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，智能热致变色窗户的隔热性能根据环境温度进行调节，已得到广泛研究，以提高商业和住宅建筑的能源效率。这些窗户通常涂有热致变色材料，这些材料在半导体相和金属相之间表现出完全可逆的、与温度相关的转变。在炎热的天气里，智能窗户会透过全部或部分可见辐射，并拒绝大部分太阳近红外辐射；因此减少了对空调的需求。在较冷的天气期间，可见光和红外 (IR) 辐射都被完全传输，从而限制了对内部加热的需求。这种智能涂层的流行材料是二氧化钒 (VO2)，因为它具有 i) 红外区域的辐射阻带，ii) 可以轻松应用于大型基材的优点，以及 iii) 降低其相位的能力通过掺杂金属化合物（最常见的是钨）来提高转变温度。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降低 30%。尽管如此，VO2 涂层的优点在寒冷气候下很快就会减弱，而在赫尔辛基或莫斯科等地，事实上它们会产生负能量平衡。造成这种性能逆转的一个非常重要的因素是 VO2 在冷透明相中表现出的高折射率，这导致大部分入射光被反射 - 对于 50 nm 厚的 VO2，可见光中的 30%-35%玻璃上的薄膜。该数字与传统玻璃窗的反射率 <4% 相比，这意味着热致变色窗在冬季比普通玻璃窗更暗、更冷，这反过来又意味着建筑物照明和供暖所需的能源实际增加。此外，污垢和污渍进一步降低了智能窗户的传输性能。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，以大幅改善目前热致变色智能窗透光性能较差的问题，为智能窗的发展铺平道路。该技术的商业化。与现有的热致变色窗户相比，我们的纳米图案窗户的透射率可能高出 72%，此外，它们无需额外处理即可同时表现出自清洁特性。这个具有挑战性的概念验证研究项目历时 24 个月，重点关注采用蛾眼纳米结构增强的智能窗户的制造和表征，并分为两个研究方向：A) 抗反射和自清洁蛾的制造和表征Eye纳米结构直接附着在玻璃上，适用于新型高端窗户产品。 B) 开发潜在的低成本热致变色聚合物薄膜来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.