CAREER: Plasmon-mediated photo-absorption and carrier recombination dynamics in semiconductor/metal hybrid nano-systems

在这个由化学部门大分子、超分子和纳米化学项目资助的项目中，来自北卡罗来纳大学夏洛特分校的马库斯·琼斯正在研究纳米级量子点和金属颗粒在光的存在下如何相互作用，以增强太阳能电池和发光二极管（led）等光电器件的功能。量子点是微小的半导体，其颜色取决于它们的大小：较大的粒子看起来比较小的粒子更红。金属纳米颗粒可以充当微型天线，引导光能进出量子点。这项研究计划旨在揭示纳米级金属和半导体之间复杂的相互作用，这可能会使技术进步，如更薄、更高效的太阳能电池和更亮的led。这项工作也被整合到一个教学和推广项目中，该项目与夏洛特教师学院合作，旨在向当地教师传授纳米科学的神奇世界，并促进他们参与短期项目，在那里他们可以自己做前沿研究。受美国国家科学基金会（NSF）在北卡罗来纳大学夏洛特分校开展的ADVANCE计划活动的启发，马库斯还在北卡罗来纳大学夏洛特分校组织了一系列研讨会，旨在提高女性在科学领域的保留率，邀请女性科学专业人士讨论作为一名女性在科学领域的挑战和回报。本研究计划旨在加深我们对纳米结构金属中量子点激子与表面等离子体模式之间共振耦合所引起的光吸收和发射效应的理解。表面等离子体共振就像局部天线一样，可以使电磁能量有效地耦合到发色团中或从发色团中输出。这可以表现为光致发光强度的增加，这归因于光吸收增加或辐射重组。耦合表面等离子体模式捕获和集中电磁能的能力，通过提高多激子产生率、提高双激子发射效率和消除荧光闪烁，为增强量子点在光收集或LED应用中的作用提供了巨大的机会。与以往的研究不同，这项工作主要集中在了解等离子体耦合对多激发量子点的光吸收和载流子复合速率的影响。单粒子和新开发的集成技术的结合被用于区分多激子荧光动力学发生在制造的混合纳米系统中，该系统被设计为能够很好地控制激子-等离子体相互作用。成功完成拟议的研究任务将(i)建立半导体和金属纳米颗粒之间距离对光吸收和辐射复合率的依赖性；（ii）解决由于量子点尺寸、形状和组成变化而产生的影响；（iii）确定单激子与带电和多激子状态诱导的光吸收和发射增强之间的差异。

In this project, funded by the Chemistry Division's Macromolecular, Supramolecular and Nanochemistry Program, Marcus Jones from the University of North Carolina at Charlotte is investigating how the interactions between nano-sized quantum dots and metal particles in the presence of light can be used to enhance the function of optoelectronic devices such as solar cells and light-emitting diodes (LEDs). Quantum dots are tiny semiconductors whose color depends on their size: larger particles appear redder than smaller ones. Metal nanoparticles can act as miniature antennas that channel light energy into or out of the quantum dots. This research program aims to unravel the complex interplay between nanoscale metals and semiconductors that could potentially enable technological advances such as thinner, more efficient solar cells and brighter LEDs. This work is also being integrated into a teaching and outreach program, which, in collaboration with the Charlotte Teachers' Institute, aims to educate local schoolteachers about the amazing world of nanoscale science and facilitates their participation in short term projects where they can do cutting-edge research for themselves. Inspired by the activities of the NSF ADVANCE initiative at UNC Charlotte, Marcus is also organizing a seminar series at UNC Charlotte, aimed at improving the retention of women in science, at which female science professionals are invited to discuss the challenges and rewards of being a woman in science.This research program aims to develop our understanding of the photo-absorption and emission effects caused by resonant coupling between excitons in quantum dots and surface plasmon modes in nanostructured metals. Acting like local antennae, surface plasmon resonances can enable efficient coupling of electromagnetic energy into or out of a chromophore. This can manifest as increased photoluminescence intensity, which is ascribed to either increased photo-absorption, or radiative recombination. The ability of coupled surface plasmon modes to capture and concentrate electromagnetic energy presents a tremendous opportunity to enhance the role of quantum dots in light harvesting or LED applications by improving multi-exciton generation yields, increasing biexciton emission efficiencies and eliminating fluorescence blinking. Unlike previous studies, this work is primarily focused towards understanding the effects of plasmonic coupling on the photo-absorption and carrier recombination rates of multi-excited quantum dots. A combination of single particle and newly developed ensemble techniques is being used to distinguish multi-exciton fluorescence dynamics occurring in fabricated hybrid nanosystems that have been designed to enable good control over exciton-plasmon interactions. Successful completion of the proposed research tasks will (i) establish the dependence of photo-absorption and radiative recombination rates on the distance between semiconductor and metal nanoparticles; (ii) resolve effects due to changes in quantum dot size, shape and composition; and (iii) identify the differences between photo-absorption and emission enhancements induced in single exciton versus charged and multi-exciton states.