Flat Glass Substrate Research Articles

Effect of processing parameters on size, density and oxygen reduction reaction (ORR) activity of Pd nanoparticles grown by spin coating

To study oxygen reduction reaction (ORR) activity Pd nanoparticles were grown on flat (Si and glass) substrate via spin coating of Pd2+ ions solution followed by chemical reduction in aqueous hydrazine hydrate solution. Growth of Pd nanoparticles was confirmed by x-ray diffraction and x-ray photoelectron spectroscopy techniques. UV–vis-NIR spectroscopy was used to optimize reduction time, whereas scanning electron microscopy was utilized to study size and distribution of grown Pd nanoparticles. It was observed that most of the Pd nanoparticles grow with unique preferable size. The preferable size and density of grown Pd nanoparticles can be precisely controlled by processing parameters (rpm, ramp and reducing agent concentration). The grown Pd nanoparticles are thermally stable up to 450°C. The ORR activity was found to be dependent on size as well as density of Pd nanoparticles.

The formation of poly-Si films on flat glass substrates by flash lamp annealing

We have succeeded the formation of polycrystalline silicon (poly-Si) films by flash lamp annealing (FLA) of 4-μm-thick intrinsic amorphous silicon (a-Si(i)) films deposited directly on flat glass substrates by tuning catalytic chemical vapor deposition conditions. The use of a-Si(i) films deposited without intentional substrate heating leads to the suppression of Si film peeling during FLA. The a-Si(i) films deposited at room temperature have low film density, low film stress, and high defect density, compared to a-Si(i) films deposited at higher temperatures. The prevention of Si film peeling may be due to the low film stress and/or the suppression of the emergence of lateral explosive crystallization by using a-Si(i) films with low film density.

Electrochemically deposited Fe2O3 nanorods on carbon nanofibers for free-standing anodes of lithium-ion batteries

Fe2O3 nanorod/carbon nanofiber (CNF) composites were prepared by the electrochemical deposition of Fe2O3 on a web of CNFs, which was then used as a free-standing anode. The conductive, three-dimensional structure of the CNF web allowed for the electrodeposition of the Fe2O3 nanorods, while its high conductivity made it possible to use the composite as a free-standing electrode in lithium-ion batteries. In addition, it was easy and cheap to fabricate by a simplification of a process of cell preparation. The nanorod-like Fe2O3 structures could only be electrodeposited on the CNFs; flake-like Fe2O3 was formed on flat conductive glass substrates. It can be attributed to the different growth mechanism of Fe2O3 on the CNFs because of the large number of reaction sites on the CNFs, differences in the precursor concentration and diffusivity within the CNF web. The formation of aggregates of the Fe2O3 particles on thicker CNFs also indicated that the CNFs had determined the Fe2O3 growth mechanism. The synthesised Fe2O3/CNF composite electrode exhibited stable rate capacities at different current densities. This suggested that CNF-based composite did not exhibit the intrinsic disadvantages of Fe2O3. Finally, carbon coatings were deposited on the Fe2O3/CNF composites to further improve their electronic conductivity and rate capability.

P‐127: Highly Efficient Light Extraction Technologies Applicable for Transparent OLED Lighting using a Corrugated Substrate

The authors fabricated OLED devices with enhanced out‐coupling efficiency, made using corrugated substrates which have nanostructures imprinted from a self‐assembled block‐copolymer pattern. We optimized the substrate for transparent OLED lighting by shortening the pattern pitch to develop a new substrate that is transparent with 0.1 % haze and an out‐coupling efficiency 1.79 times that of a device made with a flat glass substrate.

P‐148: Polymer Light‐Emitting Diodes Using the Dip Coating Method on Flexible Fiber Substrates for Wearable Displays

We demonstrated polymer light‐emitting diodes (PLEDs) using the dip coating method on a flat glass and flat polyethylene terephthalate (PET) substrates as well as on a cylinder‐shaped fiber substrate. This result enables the production of low‐cost, easily fabricated flexible fiber‐based PLEDs by roll‐to‐roll manufacturing as well as the realization of a true fiber‐based wearable display.

SF6/Ar plasma textured periodic glass surface morphologies with high transmittance and haze ratio of ITO:Zr films for amorphous silicon thin film solar cells

We report various SF6/Ar plasma textured periodic glass surface morphologies with high transmittance, haze ratio, and root mean square (rms) roughness of ITO:Zr films for amorphous silicon thin film solar cells (a-Si TFSCs). SF6/Ar plasma textured glass surface morphologies contain micro- and nano-textured features that help to scatter the light in visible and near infra-red (NIR) wavelength regions. We designed the textured glass surface morphologies with big square craters to smaller pyramids for various glass etching times from 30 to 75 min. Magnetron sputtered ITO:Zr (∼210 nm) films were deposited on textured glass surface morphologies and showed higher transmittance and haze ratio of 88.48% and 77.61%, respectively, in the visible-NIR (400–1100 nm) wavelength region. The sheet resistance and resistivity of ITO:Zr films decreased with the increase of etching time, due to high rms roughness and better step coverage. A passivation AZO (30 nm) layer was added to the ITO:Zr films, due to its better stability against hydrogen plasma exposure. The ITO:Zr/AZO films were employed as a front TCO layer and the current density–voltage (J–V) characteristics of a-Si TFSCs increased by light scattering effect, without any reduction in either the open circuit voltage (VOC) or the fill factor (FF). Relative to flat glass substrate, JSC and the efficiency of a-Si TFSCs were enhanced by 7.51% and 19.39%, respectively, for textured glass surface morphology.

High-haze and wide-spectrum hydrogenated MGZO TCO films on micro-textured glass substrates for thin-film solar cells

High-haze and wide-spectrum hydrogenated Mg and Ga co-doped ZnO (HMGZO) transparent conductive oxide films on ‘U-shaped’ micro-textured glass are developed using magnetron sputtering. The wet-chemically etched glass substrates with large crater-like features obtained via a frosting method exhibit strong light-scattering capability in a wide wavelength range (~350–1100nm). The morphological, structural, optical and electrical properties of HMGZO films on textured and flat glass are investigated in detail. The HMGZO thin films deposited on textured glasses show conformal growth and have a polycrystalline hexagonal wurtzite phase with a c-axis preferred orientation, which is similar to that of films deposited on flat glass. The electrical resistivity of HMGZO films decreases from 9.74×10−4 to 7.67×10−4Ωcm and the optical band gap Eg is in the range from 3.76 to 3.72eV as the deposition time is increased from 25 to 40min. The HMGZO films with textured glass substrate exhibit stronger light-scattering capability compared with films with flat glass substrate. Finally, an a-Si solar cell deposited on textured glass shows a higher conversion efficiency and short-circuit current density than that deposited on flat glass, as a result of effectively improved light scattering. ZnO-TCO films on low-cost chemically etched glass substrates are promising candidates as front electrodes for thin-film solar cells.

Autonomous patterning of cells on microstructured fine particles.

Regularly patterned cells can clarify cellular function and are required in some biochip applications. This study examines cell patterning along microstructures and the effect of microstructural geometry on selective cellular adhesion. Particles can be autonomously assembled on a soda-lime glass substrate that is chemically patterned by immersion in a suspension of fine particles. By adopting various sizes of fine particles, we can control the geometry of the microstructure. Cells adhere more readily to microstructured fine particles than to flat glass substrate. Silica particles hexagonally packed in 5-40 μm line and space microstructures provide an effective cell scaffold on the glass substrate. Cultured cells tend to attach and proliferate along the microstructured region while avoiding the flat region. The difference in cell adhesion is attributed to their geometries, as both of the silica particles and soda-lime glass are hydrophilic related with cell adhesiveness. After cell seeding, cells adhered to the flat region migrated toward the microstructured region. For most of the cells to assemble on the scaffold, the scaffolding microstructures must be spaced by at most 65 μm.

Plasma etching antireflection nanostructures on optical elements in concentrator photovoltaic systems

Transmission-type concentrator photovoltaic (CPV) systems are a potential candidate to achieve high efficiency and low cost solar energy. The use of optical elements in these systems creates reflection losses of incoming solar energy that account for about 8% to 12% depending on the optical design. In order to reduce these losses, we have nanostructured the air/optical-elements’ interfaces by using plasma etching methods on the Fresnel lens made of poly(methyl methacrylate) (PMMA) and the homogenizer made of glass. On flat PMMA and glass substrates, transmittance enhancement measurements are in agreement with relative Jsc gains. The field test results using a CPV module with all textured optical-elements’ interfaces achieved 8.0% and 4.3% relative Jsc and efficiency gains, respectively, demonstrating the potential of this approach to tackle the reflection losses.

Properties of an Au/Pt bilayered counter electrode in dye sensitized solar cells

A Ru/Ti bilayer to a flat glass substrate was applied as a counter electrode to improve the energy conversion efficiency of a dye-sensitized solar cell device with the structure of glass/FTO/blocking layer/TiO2/N719(dye)/electrolyte/(50 nm Ru-50 nm Ti)/glass. For comparison, a 100 nm-thick Ru counter electrode on a flat glass substrate was also prepared using the same method. The photovoltaic properties, such as the short circuit current density, open circuit voltage, fill factor, energy conversion efficiency and impedance, were characterized using a solar simulator and potentiostat. The phase of the bilayered films was examined by x-ray diffraction. The measured energy conversion efficiency of the dye-sensitized solar cell device with a Ru/Ti bilayer counter electrode was 2.40%. The efficiency was 1.48 times larger that of the dye-sensitized solar cell with the 100 nm Ru counter electrode. The new phase of RuTi led to a decrease in resistivity and an increase in catalytic activity. The interface resistance at the interface between the counter electrode and electrolyte decreased when Ru/Ti bilayer thin films were applied. This suggests that Ru/Ti bilayer thin films improve the efficiency of dye-sensitized solar cells.

Effect of wet textured glass surface morphology on the haze ratio and aspect ratio for amorphous silicon thin film solar cells

The impact of controlling the aspect ratio variation on glass substrate for a p-i-n a-Si:H solar cell was investigated and reported. Compared to a flat glass substrate (Corning Eagle XG), we demonstrate an increase of haze ratio from 1% to 79.1%, and an increment in the aspect ratio from 0.1 to 1.16, which is an increase to a high slope angle, using wet chemical etching. Optical transmittance measurements show a major improvement of from 92% to 96% for a wavelength of between 300 and 1100 nm, compared to the reference flat glass. A p-i-n a-Si:H solar cell was simulated using Advanced Semiconductor Analysis simulation based on these haze ratio and aspect ratio results, and yielded an increase in short-circuit current density (Jsc) from 15.38 to 18.74 mA/cm2, as the aspect ratio was increased from 0.1 to 0.84.

Fabrication of adjustable cylindrical mirror segments for the SMART-X telescope

The adaptive optics system for the SMARTX telescope consists of piezoelectric PbZr 0.52 Ti 0.48 O 3 (PZT) thin films deposited on the backside of the mirror. To achieve sufficient strain response from the piezoelectric films, the substrates chosen are thin, flexible glass pieces that can be slumped into the desired curvature. Preliminary testing has been performed using flat pieces and parts that were slumped into a cylindrical geometry. Commercially available boro-aluminosilicate glass segments (100 × 100 mm) were slumped along one axis to a radius of curvature of 220 mm. 2-μm-thick PZT films were deposited via RF magnetron sputtering on flat glass substrates to demonstrate the viability of the processing approach. The deposited PZT showed high yield (>95%) on 1-cm 2 electrodes. The films exhibited relative permittivity values near 1500 and loss tangents below 0.05. In addition, the remanent polarization was 20 μC/cm 2 with coercive fields near 30 kV/cm. 1-μm-thick films with comparable electrical parameters were then deposited onto the slumped substrates. To understand the piezoelectric response of the films and characterize the device performance, influence function measurements were performed. The typical cell response using a 4 V (1.3V c ) drive voltage corresponded to a 0.5 μm out-of-plane displacement, which relates to an in-plane strain value larger than 150 ppm. Both of these parameters meet benchmark requirements for reaching the targeted 0.5 arcsecond resolution goal of the SMART-X telescope. These results demonstrate a viable route to fabricate highly functional mirror segments for the SMART-X telescope.

Piezoelectric Transducers on Curved Dispersive Bending Wave and Poke-Charged Touch Screens

Ferroelectric thin films of lead zirconate titanate Pb(Zr0.52,Ti0.48)O3(PZT) and bismuth titanate Bi4Ti3O12(BiT) were prepared by photochemical metal-organic deposition as electromechanical transducers used in optoelectronic devices. Both solutions were deposited on flat and convex amorphous glass substrates to poke-charge the device or detect the touch point coordinate on new generation of free-shaped screens. The effects of optimization on UV exposure, precursor type and annealing temperature (600–800 °C) were investigated on microstructural, optical and ferroelectric properties of deposited thin films. Suppressing the non-uniformity of the film thicknesses due to repetitive deposition, actually there is no structural difference between the two types of substrates and their effects on the film properties. Polarization-voltage hysteresis loops showed relatively larger remnant polarization of P r = 9.3 µC/cm2 and 6.1 µC/cm2 for optimized UV-irradiated PZT and BiT thin films, respectively, than uncured samples.

Fundamental studies on dust fouling effects on PV module performance

This paper presents the results of study on the effect of dust fouling on the transmittance of PV module glass cover. The study included the effect of dust fouling on overall plane glass transmittance, spectral transmittance of anti-reflective coated glass and characterization of the physical and chemical properties of dust particles. Also, micro-adhesion forces of dust particles on flat glass substrates are included. The results indicated a 20% reduction in glass transmittance and a 5g/m2 of dust accumulation on the glass cover of PV modules tilted at 26° (Lat of Dhahran) and exposed for 45days. The anti-reflective coated glass exhibited less reduction in transmittance compared to non-coated plane glass. The adhesion forces of particles on flat surfaces increased with increase in particle size due to increase in contact area between the particles and the surface. At high humidity level there is an increase in the vertical adhesion due to the generated capillary forces between dust particles and glass surface.

Enhancement of light extraction efficiency of OLEDs using Si₃N₄-based optical scattering layer.

An optical scattering layer, consisting of a Si3N4 nano-pillar array and a spin-coated hydrogen silsesquioxane (HSQ) planarization layer, was introduced to an organic light-emitting diode (OLED) substrate to increase the out-coupling efficiency. After plasma enhanced chemical vapor deposition (PECVD) of the Si3N4 layer, the nano-pillar array was created using nanoimprint lithography and reactive ion etching. As the Si3N4 pillar array has a refractive index of 2.0, photons generated in the organic layer are scattered by the Si3N4 structures and thus have a higher chance of being emitted from the device. The spin-coated HSQ planarization layer produces a flat substrate, which is essential for depositing a uniform organic material layer and assuring the electric conductivity of the transparent conducting oxide (TCO) layer. In this study, Si3N4 nano-structures with a height of 100 or 300 nm were used to enhance the out-coupling efficiency of the OLED devices. Although the electrical conductivity of the TCO layer deposited on the light scattering layer was slightly degraded, the OLED devices formed with the light scattering layer exhibited a higher luminous power at given electrical power. Consequently, the use of a planarized 300-nm-thick Si3N4 layer increased the external quantum efficiency of the OLED device by 50% at 10,000 cd/m2 compared to the reference OLED device fabricated on a flat glass substrate.

Properties of the nano-thick Pt/W bilayered catalytic layer employed dye sensitized solar cells

A Pt/W bilayered catalytic layer on a flat glass substrate was used as a counter electrode to improve the energy conversion efficiency of a dye-sensitized solar cell device with the structure of 0.45 cm2 effective area of glass/FTO/blocking layer/TiO2/N719 (dye)/electrolyte/50 nm Pt/50 nm W/glass. For comparison, 100 nm-thick Pt and W counter electrodes on flat glass substrates were also prepared using the same procedure. The photovoltaic properties, such as the short circuit current density, open circuit voltage, fill factor, energy conversion efficiency and impedance were characterized using a solar simulator and potentiostat. The phases and microstructures of the catalytic layers were examined by x-ray diffraction and field emission electron microscopy. The measured energy conversion efficiencies of the dye-sensitized solar cell devices with Pt only and Pt/W bilayer counter electrodes were 4.60% and 6.54%, respectively. The interface resistance at the interface between the counter electrode and electrolyte decreased when a Pt/W bilayered thin film was applied. The increase in efficiency resulted from the effect of compressive strain field formed by the intermetallic layer of Pt2W at Pt and W layer interface. This suggests that the use of Pt/W bilayered catalytic layers improves the efficiency of the dye-sensitized solar cells compared to those using the conventional Pt layers.

Formation of ruthenium-dots on counter electrodes for dye sensitized solar cells

A 34 nm-thick ruthenium layer was deposited on a flat glass substrate by atomic layer deposition at low temperatures followed by the formation of self-aligned Ru micro or nano-dots by rapid thermal annealing for 30 seconds at 400°C. The resulting substrates were re-coated with another 34 or 69 nm-thick Ru layers by ALD at 250°C. Finally, the effective area of 0.45 cm2 dye sensitized solar cell with a glass / FTO / TiO2 / dye / electrode / (nano-dots Ru / Ru)/glass structure was fabricated. The microstructure was examined by field emission scanning electron microscopy and atomic force microscopy. The photovoltaic properties, such as the short circuit current density, open circuit voltage, fill factor, and energy conversion efficiency, were characterized using a solar simulator and potentiostat. FE-SEM confirmed that the 34 nm and 69 nm-thick Ru layers re-deposited by the second ALD process showed a 65% and 49% larger surface area, respectively, than the flat glass substrate due to the rearranged nano-dots. The ECE of the final DSSC was 2.62%, which was a 1.45 times larger than that of the 34 nm-Ru flat glass substrate. These results suggest that the efficiency of DSSCs can be improved by increasing the effective surface area of a counter electrode by low temperature ALD.

Pore Wetting Phenomena: Implications to Enhanced Oil Recovery and Geologic Carbon Storage

Pore wetting has been considered as an important factor in carbon storage and enhanced oil recovery. Previous studies were limited to the wetting measurements on flat substrates; few measurements were directly carried in a pore to indicate the pore wetting. In this paper, we used the pore contact angle measurement technique recently developed in our laboratory to measure the contact angles of fluids in a single capillary, by considering the effects of pore size, applied pressure and temperature and three different CO2 phases (gas, liquid and supercritical). The results indicate that the pore wetting only significantly changes on the CO2 phase transition boundary and then remains unchanged. The effects of pressure and temperature are not significant on the pore wetting when there is no CO2 phase variation. Our data conclude that the pore wetting of liquid in presence of CO2 is in the order of θgasCO2<θsupercriticaCO2<θliquiCO2. The pore wetting varies with glass pore size and applied liquid. The contact angles measured in a glass pore are significantly different from the ones measured on a flat glass substrate.

Structural, optical and electrical properties of Sb doped and undoped AgIn1 − xGaxSe2 and Ag(InGa)5Se8 thin films

Antimony doped and undoped nanostructured thin films of AgIn1 − xGaxSe2 and Ag(InGa)5Se8 on optically flat soda lime glass substrates are prepared by a three stage co‐evaporation process. Energy dispersive analysis of X‐rays (EDAX) and X‐ray photoelectron spectroscopy in conjunction with atomic force microscopic technique and scanning electron microscopic technique are used, respectively, for compositional and surface morphological analysis of the films. X‐ray diffraction (XRD) data on the films are analysed to estimate the influence of antimony doping and indium replacement by gallium, on the structure of the films, by determining the anion–cation bond lengths and anion displacement in the thin films. The obvious dependence of band gap on the composition of the films establishes the possibility of band gap tailoring of the films. Low temperature optical absorbance measurements in the temperature regime 90–301 K are used for investigating the effect of doping on the temperature coefficient of band gaps of the films. Rutherford scattering spectra quantify the thickness of the films for conductivity (σ) measurements. The films exhibit n‐type conductivity with two linear regions in the ln(σ) versus temperature inverse graphs, which indicate a defect activated conduction and intrinsic conduction, respectively, in the near room temperature and high temperature regions.

Experimental study of the effect of dwell time and normal load on static friction in creeping elastic–plastic polymer spherical contact

An experimental study of the effect of dwell time and normal load on static friction in a spherical polymer contact is presented. The measurements are done for different diameters of spherical tip specimens made of polytetrafluoroethylene (PTFE). These specimens are loaded against a flat glass substrate by different normal loads and under different dwell times prior to applying tangential loading. It is found that the experimental immediate friction coefficient (after zero dwell time) is about an order of magnitude smaller than the theoretical results of a model proposed by Malamut et al. [S. Malamut, Y. Kligerman, I. Etsion, Tribol. Lett. 35 (2009) 159–170]. However, the creep components of the static friction force and static friction coefficients fairly agree with the model predictions.