Charge and Surface Effects on Exciton and Hot Carrier Relaxation in Colloidal Quantum Dots

胶体量子点中激子和热载流子弛豫的电荷和表面效应

• 批准号: 0706268
• 负责人: Philippe Guyot-Sionnest
• 金额: $ 34.5万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0706268&HistoricalAwards=false
• 关键词: Charge; Surface; Effects; Exciton; Hot

Non-technical abstract:Over the last twenty years, semiconductor nanostructures have revolutionized optical technology with wide impact in communication and consumer electronics. Chemical synthesis of smaller, soluble, possibly better defined or more complex nanostructures promises to expand the impact to medical imaging, displays and solar energy. These Technologies are aggressively pursued by several venture firms. However, poor device efficiency and limited lifetimes may turn out to be show- stoppers. They are ultimately defined by the mechanisms of dissipation of the electronic energy in these tiny structures. In particular, it is becoming clear that the strong charge repulsion and the extreme surface proximity lead to very fast energy loss by yet unclear mechanisms. Understanding the generic mechanisms of the microscopic efficiency loss will be of broad importance in nanotechnology. This is the topic of this basic materials science project with physics and chemistry PhD students. The students will receive training in several research technique used in the study of these materials which will play important role in various products.Technical abstract:The project focuses on colloidal semiconductor quantum dots and how charge and surface affect their interband and intraband energy relaxation. The former is relevant to light-emitting diode or solar cell developments, while the latter may lead to infrared applications. The project quantifies how excess charge affects the stability, photo-excitation, fluorescence and relaxation. Experiments are performed on charged ensemble as well as single dots. Slow intraband relaxation would open new opportunities in engineering the nanostructure as well as in infrared applications and to date it appears to be strongly affected by the surface. The materials synthesis focuses on surface control and core/shells while the characterization involves time-resolved optical spectroscopy. The project supports the research of two PhD students at the interface of Chemistry and Physics. It also provides the scientific environment for one summer undergraduate, while the fluorescent materials are regularly used in classroom demonstration. Graduate students will receive training in broad spectrum of research technique used in the study of these materials which will play importnat role in various products.

非技术摘要：在过去的二十年里，半导体纳米结构已经彻底改变了光学技术，对通信和消费电子产生了广泛的影响。 化学合成更小、可溶、可能更好定义或更复杂的纳米结构有望扩大对医学成像、显示器和太阳能的影响。 这些技术被几家风险投资公司积极追求。 然而，较差的器件效率和有限的寿命可能会成为阻碍因素。 它们最终由这些微小结构中电子能量的耗散机制来定义。特别是，它是越来越清楚，强大的电荷排斥和极端的表面接近导致非常快的能量损失，但不清楚的机制。 了解微观效率损失的一般机制将在纳米技术中具有广泛的重要性。这是物理和化学博士生的基础材料科学项目的主题。学生们将接受在这些材料的研究中使用的几种研究技术的培训，这些材料将在各种产品中发挥重要作用。技术摘要：本项目主要研究胶体半导体量子点以及电荷和表面如何影响它们的带间和带内能量弛豫。 前者与发光二极管或太阳能电池的发展有关，而后者可能导致红外应用。该项目量化了过量电荷如何影响稳定性，光激发，荧光和弛豫。实验进行了带电的合奏以及单点。 缓慢的带内弛豫将为纳米结构的工程设计和红外应用开辟新的机会，迄今为止，它似乎受到表面的强烈影响。材料合成的重点是表面控制和核/壳，而表征涉及时间分辨光谱。 该项目支持两名博士生在化学和物理的接口的研究。 它还为一个暑期本科生提供了科学环境，而荧光材料则经常用于课堂演示。研究生将接受在这些材料的研究中使用的广泛的研究技术的培训，这些材料将在各种产品中发挥重要作用。