Inorganic Al2O3 Research Articles

Thin film Encapsulations of Flexible Organic Light Emitting Diodes

Various encapsulated films for flexible organic light emitting diodes (OLEDs) were studied in this work, where gas barrier layers including inorganic Al2O3 thin films prepared by atomic layer deposition, organic Parylene C thin films prepared by chemical vapor deposition, and their combination were considered. The transmittance and water vapor transmission rate of the various organic and inorgabic encapsulated films were tested. The effects of the encapsulated films on the luminance and current density of the OLEDs were discussed, and the life time experiments of the OLEDs with these encapsulated films were also conducted. The results showed that the transmittance are acceptable even the PET substrate were coated two Al2O3 and Parylene C layers. The results also indicated the WVTR of the PET substrate improved by coating the barrier layers. In the encapsulation performance, it indicates the OLED with Al2O3 /PET, 1 pair/PET, and 2 pairs/PET presents similarly higher luminance than the other two cases. Although the 1 pair/PET encapsulation behaves a litter better luminance than the 2 pairs/PET encapsulation, the 2 pairs/PET encapsulation has much better life time. The OLED with 2 pairs/PET encapsulation behaves near double life time to the 1 pair encapsulation, and four times to none encapsulation.

Performance Improvement of Polyvinyl Formal Based Gel Polymer Electrolyte for Lithium-Ion Batteries by Coating Al<sub>2</sub>O<sub>3</sub>

Al2O3/PVFM/Al2O3 trilayer membranes are prepared by means of simple coating of PVA-Al2O3 solution onto both sides of PVFM thin membranes, which is prepared via phase inversion method. The characteristics of the trilayer membranes and gel polymer electrolytes are investigated using FESEM, tensile testing apparatus, thermal shrinkage test, EIS and charge-discharge test. When inorganic Al2O3 particles are used to coat the PVFM membrane, drawbacks associated with gel-type membranes, namely, poor mechanical strength and thermal stability are greatly improved. Lithium ion cell with the Al2O3/PVFM/Al2O3 based GPE matched with LiFePO4 shows excellent electrochemical performance.

Optical Properties of Hybrid Inorganic/Organic Thin Film Encapsulation Layers for Flexible Top-Emission Organic Light-Emitting Diodes.

Inorganic/organic hybrid thin film encapsulation layers consist of a thin Al2O3 layer together with polymer material. We have investigated optical properties of thin film encapsulation layers for top-emission flexible organic light-emitting diodes. The transmittance of hybrid thin film encapsulation layers and the electroluminescent spectrum of organic light-emitting diodes that were passivated by hybrid organic/inorganic thin film encapsulation layers were also examined as a function of the thickness of inorganic Al203 and monomer layers. The number of interference peaks, their intensity, and their positions in the visible range can be controlled by varying the thickness of inorganic Al2O3 layer. On the other hand, changing the thickness of monomer layer had a negligible effect on the optical properties. We also verified that there is a trade-off between transparency in the visible range and the permeation of water vapor in hybrid thin film encapsulation layers. As the number of dyads decreased, optical transparency improved while the water vapor permeation barrier was degraded. Our study suggests that, in top-emission organic light-emitting diodes, the thickness of each thin film encapsulation layer, in particular that of the inorganic layer, and the number of dyads should be controlled for highly efficient top-emission flexible organic light-emitting diodes.

High performance hybrid Al2O3/poly(vinyl alcohol-co-ethylene) nanofibrous membrane for lithium-ion battery separator

Abstract High performance Al 2 O 3 @NFs/PET/NFs separator possessing hierarchically three-dimensional tortuous structure has been developed to promote the cell performance of NFs/PET/NFs separator. The separator comprises a poly (ethylene terephthalate) (PET) nonwoven sandwiched between two poly (vinyl alcohol- co -ethylene) (PVA- co -PE) nanofirous membrane and inorganic Al 2 O 3 coating layers on both sides for surface modification. The Al 2 O 3 @NFs/PET/NFs separator shows high porosity and impressively superior electrolyte affinity, thus resulting in higher ion conductivity, smaller interfacial resistance, excellent rate capabilities and cycling performance, compared to the NFs/PET/NFs separator and a commercial PP/PE/PP separator. This high cell performance can be ascribed to synergetic effects of inherent good hydrophilicity of γ -Al 2 O 3 nanopowder coatings and well-designed tortuous nanoporous structure of NFs/PET/NFs membrane. This study suggests that the Al 2 O 3 @NFs/PET/NFs separator is a desirable alternative to commercial lithium-ion battery separators, especially promising for large-sized lithium batteries.

플라즈마 중합된 Styrene을 유기박막으로 사용한 하이브리드형 OLED 봉지기술

We report thin-film organic moisture barriers based on polystyrene(PS) laminates deposition by PECVD for an encapsulation of OLEDs. The organic polystyrene thin-film has the benzene ring structure and high hydrophobic characteristics and it was polymerized by PECVD in dry process. Life time properties of Ca test were obtained 32 minutes at the RF 100W process conditions. From the AFM test, the roughness of multi-layer thin-film was more excellent rather than that of a single-layer thin-film. In addition, 5 layers of the multi-layer film properties were obtained 45 minutes. So that the optical and electrical properties were not affected with these plasma polymerized organic thin-film encapsulation. For life time improvement, the inorganic Al2O3 thin-film were deposited 5nm using ALD atomic layer deposition. The WVTR(Water Vaper Transmission Rate) value of hybrid thin-film encapsulation in the optimum process conditions was resulted by less than 10-3g/㎡/day. From the results of experiment, plasma polymerized hybrid encapsulation was suggested as the flexible display applications.

Nanocomposites of Poly(vinyl alcohol) Reinforced with Chemically Modified AL2O3: Synthesis and Characterization

The surface of α-alumina (Al2O3) nanoparticles was first modified with γ-aminopropyltriethoxy silane as a coupling agent. Then a series of poly(vinyl alcohol)/ surface modified Al2O3 nanocomposite suspensions were prepared in ethanol by a simple ultrasonic irradiation process. Composite films with 5, 10, and 15 wt % of inorganic Al2O3 nanoparticles were achieved after solvent evaporation. The formation of the composite materials were confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and optical transparencies. The FE-SEM and TEM results showed a homogenous dispersion of nanoscale inorganic particles in the poly(vinyl alcohol) matrix. TGA thermographs showed that the thermal stability of the prepared Al2O3-reinforced nanocomposites was improved, increasing with increasing content of the nanoparticles. According to the optical transparencies, the optical clar...

Photolithography-free fabrication of organic light-emitting diodes for lighting applications

We investigate the photolithography-free fabrication of organic light-emitting diodes (OLEDs) for lighting applications with an attempt to embed the deposition and patterning process of an indium–tin–oxide (ITO) anode and insulating layer into an in-line-type organic evaporation system. This scheme inevitably brings in leakage current induced by the spike-like surface of ITO. To suppress it, we cover the ITO edges with three different insulation materials (i.e. sputter-deposited inorganic Al2O3 thin film, monomer (polymer) thin film deposited by organic acrylate evaporation or thermally evaporated organic insulation layer (tris-(8-hydroxyquinoline) aluminum (Alq3))). Although small-molecule organic insulation materials that can be thermally evaporated are the most suitable for such a cost-effective fabrication process, yet their insulation capability is low due to the carrier transporting property. In this paper, we demonstrate that it can be boosted to a great extent with an increase of their thickness. It is likely that pinholes existing on the Al2O3 thin film act as leak channels, degrading the device performance. We also verify that the insulation capability of polymer fabricated by organic acrylate evaporation is just comparable with that of polyimide (PI) insulator patterned using a standard photolithography process.

A BOD biosensor based on a microorganism immobilized on an Al2O3 sol–gel matrix

A novel BOD biosensor has been fabricated from a microbial membrane on an oxygen electrode; a porous inorganic Al2O3 sol-gel matrix was used to immobilize the yeast. Use of the sensor is convenient and rapid compared with the official BOD5 method. The gelation time required to form the microorganism membrane was less than 15 min. There was linear relationship between the response (sensor current) and BOD values ranging from 10-50 mg x L(-1). The lifetime of the BOD biosensor was more than 30 days at ambient temperature.