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.

在这个由化学系高分子、超分子和纳米化学项目资助的项目中，德克萨斯大学奥斯汀分校的 Sean T. Roberts 教授和他的研究生研究了称为半导体纳米晶体的非常小的无机颗粒。 纳米晶体是含有数千个原子的微小颗粒。虽然它们比仅包含几个原子的化学分子大得多，但它们仍然比包含数万亿原子的大到足以用肉眼看到的固体材料小得多。纳米级材料是独特的，因为它们的尺寸介于分子和固体之间，但有时其特性无法通过平均两个极端尺寸轻易预测。这些纳米晶体的光学特性可以通过改变其尺寸和形状来调节，这使得它们可用于显示器、光伏电池和光电探测器等应用。然而，将这些材料加工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提高纳米晶体薄膜的导电性的表面结合分子相结合来应对这一挑战。使用光谱技术和光电导测量来研究所得结构。该项目还包括一项名为“德克萨斯州绿色能源”（GREEN）的外展活动，旨在通过向社区学院学生介绍绿色能源研究来吸引他们接触物理科学。该项目的具体目标是了解促进半导体纳米晶体与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体光电薄膜中的电荷传输。配体的性质会影响半导体纳米晶体的带隙和光学性质。这表明纳米晶体和配体之间存在一定程度的电子耦合，涉及电荷转移。该项目定量评估配体促进薄膜纳米晶体之间电荷转移的程度。为了实现这一目标，使用时间分辨拉曼光谱来绘制光激发后纳米晶体配体壳内的电荷密度变化图。二维电子光谱和光 CELIV（通过线性增加电压提取电荷）测量确定激子离域配体 (EDL) 如何改变纳米晶体薄膜中的载流子传输。

项目成果

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.

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

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.

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.

Can Exciton-Delocalizing Ligands Facilitate Hot Hole Transfer from Semiconductor Nanocrystals?

• DOI: 10.1021/acs.jpcc.6b08178
• 发表时间: 2016-12
• 期刊: Journal of Physical Chemistry C
• 影响因子: 3.7
• 作者: Michael S. Azzaro;Mark C. Babin;Shannon K. Stauffer;G. Henkelman;S. Roberts