Mechanisms for enhancing n-type polaronic transport in transition metal oxides: ionic size, pair formation/clustering, and valence effects

增强过渡金属氧化物中 n 型极化子输运的机制：离子大小、成对形成/成簇和价态效应

• 批准号: 2003563
• 负责人: Yat Li
• 金额: $ 53.22万
• 依托单位: University of California-Santa Cruz
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2003563&HistoricalAwards=false
• 关键词: Mechanisms; enhancing; type; polaronic; transport

Non-Technical Abstract This award supports a project focused on studying a group of materials called transition metal oxides. These materials are promising candidates for making devices for storing energy such as lithium-ion batteries and for converting energy such as solar cells. However, their efficiency has been fundamentally limited by the slow movement of negative and positive charges in them, restricting their use in practical applications. The main reason for the restricted movement of these charges is that they get trapped by the distortions in the materials’ atomic structure. This project will investigate the use of dopants to improve the mobility of the charges in iron oxide, a representative of these transition metal oxides. It will determine the design principles of “good” dopants that improve the transport of charges in these oxides so that they can be used in practical energy applications. The project will train undergraduate and graduate students and will engage in outreach activities involving high school students, emphasizing in broadening participation of underrepresented students.Technical Abstract This research project aims to quantitatively investigate the mechanisms that limit charge transport, including how the clustering of extrinsic n-type dopants takes place, how the interaction between electron small polarons and (clustered) dopants affects the electronic transport properties, and what steps might increase the carrier concentration in transition metal oxides. This project will initially use hematite, a representative polaronic oxide, doped with tin and other 4+/5+ ions as a model system for the study. The dopant clustering is believed to be due to ionic size mismatch, and consequently limit the carrier conductivity. The research team will use a “co-doping” strategy to improve the solubility of dopants and avoid clustering and correspondingly enhance carrier mobility as a function of doping concentration. A crucial step in this project is determining the local environment about extrinsic dopants and dopant clusters and if/how they are modified when the second dopants are incorporated; this work will combine physical measurements with first-principles simulations. The findings in this project can provide rules for rational design of polaronic oxides with improved transport properties, and more importantly, develop a fundamental understanding of key factors determining whether an isolated dopant, dopant cluster or co-doping can be beneficial or harmful for transport properties.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.

非技术摘要该奖项支持一个专注于研究一组被称为过渡金属氧化物的材料的项目。这些材料很有希望成为锂离子电池等储能设备和太阳能电池等能源转换设备的候选材料。然而，它们的效率从根本上受到了它们中正负电荷运动缓慢的限制，限制了它们在实际应用中的使用。这些电荷运动受限的主要原因是它们被材料原子结构的扭曲所困。这个项目将研究使用掺杂剂来改善氧化铁中电荷的迁移率，氧化铁是这些过渡金属氧化物的代表。它将决定“好的”掺杂剂的设计原则，这些掺杂剂可以改善这些氧化物中的电荷传输，以便它们可以用于实际的能源应用。该项目将培养本科生和研究生，并将开展涉及高中生的外联活动，重点是扩大未被充分代表的学生的参与。技术摘要本研究项目旨在定量研究限制电荷传输的机制，包括外在n型掺杂是如何发生的，电子小极化子与(簇状)掺杂之间的相互作用如何影响电子传输特性，以及哪些步骤可以增加过渡金属氧化物中的载流子浓度。本项目将初步使用具有代表性的极化性氧化物赤铁矿作为研究的模型体系，掺杂TiN等4+/5+离子。掺杂剂的聚集被认为是由于离子尺寸失配，从而限制了载流子电导。该研究团队将采用一种“共掺杂”策略，以改善掺杂剂的溶解度，避免聚集，并相应地提高载流子迁移率作为掺杂浓度的函数。这个项目的关键一步是确定非本征掺杂剂和掺杂团簇的局部环境，以及当第二种掺杂剂加入时它们是否/如何被修改；这项工作将结合物理测量和第一性原理模拟。该项目的发现可以为合理设计具有更好传输性能的极化子氧化物提供规则，更重要的是，加深对决定单独掺杂、掺杂簇或共掺杂对传输性能有利或有害的关键因素的基本了解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Doping Bottleneck in Hematite: Multipole Clustering by Small Polarons

• DOI: 10.1021/acs.chemmater.1c00304
• 发表时间: 2021-06
• 期刊: Chemistry of Materials
• 影响因子: 8.6
• 作者: T. Smart;Valentin Urena Baltazar;Mingpeng Chen;Bin Yao;Kiley Mayford;F. Bridges;Yat Li;Y. Ping-Y.-P

The impacts of dopants on the small polaron mobility and conductivity in hematite – the role of disorder

掺杂剂对赤铁矿中小极化子迁移率和电导率的影响——无序的作用

• DOI: 10.1039/d2nr04807h
• 发表时间: 2023
• 期刊: Nanoscale
• 影响因子: 6.7
• 作者: Chen, Mingpeng;Grieder, Andrew C.;Smart, Tyler J.;Mayford, Kiley;McNair, Samuel;Pinongcos, Anica;Eisenberg, Samuel;Bridges, Frank;Li, Yat;Ping, Yuan
• 通讯作者: Ping, Yuan

The critical role of synthesis conditions on small polaron carrier concentrations in hematite—A first-principles study

• DOI: 10.1063/5.0074698
• 发表时间: 2021-12
• 期刊: Journal of Applied Physics
• 影响因子: 3.2
• 作者: T. Smart;Mingpeng Chen;Andrew C. Grieder;Valentin Urena Baltazar;F. Bridges;Yat Li;Y. Ping

Insights on Thickness-Dependent Charge Transfer Efficiency Modulated by Ultrasonic Treatment in Hematite Photoanodes

• DOI: 10.1021/acs.jpcc.0c11397
• 发表时间: 2021-04-29
• 期刊: JOURNAL OF PHYSICAL CHEMISTRY C
• 影响因子: 3.7
• 作者: Freitas, Andre L. M.;Tofanello, Aryane;Li, Yat
• 通讯作者: Li, Yat