Luminescent Transparent Wood

Li, Yuanyuan; Yu, Shun; Veinot, Jonathan G. C.; Linnros, Jan; Berglund, Lars A.; Sychugov, Ilya

doi:10.1002/adom.201600834

Cited by 137 publications

(125 citation statements)

References 30 publications

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“…To address these issues, several technologies have been developed, including internal and external blinds, transparent thermal barriers, angular selective shading systems, coatings, films, and multipane windows . The development of transparent wood as an alternative transparent material has aroused wide attentions . L. Berglund's group used sodium chlorite (NaClO 2 ) method to bleach the natural wood and infiltrated polymethyl mechacrylate (PMMA) to obtain transparent wood .…”

Section: Introductionmentioning

confidence: 99%

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

Dalgo

et al. 2019

Adv Funct Materials

155

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The energy used for regulating building temperatures accounts for 14% of the primary energy consumed in the U.S. One-quarter of this energy is leaked through inefficient glass windows in cold weather. The development of transparent composites could potentially provide affordable window materials with enhanced energy efficiency. Transparent wood as a promising material has presented desirable performances in thermal and light management. In this work, the performance of transparent wood is optimized toward an energy efficient window material that possesses the following attributes: 1) high optical transmittance (≈91%), comparable to that of glass; 2) high clarity with low haze (≈15%); 3) high toughness (3.03 MJ m −3 ) that is 3 orders of magnitude higher than standard glass (0.003 MJ m −3 ); 4) low thermal conductivity (0.19 W m −1 K −1 ) that is more than 5 times lower than that of glass. Additionally, the transparent wood is a sustainable material, with low carbon emissions and scaling capabilities due to its compatibility with industryadopted rotary cutting methods. The scalable, high clarity, transparent wood demonstrated in current work can potentially be employed as energy efficient and sustainable windows for significant environmental and economic benefits.

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Section: Introductionmentioning

confidence: 99%

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

Dalgo

et al. 2019

Adv Funct Materials

155

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“…In our case, the reflection coefficient for PMMA, estimated from Fresnel equation is 4%-5% (for normal incidence) which ensures formation of a low Q-factor resonator. [25] Refractive index of PMMA in the visible range is about n = 1.5 which is enough to build up such a resonator, where high losses due to low reflection of the facets are compensated by high quantum yield of Rh6G (0.99, from the supplier). Stability of the mode pattern, as well as peak separation, with elongation of the pump line, justify that the geometry of the resonator was not changed.…”

Section: Comparative Analysis Of the Lasing Mechanism In Tw-dye Strucmentioning

confidence: 99%

Lasing from Organic Dye Molecules Embedded in Transparent Wood

Vasileva

Sychugov

et al. 2017

Advanced Optical Materials

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In this report, we demonstrate lasing action from a novel gain material containing organic dye Rhodamine 6G (Rh6G) embedded into transparent wood (TW) matrix. Besides the unusual origin and appearance of the investigated material, it has numerous advantages defined by the properties of components used for its fabrication. Organic dyes are of special interest as active media due to their broadband emission/absorption spectra and very high optical gain. [13][14][15] Transparent wood features light weight, modification accessibility, excellent mechanical performance, and structural anisotropy introduced by aligned hollow cells. [16,17] Optical transparency of TW is the most unique property, which extends its applications in various fields, including biosciences, lighting, building industry, and others. [17][18][19] Although this material (TW) is relatively new, it has already been tested for potential applications in optics, but so far only for implementation in passive photonic components. [18] However, due to its compatibility with polymer technology, TW is an interesting alternative for applications requiring optical activity, first of all lasing, where demanded materials should be inexpensive, easily handled and disposable. Material Preparation and CharacterizationAs the TW itself does not possess any optical gain, a host matrix should be "activated" with an additional optically active medium, Rh6G dye in our case. The samples with dye embedded into TW structure were prepared in three technological steps (Figure 1). At the first step, balsa wood (Ochroma pyramidale, purchased from Wentzels Co. Ltd, Sweden) of thickness of 1.0 mm and 3.0 mm was delignified using 1 wt% of sodium chlorite (NaClO 2 , Sigma-Aldrich) in acetate buffer solution (pH 4.6) at 80 °C, until the wood was totally bleached. Then the delignified wood was dehydrated with ethanol and acetone, sequentially; each procedure was repeated three times. At the second step, wood template was put in dye (Rh6G 99%, SIGMA-ALDRICH) acetone solution with a concentration of 1 × 10 −3 mole/L. Finally, the wood template was fully infiltrated into the pre-polymerized MMA solution and then cured at 75 °C for 4 h.The surface and cross-sections of the TW samples were investigated with a field-emission scanning electron microscope (Hitachi S-4800, Japan) operating at an acceleration voltage of 1 kV. The samples were roughly polished and coated with Pt/Pd before SEM imaging. The length of fibers constituting the wood material varies in range of 200-1000 µm, whereas the lumen The report on a study of laser emission from a conceptually new organic material based on transparent wood (TW) with embedded dye Rhodamine 6G molecules is presented in this paper. The lasing performance is compared to a reference organic material containing dye in a poly-methyl-methacrylate matrix. From experimental results, one can conclude that the optical feedback in dye-TW material is realized within cellulose fibers, which play the role of tiny optical resonators. Therefore, the output emis...

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“…However during recent years, the interest toward TW was significantly renewed in several research areas: material science designing multifunctional wood composites, [2,[4][5][6] energy saving technology focused on application of TW in solar cells, [7] and photonics dealing with light sources based on TW with additives. [8,9] Natural wood consists of three main components which have different refractive indices: cellulose (1.525 with light propagating www.advopticalmat.de through the material, haze is important to characterize scattering properties of medium in terms of image content. [18] In other words, haze represents dissolution of a picture seen through a material.…”

Section: Introductionmentioning

confidence: 99%

“…[9,17,19,20] However, in those reports authors analyze either light guiding by fibers inside the transparent wood [9,19] or briefly mentioned anisotropic optical (transmitted light distribution) and mechanical properties. Until recent, very few research reports mentioned anisotropic transmitted intensity distribution of the beam propagating through the TW material.…”

Section: Introductionmentioning

confidence: 99%

Light Scattering by Structurally Anisotropic Media: A Benchmark with Transparent Wood

Vasileva

Chen

et al. 2018

Advanced Optical Materials

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perpendicularly to the cellulose fibers, and 1.596 along with the fibers), hemicellulose (1.532), and lignin (1.61). [3] While holocellulose (cellulose and hemicellulose) is optically colorless, lignin is the main source of absorption (about 80-95% of wood light absorption) in the visible range. [10] Thus, lignin removing [11] or deactivating the chromophores inside lignin is required to make wood transparent. [12] Although major part of lignin is removed during chemical modification, some residual amount (1-3%) still remains in the wood [11] introducing minor absorption. A delignified wood (Figure 1a) is not yet transparent due to strong scattering of light, which occurs on the interfaces between the material structural components and air-filled voids between/within them. To minimize such scattering, the delignified template is infiltrated with a polymer of refractive index approximately matching the wood compounds. In several previous studies, polymerized methyl methacrylate (PMMA) whose refractive index is close to the average refractive index of delignified wood template (≈1.53) [11] was implemented. However, there always exists minor refractive index mismatch between the wood components and infiltrated polymer that leads to the light scattering. Moreover, as a consequence of mesoporous hierarchical structure of a wood template [13] with feature sizes scaling from micrometers-cellulose fibers, vessels, rays [14] (schematically presented in Figure 1b) down to nanometers (nanofibrils), [1,15] polymer infiltration process is not perfect, e.g., due to surface compatibility issues. This leads to formation of structural air-filled voids in the walls of the cellulose fibers consisting of nanofibrils (Figure 1c). It should be noted that additional airfilled voids can also be created via polymer shrinkage during polymerization [16] (Figure 1c). Hence, scattering in TW is caused by several factors: minor mismatch of the refractive indices between the delignified wood template and infiltrated polymer, multiscale porous hierarchical structure of the wood consisting of macro-, meso-, and nanopores, and presence of air-filled voids. Thus, despite relatively high optical transmittance, TW is, in fact, an optically anisotropic scattering medium.Traditionally optical properties of TW have been characterized via measuring the light total hemispherical luminous transmittance (referred as transmittance in the literature about TW) and haze. [11,17] While transmittance describes optical losses of a material, i.e., the fraction of the optical energy flux passing Transparent wood (TW) is a biocomposite material with hierarchical structure, which exhibits high optical transmittance and anisotropic light scattering. Here, the relation between anisotropic scattering and the internal structure of transparent wood is experimentally studied and the dependence of scattering anisotropy on material thickness, which characterizes the fraction of ballistic photons in the propagating light, is shown. The limitations of the conventional haze, as...

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Luminescent Transparent Wood

Cited by 137 publications

References 30 publications

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

A Clear, Strong, and Thermally Insulated Transparent Wood for Energy Efficient Windows

Lasing from Organic Dye Molecules Embedded in Transparent Wood

Light Scattering by Structurally Anisotropic Media: A Benchmark with Transparent Wood

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