Polymer Nanocomposite Thin Film Mirror for the Infrared Region

Druffel, Thad; Mandzy, Natalia; Sunkara, Mahendra K.; Grulke, Eric A.

doi:10.1002/smll.200700680

Cited by 31 publications

(32 citation statements)

References 15 publications

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“…[11][12][13] Approaches based on fl exible inorganic nano structured multilayers that effi ciently refl ect radiation in an arbitrary spectral range as a result of interference effects, rather than by absorption, present a promising alternative route worth to be explored. [14][15][16][17] Unfortunately, a similar approach based on the alternation of polymeric fi lms exclusively is not feasible since the refractive index contrast typically achieved is so small that a large number of layers is required to reach a signifi cant refl ectance, and only in a narrow spectral range. [ 18,19 ] The use of all-polymeric materials of high refractive index contrast to build multilayer back refl ectors or UV shields will also be an advantage in the fi eld of fl exible and polymeric solar cells, in which some approaches based on inorganic materials have already been developed.…”

Section: Doi: 101002/adom201500209mentioning

confidence: 99%

Adaptable Ultraviolet Reflecting Polymeric Multilayer Coatings of High Refractive Index Contrast

Smirnov

Ito

Calvo

et al. 2015

Advanced Optical Materials

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a series of undesirable photoreactions promoted by the absorption of UV photons, which lead to the deterioration of their mechanical and optical properties. Polymers are usually transparent to part of the UV spectrum, so a commonly employed synthetic strategy to attain UV blocking fi lms is based on embedding inorganic [3][4][5][6][7] or organic [8][9][10] UV absorbers within a polymeric matrix. The main drawback of this approximation is the short term durability of the shielding effect as a result of the photodegradation of either host, guest, or both, caused by the absorption of the same radiation from which protection is sought after. [11][12][13] Approaches based on fl exible inorganic nano structured multilayers that effi ciently refl ect radiation in an arbitrary spectral range as a result of interference effects, rather than by absorption, present a promising alternative route worth to be explored. [14][15][16][17] Unfortunately, a similar approach based on the alternation of polymeric fi lms exclusively is not feasible since the refractive index contrast typically achieved is so small that a large number of layers is required to reach a signifi cant refl ectance, and only in a narrow spectral range. [ 18,19 ] The use of all-polymeric materials of high refractive index contrast to build multilayer back refl ectors or UV shields will also be an advantage in the fi eld of fl exible and polymeric solar cells, in which some approaches based on inorganic materials have already been developed. [ 20,21 ] Very recently, some of us proved that a porous stratifi ed structure displaying strong refl ection peaks in the UV range can be attained from a block copolymer (BCP) fi lm. [ 22 ] In particular, it was demonstrated that a fi lm made of a diblock copolymer containing polystyrene (PS) and polymethyl methacrylate (PMMA), in brief [poly(styreneblock -methyl methacrylate) PS-b -PMMA)], can be used as starting material to attain ordered porous multilayers through a process that involves collective osmotic shock (COS). The fi nal structure shows alternate dense and porous layers, with signifi cant refractive index contrast, which endow it with photonic crystal properties in the UV range. At that moment, the appearance of the layered structure was hypothetically attributed to dynamic effects during the COS process occurring over ordered arrangements of isolated PMMA spheres embedded in a cross-linked PS matrix in the starting slab, which had previously been subjected to thermal and UV annealing processes. Further studies, herein reported, have demonstrated that the mechanism of formation of the porous layered structure is different to that originally A synthetic route is demonstrated to build purely polymeric nanostructured multilayer coatings, adaptable to arbitrary surfaces, and capable of effi ciently blocking by refl ection a targeted and tunable ultraviolet (UV) range. Refl ection properties are determined by optical interference between UV light beams refl ected at the interfaces between polystyrene layers of diff...

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Section: Doi: 101002/adom201500209mentioning

confidence: 99%

Adaptable Ultraviolet Reflecting Polymeric Multilayer Coatings of High Refractive Index Contrast

Smirnov

Ito

Calvo

et al. 2015

Advanced Optical Materials

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“…[19] In 2008, Druffel et al managed to fabricate the first polymernanocomposite based dielectric mirrors via spin-coating on a plastic substrate (15 single layers, maximum reflectance of 95% at λ 0 ≈ 1060 nm). [20] To allow proper curing, the TiO 2 and SiO 2 nanoparticles were functionalized, and an additional UV curing agent was added. Hence, no heat but only UV treatment was necessary to properly cure the polymer monomers after deposition.…”

Section: Introductionmentioning

confidence: 99%

Printing of Large‐Scale, Flexible, Long‐Term Stable Dielectric Mirrors with Suppressed Side Interferences

Bronnbauer

Riecke

Adler

et al. 2017

Advanced Optical Materials

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Dielectric mirrors are wavelength‐selective mirrors which are based on thin film interference effects. Their optical band can precisely be adjusted in width, position, and reflectance by the refractive index of the applied materials, the layers' thicknesses, and the amount of deposited layers. Nowadays, they are a well‐known light management tool for efficiency enhancement in, for example, semitransparent organic solar cells (OSCs) and light guiding in organic light‐emitting diodes (OLEDs). However, most of the dielectric mirrors are still fabricated by lab‐scale techniques such as spin‐coating or physical vapor deposition under vacuum. Large‐scale, fully printed (maximum 20 × 20 cm2) dielectric mirrors with adjustable reflectance characteristics are fabricated, using temperatures of maximum 50 °C and alcohol‐based inks. According to the moderate processing conditions they can be easily deposited not only on rigid glass substrates but also on flexible foils. They show high stability against humidity, light irradiation, and temperature, positioning themselves as good candidates for applications in OLEDs and OSCs. Eventually, by simulations and experiments it is verified that a moderate degree of variations in layer thickness and surface roughness can suppress side interference fringes, while not impacting the main transmittance minimum or the main reflection maximum, respectively.

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“…[4,5] Eco-friendly films that selectively reflect near-infrared radiation have also been developed. [6] As such films do not transmit heat in the near-infrared region, the increase in indoor temperature can be suppressed by applying these films to windows. For all the above optical applications, the precise control of film thickness and reflective index is necessary.…”

Section: Introductionmentioning

confidence: 99%

“…[1,6,7] It is an easy, aqueous-based, ecofriendly method carried out under room temperature and at 1 atm, and has been thoroughly explored by Gero Decher et al [8] A disadvantage was that the fabrication time was too long for many industrial applications, and consequently the idea of a spray-LBL method, where solutions were sprayed directly onto substrates, was conceived.10 Fabrication time was reported to be greatly shortened due to enhanced adsorption by the spray pressure. An automated spray LBL machine has been previously reported [9].…”

Section: Introductionmentioning

confidence: 99%

Fully automatic spray-LBL machine with monitoring the real time growth of multilayer films using Quartz Crystal Microbalance

Shiratori

Fukao

Kyung

2013

MATEC Web of Conferences

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Abstract.A fully automatic spray-LBL machine with monitoring the real time growth of multilayer films using Quartz Crystal Microbalance (QCM) techniques was newly developed. We established fully automatic spray layer-by-layer method by precisely controlling air pressure, solution flow, and spray pattern. The movement pattern towards the substrate during solution spraying allowed fabrication of a nano-scale, flat, thin film over a wide area. Optimization of spray conditions permitted fabrication of the flat film with high and low refractive indexes, and they were piled up alternatively to constitute a one-dimensional photonic crystal with near-infrared reflection characteristics. The heat shield effect of the near-infrared reflective film was also confirmed under natural sunlight. It was demonstrated that the fabrication using the automatic spray-LBL machine and real-time QCM monitoring allows the fabrication of optical quality thin films with precise thickness.

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Polymer Nanocomposite Thin Film Mirror for the Infrared Region

Cited by 31 publications

References 15 publications

Adaptable Ultraviolet Reflecting Polymeric Multilayer Coatings of High Refractive Index Contrast

Adaptable Ultraviolet Reflecting Polymeric Multilayer Coatings of High Refractive Index Contrast

Printing of Large‐Scale, Flexible, Long‐Term Stable Dielectric Mirrors with Suppressed Side Interferences

Fully automatic spray-LBL machine with monitoring the real time growth of multilayer films using Quartz Crystal Microbalance

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