The effects of the annealing temperature on the structural, morphological, and luminescent properties of SrWO4:Sm3+ thin films grown on quartz substrates by radio-frequency magnetron sputtering were investigated. The thin films were annealed at various annealing temperatures for 20 min in a rapid thermal annealer after growing the thin films. The experimental results showed that the annealing temperature has a significant effect on the properties of the SrWO4:Sm3+ thin films. The crystal structure of the as-grown SrWO4:Sm3+ thin films was transformed from amorphous to crystalline after annealing at 800℃. The preferred orientation along (112) plane and a significant increase in average grain size by 820 nm were observed with increasing the annealing temperature. The average optical transmittance in the wavelength range of 500~1,100 nm was decreased from 72.0% at 800℃ to 44.2% at an annealing temperature of 1,000℃, where the highest value in the photoluminescence intensity was obtained. In addition to the red-shift of absorption edge, a higher annealing temperature caused the optical band gap energy of the SrWO4:Sm3+ thin films to fall rapidly. These results suggest that the structural, morphological, and luminescent properties of SrWO4:Sm3+ thin films can be controlled by varying annealing temperature.
In this study, we fabricated multilayer graphene on a glass substrate by stacking the monolayer graphene synthesized via chemical vapor deposition. The electrical sheet resistance and optical transmittance were evaluated to confirm the quality of the stacked multilayer graphene. Using the fabricated multilayer graphene/glass structure, we characterized its thermal radiative property in terms of the integrated emissivity. The integrated emissivity of the multilayer graphene/glass structure was tuned from 0.91 to 0.72 when the number of graphene layers was changed from 1 to 12. We also demonstrated that the emissivity tunability provided a way to control the apparent temperature of an object that can be used in infrared stealth applications.
Smart windows are used as windows and doors to determine the cooling and heating efficiency of a building. They have characteristics that can increase the energy efficiency of a building, which leads to energy savings. In addition, smart windows can control the amount of light transmitted from the external environment of a building to the interior of a building according to the needs of the user. In this study, a 297×210 mm2 liquid crystal cell capable of controlling light transmittance was fabricated using a liquid crystal device as an optical shutter. The effect of driving voltage on the transmittance and the effect of the thermal environment on the driving stability were analyzed. We confirmed the applicability of using smart windows as exterior building materials.
A multiple-electrode-type electronic paper film can implement a single color and control the transparency, as it has multiple electrodes in one cell. Therefore, it can be used as a transparent display. In this paper, we explain the structure and driving method of a transparent electronic paper display, and then propose a control method of transmittance. Subsequently, we verify the theory by measuring the transmittance via experiment. Thus, by changing the manner of applying the voltage to three lower electrodes and one upper electrode, transmittance in eight cases could be realized. It was confirmed that the transmittance derived from the experiment could be controlled from a minimum of 6.75% to a maximum of 71.18%.
A solvent free, highly concentrated silica-acryl monomer hybrid sol was synthesized using aqueous colloidal silica as a precursor. The effects of the silica particle size, type of surface treatment agent employed, and silica content on the formation of the hybrid sol were systematically studied. The optical and physical properties of the coating solution prepared using the hybrid sol were also characterized. The viscosity of the hybrid sol tended to decrease as the particle size of the silica and the molecular weight of the surface treatment agent increased. The PET substrate coated with MPTMS-Mix (mixture, 70 wt%) solution showed the highest surface hardness (6 H) and low surface roughness (Ra= 0.044 μm), which could be attributed to an increase in packing density caused by the infiltration of small particles into the pores formed between larger particles.
This work reports the surface morphology and transmittance of copper oxide thin films for semitransparent solar cell applications. We prepared the oxide specimens by subjecting copper thin films to an oxidation reaction at annealing temperatures ranging between 100℃ and 300℃. The color of the as-deposited specimen was red, but changed to purple at the annealing temperature of 300℃. The surface morphology and transmittance of the specimens were significantly dependent on the annealing temperature and thickness of the copper films. Copper oxide nanoparticles prepared from a 20-nm-thick copper film at an annealing temperature of 300℃ provided a maximum transmittance of 93%. The obtained optical characteristics and surface morphology suggest that copper oxide thin films prepared by an oxidation reaction can be potentially employed as color- and transmittance-adjusting layer in semitransparent thin solar cells.
SnO2/Ag/Nb2O5/SiO2/SnO2 multilayer films were prepared on glass substrate by sequential using RF/DC magnetron sputtering at room temperature. The influence of top SnO2 layer thickness on optical and electrical properties of the multilayer films was investigated. Experimentally measured results exhibit transmittances over 84.3 ~ 85.8% at 550 nm wavelength. As the top SnO2 layer thickness increased from 40 to 55 nm, the sheet resistance (Rs) increased from 5.81 to 6.94 Ω/sq. The Haacke`s figure of merit (FOM) calculated for the samples with various SnO2 layer thicknesses was a maximum at 45 nm (35.3 × 10-3 Ω-1).
The dielectric thin films applied to multi-colored semitransparent thin film solar cells have been extensively studied. In this work, we prepared GeSbTe and GeTe chalcogenide thin films using magnetron sputtering, and investigated their optical and phase-change properties to replace the dielectric films. The changes of surface morphology, sheet resistance, and X-ray diffraction of the Te-based chalcogenide films support the fact that the amorphous stability of GeTe films is superior to that of GeSbTe films. While both amorphous GeSbTe and GeTe films thinner than 30 nm have optical transparency between 5% and 60%, GeTe films transmit more visible light than GeSbTe films. It is confirmed by computer simulation that the color of semitransparent silicon thin film solar cells can be adjusted with the addition of GeSbTe or GeTe films. Since it is possible to adjust the contrast of the solar cells by exploiting the phase-change property, the two kinds of chalcogenide films are anticipated to be used as an optical layer in semitransparent solar cells.
Transparent color coating films were fabricated on a glass substrate by using sol-gel hybrid binder and organic dye. Sol-gel hybrid binder coating film fabricated with PTMS of 0.03 mole showed a very high pencil hardness of 9 H. As the withdrawal speed increased from 1.0 mm/s to 5.0 mm/sec, The yellowness (b*) of coating glass also gradually increased. The transmittance of yellow color coating glass was 82.6% and the haze of coating glass was 0.35%. Red and blue color coating glasses also showed the high transmittance of 62.4% and 80.6% respectively. The surface hardness of color coating films was 6 H.
Anti-reflective (AR) thin film was fabricated on a glass substrate by sol-gel method. The coating solution was synthesized with TEOS (tetraethlyorthosilicate) and poly ethylene glycol (PEG, 4.0 wt%). As the withdrawal speed of coating was changed from 0.1 mm/sec to 0.3 mm/sec, the thickness and refractive index of prepared thin films were changed. The reflectance and transmittance of coating glass fabricated by the withdrawal speed of 0.1 mm/sec were 0.62% and 95.0% in visible light range. The refractive index and thickness of single layer thin film were n= 1.29 and ca. 99.0 nm.
Among several types of energy saving smart window technologies, the leader, the dynamic EC (electrochromic) window one needs integrated PV (photovoltaics), to minimize expensive electrical wiring as well as to obviate the need for external energy. Self-powered smart windows were reviewed according to PV types used. DSSCs (dye sensitized solar cells) were found to be compatible with EC cells, to have several categories of next generation smart windows such as PECCs (photoelectrochromic cells), PVCCs (photovoltachromic cells), EC polymer PECCs. In addition silicon solar cells and third generation solar cells were investigated. They are summarized in a table showing their advantages and disadvantages respectively for a fast comparison. The strategy to expedite the commercialization of these next generation smart windows includes developing retrofit smart window coverings for use on flexible polymer substrates adhered to the inside surface of a window and easily replaced after use for upto 10 years.
To provide the clear images from the direct light on electrical board and display devices, anti glare treatment of display cover glass is needed. In this study, the effects of surface treatment temperature, concentration, and etching solution coating thickness of the gel phase on optical elements control such as gloss, haze of reflected light and transmittance, were investigated. Cover glasses were treated at different coating thickness and additive concentration. The optical properties were examined using spectrophotometer, gloss and haze meter. The surface morphology and roughness were measured by the optical microscope and Ra measuring instrument. The etching rate and surface morphologies were dramatically affected by the concentration of acid additive in the viscous gel because of re-crystallization of components in the etching solution, hydrogel formation and coagulant after coating on glass substrate. In our experimental range, cover glass which is surface-treated with various optical properties as well as the morphology uniformity was obtained; in particular, optical properties could be controlled by etching solution coating thickness of the gel phase and the concentration of additive. The gloss was depended on the surface roughness and it showed the linear relationship between optical transmittance and haze of reflected light, respectively.
In this study, Si3N4/SnZnO/AZO/Ag/Ti/ITO multi-layer film were prepared on glass substrate by DC/RF magnetron sputtering method. To prevent interfacial reaction between Ag and ITO layer, Ti buffer layer was inserted. Optical properties and sheet resistance were studied depending on laminating times of each multi-layered film especially in visible ray. The simulation program, EMP (essentialmacleod program), was adopted and compared with experimental data to expect the experimental result. It was found out that the transmittance of the first stacked Si3N4/SnZnO/AZO/Ag/Ti/ITO multi-layer film was more than 90%. However, with increasing stacking times, the optical properties ofSi3N4/SnZnO/AZO/Ag/Ti/ITO multi-layer film get worse. Consequently, Ti layer is good for oxidation barrier, but too many uses of this layer may have an adverse effect to optical properties of TCO film.
MgZnO has attracted a lot of attention for flexible device. In the flexible substrate, the crystalstructure of the thin films as well as the surface morphology is not good. Therefore, in this study, westudied on the effects of the oxygen pressure on the structure and crystallinity of Mg0.3Zn0.7O thin films deposited on PES substrate by using pulsed laser deposition. We used X-ray diffraction and atomic forcemicroscopy in order to observe the structural characteristics of Mg0.3Zn0.7O thin films. The crystallinity ofMg0.3Zn0.7O thin films with increasing temperature was improved, Grain size and RMS of the films wereincreased. UV-visible spectrophotometer was used to get the band gap energy and transmittance. Mg0.3Zn0.7O thin films showed high transmittance over 90% in the visible region. As increased workingpressure from 30 mTorr to 200 mTorr, the bandgap energy of Mg0.3Zn0.7O thin film were decreased from3.59 eV to 3.50 eV.
To observe the optical characteristic of oxide semiconductor depending on the degree of bonding structures, SiOC, ZnO and IGZO were prepared by the RF magnetron sputter system and chemical vapor deposition. Generally, crystal ZnO, amorphous SiOC and IGZO changed the optical characteristics in according to the electro-chemical behavior due to the oxygen vacancy at an interface between different groups. Transmittance of SiOC and IGZO with amorphous structures was higher than that of ZnO with crystal structure, because of lowering the carrier concentration due to the recombination of electron and holes carriers as oxygen vacancies. Besides, the energy gap of amorphous SiOC and IGZO was higher than the energy gap of crystal ZnO. The diffusion mobility of holes is higher than the drift mobility of electrons.
Mg doped zinc tin oxide (ZTOMg) thin films were prepared on glasses by rf magnetron sputtering. O was introduced into the chamber during the sputtering. The optical properties of the films as a function of oxygen flow rate were studied. The crystal structure, elementary properties, and depth profiles of the films were investigated by X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS), respectively. Bottom-gate trdnsparent thin film transistors were fabricated on N Si wafers, and the variation of mobility, threshold voltage etc. with the oxygen flow rate were observed.
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A Study on the Chemical Properties of AZO with Crystal Structure and IGZO of Amorphous Structure Due to the Annealing Temperature Young Ho So, Jung Ho Song, Dong Myung Seo, Teresa Oh Industry Promotion Research.2016; 1(1): 1. CrossRef
We have investigated the structural, electrical and optical properties of Ga-doped ZnO (GZO) thin films prepared by RF magnetron sputtering with laboratory-made ZnO targets containing 1, 3, 5, 7 wt% of Ga2O3 powder as a doping source. The GZO thin films show the typical crystallographic orientation with c-axis regardless of Ga2O3 content in the targets. The 3,000 Å thick GZO thin films with the lowest resistivity of 7×10-4 Ω·cm are obtained by using the GZO (Ga2O3= 5 wt%) target. Optical transmittance of all films shows higher than 80% at the visible region. The optical energy band gap for GZO films increases as the carrier concentration (ne) in the film increases.
This article introduces the characterization of spin coated ZnO transparent conducting oxide on the flexible substrates. As a II-IV compound semiconductor, ZnO has a wide band gap of 3.37 eV with transparent properties. Due to this transparent properties, ZnO materials can be also employed as the transparent conducting electrode materials. Therefore, strong demands have been required for the transparent electrodes with low temperature processing and cheap cost. So, We will investigate the electrical property and optical transmittance of ZnO transparent conducting oxide through the 4-point probe resistivity meter, and ultraviolet-vis spectrometer Lamda 35, respectively.
We were studied that AZO conductive thin film can substitute for FTO electrode in dye sensitized solar cell. Three types of AZO films were deposited on soda-lime glass(AZO/glass, AZO/AZO/glass, textured AZO/AZO/glass) using RF magnetron sputtering process and investigated their properties of electrical, optical, and photoelectric conversion rate. The textured AZO/AZO/glass has the lowest resistivity of 3.079×10-4 Ω㎝ among other films. And the optical transmittance rate was better than both non textured AZO/AZO/glass and FTO/glass in the visible region. After manufacturing dye solar cells using the three types of AZO films, the textured AZO/AZO/glass showed the highest photoelectric conversion rate of 3.68% among AZO samples. But the transformation rate was slightly lower than FTO cells (4.52%). However, the conductive film of textured AZO/AZO/glass can be applicable to use an electrode in solar cells as cost-effective products.
Ga-doped ZnO-SnO2 (ZSGO) films were deposited by rf magnetron sputtering and their structural and electrical properties were investigated. In order to fabricate the target for sputtering, the mixture of ZnO, SnO2 (1:1 weight ratio) and Ga2O3 (3.0 wt%) powder was calcined at 800℃ for 1 h. The substrate temperature was varied from room temperature to 300℃. The crystallographic properties and the surface morphologies of the films were studied by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The optical transmittances of the films were measured and the optical energy band gaps were obtained from the absorption coefficients. The resistivity variation with substrate temperature was measured. Auger electron spectroscopy was employed to find the atomic ratio of Zn, Sn, Ga and O in the film deposited at room temperature. ZSGO films exhibited the optical transmittance in the visible region of more than 80% and resistivity higher than 10 Ωcm.
ZnO is an n-type semiconductor with a wide band gap near 3.37 eV. It was known that ZnO films with a resistivity of the order of 10(-4) Ωcm is not easy to obtain. 1, 3, and 5wt% Si element were added into ZnO in ordre to improve the electrical and optical characteristics. The Si-doped ZnO (SZO) was grown on a glass substrate by radio frequency (RF) magnetron sputtering at the temperature range from 100 to 500℃. X-ray diffraction (XRD) patterns of SZO film showed preferable crystal orientation of (002) plane. It was confirmed that the lowest resistivity of the SZO films was 2.44≠10(-3) Ωcm and SZO films were significantly influenced by the working temperature. The average transmittance of the films was over 80% in the visible ranges.
In this work, electrochemical characteristics and optical transmittance of carbon nanotubes (CNTs) counter electrodes which had different amount of CNTs in CNTs slurries were analyzed. Two-step heat treatment processes were applied to achieve well-fabricated CNTs electrode. Three sets of CNTs electrodes and dye-sensitized solar cells (DSSCs) with CNTs counter electrodes were prepared. As the amount of CNTs increased, sheet resistance of CNTs electrode decreased. CNTs electrode with low sheet resistance had low electrochemical impedance and fast redox reaction. On the other hand, in case of CNTs counter electrode with low density of CNTs, performance of the dye-sensitized solar cell was improved due to its high optical transmittance. We found that the transmittance of CNTs counter electrode influence the performance of dye-sensitized solar cells.
ZnO with the wide band gap near 3.37 eV is typically an n-type semiconductor in which deviation from stoichiometry is electrically active. It was known that the films with a resistivity of the order of 10-4 Ωcm is not easy to obtain. In order to improve electrical characteristic of ZnO, we added 1, 3, 5 wt% Ga element in ZnO. The Ga-doped ZnO (GZO) was grown on a glass substrate by radio frequency (RF) magnetron sputtering at the temperature range from 100 to 500℃. X-ray diffraction (XRD) patterns of GZO films showed preferable crystal orientation of (002) plane. The lowest resistivity of the GZO films was 8.9×10-4 Ωcm. GZO films significantly influenced by the working temperature. The average transmittance of the films was over 80% in the visible ranges.
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Dependences of Sputtering Times on the Structural and Electrical Properties of ZnO/Ag/ZnO Thin Films on PET by DC Sputtering Yun-Hae Kim, Jin-Woo Lee, Ri-Ichi Murakami IEEE Transactions on Nanotechnology.2013; 12(6): 991. CrossRef
Review Article: Atomic layer deposition of doped ZnO films Zhengning Gao, Parag Banerjee Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films.2019;[Epub] CrossRef
Experimental Study on Fabrication of AZO Transparent Electrode for Organic Solar Cell Using Selective Low-Temperature Atomic Layer Deposition Ki-Cheol Kim, Gen-Soo Song, Hyung-Tae Kim, Kyung-Hoon Yoo, Jeong-Jin Kang, Jun-Young Hwang, Sang-Ho Lee, Kyung-Tae Kang, Heui-Seok Kang, Young-June Cho Transactions of the Korean Society of Mechanical Engineers B.2013; 37(6): 577. CrossRef
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