论文总字数：26817字

摘 要

银纳米线（AgNW）由于其独特的光学、电学和热学性能可以满足作为锡掺杂氧化铟(ITO)的替代物来制备透明导电薄膜的要求而受到广泛关注。近年来，许多研究人员对银纳米线的生长机制和形貌控制进行了大量的研究。然而，对于Cl^-和Br^-在多元醇法合成银纳米线过程中的作用仍没有统一的解释。针对这个问题，本论文研究了Cl^-和Br^-在制备银纳米线中的作用，并且在Cl^-和Br^-共存的条件下，合成了高长径比（达2100）、高产率(gt;85%)的银纳米线。

研究发现，当单独使用NaCl添加剂时，具有较大临界尺寸的多重孪晶（MTP）能够生长成直径较大的银纳米线，产物中含有较少的银纳米颗粒（AgNP）；而当使用NaBr添加剂时，拥有较小临界尺寸的MTP能够生长成为较细的银纳米线，但产物中含有较多的银纳米颗粒。当同时使用NaCl和NaBr添加剂时，可以得到小直径、高长径比、高产率的银纳米线产物。本论文提出，可以根据卤化银晶体的电子陷阱分布(ETD)来理解不同直径、不同产率银纳米线的生长过程。另外我们发现，使用NaCl/NaBr共添加剂时，溶液中形成了混合卤化银晶体AgBr_1-xCl_x，而在AgBr_1-xCl_x晶体中，ETD是均匀分布的，这有利于合成高质量的银纳米线。

关键词：银纳米线 NaCl NaBr AgBr_1-xCl_x晶体 电子陷阱分布

Understanding the mechanism of silver nanowire

nucleation and growth

Abstract

Silver nanowires (AgNWs) have attracted wide attention due to their unique optical, electrical and thermal properties, which can be utilized as an alternative to tin doped indium oxide (ITO) to prepare transparent conductive films. In recent years, many researchers have done a lot of researches on the growth mechanism and morphology control of silver nanowires. However, there is no consensus on the role of Cl^- and Br^- in the synthesis of silver nanowires by polyol method. In this paper，we explore the role of Cl^- and Br^- in the preparation of silver nanowires. Especially，silver nanowires with large aspect ratio (up to 2100) and high yield (gt; 85%) was synthesized under the condition of co-existence of Cl^- and Br^-.

It is found that for NaCl additive, multiply-twinned particles (MTPs) with larger critical size could be formed and grow into AgNWs with large diameter, accompanied by a small amount of silver nanoparticles (AgNPs). However, for NaBr additive, thin AgNWs could grow from MTPs with smaller critical size, but the product contains a large amount of AgNPs. For the case of Cl^- and Br^- co-additives, AgNWs with small diameter, high aspect ratio and high yield was obtained. Here, we propose that the growth mechanism of AgNWs with different diameters and different yields can be understood based on the electron trap distribution (ETD) of silver halide crystals. We also found that when using the NaCl/NaBr co-additive, a mixed silver halide crystal AgBr_1-xCl_x was formed in the solution. In the AgBr_1-xCl_x crystal, the ETD was relatively uniform, which is beneficial to the synthesis of AgNWs with high quality.

Key Words: Silver nanowire; NaCl; NaBr; AgBr1-xClx crystal; Electronic traps distribution

目 录

摘要………………………………………………………………………………………………I

Abstract…………………………………………………………………………………………II

第一章 绪论……………………………………………………………………………………1

1.1 银纳米线的研究进展与现状……………………………………………………………1

1.2 银纳米线的制备方法……………………………………………………………………1

1.3 多元醇法制备银纳米线的原理…………………………………………………………2

1.4 本论文的研究内容………………………………………………………………………4

第二章 银纳米线的制备与形貌表征……………………………………………………5

2.1 银纳米线的多元醇法制备………………………………………………………………5

2.1.1 实验药品与仪器…………………………………………………………………5

2.1.2 制备过程…………………………………………………………………………5

2.1.3 表征技术…………………………………………………………………………6

2.2 银纳米线形貌的表征……………………………………………………………………7

2.3 本章小结………………………………………………………………………………9

第三章 分析与讨论…………………………………………………………………………10

3.1 银纳米线的XRD和紫外-可见光吸收光谱表征………………………………………10

3.1.1 XRD表征结果分析………………………………………………………………10

3.1.2 紫外-可见光吸收光谱表征结果分析……………………………………………12

3.2 银纳米线生长机制分析………………………………………………………………13

3.3 我们提出的电子陷阱分布(ETD)生长机制……………………………………………15

3.4 调节NaCl/NaBr浓度来控制银纳米线直径………………………………………17

3.5 本章小结………………………………………………………………………………19

结论与展望……………………………………………………………………………………21

参考文献………………………………………………………………………………………22

致谢……………………………………………………………………………………………26

第一章 绪 论

银纳米线(AgNW)由于其特有的光学、电学和热学性能，近年来引起了人们的广泛兴趣。本章将从银纳米线的研究进展与现状出发，概括了其制备方法，重点介绍了多元醇制备银纳米线的生长机制，最后提出了本论文主要研究内容。

1.1银纳米线的研究进展与现状

银纳米线目前被应用于纳米电子设备，如柔性触摸屏、薄膜太阳能电池、有机发光二极管和生物分子传感器等器件[1-5]，特别地，它们可以替代锡掺杂氧化铟(ITO)来制备透明导电薄膜。

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