Tuning the optical and electronic properties of colloidal nanocrystals by lattice strain.
Tuning the optical and electronic properties of colloidal nanocrystals by lattice strain.
复制标题
DOI：
10.1038/nnano.2008.360
复制
发表时间：
2009-01
影响因子：
38.3
通讯作者：
中科院分区：
文献类型：
--
作者：
晶格应变是一个结构参数，已被利用在微电子器件中取得了巨大的成功，但它在胶体纳米晶体中的作用仍然知之甚少。在这里，我们通过使用晶格失配的异质结构开发了应变可调的胶体纳米晶体，所述异质结构通过压缩壳的外延沉积生长（例如，ZnSe或CdS）到软且小的纳米晶体芯（例如，CdTe）。这种“压缩”核心和“拉伸”外壳的组合导致导带和价带能量的急剧变化。其结果是，我们表明，标准的I型行为的核壳量子点转换成II型纳米结构，导致电子和空穴的空间分离，延长激发态寿命，和巨大的光谱位移。这类新的应变可调量子点在可见光和近红外波长（500 nm至1050 nm）的宽范围内表现出窄光发射和高量子产率。
Lattice strain is a structural parameter that has been exploited in microelectronic devices with great success, but its role in colloidal nanocrystals is still poorly understood. Here we have developed strain-tunable colloidal nanocrystals by using lattice-mismatched heterostructures that are grown by epitaxial deposition of a compressive shell (e.g., ZnSe or CdS) onto a soft and small nanocrystalline core (e.g., CdTe). This combination of a “squeezed” core and a “stretched” shell causes dramatic changes in both the conduction and valence band energies. As a result, we show that core-shell QDs with standard type-I behavior are converted into type-II nanostructures, leading to spatial separation of electrons and holes, extended excited state lifetimes, and giant spectral shifting. This new class of strain-tunable QDs exhibits narrow light emission with high quantum yield across a broad range of visible and near-infrared wavelengths (500 nm to 1050 nm).