Tin Oxide Cathode Research Articles

Cesium hydroxide doped tris-(8-hydroxyquinoline) aluminum as an effective electron injection layer in inverted bottom-emission organic light emitting diodes

We demonstrate highly efficient inverted bottom-emission organic light-emitting diodes (IBOLEDs) by using cesium hydroxide (CsOH) doped tris-(8-hydroxyquinoline) aluminum (Alq3) as the electron injection layer on indium tin oxide cathode, which could significantly enhance the electron injection, resulting in a large increase in luminance and efficiency. The maximum luminance, current efficiency, and power efficiency reach 21000cd∕cm2, 6.5cd∕A, and 3.5lm∕W, respectively, which are 40%–50% higher in efficiency than that of IBOLEDs with cesium carbonate (Cs2CO3) doped Alq3 as the electron injection layer, where the efficiencies are only 4.5cd∕A and 2.2lm∕W. Our results indicate that CsOH doped Alq3 should be an effective electron injection layer on a wide range of electrodes to fabricate high performance OLEDs.

Electrochemical Properties of Cathode for Solid Oxide Fuel Cell

Electrochemical properties (terminal voltage, ohmic resistance and overpotential) were measured for the cell of indium tin oxide cathode (ITO, 90 mass% In2O3-10 mass% SnO2) or perovskite-type oxide cathode La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) / Gd-doped ceria electrolyte (Ce0.8Gd0.2O1.9, GDC, 600-700 μm thick)/Ni-GDC anode using 3 vol% H2O-containing H2 fuel at 873 and 1073 K. The maximum power densities for the cell with ITO cathode at 873 and 1073 K were 21 and 71 mW/cm2, respectively. Similarly, the maximum power density with LSCF was 12 and 113 mW/cm2 at 873 and 1073 K, respectively. The voltage drop was larger for the cathode than for the electrolyte or anode. The overpotential of the LSCF cathode was comparable to the ohmic resistance.

Experimental Study on Transparent Polymer Light Emitting Diodes Using LiF/Ag/Indium Tin Oxide Cathode

In this work, we successfully demonstrate the transparent polymer light emitting diodes (PLEDs) with LiF/Ag/indium tin oxide (ITO) cathode that can efficiently improve the operation voltage and enhance light output. The devices with Ag insertion layer all perform the lower turn-on voltage in the range from 4.8 to 5.8 V at 1 mA/cm2. Furthermore, these devices all show the superior luminance than the device without Ag buffer layer. However, the transparency of cathode is strongly dependent on the Ag thickness. Devices with a 1 nm-thick layer Ag exhibits a higher transparency than other devices with Ag layers, thus showing the highest luminance from the top cathode. In addition, the Ag insertion layer also plays a role to prevent the emitting layer from sputtering bombard damage. According to X-ray photoemission spectroscopy (XPS) measurement, it is observed that the Ag layer will sufficiently protect the emitting layer from sputtering penetration damage under a sputtering power of 50 W. In this paper, we present a practical structure for realizing transparent PLEDs.

Optical enhancement in semitransparent polymer photovoltaic cells

This letter reports our efforts to improve the power conversion efficiency (PCE) and the optical transparency of semitransparent poly(3-hexylthiophene) (P3HT):1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C60 (PCBM) based photovoltaic (PV) cells. Semitransparent P3HT:PCBM based solar cells were prepared based on parameters obtained by optical admittance analysis. The performance of structurally identical polymer PV cells made with a reflective calcium/silver cathode and a semitransparent Ca(10nm)∕Ag(10nm)/indium tin oxide cathode are compared. For semitransparent polymer PV cells with a 75nm thick active P3HT:PCBM blend layer, an average transmission of more than 30% was achieved with a high PCE of 1.7% under simulated AM1.5G illumination of 100mW∕cm2.

Highly efficient transparent organic light-emitting diodes by ion beam assisted deposition-prepared indium tin oxide cathode

The authors have investigated the effects of indium tin oxide (ITO) deposited by ion beam assisted e-beam evaporation on the performance of polymer light-emitting diodes. ITO was evaporated as a cathode onto a thin Mg:Ag layer by an e-beam process, and its performance as a transparent cathode was subsequently compared to that of Mg:Ag and sputtering-prepared ITO. Polymer devices’ luminance and efficiency were improved by more than ten times by ion beam assisted deposition (IBAD)-prepared ITO deposition, with little observable damage to the organic layer. Implementation of the IBAD process resulted in the reduction of the interfacial energy barrier which induced band bending. Furthermore, outcoupling with ITO resulted in enhanced luminance.

Improving the Performance of Transparent PLEDs with LiF∕Ag∕ITO Cathode

This work demonstrates the favorable performance of a transparent polymeric light-emitting diode (PLED) using an effective LiF/Ag/indium tin oxide (ITO) cathode. An Ag layer can prevent the underlying emitting layer from damage by bombardment during ITO sputtering. Devices that have an Ag layer have a lower driving voltage and lower leakage current than those without. X-ray photoelectron spectroscopy data show that Ag increases the concentration of Li in the polymer, enhancing its electron injection and transport capacities. The lower leakage current results from the fact that the work function of Ag is lower than that of ITO. The insertion of the Ag layer also enhances the optical characteristics by improving carrier balance and reducing sputtering damage.

Transparent Conductive Thin Film for Top Emitting Organic Light Emitting Diodes by Sputtering Method

The indium tin oxide (ITO) cathode electrode of top emitting organic light emitting diodes (TOLEDs) was deposited by facing targets sputtering (FTS) method which can deposit thin films with low substrate damage. And it also use a plasma-free sputtering method in which substrate is located apart from plasma. So the temperature increase of substrate due to the bombardment of high-energy particles can be restrained. The ITO thin film which is a transparent electrode was deposited on the cell (Mg:Ag/LiF/EML/HTL/ITO) using two magnetic field such as concentrated magnetic field type and distributed magnetic field type, respectively. Also, the ITO thin films were deposited by sputtering current at working gas (Ar:O2 mixture gas) pressure 1 mTorr. Electrical and optical properties of ITO thin films which deposited on amorphous glass were measured and current–voltage (I–V) characteristics of ITO thin film on the cell were measured. In the results, the leakage-current density of ITO/cell prepared at concentrated magnetic filed type and distribution magnetic filed type showed about 1×10-3 mA/cm2 at -6 V and 1×10-5 mA/cm2 at -6 V, respectively.

Experimental Study of Chemical Reaction between LiF and Polyflourene Interface during Sputtering Indium–Tin Oxide Cathode for Top Emission Polymer Light Emitting Devices

Top emission polymer light-emitting devices (PLEDs) with different heat treatments are investigated. Due to the high work function of an indium–tin-oxide (ITO) cathode as a top electrode, LiF is employed as an interlayer to increase electron injection. The PLEDs fabricated at room temperature show better electrical and optical characteristics such as current density–voltage, luminance, and current efficiency, etc., than that of PLED devices with heat treatment. To investigate the Li diffusion in the polyfluorene layer, X-ray photoelectron spectroscopy measurement before and after heat treatment is performed. The poor performance of PLEDs with heat treatments is observed due to the high trap density generated in the film because of the Li diffusion in the polyfluorene layer.

Characteristics of Indium Zinc Oxide Top Cathode Layers Grown by Box Cathode Sputtering for Top-Emitting Organic Light-Emitting Diodes

Electrical, optical, and structural properties of indium zinc oxide (IZO) films grown by a box cathode sputtering (BCS) were investigated as a function of oxygen flow ratio. A sheet resistance of , average transmittance above 88% in visible range, and root-mean-square roughness of were obtained even in the IZO layers grown at room temperature. The top-emitting organic light-emitting diodes (TOLEDs) with the IZO top cathode layer were prepared and their electrical properties compared with TOLEDs with Mg-Ag/indium tin oxide (ITO) cathode layer and TOLEDs with only thermally evaporated Mg-Ag cathode layer. In addition, the effects of oxygen flow ratio in IZO films are investigated, based on X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet/visible (UV/VIS) spectrometer, scanning electron microscopy (SEM), and atomic force microscopy (AFM) analysis results.

Plasma damage-free sputtering of indium tin oxide cathode layers for top-emitting organic light-emitting diodes

We report on plasma damage-free sputtering of an indium tin oxide (ITO) cathode layer, which was grown by a mirror shape target sputtering (MSTS) technique, for use in top-emitting organic light-emitting diodes (TOLEDs). It is shown that OLEDs with ITO cathodes deposited by MSTS show much lower leakage current (9.2×10−5mA∕cm2) at reverse bias of −6V as compared to that (1×10−1–10−2mA∕cm2 at −6V) of OLEDs with ITO cathodes grown by conventional dc magnetron sputtering. Based on high-resolution electron microcopy, x-ray diffraction, and scanning electron microscopy results, we describe a possible mechanism by which plasma damage-free ITO films are grown and their application for TOLEDs.

Improvement in performance of transparent organic light-emitting diodes with increasing sputtering power in the deposition of indium tin oxide cathode

The performance of transparent organic light-emitting diodes (OLEDs) can be substantially improved by increasing the rf sputtering power in the deposition of an indium tin oxide cathode. This dependence of device performance on sputtering power is quite different from that reported for transparent OLEDs. The effect is attributed to sputtering induced substrate-heating resulting in chemical reactions at the Al–LiF–Alq3 interface and electron injection enhancement. By effectively dissipating the energy of sputtered particles, device damage can be taken away. The findings herein show that a transparent OLED having better electron injection properties than a conventional OLED can be fabricated.

Electrochemical and Laser Deposition of Silver for Use in Metal-Enhanced Fluorescence.

We describe two reagentless methods of silver deposition for metal-enhanced fluorescence. Silver was deposited on glass positioned between two silver electrodes with a constant current in pure water. Illumination of the glass between the electrodes resulted in localized silver deposition. Alternatively, silver was deposited on an Indium Tin Oxide cathode, with a silver electrode as the anode. Both types of deposited silver produced a 5-18-fold increase in the fluorescence intensity of a nearby fluorophore, indocyanine green (ICG). Additionally, the photostability of ICG was dramatically increased by proximity to the deposited silver. These results suggest the use of silver deposited from pure water for surface-enhanced fluorescence, with potential applications in surface assays and lab-on-a-chip-based technologies, which ideally require highly fluorescent photostable systems.

Use of a Single Anionic Conductor as a Hole-Injecting Material for Polymer Light-Emitting Diodes

A single anionic conductor (SAC) was employed to improve the hole injection properties in an Al anode/SAC/poly[2-methoxy-5-(2′-(ethylhexyloxy)-1,4-phenylenevinylene) emissive layer/indium tin oxide cathode device. The SAC possesses an excellent hole-injection property, because of ionic space charge accumulation near the anode by the good chain segmental motion of the soft block in the polymer chains of the SAC. Thus, a balanced injection of an electron-hole pair can be achieved to greatly improve the quantum efficiency.

A Multilayer Iron‐Thionine Photogalvanic Cell

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