Effects of added thiol ligand structure on aggregation of non-aqueous ZnO dispersions and morphology of spin-coated films
Effects of added thiol ligand structure on aggregation of non-aqueous ZnO dispersions and morphology of spin-coated films
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DOI：
10.1039/c4ra15013a
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发表时间：
2015-02
期刊：
影响因子：
3.9
通讯作者：
Aloïs Mispelon;Junfeng Yan;Amir H. Milani;Mu Chen;Wenkai Wang;P. O’Brien;B. Saunders
中科院分区：
文献类型：
--
作者：
Aloïs Mispelon;Junfeng Yan;Amir H. Milani;Mu Chen;Wenkai Wang;P. O’Brien;B. Saunders
使用基于溶液的方法控制旋涂的半导体MEMS膜的形态的能力对于光电器件应用是潜在重要的。在这项研究中，我们试图建立添加的双官能硫醇配体结构，引发的聚集和使用ZnO纳米晶体旋涂的聚乙烯薄膜形态之间的关系。研究后者的纳米晶体是因为它们不依赖于吸附的长链配体的分散稳定性，这简化了分析，并在太阳能电池中具有潜在的应用。本研究中使用的二硫醇配体是1，2-乙二硫醇、1，2-苯二硫醇和1，4-苯二硫醇。视觉上和使用浊度测量来评估分散稳定性。构建了ZnO/1，2-乙二硫醇分散体系在氯苯中的胶体稳定相图，比较了1，2-乙二硫醇和1，2-苯二硫醇引发分散聚集的能力。用光学显微镜、扫描电镜和透射电镜研究了旋涂法制备的纳米TiO 2薄膜的形貌。数据显示，添加的1，2-苯二硫醇在触发聚集方面比1，2-乙二硫醇有效得多，并且这种效果归因于更强的链间键。此外，旋涂ZnO/1，2-苯二硫醇薄膜强烈散射光在可见光区，这是由于多分散的亚微米聚集体的形成。提出了配体引发分散ZnO纳米晶聚集的机理。我们提出了双官能硫醇配体的选择控制触发聚集和实现增强的光散射的ZnO纳米薄膜的设计规则。后者可以使染料敏化太阳能电池的高效ZnO光电极的处理更简单。
The ability to control the morphology of spin-coated semiconducting nanocrystal films using solution based methods is potentially important for optoelectronic device applications. In this study we sought to establish relationships between added bifunctional thiol ligand structure, triggered nanocrystal aggregation and spin-coated nanocrystal film morphology using ZnO nanocrystals. The latter nanocrystals were studied because they do not rely on adsorbed long-chain ligands for dispersion stability, which simplifies the analysis, and have potential application in solar cells. The dithiol ligands used in this study were 1,2-ethanedithiol, 1,2-benzenedithiol and 1,4-benzenedithiol. Dispersion stability was assessed visually and using turbidity measurements. A colloid stability phase diagram for ZnO/1,2-ethanedithiol dispersions in chlorobenzene was constructed and the ability of 1,2-ethanedithiol and 1,2-benzenedithiol to trigger dispersion aggregation was compared. The morphology of spin-coated nanocrystal films was investigated using optical microscopy, SEM and TEM. The data show that added 1,2-benzenedithiol was far more effective at triggering aggregation than 1,2-ethanedithiol and this effect was attributed to stronger inter-nanocrystal linkages. Moreover, spin-coated ZnO/1,2-benzenedithiol films strongly scattered light in the visible region which was attributed to the formation of polydisperse sub-micrometre aggregates. A mechanism for ligand triggered aggregation of dispersed ZnO nanocrystals was proposed. We propose design rules for bifunctional thiol ligand selection for controlling triggered aggregation and achieving enhanced light scattering of ZnO nanocrystal films. The latter may enable simpler processing of efficient ZnO photoelectrodes for dye sensitised solar cells.