Physics of periodic and non-periodic nanostructured chromogenic thin films and devices

周期性和非周期性纳米结构显色薄膜和器件的物理学

• 批准号: RGPIN-2014-06546
• 负责人: Ashrit, Pandurang
• 金额: $ 3.06万
• 依托单位: Université de Moncton
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633003
• 关键词: Physics; periodic; non; nanostructured; chromogenic

The principal objective of the proposed research program is to study the correlation between the nanostructure and the chromogenic properties of transition metal oxide (TMO) thin films. The in-depth understanding of the physics and chemistry related to the chromogenic properties of these nanostructured TMOs is expected to lead us to the design and realization of better performing interactive devices for various applications. The area of low dimension materials or the so called nanomaterials has become extremely important in recent years from the scientific and technological point of view. The optical, electrical and other properties of the hitherto very well-known materials can be drastically altered and/or enhanced by reducing their size in one or two or all three dimensions. This reduction in dimensions to nanometric scales induces a change in their 1) electrical behavior due to the immense grain boundary effects induced at the surfaces, 2) optical behavior due to the change in the optical constants and the porosity induced in the films and 3) chemical behavior due to the enormous surface effect created around the small amount of material (enormous surface to volume ratio). All these changes lead to the formation of a “new” or “advanced” mesoscopic state of materials. Some mesoscopic materials have been found to exhibit properties that do not exist in the bulk or natural form of these materials. Hence, a controlled induction of novel properties in hitherto well-known materials through their nanostructuring has become an important field in materials research. My aim here is to apply the nanostructuring approach to transition metal oxide based chromogenic materials and devices. Transition metal oxides (TMO) are known for their ability to exist in their various oxidation states. Some of these TMOs show drastically different optical and electrical properties between these different states. Hence, similar to the semiconductors, the TMOs can be switched reversibly between these metastable states by applying small activation energies provided in the form of either a small electric field or light or heat. They can be reversibly switched from a transparent to an opaque state or from a non-conducting to a conducting state through the action of these external forces. Thus the field of TMO based chromogenics, i.e. the reversible switching of TMOs through the action of an electric field (electrochromics) or heat (thermochromics) or light (photochromics) has attracted the attention of a lot of researchers in recent years. The growing importance of this field stems from two perspectives: building an understanding of the rich physics and chemistry underlying these reversible changes as well as the application of these interactive changes. My previous work in this direction has shown that the chromogenic performance of the TMOs depends very sensitively on the film nanostructure. By carefully controlling the nanostructure, one can effectively tailor the externally inducible reversible change in the optical and electrical properties of these materials. Further, by inducing a periodic nanostructure on optical wavelengths scale, various reversible photonic effects can be implanted. Through a patented work on such photonic devices, a new approach to manipulating light propagation has been demonstrated. I intend to continue my research in this area. More specifically, I would like to apply and explore the virtues of periodic and non-periodic nanostructuring to chromogenic materials.This work will not only lead to the in-depth understanding of the physics of these materials but also to the creation of new materials and devices for application in photonics, optics, communication and energy management & conversion

该研究计划的主要目的是研究过渡金属氧化物(TMO)薄膜的纳米结构与显色性能之间的关系。深入了解与这些纳米结构的TMO的显色性质相关的物理和化学特性，有望引导我们设计和实现性能更好的各种应用的交互设备。近年来，从科学和技术的角度来看，低维材料或所谓的纳米材料领域变得极其重要。迄今非常公知的材料的光学、电学和其他性质可以通过在一维或二维或全部三维上减小其尺寸来显著改变和/或增强。这种纳米尺度的尺寸减小导致了它们的电学行为的改变，1)由于在表面诱导的巨大的晶界效应，2)由于光学常数和薄膜中诱导的孔隙率的变化而导致的光学行为，以及3)由于少量材料(巨大的表面积与体积比)产生的巨大的表面效应而产生的化学行为。所有这些变化导致材料形成一种新的或先进的介观状态。一些介观材料已经被发现具有这些材料的块状或自然形式所不存在的性质。因此，通过纳米结构控制诱导迄今已知的材料的新性能已成为材料研究的一个重要领域。我的目标是将纳米结构方法应用于基于过渡金属氧化物的显色材料和器件。过渡金属氧化物(TMO)以其不同的氧化态存在而闻名。其中一些TMO在这些不同的状态之间显示出截然不同的光学和电学性质。因此，与半导体类似，通过施加以小电场或光或热的形式提供的小激活能，TMOS可以在这些亚稳态之间进行可逆切换。通过这些外力的作用，它们可以从透明状态可逆地切换到不透明状态，或者从非导电状态可逆地切换到导电状态。因此，基于TMO的发色学领域，即TMO在电场(电致变色)或热(热致变色)或光(光致变色)作用下的可逆开关，近年来引起了许多研究人员的关注。这一领域日益增长的重要性源于两个方面：建立对这些可逆变化背后的丰富物理和化学的理解，以及这些互动变化的应用。我以前在这方面的工作表明，TMOS的显色性能非常敏感地依赖于薄膜的纳米结构。通过仔细控制纳米结构，人们可以有效地定制这些材料在外部诱导的光学和电学性质的可逆变化。此外，通过诱导光学波长尺度上的周期性纳米结构，可以注入各种可逆的光子效应。通过对这种光子器件的专利研究，已经展示了一种操纵光传播的新方法。我打算在这方面继续我的研究。更具体地说，我想将周期性和非周期性纳米结构的优点应用于显色材料中。这项工作不仅将导致对这些材料物理的深入了解，而且将创造出应用于光子学、光学、通信和能量管理与转换的新材料和新器件