Controlling the Conductivity of Nanocrystal Solids through their Surface Chemistry

通过表面化学控制纳米晶体固体的电导率

• 批准号: 1610412
• 负责人: Sean Roberts
• 金额: $ 43.74万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1610412&HistoricalAwards=false
• 关键词: Controlling; Conductivity; Nanocrystal; Solids; through

In this project funded by the Macromolecular, Supramolecular and Nanochemistry program of the Chemistry Division, Professor Sean T. Roberts of the University of Texas at Austin and his graduate students study very small inorganic particles called semiconductor nanocrystals. Nanocrystals are tiny particles that contain thousands of atoms. While they are much larger than chemical molecules, which contain only a few atoms, they are still much smaller than solid materials that are large enough to see with the naked eye, containing trillions of atoms. Nanoscale materials are unique because they have sizes intermediate between molecules and solids, but sometimes have properties not easily predicted by averaging the two size extremes. The optical properties of these nanocrystals can be tuned by altering their size and shape, which makes them useful for applications such as displays, photovoltaic cells, and photodetectors. However, processing these materials into conductive thin films needed for electronics remains difficult. The researchers approach this challenge by combining the nanocrystals with surface-bound molecules designed to improve the electrical conductivity of nanocrystal thin films. The resulting structures are studied using spectroscopic techniques and photoconductivity measurements. This project also includes an outreach effort entitled GReen Energy At Texas (GREAT) designed to attract Community College students to the physical sciences by introducing them to green energy research. The specific goals of this project are to understand the key factors that facilitate electronic coupling between semiconductor nanocrystals and their surface ligands and to use interactions of this type to improve charge transport in nanocrystal optoelectronic films. The nature of the ligand can impact the bandgap and optical properties of semiconductor nanocrystals. This suggests some degree of electronic coupling between the nanocrystals and the ligands that involves charge transfer. This project quantitatively assesses the degree to which ligands facilitate charge transfer between nanocrystals in thin film. To accomplish this goal, time-resolved Raman spectroscopy is used to map charge density changes within nanocrystal ligand shells following photoexcitation. Two-dimensional electronic spectroscopy and photo-CELIV (charge extraction by linearly increasing voltage) measurements determine how exciton-delocalizing ligands (EDLs) modify charge carrier transport in nanocrystal thin films.

在该项目由得克萨斯大学奥斯汀分校的Sean T. Roberts教授和他的研究生研究的化学部门的大分子，超分子和纳米化学计划资助中，研究了非常小的无机颗粒，称为半导体纳米晶体。 纳米晶体是包含数千原子的微小颗粒。尽管它们比仅包含几个原子的化学分子大得多，但它们仍然比实心材料小得多，这些材料足够大，可以用肉眼看，其中包含数万亿个原子。纳米级材料是独一无二的，因为它们具有分子和固体之间的大小中间的大小，但有时通过平均两个尺寸的极端物质不容易预测特性。这些纳米晶体的光学特性可以通过改变它们的大小和形状来调整，这使其可用于显示器，光伏电池和光电遗传器等应用。但是，将这些材料处理成电子产品所需的导电薄膜仍然很困难。研究人员通过将纳米晶体与旨在改善纳米晶薄膜的电导率相结合的分子来应对这一挑战。使用光谱技术和光电导率测量研究所得的结构。该项目还包括旨在通过向绿色能源研究介绍绿色能源研究的旨在吸引社区大学生进入物理科学的旨在吸引社区大学生的宣传工作。该项目的具体目标是了解促进半导体纳米晶体及其表面配体之间电子耦合的关键因素，并利用这种类型的相互作用来改善纳米晶光晶中的电荷传输。配体的性质会影响半导体纳米晶体的带隙和光学特性。这表明纳米晶与涉及电荷转移的配体之间的电子耦合一定程度。该项目定量评估配体在薄膜中纳米晶体之间促进电荷转移的程度。为了实现这一目标，使用时间分辨的拉曼光谱法用于绘制光激发后纳米晶体配体壳内的电荷密度变化。二维电子光谱和光仪（通过线性增加电压提取）测量结果决定了纳米晶薄膜中的激子偏置配体（EDLS）如何修改电荷载流子传输。

项目成果

Charge carrier concentration dependence of ultrafast plasmonic relaxation in conducting metal oxide nanocrystals

• DOI: 10.1039/c7tc00600d
• 发表时间: 2017-06
• 期刊: Journal of Materials Chemistry C
• 影响因子: 6.4
• 作者: Robert W. Johns;Michelle A. Blemker;Michael S. Azzaro;S. Heo;Evan L. Runnerstrom;D. Milliron;S. Roberts

Achieving spin-triplet exciton transfer between silicon and molecular acceptors for photon upconversion

• DOI: 10.1038/s41557-019-0385-8
• 发表时间: 2020-02-01
• 期刊: NATURE CHEMISTRY
• 影响因子: 21.8
• 作者: Xia, Pan;Raulerson, Emily K.;Roberts, Sean T.
• 通讯作者: Roberts, Sean T.

Modulation of the Visible Absorption and Reflection Profiles of ITO Nanocrystal Thin Films by Plasmon Excitation

• DOI: 10.1021/acsphotonics.9b01825
• 发表时间: 2020-05-20
• 期刊: ACS PHOTONICS
• 影响因子: 7
• 作者: Blemker, Michelle A.;Gibbs, Stephen L.;Roberts, Sean T.
• 通讯作者: Roberts, Sean T.

Exciton-Delocalizing Ligands Can Speed Up Energy Migration in Nanocrystal Solids

• DOI: 10.1021/acs.nanolett.8b01079
• 发表时间: 2018-05-01
• 期刊: NANO LETTERS
• 影响因子: 10.8
• 作者: Azzaro, Michael S.;Dodin, Amro;Roberts, Sean T.
• 通讯作者: Roberts, Sean T.

Ligand-Enhanced Energy Transport in Nanocrystal Solids Viewed with Two-Dimensional Electronic Spectroscopy

• DOI: 10.1021/acs.jpclett.9b02040
• 发表时间: 2019-09-19
• 期刊: JOURNAL OF PHYSICAL CHEMISTRY LETTERS
• 影响因子: 5.7
• 作者: Azzaro, Michael S.;Le, Aaron K.;Roberts, Sean T.
• 通讯作者: Roberts, Sean T.