Locally Doped Nanorods: Introducing Distance-Dependence in Excitonic Nanostructures

在这个项目中，我们的目标是合成包含过渡金属掺杂的半导体纳米棒，这些掺杂位于棒上的特定区域。半导体纳米晶是一种极具吸引力的材料，可用于太阳能电池、激光器和光子学等领域的能量采集和转换。除了众所周知的尺寸量化效应，它允许通过控制纳米晶体的尺寸和形状来调节其光学和电子性能，掺杂杂质离子是制备功能纳米材料的一种日益重要的方法。过渡金属，特别是顺磁性离子，是合适的掺杂剂，因为它们可以通过它们的磁矩和与尺寸无关的荧光来检测。激发载流子在掺杂剂上的捕获速度非常快，到目前为止，这阻碍了对掺杂纳米晶体中电荷转移过程的观察。我们提出了一种一维结构，其中半导体材料的掺杂区与电荷载流子(例如异质结)的第二复合中心以纳米棒的长度分开。这将使我们能够在空间上将与掺杂相关的过程从激发和电荷复合中分离出来，从而在很短的时间内阐明光子吸收后的基本载流子动力学。该项目将引入距离作为控制半导体纳米颗粒中掺杂相关过程的新维度，并帮助设计和制造掺杂纳米颗粒，其掺杂分布的控制超出当前技术水平。这一结果将与能源材料和光伏、自旋电子学和新的荧光团高度相关。

In this project we aim to synthesise semiconductor nanorods that contain transition metal dopants localised to a specific region along the rod. Semiconductor nanocrystals are attractive materials to be used for energy harvesting and conversion in e.g. solar cells, lasers, and photonics. Apart from the well-understood size quantisation effect, which allows to tune optical and electronic properties of nanocrystals by controlling their size and shape, doping with impurity ions is an increasingly important method to manufacture functional nanomaterials. Transition metals, especially paramagnetic ions, are suitable dopants, because they can be detected by their magnetic moment and size-independent fluorescence. Trapping of excited charge carriers on dopants occurs extremely fast, which so far has hampered observation of the charge transfer process in doped nanocrystals. We propose a 1D structure in which a doped region of the semiconductor material is separated from a second recombination centre for charge carriers (e.g. a heterojunction) by the length of the nanorod. This will allow us to spatially decouple the dopant-related processes from excitation and charge recombination and hence elucidate the fundamental carrier dynamics at very short times after photon absorption. This project will introduce distance as a new dimension of control over doping-related processes in semiconductor nanoparticles and help to design and fabricate doped nanoparticles with control over dopant distribution beyond the current state of the art. The results will be highly relevant for energy materials and photovoltaics, spintronics, and new fluorophores.