Direct Interfacial Charge Separation in Plasmonic Heterostructures Revealed by Single-Particle Spectroscopy

单粒子光谱揭示等离激元异质结构中的直接界面电荷分离

• 批准号: 2225592
• 负责人: Stephan Link
• 金额: $ 49.96万
• 依托单位: William Marsh Rice University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2225592&HistoricalAwards=false
• 关键词: Direct; Interfacial; Charge; Separation; Plasmonic

Non-Technical DescriptionThis project is developing methods to understand how metal nanoparticles, 1000 times smaller than the width of a hair, capture and convert light into usable energy when contacting metal oxide semiconductors. Although metal nanoparticles efficiently absorb light, most of the absorbed energy is converted into heat. On the other hand, metal oxide semiconductors can store light energy for much longer times than metals making them useful for applications such as photodetection. However, metal oxide semiconductors do not absorb as strongly or often only at specific wavelengths, while metal nanoparticle can be designed to strongly interact with light of any color. This project overcomes these limitations by combining the high absorption of metal nanoparticles with the longer lifetimes of the absorbed light energy in metal oxide semiconductors. The principal investigator uses techniques that allow him to study how the light energy absorbed by a metal nanoparticle is transferred to an adjacent metal oxide semiconductor layer. These experiments are carried out for one nanoparticle at a time to resolve heterogeneities that arise from materials synthesis. In addition, the PI is continuing his longstanding participation in Rice University’s Civic Scientist Program and Research Experience for Teachers, allowing him to educate K-12 students about nanotechnology and inspire them to pursue scientific careers as well as to provide teachers with experience to in turn help students in those pursuits.Technical DescriptionThe goal of this project is to understand and maximize plasmon decay into charge separated states between a metal nanoparticle and an adjacent metal oxide semiconductor via direct charge transfer following plasmon excitation. The principal investigator will accomplish this goal by addressing the following objectives: 1) Design and fabricate plasmonic metal–semiconductor heterostructures and establish a correlation with interface induced plasmon decay via changes to the homogeneous plasmon linewidth; 2) Quantitatively determine charge injection into semiconductors surrounding plasmonic nanostructures using single particle ultrafast spectroscopy and correlate with efficiencies obtained from plasmon damping; 3) Apply Stokes and anti-Stokes emission spectroscopy to independently follow interfacial charge transfer through emission quenching under both one- and multi-photon excitation conditions. These proposed studies will elucidate the mechanism of interfacial charge transfer in plasmonic heterostructures and the underlying material parameters that determine efficiencies with a focus on excess energy as determined by the plasmon resonance and the relative band alignment including Schottky barrier height. Such detailed mechanistic information would be impossible to obtain without single-particle techniques due to the heterogeneity of plasmonic nanoparticle sizes and local environments. The proposed studies will potentially have a transformative impact on developing efficient photovoltaic devices based on plasmonic metal-semiconductor heterostructures taking advantage of a wide wavelength sensitivity, large absorption cross section, and long hot carrier lifetime.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术描述该项目正在开发方法来了解比头发丝宽度小 1000 倍的金属纳米颗粒在接触金属氧化物半导体时如何捕获光并将其转化为可用能量。另一方面，金属氧化物半导体可以比金属储存光能更长的时间，这使得它们可用于光电检测等应用。但是，金属氧化物半导体不吸收光能或不经常吸收光能。仅在特定波长下，而金属纳米颗粒可以设计为与任何颜色的光发生强烈相互作用，该项目通过将金属纳米颗粒的高吸收性与金属氧化物半导体中吸收光能的较长寿命相结合来克服这些限制。他使用的技术可以研究金属纳米颗粒吸收的光能如何转移到相邻的金属氧化物半导体层。这些实验一次针对一个纳米颗粒进行，以解决材料合成中产生的异质性。 PI 继续长期参与莱斯大学的公民科学家计划和教师研究经验项目，使他能够向 K-12 学生传授纳米技术知识，激励他们追求科学职业，并为教师提供经验，从而帮助学生实现这些目标技术描述该项目的目标是通过等离激元激发后的直接电荷转移来了解并最大化金属纳米粒子和相邻金属氧化物半导体之间的等离激元衰变到电荷分离状态。目标如下：1) 设计和制造等离子体金属-半导体异质结构，并通过改变均匀等离子体线宽建立与界面诱导等离子体衰变的相关性；2) 使用单粒子超快光谱定量确定注入等离子体纳米结构周围的电荷，并与从等离子体阻尼获得的效率；3）应用斯托克斯和反斯托克斯发射光谱来独立跟踪界面电荷转移这些拟议的研究将阐明等离激元异质结构中的界面电荷转移机制以及决定效率的基础材料参数，重点是由等离激元共振和由于等离子体纳米粒子尺寸和局部环境的异质性，如果没有单粒子技术，就不可能获得包括肖特基势垒高度在内的相对能带排列。潜在地对开发基于等离子体金属-半导体异质结构的光伏器件产生变革性影响，利用宽波长灵敏度、大吸收截面和长热载流子寿命效率。该奖项反映了 NSF 的法定使命，并被认为值得通过以下方式获得支持：使用基金会的智力价值和更广泛的影响审查标准进行评估。