknesses and found to be between 40° and 70° with respect to the substrate surface, depending on the bonding configuration.;The above described results confirm that the porphyrin-based multilayers can be reproducibly grown using the LbL method and CuAAC interlayer coupling on various substrates and potentially become a new class of light harvesting arrays for DSSC, molecular electronics, and sensors.
机译：我们已经开发了一种在电子束蒸发的金表面上制造薄膜分子多层膜的逐层（LbL）方法。铜（I）催化的叠氮化物-炔烃环加成（CuAAC）偶联反应用于初始表面附着和随后的LbL沉积。组装了由卟啉和多叠氮基连接基组成的分子多层膜，并通过多种表面技术对其进行了表征。薄膜的电化学和光物理性质可通过对各个结构单元进行合成修饰来调节，从而形成新的卟啉多层膜。这些膜可作为染料敏化太阳能电池（DSSC），分子电子学和传感器中的光收集阵列应用；在这里，我们证明了叠氮基末端链烷硫醇修饰的Au表面上多层膜的可再现生长趋势和光学性质。自组装单层。多层生长之后是UV-Vis吸收和镜面反射光谱。膜厚和光学常数通过光谱椭圆偏振法获得。最终的消光系数与典型的卟啉吸收光谱一致。多层在数十层上显示出一致的线性增长，其吸收率和膜厚度以及其分子结构的连续性和适度有序性。这种灵活的分子LbL技术具有控制薄膜的纳米级结构和功能的潜力。通过TM-AFM检查拓扑和局部表面粗糙度，并且通过X射线光电子能谱（XPS）发现的元素组成与组装在Au表面上的卟啉基薄膜的预期形态一致。另外，通过XPS对所得膜中的铜含量进行定量，并且研究了乙二胺四乙酸二钠盐（Na 2 EDTA）的用途以除去不定形的Cu催化剂。通过循环伏安法研究了载金多层膜作为薄膜电化学性能的试验床，并使用计时电流法测量了界面电子传递速率常数。至关重要的是检查膜中的电子传输，以确定膜在DSSC中的适用性。此外，在氧化硅表面生长的膜的特征也与在金上相似。对氧化硅支撑的薄膜进行了镜面X射线反射率（XRR）测量，得出了薄膜的平均厚度，并确认了薄膜厚度对双层数的高度线性依赖性。通过XRR和数据拟合确定宏观表面粗糙度。发现其随着层数而增加，并且通常为氧化硅支撑的膜的膜厚度的约12％。攻丝模式原子力显微镜的测量证实了薄膜的连续性和局部粗糙度，其值略大于由XRR确定的值。椭圆偏振光谱分析产生膜厚度和光学常数。膜厚与XRR衍生的膜厚相关性很好，尽管稍高一些。通过比较从DFT建模得到的分子内距离与实验膜厚度来估计平均分子生长角，发现相对于基体表面在40°至70°之间，具体取决于结合构型。;上述结果证实了卟啉可以使用LbL方法和CuAAC层间耦合在各种基板上可复制地生长基于多层的多层膜，并有可能成为用于DSSC，分子电子学和传感器的新型光收集阵列。

著录项

  • 作者

    Krawicz, Alexandra.;

  • 作者单位

    Rensselaer Polytechnic Institute.;

  • 授予单位 Rensselaer Polytechnic Institute.;
  • 学科 Chemistry Inorganic.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 149 p.
  • 总页数 149
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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