The Electronic Structure of Amorphous Carbon Nanodots
The Electronic Structure of Amorphous Carbon Nanodots
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DOI：
10.1021/jp510620j
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发表时间：
2015-06-18
影响因子：
3.3
通讯作者：
Clark, Timothy
中科院分区：
文献类型：
--
作者：
Margraf, Johannes T.;Strauss, Volker;Clark, Timothy
我们用半经验分子轨道理论对氢钝化的非晶态碳纳米结构进行了研究，以期对影响其电子性质的因素有所了解。首先使用熔融/淬火协议中的周期计算来构建非晶态结构。纯周期性非晶态碳结构及其掺杂氮和/或氧的对应结构具有较大的电子带隙。令人惊讶的是，元素组成和sp(3)原子数目等参数对电子结构的影响很小。取而代之的是，SP(2)网络在有效共轭方面的精确拓扑定义了带隙。从周期性结构中切出了不同结构和尺寸的非晶态碳纳米点。我们的计算预测了局域电子表面态的出现，这引起了有趣的效应，如两性反应性和预测的近紫外/可见光范围内的光学带隙。光学和电子能隙表现出与无机胶体量子点类似的对颗粒尺寸的依赖关系。
We have studied hydrogen-passivated amorphous carbon nanostructures with semiempirical molecular orbital theory in order to provide an understanding of the factors that affect their electronic properties. Amorphous structures were first constructed using periodic calculations in a melt/quench protocol. Pure periodic amorphous carbon structures and their counterparts doped with nitrogen and/or oxygen feature large electronic band gaps. Surprisingly, descriptors such as the elemental composition and the number of sp(3)-atoms only influence the electronic structure weakly. Instead, the exact topology of the sp(2)-network in terms of effective conjugation defines the band gap. Amorphous carbon nanodots of different structures and sizes were cut out of the periodic structures. Our calculations predict the occurrence of localized electronic surface states, which give rise to interesting effects such as amphoteric reactivity and predicted optical band gaps in the near-UV/visible range. Optical and electronic gaps display a dependence on particle size similar to that of inorganic colloidal quantum dots.