Anti-reflective coatings (ARCs) have evolved into highly effective reflectance and glare reducing components for various optical and opto-electrical equipments. Extensive research in optical and biological reflectance minimization as well as the emergence of nanotechnology over the years has contributed to the enhancement of ARCs in a major way. In this study the prime objective is to give a comprehensive idea of the ARCs right from their inception, as they were originally conceptualized by the pioneers and lay down the basic concepts and strategies adopted to minimize reflectance. The different types of ARCs are also described in greater detail and the state-of-the-art fabrication techniques have been fully illustrated. The inspiration that ARCs derive from nature (‘biomimetics’) has been an area of major research and is discussed at length. The various materials that have been reportedly used in fabricating the ARCs have also been brought into sharp focus. An account of application of ARCs on solar cells and modules, contemporary research and associated challenges are presented in the end to facilitate a universal understanding of the ARCs and encourage future research.

Anti-reflective coatings: A critical, in-depth review

Advances in engineered surfaces for functional performance

Optical reflection, or in other words the loss of reflection, from a surface becomes increasingly crucial in determining the extent of the light-matter interaction. The simplest example of using an anti-reflecting (AR) surface is possibly the solar cell that incorporates an AR coating to harvest sunlight more effectively. Researchers have now found ways to mimic biological structures, such as moth eyes or cicada wings, which have been used for the AR purpose by nature herself. These nanoscopic biomimetic structures lend valuable clues in fabricating and designing gradient refractive index materials that are efficient AR structures. The reflectance from a selected sub-wavelength or gradient index structures have come down to below 1% in the visible region of the spectrum and efforts are on to achieve broader bands of such enhanced AR regime. In addition to the challenge of broader bands, the performance of AR structures is also limited by factors such as omnidirectional properties and polarization of incident light. This review presents selected state-of-the-art AR techniques, reported over the last half a century, and their guiding principles to predict a logical trend for future research in this field.

Anti-reflecting and photonic nanostructures

Recent progress in antireflection and self-cleaning technology – From surface engineering to functional surfaces

In this report, the development of conventional, mass-printing strategies into high-resolution, alternative patterning techniques is reviewed with the focus on large-area patterning of flexible thin-film transistors (TFTs) for display applications. In the first part, conventional and digital printing techniques are introduced and categorized as far as their development is relevant for this application area. The limitations of conventional printing guides the reader to the second part of the progress report: alternative-lithographic patterning on low-cost flexible foils for the fabrication of flexible TFTs. Soft and nanoimprint lithography-based patterning techniques and their limitations are surveyed with respect to patterning on low-cost flexible foils. These show a shift from fabricating simple microlense structures to more complicated, high-resolution electronic devices. The development of alternative, low-temperature processable materials and the introduction of high-resolution patterning strategies will lead to the low-cost, self-aligned fabrication of flexible displays and solar cells from cheaper but better performing organic materials.

Fabrication of Transistors on Flexible Substrates: from Mass‐Printing to High‐Resolution Alternative Lithography Strategies

An antireflective optical film with subwavelength structures replicated by use of a roll-to-roll micro-replication process (RMRP) is investigated. Firstly, a single layer of a nanostructure on a polymer film is designed for an antireflection purpose by the finite difference time domain method in the visible light spectrum. Structures of a conical cylinder array, with spatial period of 400 nm, diameter of 200 nm and height of 350 nm, are numerically obtained. Then, such structures are fabricated by RMRP combining originated structure fabrication realized by deep ultra-violet lithography and dry etching, Ni mold electroplating and replication by using the roll-to-roll process imprinting into the flexible polyethylene terephthalate substrate. A nanostructure roller mold bonded with Ni molds has been successfully fabricated and coated with the self-assembly monolayer process for the purpose of fabricating an anti-adhesion film and improving the lifetime of the Ni molds. The duplicated nanostructure films show a good optical quality of antireflection (AR ≤ 2.45% in a 400–700 nm spectral range) and are in good agreement with the theoretical predictions. The experimental results show that the developed process is a promising and cost-effective method for the continuous duplication of flexible devices with nano-scaled feature sizes used in nanophotonics by RMRP.

https://ir.nctu.edu.tw:443/bitstream/11536/8670/1/000257128100002.pdf

Fabrication of an antireflective polymer optical film with subwavelength structures using a roll-to-roll micro-replication process

Design of a solar concentrator combining paraboloidal and hyperbolic mirrors using ray tracing method

https://ir.nctu.edu.tw:443/bitstream/11536/7683/1/000262250400016.pdf

Subwavelength structures for broadband antireflection application

A solar concentrator with two reflection mirrors designed by using a ray tracing method

http://ntur.lib.ntu.edu.tw/bitstream/246246/87006/1/48.pdf

Chi Feng Chen

Papers

Fabrication of an antireflective polymer optical film with subwavelength structures using a roll-to-roll micro-replication process

Design of a solar concentrator combining paraboloidal and hyperbolic mirrors using ray tracing method

Subwavelength structures for broadband antireflection application

A solar concentrator with two reflection mirrors designed by using a ray tracing method

Fabrication of long hexagonal micro-lens array by applying gray-scale lithography in micro-replication process