Functional Optical Films Research Articles

Performance of multifunctional antibacterial moisture barrier films with different Zn/Al ratios fabricated by plasma enhanced atomic layer deposition

This study investigated Zn–Al composite oxide-based antibacterial moisture barrier film for flexible electronic devices using PEALD. Diethyl zinc and trimethyl aluminium precursors were used to deposit Zn and Al atoms, respectively, which were oxidised using oxygen plasma. The transmittance, refractive index, and water vapour transmission rate (WVTR), as well as the antibacterial and antifungal properties of the Zn–Al composite oxide thin films with different Zn/Al ratios were evaluated comparatively. The deposited films exhibited a linear change in refractive index from 1.66 to 1.87 and transmittance from 87.8 to 78.3% with an increase in the Zn ratio from 24.7 to 100. Furthermore, the film with a Zn ratio of 10.4 showed the best WVTR of 9.06 × 10−4 g/m2/day. In addition, the antibacterial and antifungal properties of the Zn–Al composite oxide thin films were evaluated through antibacterial and mould growth tests, respectively. All samples exhibited high antibacterial activities of 6.2 and 4.7 against Escherichia coli and Staphylococcus aureus, respectively, and no mould growth occurred on the surfaces of the Zn–Al composite oxide films. The antibacterial moisture-barrier films developed in this study can apply such as protecting human health, next-generation flexible touch displays and functional optical films.

Intense pulsed UV light treatment to design functional optical films from perhydropolysilazane: an alternative to conventional heat treatment processes

Intense pulsed UV light treatment to design functional optical films from perhydropolysilazane: an alternative to conventional heat treatment processes

P‐8.6: Research on Multifunctional Integrated Diffusion Plate in Backlight System

As one of key components of LCD device, backlight module can provide homogenized and high‐brightness light source for LCD panel. Generally, optical material in conventional straight down type backlight module include one diffusion plate and several functional optical films to further increase the homogenization of light source and the brightness of LCD panel. However, such multi‐film structure greatly increases not only the assemble complexity but also the cost of LCD device. Thus, it is desirable to integrate the multiple functions of these optical films in backlight module on single optical plate.In this report, we design and prepare a new composite optical plate that combining the diffusion with brightness‐enhancement functions. Firstly, optical plate with three layers was prepared by a co‐extrusion method, the upper surface of first layer was imprinted with prisms to enhance the brightness, and the third layer was added light diffusion particles to homogenize the light. In order to further increase the brightness‐enhance effect, another brightness enhance film was then bonded on the surface of the first layer of the optical plate.Obviously, the application of this multi‐functional composite optical plate will greatly reduce assembly complexity of LCD panel, improve the assembly efficiency and save the equipment investment and labour force, which finally reduces the cost of the whole backlight module. Therefore, the prepared composite optical plate meets the requirement of automatic manufacturing engineering and low cost of the backlight module industry, and has broad application prospects.

Fabrication of Viewing Angle Direction Brightness-Enhancement Optical Films using Surface Textured Silicon Wafers

We demonstrate a low-cost, superbly efficient way of etching for the nano-, and micro-sized pyramid patterns on (100)-oriented Si wafer surfaces for use as a patterned master. We show a way of producing functional optical films for the viewing angle direction brightness-enhancement of Lambertian LED (light emitting diode)/OLED (organic light emitting diode) planar lighting applications. An optimally formulated KOH (Potassium hydroxide) wet etching process enabled random-positioned, and random size-distributed (within a certain size range) pyramid patterns to be developed over the entire (100) silicon wafer substrates up to 8" and a simple replication process of master patterns onto the PC (poly-carbonate) and PMMA (poly-methyl methacrylate) films were performed. Haze ratio values were measured for several film samples exhibiting excellent values over 90% suitable for LED/OLED lighting purposes. Brightness was also improved by 13~14% toward the viewing angle direction. Computational simulations using LightTools<TEX>$^{TM}$</TEX> were also carried out and turned out to be in strong agreement with experimental data. Finally, we could check the feasibility of fabricating low-cost, large area, high performance optical films for commercialization.

Numerical and experimental study of the filling stage of roll-to-roll UV embossing process with micro features

Roll-to-roll (R2R) UV embossing is a promising low cost and high throughput process that leverages on rapid photo-curing to achieve high embossing speeds for manufacturing large area functional films. There are many potential commercial applications of this process such as flexible displays and functional optical films. However, productivity improvement was hindered by the low web speed at which the system can run without losing the feature fidelity. The current work aims to study the filling-stage of the R2R UV embossing process for s via numerical simulation and experimental validation, in order to better understand the process and identify the limiting factor for productivity improvement. Coupled Eulerian---Lagrangian algorithm was employed in the simulation to consider both deformation of the solid backing film and flow of the liquid UV resin. Their interaction is deemed to influence the mold filling distance. Model predicts that for the web speed of 3 and 30 m/min, the mold filling distance increases fractionally from 2.4 to 2.8 mm, indicating that the filling stage plays a minor role in the feature fidelity control if air entrapment is not considered. Experiments with the micro feature embosser further validate the simulation in a way that to point out it is the air entrapment which causes the incomplete filling. Some basic design rules of the micro features are also provided.

Fabrication of hybrid structures using UV roll-typed liquid transfer imprint lithography for large areas

Recently, nanoscale and micro-scale hybrid structures have become the focus of significant research interest due to their potential for use in anti-reflection films, anti-fingerprint films, solar cells, nanofluidic and microfluidic channels, and some functional optical films. Moreover, the nanopatterning lithography systems using roll-typed stamps have become increasingly appealing technologies for undertaking mass production and for continuous fabrication of hybrid patterns on large area substrates. In this study, we propose a roll-typed liquid transfer imprint lithography (R-LTIL) system and process for fabrication of nanoscale and microscale hybrid patterns on flat and micro lens substrates. Using the proposed system, nanoscale patterns that are 350nm hole and 250nm in height are flawlessly transferred to 6in. Si wafer and microscale lens substrates.

Micro lens-on-lens array

Four different types of micro lens-on-lens array structures, one of which corresponds to an array of a compound eye lens, were fabricated on a commercial plastic film using a novel fabrication technique. All lens-on-lens structures were fabricated not as an isolated lens but as an array on a transparent plastic film on a large scale. The technique developed in this work is expected to provide a route to new functional optical films.

Large area pattern replication by nanoimprint lithography for LCD–TFT application

Nanoimprint lithography is a high-throughput, low-cost, non-conventional lithographic method for fabricating micro/nanoscale patterns. In this study, we will present recent achievement in developing nanoimprint lithography for LCD–TFT fabrication. We fabricated metal gate for LCD–TFT with imprinting process. First, mold is pressed into a thin resist cast on a Cr layer which is deposited on a glass substrate. And the pressed resin is exposed to UV for curing, followed by demolding process. To acquire metal gate for LCD–TFT, subsequent process such as RIE with O 2 Plasmas, wet etching of Cr and striping of remained resin is followed. Finally, the fabricated metal gate has 3.5 μm level width, 97% uniformity overall on 1G size in a single imprint. Herewith nanoimprint lithography can substitute conventional photolithography steps in LCD–TFT process. Also it is expected that large area fine pattering such as functional optical films and PCBs could be effectively produced by nanoimprint process.

Design and Fabrication of Micro Optical Film by Ultraviolet Roll Imprinting

With increasing demand for large-scale functional optical films with microstructure in the field of flat panel displays, a technology capable of fabricating large-scale polymeric micro-patterns has received much attention. To fabricate large-area micro-optical films, we designed and constructed an ultraviolet roll imprinting system consisting of a roll stamp, a material dispensing unit, a pair of flattening rollers, a contact roller, and a releasing roller. Two methods for fabricating roll stamps were considered: direct machining of the roll base and wrapping a flat stamp around the roll base. As practical examples of the roll imprinting process, we designed and fabricated a lenticular lens array, a pyramidal pattern, and a microlens array, and measured and analyzed their geometrical and optical properties. Our results suggest that the proposed UV roll imprinting process is a feasible method for mass producing large-scale functional optical films.

Polarizing Properties of Functional Optical Films Based on Lyotropic Chromonic Liquid Crystals

We report results of the optical characterization of dried thin films obtained from the well-aligned nematic phase of a lyotropic chromonic liquid crystal (LCLC) by two different deposition techniques. The first one, the electrostatic layer-by-layer deposition technique, was used to prepare aligned LCLC films of a nanometer thickness in the form of a monomolecular layer and multi-layered stack. The second technique is the direct deposition technique. The films' optical characteristics such as dispersion of the light absorption indices, birefringence, polarizing efficiency, contrast ratio, transmittance of unpolarized light, were measured and compared with the correspondent characteristics of a cell filled with nematic solution of the same LCLC material.