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The VO2 and VO2 -SiO2 composite films were prepared by sol-gel method. The phase structure and transmittance of films were characterized by X-ray diffraction (XRD) and ultraviolet visible spectrophotometer. The results reveal that the prepared VO2 film is monoclinic phase (B), and the XRD patterns of VO2 -SiO2 composite film is similar to that of VO2 film. The optical transmittance of films have reached over 90% within the range of 450 nm to 800 nm. The laser induced damage threshold (LIDT) of VO2 -SiO2 composite film is 3. 9 J/cm2, which is 77. 3% higher than that of VO2 film. The difference in damage morphology between VO2 film and VO2 -SiO2 film were studied by FESEM and step analyzer. The VO2 film exhibits melt type damage, while the VO2 -SiO2 film exhibits melt type damage and stress damage. In addition, laser-induced damage models for different films were constructed and damage characteristics and underlying mechanisms were discussed. [ABSTRACT FROM AUTHOR]

The results of a study of the optical, electrophotographic and holographic parameters of As-Se condensates from the prehistory of the original bulk materials are presented. It has been established that the electrophotographic parameters of freshly deposited As40Se60 layers change significantly with temperature; the dependences of the maximum charging potential (U0) and the half-decay time of the potential (τ1/2) of electrophotographic As40Se60 layers in the dark on the processing temperature of the melt of the starting material are shown. The dependence of the half-life of the potential in the dark, as well as the properties of bulk samples, has an extremum in the region of Tsub~500°C. The correlation between the dependences of the properties of bulk samples and the electrophotographic parameters of the layers on Tsub indicates that the structural features of the source material in the deposition mode used affect the structure of the films.

The results of a study of the optical, electrophotographic and holographic parameters of As-Se condensates from the prehistory of the original bulk materials are presented. It has been established that the electrophotographic parameters of freshly deposited As40Se60 layers change significantly with temperature; the dependences of the maximum charging potential (U0) and the half-decay time of the potential (τ1/2) of electrophotographic As40Se60 layers in the dark on the processing temperature of the melt of the starting material are shown. The dependence of the half-life of the potential in the dark, as well as the properties of bulk samples, has an extremum in the region of Tsub~500°C. The correlation between the dependences of the properties of bulk samples and the electrophotographic parameters of the layers on Tsub indicates that the structural features of the source material in the deposition mode used affect the structure of the films. [ABSTRACT FROM AUTHOR]

Using the successive ionic layer adsorption and reaction (SILAR) method, we successfully deposited thin films (TFs) of both pure cadmium oxide (CdO) and strontium (Sr) CdO onto glass slides. Analysis of the films’ structure and morphology, conducted via field emission scanning electron microscopy and X-ray diffraction, revealed a polycrystalline cubic structure with porous nanoflake agglomerates. Further characterization involved ultraviolet–visible spectroscopy and photoluminescence spectrum measurements to explore the optical attributes of the CdO films. Notably, we observed significant impacts of Sr doping on both optical transmittance and photoluminescence emission intensity in the CdO nanostructures. Electrical measurements, carried out using four-probe Iviumstat analysis, demonstrated variations in resistivity with different levels of Sr doping. These findings highlight the potential for controlling specific physical features of CdO through Sr doping, making it a promising candidate for various device applications. [ABSTRACT FROM AUTHOR]

Wood is a natural composite material mainly consisting of three components, i.e., cellulose, hemicellulose, and lignin. It exhibits a complex hierarchical structure characterized by open channels, aligned in the growth direction, having specific porosity at micro-, meso-, and macro-scale, and an extended opacity, due to adsorption phenomena because of the presence of lignin and scattering, as different refractive indexes characterize its components. Even if during the historical ages some of its applications have been replaced by other materials, wood still covers a large part of common uses, which range from biomass for energy recovery to material for the building sector, or from artifacts to household/furniture manufacturing. Despite its real invention dating to 1992, only about ten years ago two independent research groups, one from the University of Maryland (USA) and the other from the Royal Institute of Technology (Sweden) rediscovered and started to thoroughly investigate the so-called transparent wood (TW). TW can be derived from almost any wood biomass through specific chemical treatments focused on lignin. These aim to completely remove this component from wood or to eliminate the chromophore groups present in the pristine material, hence obtaining, after direct densification or after infiltration with a suitable polymer resin, a new material with very high transparency, toughness, and lightness. These characteristics can further be combined with other specific features (such as environmental protection, flame retardancy, photoluminescence, and energy storage ability, among others), which open the way toward the development of new, up-to-date, advanced, and sustainable materials for both structural and functional purposes, fulfilling the current concepts of circular economy and sustainability. The present review is aimed at providing the reader with an overview of the characteristics of transparent wood, describing the latest applications and, finally, discussing some challenging issues and perspectives for possible developments in the forthcoming years.

We reported the growth of (AlGa)2O3 layers on (11 2 ¯ 0), (10 1 ¯ 0), and (10 1 ¯ 2) α -Al2O3 substrates using MBE, and the electrical characterization of Si-doped (AlGa)2O3 layers. The Ga2O3 layers grown on (10 1 ¯ 0) and (10 1 ¯ 2) α -Al2O3 were α -phase single crystals, while the Ga2O3 layer grown on (11 2 ¯ 0) α -Al2O3 consisted of (11 2 ¯ 0) α -Ga2O3 and ( 2 ¯ 01) β -Ga2O3. The Al composition of the (11 2 ¯ 0) and (10 1 ¯ 0) (AlGa)2O3 layers was controlled by varying the Al flux. The Si-doped (10 1 ¯ 0) α -(Al x Ga1- x )2O3 layers with x = 0–0.41 were electrically conducting. [ABSTRACT FROM AUTHOR]

With the rapid development of flexible electronics industry, the conventional PET, PEN and other plastic substrates are unable to satiate the requirement due to higher cost and low light extraction efficiency. Paper has broad prospects as a flexible substrate due to its wide access, low-cost and thinness. In this paper, we integrated epoxy resin into sulfuric acid paper to fabricate a new type of substrate: plastic-paper. The plastic-paper has excellent optical properties, mechanical properties as well as water and chemical stability, as found through testing. Results show that the surface flatness and wettability of the paper are improved by the application of epoxy resin coating. The plastic-paper has a high optical transmittance up to 88.25%, reaching the same level with PET substrate. And the plastic-paper also has a high transmittance haze of 62.9%, which is far higher than PET substrate. The plastic-paper has a tensile strength up to 108.4 MPa, along with excellent water and chemical stability. Successful fabrication the organic light-emitting device on the plastic-paper surface and emitted uniform light based on the principle of light-emitting electrochemical cell (LEC), under atmospheric condition. The best device performance with a maximum luminance of 396. 2 cd m-2, a maximum current efficiency of 0.64 cd A-1, which is 2.9 times higher than that of PET substrates, providing more excellent optoelectronic properties. The developed plastic-paper with high optical transmittance and high optical haze holds a great potential in flexible optoelectronic devices. [ABSTRACT FROM AUTHOR]

Molybdenum trioxide/indium/silver/indium/molybdenum trioxide layers were evaporated on the polyethylene terephthalate and glass substrates using thermal evaporation coating machine. In this study, we compare the electrical, optical, and topological properties of dielectric/metal/dielectric fabricated on the polyethylene terephthalate substrate and glass substrate. In this way, the influence of dielectric and metal thicknesses on the electroptical behavior and topological properties of the transparent conductive film are studied. Furthermore, the influence of the substrate temperature on the physical properties of prepared thin films is investigated. The results show that by increasing molybdenum trioxide film thickness, the sheet resistance increases. We find that the prepared thin films on the glass substrate has high optical transmittance with respect to its on the polyethylene terephthalate substrate. We also find that by increasing the substrate temperature, figure of merit decreases. It means that the maximum figure of merit is achieved at the room substrate temperature. [ABSTRACT FROM AUTHOR]

An optically transparent antenna fed by a coplanar L-probe is proposed in this paper. Indium-doped tin oxide (ITO) with a sheet resistance of 3.5 Ω/sq etched on a soda-lime glass substrate is used as radiation array and ground to achieve high optical transmittance. TM $ _{10} $ 10 and TM $ _{20} $ 20 modes are excited simultaneously to expand work bandwidth. The fabricated antenna achieves a –10 dB reflection bandwidth of 27.5% from 4.7 to 6.2 GHz with the overall size of 42 mm × 42 mm × 3.3 mm. Different from many antennas composed of ITO, the proposed antenna exhibits directional radiation patterns with the maximum realized gain of 4.6 dBi and the maximum efficiency of 61%. Meanwhile, the optical transmittance of the antenna can reach above 58%. [ABSTRACT FROM AUTHOR]

In this paper, a detailed model of a photovoltaic (PV) panel is used to study the accumulation of dust on solar panels. The presence of dust diminishes the incident light intensity penetrating the panel's cover glass, as it increases the ref lection of light by particles. This phenomenon, commonly known as the "soiling effect", presents a significant challenge to PV systems on a global scale. Two basic models of the equivalent circuits of a solar cell can be found, namely the single-diode model and the two-diode models. The limitation of efficiency data in manufacturers' datasheets has encouraged us to develop an equivalent electrical model that is efficient under dust conditions, integrated with optical transmittance considerations to investigate the soiling effect. The proposed approach is based on the use of experimental current-voltage (I-V) characteristics with simulated data using MATLAB/Simulink. Our research outcomes underscores the feasibility of accurately quantifying the reduction in energy production resulting from soiling by assessing the optical transmittance of accumulated dust on the surface of PV glass. [ABSTRACT FROM AUTHOR]

Anion doping of tungsten trioxide by nitrogen is used to obtain electrochrome cathode materials, the spectral transmittance of which can be controlled by the doping level. A series of samples was synthesized by reactive magnetron sputtering of a metal tungsten target in a mixture of argon, nitrogen, and oxygen gases, the flow rate of the latter was varied at a constant pressure of the gas mixture. Warm-colored tungsten oxynitride films were prepared at higher doping levels with their morphology and elemental composition characterized using scanning electron microscopy, crystal structure described using X-ray diffraction and the valence state of constituents revealed with X-ray photoelectron spectroscopy techniques. Optical properties were measured by making use of transmission spectrophotometry and spectroscopic ellipsometry. These extensive experimental studies revealed an increase in absorption towards shorter wavelengths below the wavelength of 0.5 µm with an increase in the doping level. At the same time, it was found that with an increase in the doping level, partial reduction of the tungsten occurs, and the fraction of non-stoichiometric oxygen steadily increases to half of the total oxygen content. It is a common belief that the imperfection of the doped material facilitates the intercalation of the material by electrolyte ions. [ABSTRACT FROM AUTHOR]

In this study, highly c-axis-oriented ZnO:TM (TM = Co, Fe, and Mn) thin films doped with different doping levels (x = 0–10 at%) of TM were grown by chemical (sol-gel) and physical (magnetron sputtering) film deposition methods. These films were scrutinized by XRD, AFM, FESEM, EDX, XPS, Uv-Vis spectrophotometer, and VSM magnetometer. All the films have a powerful preferential c-axis orientation with a hexagonal polycrystalline structure. Comparatively, the stronger c-axis orientation and higher crystalline quality were observed for the chemically fabricated films than those physically derived. The chemically derived films had relatively higher roughness and it was decreased with increasing TM doping concentration. Compared to the ZnO, an increment in the crystallinity of chemically derived films was observed with an enhanced TM doping ratio, whereas a decrement in physically derived films was observed. The existence of Zn, Mn, Co, Fe, and O atoms and Zn2+, Co2+, Mn2+, and Fe2+ ions were determined. Optical analysis revealed that the transmittance of chemically derived ZnO:TM thin films was relatively higher than physically produced, and the optical band gap of the films produced by both techniques was in good agreement with each other except for the ZMO. Magnetic measurements showed a clear room temperature ferromagnetic behavior for the ZnO:Mn and ZnO:Fe films. In contrast, paramagnetic behavior was observed for the chemically and physically produced ZnO:Co films. Among all films, the highest ferromagnetic response was obtained for the ZnO:Fe films due to their high crystallinity and purity. These outcomes reflect the produced films have great potential to be promising materials for optoelectronic and spintronic applications. [ABSTRACT FROM AUTHOR]

Ti1-xHoxO2 (x= 0.0, 0.01, 0.02, 0.03) thin films are synthesized by a sol-gel method and deposited by a dip-coating technique on the glass substrates. The films’ crystal structures are examined by an X-ray diffraction technique, while the morphological properties are investigated by scanning electron microscopy and atomic force microscopy. UV-Vis and photoluminescence spectrophotometry are used to analyze the optical properties. Based on the X-ray diffraction patterns, all the films belong to the anatase phase. It is observed that the surface characteristics, such as the morphology, film thickness, and roughness change significantly with the holmium substitution. The optical investigations reveal that the transmittance, band gap energies, and luminescence properties can be adjusted by the holmium substitution. According to the current study, holmium substituted TiO2 thin films with improved optical properties may be a suitable candidate for applications that require a wide band gap and high optical transparency as well as luminescence properties.

Metal mesh transparent electrodes present a promising alternative to Indium-Tin Oxide (ITO) due to their adjustable period and favourable trade-off between transmittance and conductivity. In this work, a template-free, non-high temperature hybrid additive manufacturing approach of the polyacrylonitrile (PAN)/Cu core–shell structure high-resolution metal mesh flexible transparent electrode (FTE) is proposed. The electric field-driven (EFD) 3D printing method was employed to print ultra-fine lines with widths as low as 1 μm. The composite-plating process combining electroless plating and electroplating has solved the structural defects of single deposition process. The prepared FTE has an excellent conductivity down to 1 Ω/sq and 89% light transmission (at 550 nm). Its exceptional mechanical properties and environmental stability make it suitable for diverse working environments. Even after undergoing 2000 bends at a radius of 3 mm, the resistance change rate remains as low as 1.4%. The resistance exhibits an approximately 8% change rate in the acid–base environment experiments conducted over 72 h. The flexible touch screen prepared with this FTE exhibits excellent writing performance in both flat and curved working scenarios. Furthermore, the significant potential of this FTE in the field of optoelectronics is effectively demonstrated through its exceptional luminescent performance in electroluminescent devices.

Highlights: What are the main findings? The connection between cavity pressure, clamping force, and tie bar elongation is revealed and applied. The quality of the product is predicted based on the tie bar elongation, and the method is non-destructive, online, and highly efficient. What is the implication of the main finding? The NSGA III algorithm can solve the multi-objective optimization problem while making the final obtained Pareto solution as well as being uniformly distributed. LSR lenses with low residual stress and high transmittance can be produced using this method. This study aimed to improve the injection molding quality of LSR material lenses by optimizing the process parameters. To achieve this goal, we employed the population-based optimization algorithm NSGA-III, which can simultaneously optimize multiple objective functions and identify an equilibrium point among them, thereby reducing the time required to find the optimal process parameters. We utilized analysis software to simulate the injection molding process of LSR material lenses, with a specific focus on examining the relationship between tie bar elongation and the optimized process parameters. During the study, we intentionally varied key process parameters, including the melt temperature, holding pressure, and holding time, to analyze their impact on the residual stress of the final product. In order to investigate the intricate relationship between the tie bar yield, injection molding process parameters, and lens residual stress, we installed strain sensors on the tie bar to continuously monitor changes in clamping force throughout the injection molding process. The experimental results showed that both the tie bar force and mold cavity pressure exerted significant influence on residual stresses. By applying the NSGA-III algorithm for optimization, we successfully determined the optimal process parameters, which included a melt temperature of 34.92 °C, a holding pressure of 33.97 MPa, and a holding time of 9.96 s. In comparison to the initially recommended process parameters during the design phase, the optimized parameters led to reductions of 12.98% in clamping force and 47.14% in residual stress. Furthermore, the average transmittance of the actual product remained within the range of 95–98%. In summary, this approach not only enables the prediction of the lens's residual stress trends based on the tie bar elongation, but also leads to a substantial enhancement of lens quality, characterized by reduced residual stress and improved transmittance through the optimization of process parameters. This methodology can serve as a valuable guide for optimizing real-world injection molding processes. [ABSTRACT FROM AUTHOR]

Al-doped ZnO combines high transparency and conductivity with abundant and non-toxic elements; making it suitable for optoelectronic devices with large-scale applications. In order to check the quality of the material deposited over large areas, spectroscopic ellipsometry is a powerful technique that allows the determination of various optical and electrical parameters by applying suitable oscillator models. This technique is used here to obtain sheet resistance and visible transmittance data at several equidistant points of Al:ZnO thin films deposited using DC sputtering on 15 cm × 15 cm glass substrates. Independent measurements using other optical (spectrophotometry) and electrical (four point probe) methods show analogous visible transmittance but somewhat higher resistance values than those obtained with ellipsometry, which is explained by the contribution of grain-boundary scattering compared to in-grain properties provided using ellipsometry. However, the mapping of the data gives a similar spatial distribution to the different types of measurement; therefore, proving the capacity of ellipsometry to study with a single tool the uniformity of the optical and electrical characteristics of large areas. [ABSTRACT FROM AUTHOR]

Transparent wood-based materials show great potential for energy-efficient housing and construction due to their ideal optical performances, good mechanical strengths, and low thermal conductivity. However, it still remains a great challenge to fabricate UV-blocking and strong transparent wood-based materials with isotropic optical and mechanical properties, mainly due to the natural anisotropy of wood. Herein, we describe a facile strategy to prepare transparent wood-based biocomposites by integrating delignified wood particles with poly(vinyl alcohol) (PVA) impregnation prior to the compression treatment. This method enables biocomposites to show desirable isotropic optical and mechanical properties, easily tunable high wood component percentage and UV-blocking ability. The enhanced interfacial bonding between wood particles and PVA polymer, together with a similar refractive index, synergistically contributes to excellent performance. The resulting biocomposites (approximately thickness of 1 mm) possess isotropic optical and UV-blocking properties and have a maximum optical transmittance of 62%. The highest tensile strength and flexural strength can reach 86.8 and 158.8 MPa, respectively. Moreover, they display low thermal conductivity (0.38–0.42 W m−1 k−1) and suitable thermal stability. Therefore, this study provides a new method to optimize the properties of transparent wood-based materials for utilization in energy-saving building fields. [ABSTRACT FROM AUTHOR]

In this study, we investigated the potential of multilayer TCO structures, specifically those made up of Indium Tin Oxide (ITO) and Indium Zinc Oxide (IZO), for crystalline silicon heterojunction solar cells (SHJ). We used the radiofrequency (RF) magnetron sputtering method to deposit various thin-film structures under various deposition temperatures and evaluated their electrical, optical, and morphological properties. The objective was to obtain films with lower sheet resistances and higher transmittances than those of single-layer thin films. Our results show that the ITO/IZO/ITO/IZO/ITO multilayer film structure deposited at 200 °C achieves the best sheet resistance of 18.5 Ohm/sq and a high optical transmittance of over 90% at a 550 nm wavelength. This indicates that multilayer TCO structures have the potential to be more optically and electrically efficient, and that they can improve the performance of optoelectronic devices. Finally, a power conversion efficiency of 17.46% was obtained for a silicon heterojunction (SHJ) solar cell fabricated using an ITO/IZO/ITO/IZO/ITO multilayer film structure deposited at 200 °C as a front TCO. Our study provides valuable insights into the field of TCOs and offers a promising avenue for future research. [ABSTRACT FROM AUTHOR]

Ti1-xHoxO2 (x= 0.0, 0.01, 0.02, 0.03) thin films are synthesized by a sol-gel method and deposited by a dip-coating technique on the glass substrates. The films' crystal structures are examined by an X-ray diffraction technique, while the morphological properties are investigated by scanning electron microscopy and atomic force microscopy. UV-Vis and photoluminescence spectrophotometry are used to analyze the optical properties. Based on the X-ray diffraction patterns, all the films belong to the anatase phase. It is observed that the surface characteristics, such as the morphology, film thickness, and roughness change significantly with the holmium substitution. The optical investigations reveal that the transmittance, band gap energies, and luminescence properties can be adjusted by the holmium substitution. According to the current study, holmium substituted TiO2 thin films with improved optical properties may be a suitable candidate for applications that require a wide band gap and high optical transparency as well as luminescence properties. [ABSTRACT FROM AUTHOR]

Transparent conductors (TC) have been widely applied in a wide range of optoelectronic devices. Nevertheless, different transparent spectral bands are always needed for particular applications. In this work, indium tin oxide (ITO)-free TCs with tunable transparent bands based on the film structure of TiO2/Ag/AZO (Al-doped ZnO) were designed by the transfer matrix method and deposited by magnetron sputtering. The transparent spectra and figure-of-merit (FOM) were effectively adjusted by precisely controlling the Ag layer's thickness. The fabricated as-deposited samples exhibited an average optical transmittance larger than 88.3% (400–700 nm), a sheet resistance lower than 7.7 Ω.sq−1, a low surface roughness of about 1.4 nm, and mechanical stability upon 1000 bending cycles. Moreover, the samples were able to hold optical and electrical properties after annealing at 300 °C for 60 min, but failed at 400 °C even for 30 min. [ABSTRACT FROM AUTHOR]

Abstract Zinc oxide is one of the most researched semiconductors owing to the outstanding properties that make it useful in various industrial applications, such as solar cells and other optoelectronics. In this work, ZnO thin films were prepared in five different concentrations and doped with four nitrogen atoms from triethylene tetramine (TETA) to fabricate a ZnO for optoelectronic applications using an electrodeposition technique. The doped ZnO thin films were synthesized and deposited on ITO glass substrates. The deposited thin films were annealed at 400°Cfor 60min in a furnace under the same conditions. The thin films' optical, electrical, and surface morphological properties were characterized using UV–Vis Spectrophotometer, Four Point Probe (FPP), and Scanning Electron Microscope (SEM), respectively. The optical properties confirmed the film's suitability for various transparent device applications with a high optical transmittance of about 90% at the wavelength between 250 and 950 nm. The optical band gaps of 3.25 eV to 3.50 eV were obtained at ZnO concentrations from 0.2 M to 1.0 M. The SEM images depicted a polycrystalline nature of the films with irregular nanoparticle shapes across the substrates. Electrical results established the high conductivity of nitrogen-doped ZnO thin films, thereby making the thin films suitable as transparent conducting oxides for devices such as solar cells and optoelectronics.

There is an increased research interest in methods for transparent wood production and its use. Wood transparency could be achieved by its delignification followed by an impregnation process with polymers having proper optical properties. However, delignification processes are mainly time consuming and not environmentally friendly. The possibility of treating mahogany wood (Swietenia macrophylla King) with 20% hydrogen peroxide for 70, 100, 135, and 170 min at 103 °C is presented in this research. According to the treatment duration, lignin content decreased 40 to 94% relative to its initial content in the control samples, whilst the cell structure remained intact. Due to the light scatter effect, caused mainly by wood tissue structure, the direct optical transmittance of treated samples in the visible light spectrum (400 to 800 nm) was less than 40%. Simultaneously, the total optical transmittance of samples treated for 100 and 135 min reached values between 70 to 80% with high values of the haze at approximately 30 and 60%. Optical transmittance in the visible spectrum area of the samples treated for 170 min was from 45 to 80% and the haze from 25 to 45%.

Experiments of soiling effects on the performances of a PV panel have been performed using dust collected from two sites in the region of Agadir-Morocco. The optical transmittance of the front glass was found to depend on the nature and density of dust. The nature of dust was studied by means of scanning electron microscopy and energy dispersive x-ray spectroscopy. It was found that the granulometry of dust particles depends on the study area. For a dust density of around 20 g/m², the maximum power Pmax of the solar panel decreases drastically from 30 to 20 W for the (HP) site, and no more than 14 W for the (AD) site. The diversity of the behavior of the soiled panel was explained in terms of the size of the particles collected from each area. The transmission of light across the front glass of the PV panel is more affected when the sizes of particles are small. [ABSTRACT FROM AUTHOR]

In presented work we have reported that polyvinylpyrrolidone (PVP) is suitable organic solvent for mechanical exfoliation of crystalline graphite to graphene in aqueous solution through kitchen blender technique. Morphological, structural and optical, properties of graphene samples were characterized by scanning electron microscopy, Raman scattering and UV-Visible spectroscopy. Scanning electron microscopy demonstrates folded morphology of graphene flakes with ~4 nm thickness. Raman scattering was revealed the high-quality graphene with low levels of defects after the exfoliation process of graphite/PVP dispersions. The G band at ~1582 cm−1 on Raman spectra is related with stretching vibrations of carbon atoms. The broadening of the G band is not observed, that indicated on absence of the basal plane defects in the graphene structure, which can be introduced during exfoliation by the kitchen blender. The ratio of the intensity of 2D and G bands equal to 1.66 (I2D/IG>1) and the value of 2D band full width at half maximum is 79.88 cm–1, indicated a few-layer graphene (FLG) structure. The defects quantity identified by the intensity ratio of the D and G bands, ID/IG is 0.18, significantly lower than that reported for graphene oxide with basal plane defects (> 1) and for sonication dispersed graphene (~ 0.6). The graphene dispersions were characterized by UV–Vis spectroscopy, minimum transmittance observed at around 270 nm is attributed to the π→π* transitions of aromatic C–C bonds in graphene. The optical transmittance minimum and the overall high transmittance decreasing values observed between 270 and 800 nm strongly suggest the presence of two-dimensional material in the dispersion, thus confirming the successful exfoliation of graphite to graphene by blending. We demonstrate the simple and nontoxic method to product high-quality FLG sheets, free from defects, using a kitchen blender and eco-friendly polyvinylpyrrolidone as an organic exfoliant. [ABSTRACT FROM AUTHOR]

Zinc oxide is one of the most researched semiconductors owing to the outstanding properties that make it useful in various industrial applications, such as solar cells and other optoelectronics. In this work, ZnO thin films were prepared in five different concentrations and doped with four nitrogen atoms from triethylene tetramine (TETA) to fabricate a ZnO for optoelectronic applications using an electrodeposition technique. The doped ZnO thin films were synthesized and deposited on ITO glass substrates. The deposited thin films were annealed at 400°Cfor 60min in a furnace under the same conditions. The thin films' optical, electrical, and surface morphological properties were characterized using UV–Vis Spectrophotometer, Four Point Probe (FPP), and Scanning Electron Microscope (SEM), respectively. The optical properties confirmed the film's suitability for various transparent device applications with a high optical transmittance of about 90% at the wavelength between 250 and 950 nm. The optical band gaps of 3.25 eV to 3.50 eV were obtained at ZnO concentrations from 0.2 M to 1.0 M. The SEM images depicted a polycrystalline nature of the films with irregular nanoparticle shapes across the substrates. Electrical results established the high conductivity of nitrogen-doped ZnO thin films, thereby making the thin films suitable as transparent conducting oxides for devices such as solar cells and optoelectronics. [ABSTRACT FROM AUTHOR]

The use of titanium dioxide (also known as titania) in solar cells, biomaterials, and photocatalytic processes has generated an ever-increasing amount of interest. Titania is widely used in a variety of applications because it is nanocrystalline, chemically stable, has a high refractive index, is mechanically hard, and transmits visible light well. In this work, titania nanoparticles were formed via sol–gel synthesis, wherein the effect of varying pH values such as 3, 5, 7, 9, and 11 has been investigated on the synthesized nanoparticles by studying their structural characteristics and analyzing their optical transmittance. Structural analysis of the synthesized TiO2 shows formation of the brookite phase at all pH values under as-synthesized conditions. Moreover, structural parameters including crystallite size, dislocation density, and unit cell volume were also calculated. Cell volume was calculated at various pH levels and measured between 255.7 and 257.2 Å3. Optical analysis shows a transmission increase with a pH increase, and maximum transmission has been observed above 80% for a pH value of 11. [ABSTRACT FROM AUTHOR]

In this work, 0.8(K 2 O-Na 2 O-2Nb 2 O 5)−0.2((1- x)B 2 O 3 - x P 2 O 5) (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) glass-ceramics have been fabricated. The effects of P 2 O 5 on the microstructure and properties of the glass-ceramics were comprehensively studied. The addition of P 2 O 5 promotes the transition of the glass network structure from a negatively charged [B∅ 4 ]- tetrahedron to an electrically neutral [BP∅ 4 ] tetrahedron. With the increase of P 2 O 5 content, the formation of K 2 B 4 O 7 is inhibited, with major phase of Na 0.9 K 0.1 NbO 3 and minor phase of K 2 B 4 O 7. It is found that the band gap width of the glass-ceramics increases from 3.34 eV to 3.52 eV firstly and then decreases to 3.43 eV. The grain size of the glass-ceramics decreases from 150 nm to 50 nm. High optical transmittance (63%), large discharge energy density (4.58 J/cm3) and large energy storage efficiency (98%) have been simultaneously obtained for K 2 O-Na 2 O-Nb 2 O 5 -B 2 O 3 -P 2 O 5 glass-ceramics, which are potential for the applications of the transparent pulse capacitors. [ABSTRACT FROM AUTHOR]

Anion doping of tungsten trioxide by nitrogen is used to obtain electrochrome cathode materials, the spectral transmittance of which can be controlled by the doping level. A series of samples was synthesized by reactive magnetron sputtering of a metal tungsten target in a mixture of argon, nitrogen, and oxygen gases, the flow rate of the latter was varied at a constant pressure of the gas mixture. Warm-colored tungsten oxynitride films were prepared at higher doping levels with their morphology and elemental composition characterized using scanning electron microscopy, crystal structure described using X-ray diffraction and the valence state of constituents revealed with X-ray photoelectron spectroscopy techniques. Optical properties were measured by making use of transmission spectrophotometry and spectroscopic ellipsometry. These extensive experimental studies revealed an increase in absorption towards shorter wavelengths below the wavelength of 0.5 µm with an increase in the doping level. At the same time, it was found that with an increase in the doping level, partial reduction of the tungsten occurs, and the fraction of non-stoichiometric oxygen steadily increases to half of the total oxygen content. It is a common belief that the imperfection of the doped material facilitates the intercalation of the material by electrolyte ions.

Article Highlights 1. The solid-state reaction method is used to synthesize pressure-dependent delafossite CuCrO2 samples. 2. The solid-state reaction process and pressure effect may cause cooper and oxygen vacancies of the CuCrO2 samples. 3. In all samples below 100 K, there might be antiferromagnetic behavior and above 100 K paramagnetic behavior actively occur.

Transparent wood is promising for energy‐saving buildings, but its poor mechanical properties in transverse direction dramatically limit its applications. To resolve the problem, a novel processing technology is developed to fabricate laminated transparent woods. Various kinds of transparent woods are prepared by stacking partially impregnated woods in different styles and then compressing them. The wood template contents in these transparent woods are significantly increased by the partial impregnation compared with traditional full impregnation. The influence of lamination structures on the properties of the transparent woods is also evaluated. As the number of laminate layers increases from one to three, the optical transmittance reduces from ≈70% to 44%, respectively, while the haze increases from 32% to 66%. The isotropy of scatter light distribution could be achieved by controlling lamination structures for more uniformity in indoor illumination. The mechanical properties of the transparent woods are dramatically enhanced, and the highest tensile and flexural strength can reach 134.0 and 192.3 MPa, respectively. Additionally, the direction‐dependence of mechanical strength is reduced by cross‐laminating. The adjustable optical features, excellent mechanical strengths, and low thermal conductivity endow the prepared transparent woods a promising candidate for energy‐efficient buildings applications. [ABSTRACT FROM AUTHOR]

Silica glass composites, with biserial and hierarchical percolative network made of carbon nanofibers (CNFs), was fabricated using a layer-by-layer technique and spark plasma sintering to obtain high optical transmittance and electrical conductivity. Owing to the network, the critical volume fraction, V c , for the CNF percolation in the silica glass-matrix composite (0.5–0.7 vol%), when the electrical conductivity of the composite drastically increased with change from insulator (∼10−10 S/m) to conductor (∼10−1 S/m), is smaller than theoretical V c predicted for the three-dimensional random orientation of CNFs (2.6 vol% for the CNF aspect ratio of 30). The conductivity of the composite with above the V c of CNFs (∼10 S/m) is higher than that reported for the polymer-matrix composite (∼10−5–∼10−3 S/m). Furthermore, high optical transmittance was observed for the electrically conductive composite with V c of CNFs. [ABSTRACT FROM AUTHOR]

This study aimed to improve the injection molding quality of LSR material lenses by optimizing the process parameters. To achieve this goal, we employed the population-based optimization algorithm NSGA-III, which can simultaneously optimize multiple objective functions and identify an equilibrium point among them, thereby reducing the time required to find the optimal process parameters. We utilized analysis software to simulate the injection molding process of LSR material lenses, with a specific focus on examining the relationship between tie bar elongation and the optimized process parameters. During the study, we intentionally varied key process parameters, including the melt temperature, holding pressure, and holding time, to analyze their impact on the residual stress of the final product. In order to investigate the intricate relationship between the tie bar yield, injection molding process parameters, and lens residual stress, we installed strain sensors on the tie bar to continuously monitor changes in clamping force throughout the injection molding process. The experimental results showed that both the tie bar force and mold cavity pressure exerted significant influence on residual stresses. By applying the NSGA-III algorithm for optimization, we successfully determined the optimal process parameters, which included a melt temperature of 34.92 °C, a holding pressure of 33.97 MPa, and a holding time of 9.96 s. In comparison to the initially recommended process parameters during the design phase, the optimized parameters led to reductions of 12.98% in clamping force and 47.14% in residual stress. Furthermore, the average transmittance of the actual product remained within the range of 95–98%. In summary, this approach not only enables the prediction of the lens’s residual stress trends based on the tie bar elongation, but also leads to a substantial enhancement of lens quality, characterized by reduced residual stress and improved transmittance through the optimization of process parameters. This methodology can serve as a valuable guide for optimizing real-world injection molding processes.

Al-doped ZnO combines high transparency and conductivity with abundant and non-toxic elements; making it suitable for optoelectronic devices with large-scale applications. In order to check the quality of the material deposited over large areas, spectroscopic ellipsometry is a powerful technique that allows the determination of various optical and electrical parameters by applying suitable oscillator models. This technique is used here to obtain sheet resistance and visible transmittance data at several equidistant points of Al:ZnO thin films deposited using DC sputtering on 15 cm × 15 cm glass substrates. Independent measurements using other optical (spectrophotometry) and electrical (four point probe) methods show analogous visible transmittance but somewhat higher resistance values than those obtained with ellipsometry, which is explained by the contribution of grain-boundary scattering compared to in-grain properties provided using ellipsometry. However, the mapping of the data gives a similar spatial distribution to the different types of measurement; therefore, proving the capacity of ellipsometry to study with a single tool the uniformity of the optical and electrical characteristics of large areas.

This study focuses on the effect of the substrate temperature (TS) on the quality of VO2 thin films prepared by DC magnetron sputtering. TS was varied from 350 to 600 °C and the effects on the surface morphology, microstructure, optical and electrical properties of the films were investigated. The results show that TS below 500 °C favors the growth of V2O5 phase, whereas higher TS (≥500 °C) facilitates the formation of the VO2 phase. Optical characterization of the as-prepared VO2 films displayed a reduced optical transmittance ( T ˜ ) across the near-infrared region (NIR), reduced phase transition temperature (Tt), and broadened hysteresis width (ΔH) through the phase transition region. In addition, a decline of the luminous modulation (Δ T ˜ lum) and solar modulation ( Δ T ˜ sol ) efficiencies of the as-prepared films have been determined. Furthermore, compared with the high-quality films reported previously, the electrical conductivity (σ) as a function of temperature (T) reveals reduced conductivity contrast (Δσ) between the insulating and metallic phases of the VO2 films, which was of the order of 2. These outcomes indicated the presence of defects and unrelaxed lattice strain in the films. Further, the comparison of present results with those in the literature from similar works show that the preparation of high-quality films at TS lower than 650 °C presents significant challenges. [ABSTRACT FROM AUTHOR]

There is an increased research interest in methods for transparent wood production and its use. Wood transparency could be achieved by its delignification followed by an impregnation process with polymers having proper optical properties. However, delignification processes are mainly time consuming and not environmentally friendly. The possibility of treating mahogany wood (Swietenia macrophylla King) with 20% hydrogen peroxide for 70, 100, 135, and 170 min at 103 °C is presented in this research. According to the treatment duration, lignin content decreased 40 to 94% relative to its initial content in the control samples, whilst the cell structure remained intact. Due to the light scatter effect, caused mainly by wood tissue structure, the direct optical transmittance of treated samples in the visible light spectrum (400 to 800 nm) was less than 40%. Simultaneously, the total optical transmittance of samples treated for 100 and 135 min reached values between 70 to 80% with high values of the haze at approximately 30 and 60%. Optical transmittance in the visible spectrum area of the samples treated for 170 min was from 45 to 80% and the haze from 25 to 45%. [ABSTRACT FROM AUTHOR]

Low-emissivity (low-e) glass has garnered considerable attention for implementation in energy-saving windows, which can effectively decrease the energy consumption of buildings. However, the traditional vacuum-coating technology of low-e films greatly enhances the cost of energy-saving windows, and the influence of the vacuum-coating parameters on the optical characteristics of low-e films necessitates a complex optimization process. Herein, we prepared Ag NWs with controllable diameters using the polyol method, and the alignment of the Ag NW film coating on glass substrates was regulated by the shear force of the liquid flow generated through magnetic stirring. After optimization, the low-εMIR windows based on aligned Ag NW (60 nm) coatings showed an optical transmittance of 84.4% and a low εMIR of 0.3, which were superior to those of commercial low-εMIR glass (T: 65.6%; εMIR: 0.4). The simplicity and low cost of aligned Ag NW coatings for low-e glass open up a new avenue for reducing energy consumption in existing windows. [ABSTRACT FROM AUTHOR]

Parylene C (PC) films have been widely used in many fields, such as metal anti-corrosion, electronic packaging, etc. However, the relatively poor mechanical properties and the deteriorated water barrier performance due to the easy fracture under external stress have restricted their application. It is a relatively simple and good method to maintain the water vapor barrier and enhance the mechanical properties of PC film by covering a flexible coating on its surface. In this work, a new polyurethane acrylate (PUA) coating was prepared and coated on the PC film by ultraviolet curing technology to form the PC/PUA composite film. The results showed that the PUA coatings could improve the water vapor barrier and mechanical properties of the PC film simultaneously. The water vapor transmittance rate was reduced from 1.1791 g·(m−2·day−1) of the original PC film to 0.5636 g·(m−2·day−1) of the PC/PUA composite film. The elongation at break and the impact energy were increased to 48.36% and 41.67%, respectively, which would widen the application of PC films in the fields of flexible electronics or smart wear.

Transparent conductors (TC) have been widely applied in a wide range of optoelectronic devices. Nevertheless, different transparent spectral bands are always needed for particular applications. In this work, indium tin oxide (ITO)-free TCs with tunable transparent bands based on the film structure of TiO2/Ag/AZO (Al-doped ZnO) were designed by the transfer matrix method and deposited by magnetron sputtering. The transparent spectra and figure-of-merit (FOM) were effectively adjusted by precisely controlling the Ag layer’s thickness. The fabricated as-deposited samples exhibited an average optical transmittance larger than 88.3% (400–700 nm), a sheet resistance lower than 7.7 Ω.sq−1, a low surface roughness of about 1.4 nm, and mechanical stability upon 1000 bending cycles. Moreover, the samples were able to hold optical and electrical properties after annealing at 300 °C for 60 min, but failed at 400 °C even for 30 min.

The accurate estimation of skin and skull optical properties over a wide wavelength range of laser radiation has great importance in optogenetics and other related applications. In the present work, using the Kubelka–Munk model, finite-element solution of the diffusion equation, inverse adding-doubling (IAD), and Monte-Carlo simulation, we estimated the refractive index, absorption and scattering coefficients, penetration depth, and the optical fluence distribution in rabbit head tissues ex vivo, after dividing the heads into three types of tissues with an average thickness of skin of 1.1 mm, skull of 1 mm, and brain of 3 mm. The total diffuse reflectance and transmittance were measured using a single integrating sphere optical setup for laser radiation of 532, 660, 785, and 980 nm. The calculated optical properties were then applied to the diffusion equation to compute the optical fluence rate distribution at the boundary of the samples using the finite element method. Monte-Carlo simulation was implemented for estimating the optical fluence distribution through a model containing the three tissue layers. The scattering coefficient decreased at longer wavelengths, leading to an increase in optical fluence inside the tissue samples, indicating a higher penetration depth, especially at 980 nm. In general, the obtained results show good agreement with relevant literature. [ABSTRACT FROM AUTHOR]

The revolutionary transformation of opaque wood into a transparent material, with combination of high optical transmittance and high haze, has gained widespread interest in the realms of advanced functional materials. However, the thickness of transparent wood composite (TWC) is limited to a few millimeters which restricts potential use. In this study, TWC were prepared using transverse sections of poplar (Populus deltoides) in thickness ranging from 1.5 to 15 mm by lignin modification bleaching followed by epoxy resin infiltration. The effects of bleaching duration as well as sample thickness on the optical properties of TWC were investigated. TWC was characterized using scanning electron microscopy and FTIR spectroscopy. The optical properties of TWC were measured using UV-VIS-NIR spectroscopy. The results indicated that light transmittance depended on severity of bleaching, lignin content and sample thickness. [ABSTRACT FROM AUTHOR]

The optical degradation of encapsulants from ultraviolet (UV) radiation has historically resulted in a significant loss in performance throughout the life of a photovoltaic (PV) module. International Electrotechnical Commission (IEC) test methods have recently been developed to screen for PV encapsulants prone to loss in optical performance. The present study was performed to benchmark polymeric packaging materials relative to IEC 62788‐1‐4 (covering the measurement of optical transmittance) and IEC 62788‐1‐7 (on the durability of transmittance), provide feedback toward improvement of the methods, and develop insight regarding optical degradation. Contemporary materials were examined, including poly(ethylene‐co‐vinyl acetate) (EVA), thermoplastic polyolefin (TPO), polyolefin elastomer (POE), and polyvinyl butyral (PVB) encapsulants; a poly(ethene‐co‐tetrafluoroethene)/poly(ethylene terephthalate) (ETFE/PET) transparent backsheet; and a polystyrene (PS) working reference material. The use of silica‐, specialty‐, and rolled‐glass was also compared in laminated coupons. Specimen size was separately examined from 2.5 to 12.5 cm. Weathering was performed with a xenon source, using IEC TS 62788‐7‐2 methods A2, A3, A4, and A5 (chamber temperature of 55°C, 65°C, 75°C, or 85°C), respectively. Characterizations were made using a UV–visible–near‐infrared (UV–VIS–NIR) spectrophotometer (transmittance and reflectance, with and without an integrating sphere), a UV–VIS fluorescence spectrophotometer, a camera, and an optical microscope. Performance was analyzed, including solar weighted transmittance, yellowness index, UV cut‐off wavelength, and haze (scattering). Separate Arrhenius analyses were performed to assess retention of transmittance and changes in yellowness index. The activation energy for both characteristics was found to range from 15–80 kJ·mol−1, with an average of 48 kJ·mol−1, similar to the average of 45 kJ·mol−1 identified in the previous international PV Quality Assurance Task Force (PVQAT) Task Group 5 (TG5) study of more traditional encapsulants. The separate degradation modes of discoloration and scattering were distinguished in the encapsulants using a comprehensive spectral characterization. Based on these results, the IEC 62788‐1‐7 pass/fail criteria of 5% change in transmittance was confirmed to identify a known bad encapsulant. [ABSTRACT FROM AUTHOR]

Summary: The concept of solar energy absorption or photothermal energy conversion of nanofluids as a working fluid is a promising idea utilized in various applications. However, the lack of diversity of the base agents restricts the usage of solar thermal conversion systems in extreme conditions such as extreme cold or hot environments. The ionic liquids were used as a base agent to broaden the applicable conditions of the solar thermal conversion system considering the remarkable favorable characteristics of ionic liquids. In this study, key factors of solar energy conversion characteristics and performance of the various 1‐hexyl‐3‐methylimidazolium cation‐based ionic liquids and MWCNT nanoparticle‐enhanced ionic liquids (NEILs) were experimentally investigated. This study dives deep into the optical properties of the ionic liquids compared to the previous studies in the open literature. In the manufacturing process, MWCNT nanoparticles are dispersed in various ionic liquids at 20 kHz and coated with the Gum‐Arabic. It was found that 1‐hexyl‐3‐methylimidazolium cation‐based pure room temperature ionic liquids were almost transparent in the visible light spectrum with nearly 0% absorbance; however, adding a small amount of additional MWCNT nanoparticles sharply increased the absorbance rate up to nearly 100% (F ≈ 1). Besides, the transmittance of the MWCNT NEILs decreased with the increasing concentration. Under the simulated solar light, the final temperature of the samples increased with the increasing concentration of MWCNT NEIL. Moreover, the maximum photothermal energy conversion efficiency (ηPEC) of each MWCNT NEILs was 38.0%, 40.9%, 40.2%, and 39.8% in the case of [HMIM][Tf2N], [HMIM][TfO], [HMIM][Pf6], and [C12MIM][Tf2N], respectively, at a concentration and operating time of 1 wt% and 7200 seconds. In addition, SER value sharply increased with the increasing nanoparticle concentration, and it almost doubled compared to the base agents. Furthermore, the nanoparticle concentration affects the solar energy absorption capability of ionic liquids more than anions in their chemical structure. This study can deliver the necessary data to design a direct absorption solar thermal collector using ionic liquids, which are new green designer working fluids. [ABSTRACT FROM AUTHOR]