Probing electronics as a function of size and surface of colloidal germanium nanocrystals
Probing electronics as a function of size and surface of colloidal germanium nanocrystals
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探测电子学与胶体锗纳米晶体尺寸和表面的函数关系
DOI：
10.1021/jp511929v
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发表时间：
2014
影响因子：
3.7
通讯作者：
Susan M. Kauzlarich
中科院分区：
文献类型：
--
作者：
Alexandra L. Holmes;Jeanette Hütges;Klaus Meerholz;Susan M. Kauzlarich
无机半导体纳米粒子对于受益于其尺寸依赖性的应用具有重要意义。本文主要研究了溶液微波法合成Ge纳米晶的特性。研究了三种不同封端的Ge纳米碳：油胺（OAM）、十二烷硫醇（DDT）和一种功能化的N4，N4，N4′，N4′-四苯基联苯-4，4 ′-二胺（TPD），后者通常用作空穴传输单元。光学带隙遵循量子限制的预期趋势;然而，绝对值取决于配体。我们发现，DDT帽盖的Ge NC功能始终大于OAM帽盖的Ge NC的类似大小的带隙。循环伏安法（CV）被用来确定的价带能量的OAM覆盖的锗纳米碳，和导带能量估计从光学间隙。相比之下，DDT封端的Ge NCs和OAM/DDT封端的Ge NCs在循环伏安法中没有表现出氧化信号。这是由于通过更强的Ge-S表面键去除了OAM覆盖的Ge纳米晶的表面缺陷。TPD封端的Ge NC进行了研究，并显示出位移到略高的氧化电位相比，自由配体和带隙值之间的OAM封端和DDT封端的Ge NC。较高的氧化电位归因于TPD取向，并且带隙值反映了由于配体空间位阻而导致的表面上较低的Ge-S键数。
Inorganic semiconductor nanoparticles are of significant interest for applications that benefit from their size-dependent properties. The work presented here focuses on the characterization of solution-based microwave synthesized Ge nanocrystals (NCs). Three differently capped Ge NCs were investigated: oleylamine (OAM), dodecanethiol (DDT), and a functionalizedN4,N4,N4′,N4′-tetraphenylbiphenyl-4,4′-diamine (TPD) ligand, which is commonly used as hole-transporting units. The optical gaps followed the expected trend for quantum confinement; however, the absolute value depended upon the ligand. We found that the DDT-capped Ge NCs feature consistently larger bandgaps than OAM-capped Ge NCs of a similar size. Cyclic voltammetry (CV) was used to determine the valence band energy for OAM-capped Ge NCs, and the conduction band energy was estimated from the optical gap. By contrast, DDT-capped Ge NCs and the OAM/DDT-capped Ge NCs did not exhibit an oxidative signal in the cyclic voltammetry. This was attributed to the removal of surface defects of OAM-capped Ge NCs through stronger Ge–S surface bonds. TPD-capped Ge NCs were investigated and showed a shift to slightly higher oxidation potential compared with the free ligand and bandgap values in between that of the OAM-capped and DDT-capped Ge NCs. The higher oxidation potential is attributed to TPD orientation, and the bandgap value reflects the lower number of Ge–S bonds on the surface due to ligand sterics.