Measuring the Dynamics of Excitons in 1D Semiconductor Quantum Wires with Quantum State Resolution

用量子态分辨率测量一维半导体量子线中激子的动力学

基本信息

批准号：
1905751
负责人：
Richard Loomis
金额：
$ 45万
依托单位：
Washington University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-07-01 至 2023-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1905751&HistoricalAwards=false
关键词：
Measuring Dynamics Excitons 1D Semiconductor

项目摘要

Nontechnical Description: In photovoltaic (PV) devices it would be ideal for every photon that impinges on the device to be absorbed and for at least one electron and one hole to be separately collected as current and electricity with little or no loss of energy within the system, regardless of the color of light or energy of the photon absorbed. PV devices that incorporate semiconductor nanoparticles (NPs) as the absorbing medium offer the advantages of tunable absorption energies through size control and large absorption efficiencies. When light with energy in excess of the band gap of the semiconductor NPs is absorbed, the photogenerated electrons and holes relax down to the lowest-energy states. The efficiency for the charge carrier relaxation depends on numerous factors, including the densities of electron and hole states, the roles and rates of different energy-transfer mechanisms, the temperature, and the chemical environment of the NPs. The research team is synthesizing NPs with varying sizes, shapes, semiconductor materials, and chemically passivated surfaces. Several optical spectroscopy and microscopy techniques are being implemented, and new models are being developed to characterize the relaxation dynamics in the semiconductor NPs. The ultimate goals of the research activities are to not only characterize the relaxation dynamics of the carriers, but to develop novel nanostructures with properties that are optimal for the light-to-electricity conversion of PV devices. The research project is highly interdisciplinary, and graduate and undergraduate students, especially those from underrepresented backgrounds, are gaining the expertise needed to become the next generation of scientists. The educational mission of the principal investigator extends beyond the research team as educational videos on the physics of light and on the importance of alternative energy sources are being developed and disseminated to the public and local schools.Technical Description: The relaxation dynamics and efficiencies of photogenerated electrons and holes in semiconductor nanoparticles (NPs) ultimately limit the yields of photovoltaic devices that incorporate NPs as the absorbing medium. The goals of the research are to accurately characterize the intraband relaxation dynamics (IRD) and mechanisms for carrier relaxation in semiconductor NPs. Specific research activities that include nanoparticle synthesis, electron microcopy and imaging, and optical spectroscopy in both the time- and frequency-domains are characterizing the IRD of the electrons and holes. The team is paying particular attention to the roles of dimensionality and the densities of states on the rates and efficiencies of electron and hole relaxation to the band edge. Carriers in one-dimensional semiconductor quantum wires (QWs) and belts (QBs) can have translational kinetic energy and delocalization along their lengths. This dimensionality gives rise to a continuum of states that can be accessed during carrier relaxation. These one-dimensional NPs contrast those of widely studied zero-dimensional quantum dot (QD) and two-dimensional quantum platelet (QP) systems. Time-resolved transient absorption experiments are performed on NPs with contrasting dimensionality to identify the role of the states, kinetic energy, and momentum on the carrier IRD. A new model, quantum-state renormalization is being developed to help unravel the dynamics from complicated transient absorption spectra recorded on ensembles of the NPs. The efforts are complemented through a long-standing collaboration with the synthetic group of William E. Buhro (Wash. U.) and a new collaboration with the ultrafast spectroscopy group of Martin Zanni (U. Wisconsin).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：在光伏（PV）设备中，对于每个光子所吸收的设备上的每个光子，至少一个电子和一个孔被分别收集为电流，并且在系统中几乎没有或没有能量损失，无论光子吸收的光或能量的能量在系统中，无需损失。将半导体纳米颗粒（NP）作为吸收培养基的PV设备通过大小控制和较大的吸收效率提供了可调吸收能的优势。当能够超过半导体NP的带隙的能量被吸收时，光生的电子和孔会放松到最低能量状态。电荷载体松弛的效率取决于许多因素，包括电子和孔状态的密度，不同能量转移机制的作用和速率，NP的温度和化学环境。研究团队正在合成具有不同尺寸，形状，半导体材料和化学钝化表面的NP。正在实施几种光谱和显微镜技术，并开发了新模型来表征半导体NP中的弛豫动力学。研究活动的最终目标不仅是表征载体的放松动力学，而且要开发具有具有最佳性能的新型纳米结构，这些纳米结构是PV设备的光到电性转换。该研究项目是高度跨学科的，毕业生和本科生，尤其是来自代表性不足的研究生，正在获得成为下一代科学家所需的专业知识。 The educational mission of the principal investigator extends beyond the research team as educational videos on the physics of light and on the importance of alternative energy sources are being developed and disseminated to the public and local schools.Technical Description: The relaxation dynamics and efficiencies of photogenerated electrons and holes in semiconductor nanoparticles (NPs) ultimately limit the yields of photovoltaic devices that incorporate NPs as the absorbing 中等的。该研究的目标是准确表征半导体NPS中载体松弛的机内放松动力学（IRD）和机制。特定的研究活动，包括纳米颗粒合成，电子微拷贝和成像，以及时间和频域中的光谱谱图，都表征了电子和孔的IRD。该团队特别关注维度的作用以及国家对电子和孔放松对带边缘的效率和效率的密度。一维半导体量子线（QW）和皮带（QB）中的载体可以沿其长度具有转化的动能和离域。这种维度产生了在载体放松期间可以访问的连续状态。这些一维的NP对比零维量子点（QD）和二维量子血小板（QP）系统的NP对比。时间分辨的瞬态吸收实验是在具有对比度的NP上进行的，以确定状态，动能和动量对载体IRD的作用。正在开发一种新的模型，量子状态重新归如此，以帮助从NPS的集合中记录的复杂瞬态吸收光谱揭示动力学。通过与William E. Buhro的合成小组的长期合作以及与Martin Zanni（U. Wisconsin）的UltraFast Spectroscoppoy小组的新合作进行的长期合作，可以得到补充。这一奖项反映了NSF的法定任务，并被认为是通过基金会的知识优点和广泛的criperia criperia criperia的评估来通过评估来获得的。

项目成果

期刊论文数量（8）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Bound-Ion Pair X-Type Ligation of Cadmium and Zinc Dithiocarbamates on Cadmium Selenide Quantum Belts

硒化镉量子带上二硫代氨基甲酸镉和二硫代氨基甲酸锌的束缚离子对 X 型连接

DOI：
10.1021/acs.inorgchem.2c00226
发表时间：
2022
期刊：
Inorganic Chemistry
影响因子：
4.6
作者：
Meyer, Hailey M.;Morrison, Calynn E.;Loomis, Richard A.;Buhro, William E.
通讯作者：
Buhro, William E.

Methods for the ICP-OES Analysis of Semiconductor Materials

DOI：
10.1021/acs.chemmater.0c00255
发表时间：
2020-03-10
期刊：
CHEMISTRY OF MATERIALS
影响因子：
8.6
作者：
Morrison, Calynn;Sun, Haochen;Buhro, William E.
通讯作者：
Buhro, William E.

Photo-Induced State Shifting in 1D Semiconductor Quantum Wires

一维半导体量子线中的光致状态转移

DOI：
10.1021/acs.jpcc.0c04755
发表时间：
2020
期刊：
The Journal of Physical Chemistry C
影响因子：
0
作者：
Sanderson, William M.;Schrier, Joshua;Loomis, Richard A.
通讯作者：
Loomis, Richard A.

Intraband Relaxation Dynamics of Charge Carriers within CdTe Quantum Wires

CdTe 量子线内电荷载流子的带内弛豫动力学

DOI：
10.1021/acs.jpclett.0c01326
发表时间：
2020
期刊：
The Journal of Physical Chemistry Letters
影响因子：
0
作者：
Sanderson, William M.;Wang, Fudong;Schrier, Joshua;Buhro, William E.;Loomis, Richard A.
通讯作者：
Loomis, Richard A.

Facet-Specific Electron Transfer in Pseudo-Two-Dimensional Wurtzite Cadmium Selenide Nanocrystals