Biologically Inspired Nanostructures for Smart Windows with Antireflection and Self-Cleaning Properties

用于智能窗户的仿生纳米结构，具有抗反射和自清洁特性

• 批准号: EP/K015354/1
• 负责人: Ioannis Papakonstantinou
• 金额: $ 12.74万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FK015354%2F1
• 关键词: Biologically; Inspired; Nanostructures; Smart; Windows

Smart thermochromic windows whose insulation properties are tuned by the ambient temperature have been investigated extensively over recent years to improve energy efficiency of commercial and residential buildings. These windows are typically coated with thermochromic materials that exhibit a fully reversible, temperature dependent transition between semiconductor and metallic phases. During hot weather, a smart window passes all or part of the visible radiation incident and rejects the majority of the Sun's near-infrared radiation; thus the need for air conditioning is reduced. During cooler weather, both visible and infrared (IR) radiation is fully transmitted, limiting the need for internal heating. A popular material for such intelligent coatings is Vanadium dioxide (VO2) due to i) the radiation stop-band manifesting in the IR region, ii) the advantage that it can easily be applied to large substrates and iii) the ability to lower its phase transition temperature by doping it with metal compounds, most commonly tungsten. Calculations have shown that a VO2 coating can deliver a 30% reduction in energy consumption of buildings in countries with hot climates such as Italy and Egypt. Nonetheless, the merits of VO2 coatings quickly diminish in colder climates and in places like Helsinki or Moscow they, in fact, deliver a negative energy balance. One very important factor for this performance reversal is the high refractive index that VO2 exhibits in its cold-transparent phase, which results in a large portion of the incident light being reflected - 30%-35% in the visible for a 50 nm thick VO2 film on glass. This figure compares with <4% reflectivity in conventional glass windows, meaning that a thermochromic window is much darker and colder than its plain glass counterpart in the winter, which in turn translates to an actual increase in the energy required for lighting and heating a building. In addition, dirt and stains further degrade the transmission properties of a smart window. In order to overcome the above limitations, moth-eye type structures engineered to exhibit broadband and wide-angle antireflection properties are proposed, for the first time, to substantially improve the currently poor transmission properties of thermochromic smart windows and to pave the way for the commercialization of this technology. Our nanopatterned windows potentially have 72% higher transmission compared to existing thermochromic windows and in addition, they exhibit simultaneous self-cleaning properties without additional processing. This challenging, proof-of-concept, 24-month research project focuses on the fabrication and characterization of smart windows enhanced with moth-eye nanostructures and is divided into two research streams: A) Fabrication and characterization of antireflection and self-cleaning moth-eye nanostructures directly onto glass, appropriate for new high-end window products. B) Development of potentially low-cost thermochromic polymer thin-film to retrofit existing non-smart windows.

近年来，为了提高商业和住宅建筑的能效，人们对智能热致变色窗进行了广泛的研究，这种窗的隔热性能可以根据环境温度进行调整。这些窗口通常涂有热致变色材料，在半导体和金属相之间表现出完全可逆的、依赖于温度的转变。在炎热的天气，智能窗户可以通过全部或部分可见光辐射，并拒绝大部分太阳的近红外辐射；因此，减少了对空调的需求。在较凉爽的天气，可见光和红外线(IR)辐射都能充分传输，限制了对内部供暖的需要。用于这类智能涂层的一种流行材料是二氧化钒(VO2)，因为：i)在红外区域显示出辐射阻带，ii)它可以很容易地应用于大型基片，iii)通过在金属化合物中掺杂，可以降低其相变温度，最常见的是钨。计算表明，在意大利和埃及等气候炎热的国家，VO2涂层可以使建筑物的能耗减少30%。尽管如此，VO2涂层的优点在较冷的气候下很快就会减弱，在赫尔辛基或莫斯科等地，它们实际上提供了负能量平衡。这种性能逆转的一个非常重要的因素是VO2在其冷透明相表现出的高折射率，这导致很大一部分入射光在可见光中被反射-对于50 nm厚的VO2薄膜在玻璃上的可见光反射-30%-35%。这一数字与传统玻璃窗4%的反射率相比，意味着热色玻璃窗在冬天比普通玻璃窗更暗更冷，这反过来又意味着建筑照明和供暖所需的能源实际增加了。此外，污垢和污渍还会进一步降低智能窗的传输性能。为了克服上述限制，首次提出了具有宽带和广角减反射特性的蛾眼型结构，以显著改善目前较差的热致变色智能窗的传输性能，并为该技术的商业化铺平道路。与现有的热致变色窗口相比，我们的纳米镀膜窗口的透过率可能高出72%，此外，它们还显示出同时的自清洁性能，而无需额外的处理。这项为期24个月的具有挑战性的概念验证研究项目专注于用蛾眼纳米结构增强的智能窗户的制造和表征，分为两个研究流：a)直接在玻璃上制造和表征减反射和自清洁蛾眼纳米结构，适用于新的高端窗户产品。B)开发潜在的低成本热致变色聚合物薄膜，以改造现有的非智能窗户。

项目成果

Fundamental limits of concentration in luminescent solar concentrators revised: the effect of reabsorption and nonunity quantum yield

• DOI: 10.1364/optica.2.000841
• 发表时间: 2015-10-20
• 期刊: OPTICA
• 影响因子: 10.4
• 作者: Papakonstantinou, Ioannis;Tummeltshammer, Clemens
• 通讯作者: Tummeltshammer, Clemens

Flexible and fluorophore-doped luminescent solar concentrators based on polydimethylsiloxane.

• DOI: 10.1364/ol.41.000713
• 发表时间: 2016-02
• 期刊: Optics letters
• 影响因子: 3.6
• 作者: C. Tummeltshammer;Alaric Taylor;A. Kenyon;I. Papakonstantinou

Losses in luminescent solar concentrators unveiled

• DOI: 10.1016/j.solmat.2015.08.008
• 发表时间: 2016-01-01
• 期刊: SOLAR ENERGY MATERIALS AND SOLAR CELLS
• 影响因子: 6.9
• 作者: Tummeltshammer, C.;Taylor, A.;Papakonstantinou, I.
• 通讯作者: Papakonstantinou, I.