Showing papers on "Transmittance published in 2016"
TL;DR: In this article, a simple, scalable method is proposed to fabricate transparent conductive thin films using delaminated Ti3C2 MXene flakes by spray coating, which can be used as transparent conductors in electronic, electrochromic, and sensor applications.
Abstract: MXenes, a new class of 2D transition metal carbides and carbonitrides, show great promise in supercapacitors, Li-ion batteries, fuel cells, and sensor applications. A unique combination of their metallic conductivity, hydrophilic surface, and excellent mechanical properties renders them attractive for transparent conductive electrode application. Here, a simple, scalable method is proposed to fabricate transparent conductive thin films using delaminated Ti3C2 MXene flakes by spray coating. Homogenous films, 5–70 nm thick, are produced at ambient conditions over a large area as shown by scanning electron microscopy and atomic force microscopy. The sheet resistances (Rs) range from 0.5 to 8 kΩ sq−1 at 40% to 90% transmittance, respectively, which corresponds to figures of merit (the ratio of electronic to optical conductivities, σDC/σopt) around 0.5–0.7. Flexible, transparent, and conductive films are also produced and exhibit stable Rs values at up to 5 mm bend radii. Furthermore, the films' optoelectronic properties are tuned by chemical or electrochemical intercalation of cations. The films show reversible changes of transmittance in the UV–visible region during electrochemical intercalation/deintercalation of tetramethylammonium hydroxide. This work shows the potential of MXenes to be used as transparent conductors in electronic, electrochromic, and sensor applications.
529 citations
TL;DR: In this article, it is shown that to achieve high performance ultraviolet WGPs a material with large absolute value of the complex permittivity and extinction coefficient at the wavelength of interest has to be utilized.
Abstract: Wire grid polarizers (WGPs), periodic nano-optical metasurfaces, are convenient polarizing elements for many optical applications. However, they are still inadequate in the deep ultraviolet spectral range. It is shown that to achieve high performance ultraviolet WGPs a material with large absolute value of the complex permittivity and extinction coefficient at the wavelength of interest has to be utilized. This requirement is compared to refractive index models considering intraband and interband absorption processes. It is elucidated why the extinction ratio of metallic WGPs intrinsically humble in the deep ultraviolet, whereas wide bandgap semiconductors are superior material candidates in this spectral range. To demonstrate this, the design, fabrication, and optical characterization of a titanium dioxide WGP are presented. At a wavelength of 193 nm an unprecedented extinction ratio of 384 and a transmittance of 10% is achieved.
332 citations
TL;DR: In this article, the out-of-plane fabrication capability of the recently developed method of electrohydrodynamic nanoDrip printing to pattern gold and silver nanogrids with line widths from 80 to 500 nm is demonstrated.
Abstract: The transparent conducting electrode is an essential component in many contemporary and future devices, ranging from displays to solar cells. Fabricating transparent electrodes requires a balancing act between sufficient electrical conductivity and high light transmittance, both affected by the involved materials, fabrication methodology, and design. While metal films possess the highest conductivity at room temperature, a decent optical transmittance can only be achieved with ultrathin films. Structuring the metal into optically invisible nanowires has been shown to be promising to complement or even substitute transparent conductive oxides as dominant transparent electrode material. Here the out-of-plane fabrication capability of the recently developed method of electrohydrodynamic NanoDrip printing to pattern gold and silver nanogrids with line widths from 80 to 500 nm is demonstrated. This fully additive process enables the printing of high aspect ratio nanowalls and by that significantly improves the electrical performance, while maintaining the optical transmittance at a high level. Metal grid transparent electrodes optimized for low sheet resistances (8 Ω sq−1 at a relative transmittance of 94%) as well as optimized for high transmittance (97% at a sheet resistance of 20 Ω sq−1) are reported, which can be tailored on demand for the use in various applications.
206 citations
TL;DR: In this article, self-consistent optical constants of SiO2 and Ta2O5 films were obtained for their relevance in optical coatings from the near ultraviolet to the near infrared spectral ranges, where they are transparent and have a high refractive index contrast.
Abstract: Self-consistent optical constants of SiO2 and Ta2O5 films have been obtained for their relevance in optical coatings from the near ultraviolet to the near infrared spectral ranges, where they are transparent and have a high refractive index contrast Particular attention has been paid to wavelengths close to and shorter than each material cutoff The far and the extreme ultraviolet ranges are also covered here, where few (SiO2) or almost no optical constant data (Ta2O5) were available for films of these materials This work is aimed at filling the lack of self-consistent sets of optical constants with data in a very broad spectral range, which can be widely applied in multilayer design for the everyday use of these materials in multilayer coatings Oxide films were deposited by reactive electron-beam evaporation onto various sorts of substrates at 573 K Transmittance, reflectance, and ellipsometry measurements were performed for each oxide in spectral intervals jointly covering from the extreme ultraviolet to the near infrared; starting with these measurements along with extrapolations, an iterative and double Kramers-Kronig analysis procedure has been followed to obtain a self-consistent set of optical constants per material With the final data sets, we have satisfactorily reproduced the experimental measurements Global data self-consistency was successfully evaluated through sum rules, and local consistency at each photon energy range was also evaluated through a novel sum-rule method which involves window functions
175 citations
TL;DR: This work presents a novel way to manipulate VO2 photonic structures to modulate light transmission as a function of wavelength at different temperatures.
Abstract: Two-dimensional (2D) photonic structures, widely used for generating photonic band gaps (PBG) in a variety of materials, are for the first time integrated with the temperature-dependent phase change of vanadium dioxide (VO2). VO2 possesses thermochromic properties, whose potential remains unrealized due to an undesirable yellow-brown color. Here, a SiO2/VO2 core/shell 2D photonic crystal is demonstrated to exhibit static visible light tunability and dynamic near-infrared (NIR) modulation. Three-dimensional (3D) finite difference time domain (FDTD) simulations predict that the transmittance can be tuned across the visible spectrum, while maintaining good solar regulation efficiency (ΔTsol = 11.0%) and high solar transmittance (Tlum = 49.6%). Experiments show that the color changes of VO2 films are accompanied by NIR modulation. This work presents a novel way to manipulate VO2 photonic structures to modulate light transmission as a function of wavelength at different temperatures.
145 citations
TL;DR: It is believed that this multi-layer graphene/PET structure, which exhibits high-performance microwave absorption and shielding, has great potential for applications in transparent EMI shielding devices, especially if EMI absorption is required.
Abstract: A high-performance electromagnetic interference (EMI) shielding structure based on pure graphene (without doping) consists of several graphene sheets separated by transparent polyethylene terephthalate (PET) films. We report the theoretical and experimental design, and characterization of the multi-layer graphene/PET structures. With a total graphene thickness of only 4 nm, the graphene/PET sample demonstrated an average shielding effectiveness of 19.14 dB at 18–26.5 GHz, with a maximum microwave absorbance of 95.82% at 25.7 GHz, while maintaining a normalized visible transmittance of 80.5%. For the multi-layer graphene/PET samples, the contribution of absorption to the total shielding exceeds 96%, indicating that absorption is the dominant shielding mechanism, instead of reflection. The microwave absorbance of the multi-layer graphene/PET structure increases rapidly from the mono- to the four-layer structures, and then more gradually as the number of layers continues to increase when the thickness of PET is 1 mm. In addition, the microwave absorbance can be improved two-fold by increasing the separation between graphene layers. We believe that this multi-layer graphene/PET structure, which exhibits high-performance microwave absorption and shielding, has great potential for applications in transparent EMI shielding devices, especially if EMI absorption is required.
121 citations
TL;DR: This study proposed a simple methodology for large-scale production of high-transparency, low-haze CNP comprising both long cellulose nanofibrils (CNFs) and short cellulose Nanocrystals (CNCs) by varying the CNC/CNF ratio in the hybrid CNP, which could tailor its total transmittance, directTransmittance and diffuse transmittances.
Abstract: Paper is an excellent candidate to replace plastics as a substrate for flexible electronics due to its low cost, renewability and flexibility Cellulose nanopaper (CNP), a new type of paper made of nanosized cellulose fibers, is a promising substrate material for transparent and flexible electrodes due to its potentially high transparency and high mechanical strength Although CNP substrates can achieve high transparency, they are still characterized by high diffuse transmittance and small direct transmittance, resulting in high optical haze of the substrates In this study, we proposed a simple methodology for large-scale production of high-transparency, low-haze CNP comprising both long cellulose nanofibrils (CNFs) and short cellulose nanocrystals (CNCs) By varying the CNC/CNF ratio in the hybrid CNP, we could tailor its total transmittance, direct transmittance and diffuse transmittance By increasing the CNC content, the optical haze of the hybrid CNP could be decreased and its transparency could be increased The direct transmittance and optical haze of the CNP were 751% and 100%, respectively, greatly improved from the values of previously reported CNP (311% and 620%, respectively) Transparent, flexible electrodes were fabricated by coating the hybrid CNP with silver nanowires (AgNWs) The electrodes showed a low sheet resistance (minimum 12 Ω sq(-1)) and a high total transmittance (maximum of 825%) The electrodes were used to make a light emitting diode (LED) assembly to demonstrate their potential use in flexible displays
121 citations
TL;DR: A negative value for the nonlinear refraction in graphene is experimentally observed and unambiguously verified by performing a theoretical analysis arising from the conductivity of the graphene monolayer.
Abstract: A negative value for the nonlinear refraction in graphene is experimentally observed and unambiguously verified by performing a theoretical analysis arising from the conductivity of the graphene monolayer. The nonlinear optical properties of multi-layer graphene are experimentally studied by employing the Z-scan technique. The measurements are carried out at 1150, 1550, 1900 and 2400 nm with a 100-femtosecond laser source. Under laser illumination the multi-layer graphene exhibits a transmittance increase due to saturable absorption, followed by optical limiting due to two-photon absorption. The saturation irradiance Isat and the two-photon absorption coefficient β are measured in the operating wavelength range. Furthermore, an irradiance-dependent nonlinear refraction is observed and discriminated from the conventional nonlinear refraction coefficient n2, which is not irradiance dependent. The values obtained for the irradiance-dependent nonlinear refraction are in the order of ∼10−9 cm2W−1, approximately 8 orders of magnitude larger than any bulk dielectrics.
110 citations
TL;DR: In this article, a flexible and transparent triboelectric nanogenerator (FT-TENG) was developed that has a well-ordered nest-like porous polydimethylsiloxane (NP-PDMS) film and graphene transparent electrodes.
Abstract: A flexible and transparent triboelectric nanogenerator (FT-TENG) has great potential for application in self-powered biosensor systems, electronic skin and wearable electronic devices. However, improving the output performance with little damage to its optical properties is challenging. Herein, we have developed an FT-TENG that has a well-ordered nest-like porous polydimethylsiloxane (NP-PDMS) film and graphene transparent electrodes. The NP-PDMS film with ordered pores is fabricated by hydrochloric acid etching of 500 nm sized ZnO spheres made of aggregated nanoparticles, having a light transmittance of 81.8% and a water contact angle of 118.62°. The FT-TENG based on the NP-PDMS film with a porosity of 12%, gives a maximum output of 271 V and 7.8 μA, which are respectively, 3.7 and 2.1-fold of those of a TENG with a flat PDMS film. The peak output power reaches 0.39 mW with a load resistance of 9.01 MΩ. The dielectric constant and effective thickness of the NP-PDMS film and the capacitance and charge transfer of the FT-TENG are systematically investigated. This work provides a novel and effective method to enhance the performance of FT-TENGs with little damage to their optical properties.
108 citations
TL;DR: In this paper, the authors describe a versatile optical microscope setup to carry out differential reflectance and transmittance spectroscopy in 2D materials with a lateral resolution of ~1 micron in the visible and near-infrared part of the spectrum.
Abstract: Optical spectroscopy techniques such as differential reflectance and transmittance have proven to be very powerful techniques to study 2D materials. However, a thorough description of the experimental setups needed to carry out these measurements is lacking in the literature. We describe a versatile optical microscope setup to carry out differential reflectance and transmittance spectroscopy in 2D materials with a lateral resolution of ~1 micron in the visible and near-infrared part of the spectrum. We demonstrate the potential of the presented setup to determine the number of layers of 2D materials and to characterize their fundamental optical properties such as excitonic resonances. We illustrate its performance by studying mechanically exfoliated and chemical vapor-deposited transition metal dichalcogenide samples.
102 citations
TL;DR: This work demonstrates a transparent conductor with optical loss lower than that of single-layer graphene, and transmission higher than 98% over the visible wavelength range, by an optimized antireflection design consisting in applying Al-doped ZnO and TiO2 layers with precise thicknesses to a highly conductive Ag ultrathin film.
Abstract: Transparent conductors are essential in many optoelectronic devices, such as displays, smart windows, light-emitting diodes and solar cells. Here we demonstrate a transparent conductor with optical loss of ∼1.6%, that is, even lower than that of single-layer graphene (2.3%), and transmission higher than 98% over the visible wavelength range. This was possible by an optimized antireflection design consisting in applying Al-doped ZnO and TiO2 layers with precise thicknesses to a highly conductive Ag ultrathin film. The proposed multilayer structure also possesses a low electrical resistance (5.75 Ω sq−1), a figure of merit four times larger than that of indium tin oxide, the most widely used transparent conductor today, and, contrary to it, is mechanically flexible and room temperature deposited. To assess the application potentials, transparent shielding of radiofrequency and microwave interference signals with ∼30 dB attenuation up to 18 GHz was achieved. Transparent conductors are fundamental for optoelectronics. Using the transfer matrix method to optimise a multistructure of anti-reflection coatings containing an ultrathin metal film, Maniyaraet al. achieve the highest transmittance of an antireflection transparent conductor combined with low resistance.
TL;DR: In this paper, the authors proposed a new substrate called plastic-paper, which has a high optical transmittance and high optical haze in a broadband wavelength, and demonstrated an improvement in efficiency for both organic light emitting diodes (OLED) and typical GaAs solar cells.
Abstract: Optoelectronic devices are ubiquitously built on substrates. To increase the efficiencies of light coupling into and out of optoelectronic devices, such as thin film solar cells and flexible lighting, a substrate with high transmittance and high haze is desired. Unfortunately, optical transmittance and optical haze are usually contrasting to each other in common substrates: plastic is highly transparent but with a low optical haze, whereas paper has a high optical haze but a low total transmittance. Herein, we combine these two materials through a simple templated infiltration approach to achieve a new type of substrate, plastic–paper, which has a high optical transmittance (>85%) and high transmittance haze (>90%) in a broadband wavelength. The plastic–paper has an ultra-flat surface, is mechanically flexible, durable in different solvents and compatible with standard processing in semiconductors, which are shown by organic light emitting diodes (OLED) fabricated directly onto the plastic–paper substrate. Plastic–paper leads to improved light coupling into and out of optoelectronic devices and demonstrates an improvement in efficiency for both OLED and typical GaAs solar cells. The fabrication method is also fully scalable with roll-to-roll production. The newly developed low-cost, high-performance transparent and hazy substrate is attractive for a range of optoelectronic devices.
TL;DR: In this article, the authors demonstrate theoretically and prove experimentally that microwave absorptance of graphene can be enhanced considerably by depositing graphene on a dielectric substrate, and obtain 80% and 65% absorbance at 30 GHz and 1'THz, respectively.
Abstract: Fresnel equations predict that an ultrathin free standing conductive film, thousands times thinner than skin depth, is capable to absorb up to 50% of incident electromagnetic radiations. In the microwave range, the same holds true for a free standing graphene sheet. We demonstrate theoretically and prove experimentally that microwave absorptance of graphene can be enhanced considerably by depositing graphene on a dielectric substrate. On the experimental side, we obtain 80% and 65% absorptance at 30 GHz and 1 THz, respectively. Theory predicts that higher absorptance can be achieved with a suitable choice of the dielectric permittivity and the thickness of the substrate. Absorption can also be maximized by choosing the optimum incidence angle for s-polarized waves in free space or by working in the vicinity of the cut-off frequency of the transverse electric mode in waveguide configuration. The polarization sensitivity of the transmittance and reflectance of graphene layers can be used to tune the polariz...
TL;DR: In this paper, the state-of-the-art reviews on the synthesis, optoelectronic properties, applications and challenges of these nanostructured materials for fabricating transparent conducting films (TCFs) are provided.
Abstract: Commercial indium tin oxide (ITO) has several drawbacks for optoelectronic applications such as high cost due to indium scarcity and high temperature deposition process, mechanical brittleness, and the complicated manufacturing process where lithographic patterning is needed. Its brittle nature can lead to cracking when used in applications involving bending, such as touch screens and flexible displays. Therefore, novel transparent conducting films (TCFs) based on nanomaterials with a similar or improved optoelectronic performance and good mechanical flexibility are needed for next-generation stretchable and wearable devices. Carbon nanotubes, graphene and metallic nanowires have been explored as alternatives, and they show great promise for a wide variety of optoelectronic applications. In particular, graphene films have a higher transmittance over a wider wavelength range than single-walled carbon nanotube (SWNT) films. For equivalent sheet resistance, the graphene films exhibit optical transmittance comparable to that of ITO in visible wavelength, but far superior transmittance in infrared spectral region. This article provides the state-of-the-art reviews on the synthesis, optoelectronic properties, applications and challenges of these nanostructured materials for fabricating TCFs.
TL;DR: In this paper, a hexagonal cross-section ZnO nanorods in the wurtzite phase were grown onto a TiO2 buffer thin film of anatase.
Abstract: The optical band gap energy of ZnO nanorods was estimated by different methods found in literature. These nanorods were deposited onto TiO2 covered borosilicate glass substrates by aerosol assisted chemical vapor deposition. Characterization techniques were employed to reveal the crystalline structure, surface morphology and optical properties of the sample. The analysis proved that hexagonal cross-section ZnO nanorods in the wurtzite phase were grown onto a TiO2 buffer thin film of anatase. Variations in the components of transmittance and reflectance were associated with the development of a rough surface. Such fluctuations were correlated with the equations employed to estimate the optical band gap. The different methods indicated band gap values of 3.17 to 3.24 eV. The energy band gap of 3.24 eV agrees to that reported in the literature for ZnO nanorods. Fluorescence spectroscopy confirmed the accuracy of the mathematical predictions since an emission at 380 nm (3.26 eV) was seen.
TL;DR: In this article, a completely continuous and smooth copper ultrathin film is fabricated by a simple room-temperature reactive sputtering process involving controlled nitrogen doping, which exhibits an optimized average transmittance of 84% over a spectral range of 380 −1000 nm and a sheet resistance lower than 20 Ω sq−1, with no electrical degradation after exposure to strong oxidation conditions for 760 h.
Abstract: Copper has attracted significant interests as an abundant and low-cost alternative material for flexible transparent conducting electrodes (FTCEs). However, Cu-based FTCEs still present unsolved technical issues, such as their inferior light transmittance and oxidation durability compared to conventional indium tin oxide (ITO) and silver metal electrodes. This study reports a novel technique for fabricating highly efficient FTCEs composed of a copper ultrathin film sandwiched between zinc oxides, with enhanced transparency and antioxidation performances. A completely continuous and smooth copper ultrathin film is fabricated by a simple room-temperature reactive sputtering process involving controlled nitrogen doping (<1%) due to a dramatic improvement in the wettability of copper on zinc oxide surfaces. The electrode based on the nitrogen-doped copper film exhibits an optimized average transmittance of 84% over a spectral range of 380 −1000 nm and a sheet resistance lower than 20 Ω sq−1, with no electrical degradation after exposure to strong oxidation conditions for 760 h. Remarkably, a flexible organic solar cell based on the present Cu-based FTCE achieves a power conversion efficiency of 7.1%, clearly exceeding that (6.6%) of solar cells utilizing the conventional ITO film, and this excellent performance is maintained even in almost completely bent configurations.
TL;DR: Application of the reference standards in nonlinear transmittance measurements is discussed and significant improvement of the accuracy is achieved by means of rigorous evaluation of the quadratic dependence of the fluorescence signal on the incident photon flux in the whole wavelength range.
Abstract: Degenerate two-photon absorption (2PA) of a series of organic fluorophores is measured using femtosecond fluorescence excitation method in the wavelength range, λ2PA = 680-1050 nm, and ~100 MHz pulse repetition rate. The function of relative 2PA spectral shape is obtained with estimated accuracy 5%, and the absolute 2PA cross section is measured at selected wavelengths with the accuracy 8%. Significant improvement of the accuracy is achieved by means of rigorous evaluation of the quadratic dependence of the fluorescence signal on the incident photon flux in the whole wavelength range, by comparing results obtained from two independent experiments, as well as due to meticulous evaluation of critical experimental parameters, including the excitation spatial- and temporal pulse shape, laser power and sample geometry. Application of the reference standards in nonlinear transmittance measurements is discussed.
TL;DR: In this article, a light shutter consisting of a dye-doped cholesteric liquid crystal (ChLC) layer and a polymer-dispersed liquid crystal film for simultaneous control of haze and transmittance is demonstrated.
TL;DR: Porous thermochromic pure and tungsten (W)-doped vanadium dioxide (VO2) films have been prepared on silica substrates by spin coating via a sol-gel process and annealing in ammonia (NH3) atmosphere.
Abstract: Porous thermochromic pure and tungsten (W)-doped vanadium dioxide (VO2) films have been prepared on silica substrates by spin coating via a sol–gel process and annealing in ammonia (NH3) atmosphere. NH3 with weak reducing capacity can prevent V4+ from further oxidization and contribute to the formation of porous structure. These films exhibit enhanced visible transparency and switching property at near-infrared wavelengths across the metal–insulator transition (MIT). The transmittance change in the VO2 film annealed at 2.0 × 103Pa is as high as 52.9 % at λ = 2000 nm, and its solar modulation efficiency reaches up to 9.4 %. W-doping shifts the MIT temperature of the VO2 films from 55 to 28 °C, while the films remain the excellent modulating ability in near-infrared region, and the decreasing efficiency of V0.99W0.01O2 film can achieve to 20 K/at.%, which will greatly favor the practical application of VO2-based smart windows. Transmittance spectra for pure VO2 film in the range of 250–2500 nm and the recorded transmittance–temperature hysteresis loop in the range of 20–90 °C of the W-doping VO2 films after annealing at 500 °C for 30 min (middle inset).
TL;DR: In this article, a double layer of WO3/VO2/WO3 sandwich structure was deliberately designed and deposited by a reactive magnetron sputtering technique, which not only functions as an antireflection (AR) layer to enhance the luminous transmittance (Tlum) of VO2, but also performs as a good protective layer for thermochromic VO2.
Abstract: A novel thermochromic WO3/VO2/WO3 sandwich structure was deliberately designed and deposited by a reactive magnetron sputtering technique The double layer of WO3 not only functions as an antireflection (AR) layer to enhance the luminous transmittance (Tlum) of VO2, but also performs as a good protective layer for thermochromic VO2 Basically, the bottom WO3 layer functions as a buffer beneficial for the formation of the intermediate VO2 layer and serves as an AR layer while the intermediate VO2 layer with primary monoclinic phase acts as an automatic solar/heat control for energy saving The top WO3 layer acts as another AR layer, and provides protection in a complex environment An obvious increase in Tlum by 49% (from 372% to 554%) is found for VO2 films after introducing double-layer WO3 AR coating The VO2 deposited on glass exhibits good thermochromism with an optical transition at 545 °C, which decreases to 52 °C in WO3/VO2/WO3 sandwich structure, and the hysteresis loop is sharper around the transition temperature, which may be ascribed to the strain and interfacial diffusion In comparison with single-layer VO2, the durability in automatic solar/heat control of sandwich-structure VO2 films is improved nearly 4 times in high temperature and humidity conditions This multilayer will open a new avenue for the design and integration of advanced thermochromic heterostructures with controllable functionalities for intelligent window and sensing system applications
TL;DR: In this paper, the authors report quantitative reflectance and transmittance measurements performed on individual microcrystals of CH3NH3PbBr3, with thicknesses ranging from 155 to 1907 nm.
Abstract: Lead-based, inorganic–organic hybrid perovskites have shown much promise in photovoltaics, and the ability to tune their band gap makes them attractive for tandem solar cells, photodetectors, light-emitting diodes, and lasers. A crucial first step toward understanding a material’s behavior in such optoelectronic devices is determining its complex refractive index, n + ik; however, optically smooth films of hybrid perovskites are challenging to produce, and the optical properties of films of these materials have been shown to depend on the size of their crystallites. To address these challenges, this work reports quantitative reflectance and transmittance measurements performed on individual microcrystals of CH3NH3PbBr3, with thicknesses ranging from 155 to 1907 nm. The single crystals are formed by spin-coating a film of precursor solution and then stamping it with polydimethylsiloxane (PDMS) during crystallization. By measuring crystals of varying thickness, n and k values at each wavelength (405–1100 nm...
TL;DR: The present work shows promising characteristics of Cu-based THR coating for energy-saving building industry and utilizes Cu, a low-cost material, in-lieu of silver which is widely used in current commercial heat reflecting coating on glass.
Abstract: Multilayer coating structure comprising a copper (Cu) layer sandwiched between titanium dioxide (TiO2) were demonstrated as a transparent heat reflecting (THR) coating on glass for energy-saving window application. The main highlight is the utilization of Cu, a low-cost material, in-lieu of silver which is widely used in current commercial heat reflecting coating on glass. Color tunable transparent heat reflecting coating was realized through the design of multilayer structure and process optimization. The impact of thermal treatment on the overall performance of sputter deposited TiO2/Cu/TiO2 multilayer thin film on glass substrate is investigated in detail. Significant enhancement of transmittance in the visible range and reflectance in the infra-red (IR) region has been observed after thermal treatment of TiO2/Cu/TiO2 multilayer thin film at 500 °C due to the improvement of crystal quality of TiO2. Highest visible transmittance of 90% and IR reflectance of 85% at a wavelength of 1200 nm are demonstrated for the TiO2/Cu/TiO2 multilayer thin film after annealing at 500 °C. Performance of TiO2/Cu/TiO2 heat reflector coating decreases after thermal treatment at 600 °C. The wear performance of the TiO2/Cu/TiO2 multilayer structure has been evaluated through scratch hardness test. The present work shows promising characteristics of Cu-based THR coating for energy-saving building industry.
TL;DR: In this paper, a DC-reactive magnetron sputtering at substrate bias voltage of −160 V and a low substrate temperature of 200 V was used to sample VO2 thin films.
TL;DR: In this article, a semi-transparent perovskite solar cells are proposed that are not only highly efficient but also very effective in thermal-mirror operation, with the optimal top transparent electrode design based on thin metal layer capped with high-index dielectric layer for selective transmittance in visible and high reflectance in near-infrared (NIR) region.
Abstract: Device architectures for semi-transparent perovskite solar cells are proposed that are not only highly efficient but also very effective in thermal-mirror operation. With the optimal top transparent electrode design based on thin metal layer capped with a high-index dielectric layer for selective transmittance in visible and high reflectance in near-infrared (NIR) region, the proposed see-through devices exhibit average power conversion efficiency as large as 13.3% and outstanding NIR rejection of 85.5%, demonstrating their great potential for ideal “energy-generating and heat-rejecting” solar windows that can make a smart use of solar energy.
TL;DR: In this paper, a low cost combination of inverted layer processing of silver nanowires (AgNWs) to produce a conductive network in a polyimide surface, followed by electroless plating of Cu to further enhance conductivity, results in a highly efficient (>55dB) EMI shielding film that is less than 10μm thick, transparent (> 58% transmittance), and sufficiently flexible to maintain its conductivity after bending to a radius of 3mm for 10,000 times.
TL;DR: In this paper, an in-depth study of the structural and compositional material changes induced by specific postannealing treatments is presented, based on aluminum zinc oxide (AZO) and hydrogenated AZO (H) thin films grown by rf-magnetron sputtering at room temperature that allows an extensive understanding of the films' electrical/structural changes and the ability to tune their physical parameters to yield increasingly better performances.
Abstract: Indium tin oxide (ITO) is the current standard state-of-the-art transparent conductive oxide (TCO), given its remarkable optical and electrical properties. However, the scarcity of indium carries an important drawback for the long-term application due to its intensive use in many optoelectronic devices such as displays, solar cells, and interactive systems. Zinc oxide-based TCOs can be a cost-effective and viable alternative, but the limitations imposed by their transmittance versus resistivity tradeoff still keep them behind ITO. In this work, an in-depth study of the structural and compositional material changes induced by specific postannealing treatments is presented, based on aluminum zinc oxide (AZO) and hydrogenated AZO (AZO:H) thin films grown by rf-magnetron sputtering at room temperature that allows an extensive understanding of the films' electrical/structural changes and the ability to tune their physical parameters to yield increasingly better performances, which put them in line with the best ITO quality standards. The present investigation comprises results of thermal annealing at atmospheric pressure, vacuum, forming gas, H2 and Ar atmospheres and plasmas. Overall the study being performed leads to a decrease in resistivity above 40%, reaching ρ ≈ 3 × 10−4 Ω cm, with an average optical transmittance in the visible region around 88%. Such results are equivalent to the properties of state-of-the-art ITO.
TL;DR: Angle insensitive color filter based on Metal-SiOx-Metal structure is proposed in this paper, which can keep the same perceived transmitted color when the incidence angle changes from 0° to 60°, especially for p-polarization light.
Abstract: Angle insensitive color filter based on Metal-SiOx-Metal structure is proposed in this paper, which can keep the same perceived transmitted color when the incidence angle changes from 0° to 60°, especially for p-polarization light. Various silicon oxide films deposited by reaction magnetron sputtering with a tunable refractive index from 1.97 to 3.84 is introduced to meet the strict angle insensitive resonance conditions. The angle resolved spectral filtering for both p-polarization light and s-polarization light are quite well, which can be attributed to the different physical origins for the high angular tolerance for two polarizations. Finally, the effect of SiOx absorption and Ag thickness on the peak transmittance are analyzed.
18 Oct 2016
TL;DR: In this paper, the authors demonstrate anti-reflective layers composed of hierarchical nano/microscale features that are prepared on Si using a combination of wet and dry etching processes, and which are both scalable and affordable.
Abstract: The creation of anti-reflective surfaces is reliant on the engineering of the surface textures and patterns to enable efficient trapping or transmission of light. Here we demonstrate anti-reflective layers composed of hierarchical nano/microscale features that are prepared on Si using a combination of wet and dry etching processes, and which are both scalable and affordable. The performance of the structured surfaces was tested through optical measurements of the reflectance, transmittance, and scattering spectra from the visible to mid-infrared wavelength regions, and the results were verified using numerical simulations to identify the performance of the textured anti-reflective layers. The anti-reflective properties of the layers were shown to be dramatically improved by the composite nanostructured surfaces over a broad spectral range, which thus provides a basis for the design rules that are essential for the progress towards effective anti-reflector fabrication. At normal incidence, the hierarchical...
TL;DR: In this article, the authors have shown that the optical band gap of four types of polymer and ZnO nanoparticles have been prepared as flexiable foil by using the casting method and the analysis of energy dispersive X-ray (EDX) is satisfied of the high purity of as-prepared samples.
Abstract: Polymers/ZnO nanocomposites have been receiving great interest due to their wide range of applications in optical devices. So, there is an essential need to enhance their optical properties. In this work, nanocomposites of four types of polymer and ZnO nanoparticles have been prepared as flexiable foil by using the casting method. Poly (methyl methacrylate) (PMMA), poly (vinylidene fluoride) (PVDF), polyvinyl alcohol (PVA), and polystyrene (PS) are used as polymer matrix while different concentrations of ZnO nanoparticles are used as filler. The analysis of energy dispersive X-ray (EDX) is satisfied of the high purity of as-prepared samples. UV-visible transmittance spectra have shown low transmittance in UV region which is inversely proportional with the concentration of ZnO nanoparticles. Linear absorption coefficient (α) has shown the presence of absorption edges. The energy gap is calculated, it is noticed that the optical band gap of all nanocomposites are red shifted. The values of the energy gap for all samples decreased with the increase of the weight percentage of ZnO nanoparticles in nanocomposites. However, the decrement in nanocomposites samples is different.
TL;DR: The transfer-free measurement of carrier dynamics and transport of direct CVD grown graphene on glass with the aid of ultrafast transient absorption microscopy (TAM) is reported and the great feasibility of good quality graphene glass toward scalable and practical TCE applications is presented.
Abstract: In this work, we report the transfer-free measurement of carrier dynamics and transport of direct chemical vapor deposition (CVD) grown graphene on glass with the aid of ultrafast transient absorption microscopy (TAM) and demonstrate the use of such graphene glass for high-performance touch panel applications. The 4.5 in.-sized graphene glass was produced by an optimized CVD procedure, which can readily serve as transparent conducting electrode (TCE) without further treatment. The graphene glass exhibited an intriguing optical transmittance and electrical conductance concurrently, presenting a sheet resistance of 370–510 Ω·sq–1 at a transmittance of 82%, much improved from our previous achievements. Moreover, direct measurement of graphene carrier dynamics and transport by TAM revealed the similar biexponential decay behavior to that of CVD graphene grown on Cu, along with a carrier mobility as high as 4820 cm2·V–1·s–1. Such large-area, highly uniform, transparent conducting graphene glass was assembled t...