A Route Towards Efficient Energy Relaxation from Nanocrystals to Oxide-free Semiconductor Surfaces

从纳米晶体到无氧化物半导体表面的有效能量弛豫之路

• 批准号: 1207123
• 负责人: Anton Malko
• 金额: $ 38.99万
• 依托单位: University of Texas at Dallas
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1207123&HistoricalAwards=false
• 关键词: Route; Towards; Efficient; Energy; Relaxation

Abstract Technical: Energy-transfer-based hybrid nanostructures judiciously engineered from components with separate functionalities offer a versatile platform for optoelectronic device applications. Light absorption in the strongly absorbing component of the hybrid is followed by non-contact electromagnetic energy transfer from the resulting excitons in nanostructures to electron-hole pairs in the conductive semiconductor thin film. This electromagnetic manipulation of excitations in nanoscale materials with well-controlled interfaces is an important step towards the next generation of functional nanodevices, which does not rely on charge transfer between the components. This project focuses on the fundamental principles of radiative and non-radiative energy transfer phenomena between highly absorbing nanocrystal quantum dots (NQDs) and high-mobility Si semiconductor components combined in layered hybrid nanostructures. The first effort aims to study non-radiative energy transfer from monolayers of NQDs covalently grafted on Si surfaces. To facilitate complete light absorption, multilayer NQD structures are to be fabricated and energy 'funneling' diffusion via non-radiative interactions between nanocrystal layers into Si substrate is explored and optimized. The second task focuses on radiative coupling of nanocrystal emission to waveguiding modes in Si nanomembranes. Placed in the vicinity of a high dielectric constant material such as Si, the nanocrystal emission is converted to waveguide modes in the Si layer where it is eventually absorbed, contributing to overall energy transfer. The third direction explores the applicability of new multishell NQDs that possess long-lived multiexitonic states for energy transfer. The overall energy transfer efficiency of planar NQD/Si structures is assessed by employing time-resolved photoluminescence spectroscopy combined with photocurrent measurements. The results of this research will lead to the understanding of energy transfer pathways in hybrid excitonic structures that overcome charge trapping related to interfacial states. Together with modeling tools and guidelines for achieving desired functionalities, these results could be applied to engineer practical architectures for efficient photovoltaic structures.Non-technical: Nanostructures composed on nanoparticles attached to thin silicon films offer a versatile platform for modern photonics with applications in advanced sensing, photovoltaics and novel light emitting sources. The fundamental research results of this project are expected to significantly impact our understanding of energy transfer phenomena and manipulation in these nanostructures leading to more efficient optoelectronic devices of great benefit to society. Students participating in this research are able to acquire expertise in the field of excitonics and hybrid nanomaterials. The research is inherently interdisciplinary in nature, allowing students to gain proficiency in physics, photonics and materials science and to develop both experimental and modeling skills. A strong effort is devoted to involve undergraduate and pre-college students and facilitate their interest in science. The PI of this project is committed to knowledge transfer via enhancing the curriculum by developing a course on Photonics Applications for Sustainable Energy and the interaction with the local industry.

摘要技术：基于能量转移的混合纳米结构由具有独立功能的组件精心设计而成，为光电器件应用提供了一个多功能平台。混合体的强吸收组分中的光吸收之后是从纳米结构中产生的激子到导电半导体薄膜中的电子空穴对的非接触电磁能转移。 这种对具有良好控制界面的纳米级材料中的激发进行电磁操纵是迈向下一代功能性纳米器件的重要一步，该器件不依赖于组件之间的电荷转移。该项目重点研究高吸收纳米晶体量子点（NQD）和层状混合纳米结构中组合的高迁移率硅半导体元件之间的辐射和非辐射能量转移现象的基本原理。第一项工作旨在研究共价接枝在硅表面上的单层 NQD 的非辐射能量转移。为了促进完全的光吸收，将制造多层 NQD 结构，并探索和优化通过纳米晶体层之间的非辐射相互作用进入硅基板的能量“漏斗”扩散。第二项任务侧重于纳米晶体发射与硅纳米膜中波导模式的辐射耦合。纳米晶体放置在硅等高介电常数材料附近，纳米晶体发射在硅层中转换为波导模式，最终被吸收，从而有助于整体能量传输。第三个方向探索具有长寿命多激子态的新型多壳层 NQD 在能量转移方面的适用性。通过采用时间分辨光致发光光谱结合光电流测量来评估平面 NQD/Si 结构的整体能量转移效率。这项研究的结果将有助于理解混合激子结构中的能量转移途径，克服与界面态相关的电荷捕获。与实现所需功能的建模工具和指南一起，这些结果可以应用于设计高效光伏结构的实用架构。非技术性：由附着在硅薄膜上的纳米颗粒组成的纳米结构为现代光子学提供了一个多功能平台，可应用于先进传感、光伏和新型发光源。该项目的基础研究成果预计将显着影响我们对这些纳米结构中能量转移现象和操纵的理解，从而产生更高效的光电器件，为社会带来巨大利益。参与这项研究的学生能够获得激子学和混合纳米材料领域的专业知识。该研究本质上是跨学科的，使学生能够熟练掌握物理学、光子学和材料科学，并培养实验和建模技能。我们致力于吸引本科生和预科生的参与，并培养他们对科学的兴趣。该项目的负责人致力于通过开发可持续能源光子学应用课程以及与当地行业的互动来加强课程，从而实现知识转移。