Monolithic graded-refractive-index glass-based antireflective coatings. Broadband/omnidirectional light harvesting and self-cleaning characteristics

Journal Article · Thu Apr 23 00:00:00 EDT 2015 · Journal of Materials Chemistry C

DOI:https://doi.org/10.1039/C5TC00499C· OSTI ID:1195808

Aytug, Tolga ^[1]; Lupini, Andrew R. ^[1]; Jellison, Gerald E. ^[1]; Joshi, Pooran C. ^[1]; Ivanov, Ilia H. ^[1]; Liu, Tao ^[1]; Wang, Peng ^[2]; Menon, Rajesh ^[2]; Trejo, Rosa M. ^[1]; Lara-Curzio, Edgar ^[1]; Hunter, Scott R. ^[1]; Simpson, John T. ^[1]; Paranthaman, M. Parans ^[1]; Christen, David K. ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2. Univ. of Utah, Salt Lake City, UT (United States)

The design of multifunctional coatings impact impact the performance of many optical systems and components. Such coatings should be mechanically robust, and combine user-defined optical and wetting functions with scalable fabrication formulations. By taking cues from the properties of some natural biological structures, we report here the formation of low-refractive index antireflective glass films that embody omni-directional optical properties over a wide range of wavelengths, while also possessing specific wetting capabilities. The coatings comprise an interconnected network of nanoscale pores surrounded by a nanostructured silica framework. These structures result from a novel fabrication method that utilizes metastable spinodal phase separation in glass-based materials. The approach not only enables design of surface microstructures with graded-index antireflection characteristics, where the surface reflection is suppressed through optical impedance matching between interfaces, but also facilitates self-cleaning ability through modification of the surface chemistry. Based on near complete elimination of Fresnel reflections (yielding >95% transmission through a single-side coated glass) and corresponding increase in broadband transmission, the fabricated nanostructured surfaces are found to promote a general and an invaluable ~3–7% relative increase in current output of multiple direct/indirect bandgap photovoltaic cells. Moreover, these antireflective surfaces also demonstrate superior resistance against mechanical wear and abrasion. Unlike conventional counterparts, the present antireflective coatings are essentially monolithic, enabling simultaneous realization of graded index anti-reflectivity, self-cleaning capability, and mechanical stability within the same surface. Moreover, the concept represents a fundamental basis for development of advanced coated optical quality products, especially where environmental exposure is required.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1195808
• Journal Information: Journal of Materials Chemistry C, Vol. 3, Issue 21; ISSN 2050-7526
• Publisher: Royal Society of Chemistry
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING