Large-Scale Bio-Inspired Flexible Antireflective Film with Scale-Insensitivity Arrays

Wang, Ze; Ding, Hanliang; Liu, Delei; Xu, Chuan; Li, Bo; Niu, Shichao; Li, Jian; Liu, Linpeng; Zhao, Jie; Zhang, Junqiu; Mu, Zhengzhi; Han, Zhiwu; Ren, Luquan

doi:10.1021/acsami.1c02046

Cited by 28 publications

(14 citation statements)

References 42 publications

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“…This implies that the microstructured arrays can overcome impedance mismatch and enhance the spectral absorption of SiO 2 in these wavelengths. [ 47 ] These simulation results suggest that the microstructured pattern is conducive to obtaining a stronger coupling with the structure and a smoother index matching with the environment, thus leading to a higher extinction in the thermal infrared wavelength range.…”

Section: Resultsmentioning

confidence: 92%

Iridescent Daytime Radiative Cooling with No Absorption Peaks in the Visible Range

Ding

Pattelli

Xü

et al. 2022

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Traditional cooling technologies suffer from several limitations: basically, they all rely on electricity, have high energy needs, and discharge waste heat into the surrounding environment which in turn contributes to global warming and the urban heat island effect. [2][3][4] For these reasons, the recent development of passive radiative sky cooling materials is attracting a growing interest due to its environmentally friendly nature and energy-free working principle. [5] In recent years, hundreds of candidate materials have been proposed, offering a range of passive cooling performances during daytime hours and even under direct sunlight. Two essential requirements for sub-ambient radiative cooling under direct sunlight are a high reflectivity above 90% in the solar spectral range (0.25-2.5 µm), and a strong, preferably selective emissivity in the atmospheric transparency window (8-13 µm). [6,7] This demanding combination of optical properties is generally achieved through both the selection of specific materials with appropriate absorption bands and the micro and nanoengineering of coatings. These materials can be generally divided into four main categories, namely dielectric multilayer films, [8][9][10][11][12] organic-inorganic composite materials, [13][14][15] Coatings for passive radiative cooling applications must be highly reflected in the solar spectrum, and thus can hardly support any coloration without losing their functionality. In this work, a colorful daytime radiative cooling surface based on structural coloration is reported. A designed radiative cooler with a bioinspired array of truncated SiO 2 microcones is manufactured via a self-assembly method and reactive ion etching. Complemented with a silver reflector, the radiative cooler exhibits broadband iridescent coloration due to the scattering induced by the truncated microcone array while maintaining an average reflectance of 95% in the solar spectrum and a high thermal emissivity (ε) of 0.95, owing to the reduced impedance mismatch provided by the patterned surface at infrared wavelengths, reaching an estimated cooling power of ≈143 W m -2 at an ambient temperature of 25 °C and a measured average temperature drop of 7.1 °C under direct sunlight. This strong cooling performance is attributed to its bioinspired surface pattern, which promotes both the aesthetics and cooling capacity of the daytime radiative cooler.

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Section: Resultsmentioning

confidence: 92%

Iridescent Daytime Radiative Cooling with No Absorption Peaks in the Visible Range

Ding

Pattelli

Xü

et al. 2022

Small

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“…b) Previously reported sticker-type AR films, including the main developments of this study in terms of the thickness and reflectance, represented in the historical graph. [18,19,22,29,[31][32][33][34] 2. Results…”

Section: Introductionmentioning

confidence: 99%

“…a) Schematic illustration of a flexible PSC with a SUPA and commercial AR film.Compared to flexible SUPA with a high bending rate, commercial AR film can cause damage to perovskite-layer even at low bending rate due to high flexural rigidity. b) Previously reported sticker-type AR films, including the main developments of this study in terms of the thickness and reflectance, represented in the historical graph [18,19,22,29,[31][32][33][34].…”

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confidence: 99%

Optically and Mechanically Engineered Anti‐Reflective Film for Highly Efficient Rigid and Flexible Perovskite Solar Cells

Choi

Jang

Kim

et al. 2022

Advanced Energy Materials

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phase stabilizing, [8] charge carrier management, [9] pseudo-halide anion engineering, [10] and intact 2D/3D perovskite bilayer employment; [5] up to 25.5% certificated PCE of the device has been reported.Most of the previous investigations were focused on inner device factors such as materials and junctions of the PSC. [11][12][13][14][15][16][17] However, gathering entire light wavelength (350-850 nm) and putting it into the PSC are equally important to enhancing the PCE by controlling the mechanism inside the PSC. Once a sticker-type anti-reflective (AR) film is simply attached to the device, it effectively increases light transition efficiency (LTE, defined as the amount of external light transmitted to the device) independently of the development of inner device technology. On account of efficient transference of external sunlight into the PSC with the aid of AR film, the external quantum efficiency (EQE) of PSC increases across the entire wavelength which means increase of short-circuit current density (J sc ). [18,19] Therefore, the application of proper sticker-type AR film to PSCs is the most effective and easiest approach to increasing the PCE of the photovoltaic devices. [20,21] Such a sticker-type AR film has been continuously developed with the progress of PSC, with the help of its high LTE and easy applicability on transparent substrates. [22][23][24][25] To obtain high LTE for PSC, the highest priority for AR film is to reduce reflection of incident light by effectively reducing the difference in refractive index (n) that occurs at the substrate interface, because the reflection is caused by the sudden change of refractive index at the interface between the air and substrate. Therefore, it is necessary to use a material with low refractive index for AR film. In addition, forming nanostructures on surface of the AR film can enhance the AR effect based on the structural gradient change of the refractive index from air to substrate. [26][27][28][29] Furthermore, in order to expand and commercialize the gradually developing PSC technology, advanced AR film that can be easily applied to flexible and lightweight PSC (that is important for the wearable and portable electronic devices) is needed. For this reason, a sticker-type ultra-thin AR film is essential. The thinner the AR film attached to the flexible PSC, the better the mechanical stability of the device due to the reduction of the applied stress on the perovskite layer. [30] However, the commercial AR film is developed by biasing toward Sticker-type anti-reflective (AR) film is a powerful route to achieve the highest efficiency and commercialization of perovskite solar cells (PSCs) by improving the light transition efficiency (LTE). However, conventionally used AR film has high flexural rigidity owing to its limitation of material and thickness, thereby hindering its application to high-efficiency flexible devices. This paper proposes a sticker-type ultra-thin perfluoropolyether (PFPE) AR film (SUPA) made of PFPE (n = 1.34) that is fabricated thro...

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“…Many living creatures in nature have a special own surviving method, and many studies of bio‐mimicking have been widely conducted to apply their novel living methods in our life. [ 1–6 ] One of the most famous studies in the biomimetics is a dry adhesive inspired by gecko foot. The gecko foot consists of numerous micro/nano hierarchical hair, which is composed of 30–130 µm long setae and 0.2–0.5 µm spatula‐shaped terminating structures and can be strongly attached to the surface by the “van der Waals forces.” [ 7–11 ] Notably, although the gecko lizards can stick with an adhesion strength of more than 100 kPa, they can move in speeds as high as 0.8 m s −1 through their extraordinary adhesion switching capability.…”

Section: Introductionmentioning

confidence: 99%

Surface Adaptable and Adhesion Controllable Dry Adhesive with Shape Memory Polymer

Lee

Song

Park

et al. 2022

Macromol. Rapid Commun.

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Gecko feet consist of numerous micro/nano hierarchical hairs and exhibit a high adhesion onto various surfaces by van der Waals forces. The gecko, despite its mighty adhesion, can travel efficiently with a rapid adhesion switching due to the end of the hairs on the gecko feet are slanted in one direction. Herein, a shape memory polymer (SMP)‐based switchable dry adhesive (SSA), inspired by gecko feet, having tremendous surface adaptability and adhesion switching capability, is reported. The SSA shows not only high adhesion to the various surfaces (≈332.8 kPa) but also easy detachment (nearly 3.73 kPa) due to the characteristic of SMP, which can reversibly recover from a deformed shape to its initial shape. On the basis of the novel adhesion switching property, it is suggested the SSA‐applied advanced glass transfer system can lead to feasible application. This experiment confirms that an ultrathin and light glass film is transferred easily and sustainably, and it is believed that the SSA may be a breakthrough and a powerful alternative for not only conventional dry adhesives but also the next‐level transfer systems.

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Large-Scale Bio-Inspired Flexible Antireflective Film with Scale-Insensitivity Arrays

Cited by 28 publications

References 42 publications

Iridescent Daytime Radiative Cooling with No Absorption Peaks in the Visible Range

Iridescent Daytime Radiative Cooling with No Absorption Peaks in the Visible Range

Optically and Mechanically Engineered Anti‐Reflective Film for Highly Efficient Rigid and Flexible Perovskite Solar Cells

Surface Adaptable and Adhesion Controllable Dry Adhesive with Shape Memory Polymer

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