Patterned Indium Tin Oxide Research Articles

Selective recovery of indium from the etching waste solution of the flat-panel display fabrication process

The waste byproducts from the indium-consuming fabrication processes are considered as the viable resource for indium due to the unique preference to the element in designing optoelectronic devices. The present work introduces a new technique for the selective recovery of indium from the etching waste, which produced during the patterning of indium tin oxide (ITO) layer on the flat-panel displays. The process includes the application of a solid phase extraction (SPE) assembly, known as molecular recognition technology (MRT) gel, consisting of a metal-selective ligand immobilized to silica gel or polymer substrates. The samples were the real solution of etching waste from the liquid-crystal display fabrication process, and the simulated waste solution prepared using the commercially available etching solution composition containing ethanedioic acid. The retention and the corresponding indium recovery rate (%) were the key characteristics for the appraisal of MRT-SPE types: AnaLig TE 02 (TE 02), AnaLig TE 03, AnaLig TE 07, AnaLig TE 13 and AnaLig PM 02. The other conclusive factors were the influence of ion intensity in solution and the interfering effects from tin, the co-content element in the ITO-formulation. The TE 02 MRT-SPE came across all the requisite aspects for the selective recovery of indium from the etching effluent. The indium retention or recovery with TE 02 MRT-SPE from the real etching waste solution was in the range of 97 to 99% with the relative standard deviation of <4.4%. The separation of the ITO co-element tin from the waste mixture was successively selective, and thereby minimizes the possibility of interference. A three-step elution with 0.3molL−1 HNO3, 6molL−1 HCl and 1molL−1 HCl/10mmolL−1 EDTA was required to accomplish the sequential selectivity in the process. The indium retention capacity of the TE 02 MRT-SPE was 0.147mmolg−1.

Design and fabrication of tunable liquid crystal diffractive lens

A type of tunable liquid crystal diffractive lens (TLCDL) for monochromatic wave base on multiorder diffraction is proposed and demonstrated. Two TLCDLs were designed using patterned indium tin oxide and a conductive surface relief electrode, respectively. The focus tuning mechanism of the lens has been proved using multiorder diffractive structure. One TLCDL with three switchable focal lengths was fabricated using an imprinting technique, which significantly reduced fabrication complexity. Electro-optic performances of the TLCDL were studied with monochromatic illumination. High image quality with low operating voltage and fast response time has been realized.

Ultra-violet laser processing of graphene on SiO2/Si

A graphene transparent electrode might be used in industry in the near future instead of indium tin oxide (ITO). For patterning of ITO, the maskless laser process was reported as a simple and fast process. In this paper, effects of ultra-violet laser irradiation to graphene on SiO2/Si are investigated. The experimental results show that the threshold thickness of graphene for complete removal from the SiO2/Si substrate by laser irradiation is approximately 10nm. Thinner graphene layers than the threshold thickness were removed by laser irradiation with a power density of larger than approximately 3.5MW/cm^2. The mechanism for the observed complete removal of graphene should be ejection due to the supersonic elastic vibration of the substrate caused by pulsed laser irradiation.

Ultrafast laser parallel microprocessing using high uniformity binary Dammann grating generated beam array

Ultrafast laser parallel processing using diffractive multi-beam patterns generated by a spatial light modulator (SLM) has demonstrated a great increase in processing throughput and efficiency. Applications ranging from surface thin film patterning to internal 3D refractive index modification have been recently reported with the parallel processing technology. Periodic and symmetrical geometry design (e.g. N×M beam array) of the multi-beam pattern must be avoided to guarantee the required high uniformity in these applications, which, however, limited the processing flexibility. In this paper, Dammann gratings are used to create diffractive 1×5 and 5×5 beam arrays for the parallel processing. The 0-th order, observed slightly stronger than the other higher orders, can be adjusted by superimposing a Fresnel zone lens (FZL) and tuning the degree of defocusing at the processing plane. The uniformity (presented by the variation of the machined hole diameter) is measured to be <4% after the adjustment. Additionally, a parallel surface patterning of indium tin oxide (ITO) thin film with periodic array structures was demonstrated using the Dammann grating generated beam array without requiring the complicated geometry separation and the time-consuming positioning.

Texture design of electrodes for efficiency enhancement of organic solar cells

We report a simple solution-based approach to form ordered patterns of an indium tin oxide (ITO) electrode and underlying reasons for the improvement in power conversion efficiency (PCE) of organic solar cells (OSCs) built on the nanostructured ITO electrode. The patterning of ITO was achieved by using nanospheres as the template to erode ITO by wet chemical etching. Using a textured ITO anode for poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61-butyric acid methylester (PCBM) (P3HT:PCBM) OSCs enhanced PCE by 15% with respect to the non-patterned ITO anode. The improvement is mostly attributed to the morphological and interfacial changes stemming from the textured ITO electrode as well as enhanced light absorption due to the optimal morphology and refractive index change of patterned ITO. With its simplicity and time-saving, this method of fabricating a unique pattern of ITO electrodes can be widely applicable to a variety of large-area thin film solar cells.

Effects of ITO Pattern on the Electrical and Optical Characteristics of LEDs

We studied on the effects of patterned indium-tin oxide (ITO) on the electrical and optical characteristics of GaN-based light-emitting diodes (LEDs) in detail. In our experiment, LEDs with varied patterned ITO layers are fabricated. The electrical and optical characteristics are analyzed through the diode equation and 3D electro-thermal simulation, the rate equation and Monte-Carlo ray-tracing simulation, respectively. The analysis results indicate that the light output power (LOP) of the LEDs with patterned ITO achieve an enhancement of 12.7% compared to that of the LEDs with planar ITO. Moreover, the series resistance and ideality factor are the minimum when ITO is planar, and will increase with spacing of ITO pattern decreasing due to the degeneration of current spreading and ohmic contact. However, the light extraction efficiency (LEE) is smaller for LEDs with planar ITO and will increase with spacing decreasing, which is due to the increase of probability of photon redirecting and escaping. These analysis results are helpful to understand the effects of ITO pattern on electrical and optical characteristics and therefore to design an optimal pattern structure.

Multicomponent Patterning of Indium Tin Oxide

We report a versatile functionalization and pattering technique that permits multicomponent pattern-specific modification of indium tin oxide (ITO) with organic species. The method relies on a bilayered molecular system that simultaneously protects ITO from degradation and provides uniform chemical functionality suitable for further elaboration. Pattern-specific modification is achieved via specific reaction between functionality on an elastomeric stamp and functionality of cognate reactivity at the surface of a bilayered molecular substrate. We demonstrate that a single molecular system in a combination with different printing approaches can be used to immobilize multiple organic functionalities with exquisite spatial control on a single ITO surface. Our study provides the first general approach that permits patterning and functionalization of ITO with different molecules using a single set of printing conditions and materials.

Enhanced light extraction in organic light-emitting devices: Using conductive low-index layers and micropatterned indium tin oxide electrodes with optimal taper angle

We present our study on organic light-emitting diodes (OLEDs) in which outcoupling is enhanced based on a bilayer electrode consisting of a conductive low-index layer and micro-patterned indium tin oxide (ITO) layers. Optical simulation reveals that the taper angle of an ITO pattern is among the most critical parameters influencing the outcoupling efficiency in the proposed structure. A fabrication method based on a lift-off process is then employed to control the taper angle of the ITO pattern to be in the optimal range. OLEDs with the proposed electrode structure exhibit 50%–70% enhancement in external quantum efficiency over reference devices.

Effects of ultra-violet laser irradiation on graphene

► Graphene can be applied for transparent electrodes instead of ITO . ► Maskless laser process was formerly reported for ITO patterning. ► Raman spectra was measured before and after UV laser irradiation . ► D/G ratio of Raman spectra was affected by lasers indicating defect generation. ► Resistance was more sensitive than Raman spectrum. Graphene can be applied for transparent electrodes instead of indium tin oxide (ITO). For patterning of ITO, the maskless laser process was reported as a simple and fast process. Raman spectra and electrical resistances of graphene were measured before and after ultra-violet laser irradiation to investigate the possibility of maskless laser process. The Raman spectrum was affected by laser irradiation (>3 MW/cm 2 ), indicating defects generation. The resistance was more sensitive to laser irradiation than the Raman spectrum.

Enhanced photoefficiency in positive-tone direct patterning of metal complexes for forming patterned indium tin oxide films

The efficiency of positive-tone directly photo-patternable 4-(2-nitrobenzyloxycarbonyl)catechol and 4-(6-nitroveratryloxycarbonyl)catechol complexes of indium tin was improved by tuning the solubility of the complexes and by chelation of maltol as a cooperative photo-solvolytic component, such that films could be patterned at up to 4.88mW·s/nm in terms of resultant indium tin oxide (ITO). Patterned indium tin complexes were thermally transformed to pattern shape preserved ITO by anisotropic contraction and oxidation. The photo-reaction of these ligands and related derivatives was characterized by nuclear magnetic resonance analysis showing decomposition to the respective carboxylic acid for which linear rate constants were approximated, further elucidating the mechanism and mechanics of selective solubility.

이층 박막 구조에서 ITO 전극의 레이저 직접 패터닝 시레이저 식각 패턴 중첩 비율의 변화

Laser direct patterning of indium tin oxide(ITO) is one of new methods of direct etching process to replace the conventional photolithography. A diode pumped Q-switched Nd: (

Growth of Indium Oxide Nanowalls on Patterned Conducting Substrates: Towards Direct Fabrication of Gas Sensors

Nanowall materials are ideal two-dimensional structures with high surface-to-volume ratios and open edge geometries. We first report on the growth and characterization of indium oxide nanowalls on transparent and conducting indium tin oxide substrates. The nanosheets that compose the nanowalls are single-crystalline and are approximately 8 nm in thickness. The density and the lateral dimensions of the nanosheets on the substrate can be controlled by the growth time. Adopting a bridgework-like strategy, we directly construct indium oxide nanowall gas sensors on the patterned indium tin oxide substrates. The pattern lines on the substrates are etched using transparent plastic adhesive tape as shadow mask, which is both simple and cheap in comparison with the conventional photolithography technique. The sensors exhibit fast response/recovery behavior and good reproducibility to NO(2) gas under mild testing conditions, such as room temperature, ambient pressure, dry air background, and 1.5 V dc bias, and can achieve a detection limit as low as 50 ppb. We propose an assumption that the gas adsorption is composed of deep adsorption and probe adsorption to explain the interesting gas-sensing behavior of the indium oxide nanowalls. We suggest that the work reported herein, including the facile growth of indium oxide nanowalls, the bridgework-like strategy to directly construct electronic devices, and the high gas-sensing performance of the indium oxide nanowalls sensors, is a significant step towards the real applications of novel semiconductor nanostructures.

Bifunctional ITO layer with a high resolution, surface nano-pattern for alignment and switching of LCs in device applications

We describe a novel method for liquid crystal (LC) alignment using nano-patterns of electrically conductive indium–tin oxide (ITO) layers with high resolution (ca< 20 nm) and high aspect ratio (ca 10), fabricated based on the secondary sputtering phenomenon. The ITO pattern developed in this manner not only provides high anchoring energy comparable to that of rubbed polyimides, but also maintains its low resistivity as an electrode. As a result, the patterned ITO can function as an electrode and alignment layer at the same time, which facilitates successful fabrication of bifunctional conductive alignment layer for LC devices. The LC cells fabricated using patterned ITO substrates show highly stable alignment of LCs over large area and good electro-optical responses. Moreover, systematic approach made by the precise control of pattern dimensions allows us to estimate a critical anchoring energy required for an effective LC alignment based on Berreman's theory.

Enhanced performance of organic light-emitting devices by using electropolymerized poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film as the anode modification layer

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films were prepared by electropolymerization on patterned indium tin oxide substrates in isopropanol solution. The thickness and doping level of the PEDOT:PSS films were controlled by adjusting the electropolymerization time and the concentration of poly(styrene sulfonate) acid, respectively. Organic light-emitting diodes were fabricated using the electropolymerized PEDOT:PSS film as the anode modification layer. The dependence of the performance on thickness of PEDOT:PSS films was investigated. It is shown that the performance of the device can be further enhanced when the thickness of PEDOT:PSS films reached an optimum condition. This method facilitates manufacturing procedures of conducting polymers films and may offer an economical route for producing organic electroluminescent devices.

Optical panel with full multitouch using patterned indium tin oxide

This study proposes an optical panel with full multitouch using the patterned indium tin oxide (ITO) and an algorithm matrix to avoid ghost points. The patterned ITOs include the virtual high and low impedances. The algorithm matrix with two configurations of equivalent circuits for array scanning is derived using the voltage divider rule. The fabrication process of the multitouch panel is carried out using microelectromechanical systems technology. The optical characteristics of the multitouch panel in the UV, visible, and IR regions are measured using photometric analysis. The multitouch panel, containing sensing pixels of 30×30 arrays, has a pixel size of 2×2 mm2 and a pitch distance of 2 mm. The average values of high and low impedances are 53.23 and 9.3 k Ω, respectively. The maximum transmittance is about 74.2% at the wavelength of 692 nm. The multitouch panel based on high and low impedance patterns has been specifically designed to offer good adjacent touch resolution and sensitivity for reality multitouch applications. In addition, the patterned design and the algorithm matrix provide unlimited multitouch points and avoid ghost points.

Electrically modulated attachment and detachment of animal cells cultured on an optically transparent patterning electrode

The purpose of this study was to develop the modulation methods for the attachment and detachment of specifically positioned adhesive animal cells cultured on an electrode surface with the application of a weak electrical potential. A patterned indium tin oxide (ITO) optically transparent working electrode was placed on the bottom of a chamber slide with a counter-(Pt) and reference (Ag/AgCl) electrode. The ITO patterning was formed by a reticulate ITO region and arrayed square glass regions of varying size. Using the 3-electrode culture system, the author succeeded in modulation of the attachment and detachment of animal cells on the working electrode surface. Animal cells suspended in serum or sera containing medium were drawn to and attached on a reticulate ITO electrode region to which a +0.4-V vs. Ag/AgCl-positive potential was applied. Meanwhile, the cells were successfully placed on the square glass regions by -0.3-V vs. Ag/AgCl-negative potential application. Animal cells were detached not only from the ITO electrode but also from the square glass regions after the application of a ±10-mV vs. Ag/AgCl, 9-MHz [corrected] rectangular wave potential in PBS(-) for 30-60 min. Rectangular wave potential-induced cell detachment is almost completely noncytotoxic, and no statistical differences between trypsinization and the high frequency wave potential application were observed in HeLa cell growth. The electrical modulation of the specifically positioned cell attachment and detachment techniques holds potential for novel optical microscopic cell sorting analysis in lab-on-chip devices.

Scanning electrochemical microscopy as an etching tool for ITO patterning

This work presents a new patterning technique of Indium Tin Oxide (ITO) thin films using the microelectrode of a Scanning Electrochemical Microscope (SECM). With the development of new display technologies, patterned indium tin oxide (ITO) films have enormous growth potential and can find applications in any device that requires transparent and conductive electrodes. To optimize the performances of such devices, a clean patterning technique providing straight sidewalls and control of surface chemistry and physical properties is needed. We report here a simple and one-step patterning technique of ITO using scanning electrochemical microscopy as a soft etching tool. This electrochemical wet-lithographic technique provides a fast and low cost patterning process and is performed in an aqueous acid electrolytic solution. This maskless technique leads to a clean etching with straight walls and no redeposition of the ablated part. The subjacent substrate (glass or polymer) is not damaged by this technique and the electrical and/or optical properties of the remaining ITO film are preserved.

Visible ITO Pattern in Capacitive Touch Lens: Cause and Countermeasure

ABSTRACTMarket demand for touch panel/lens has been exceptionally high for the recent years due to smartphones, tablet PCs, etc. Among the available technologies to envision touch functionality, capacitive touch screen has received the great attention due to the various superiorities over the competing ones. Capacitive touch screen features two transparent conductive electrodes, such as ITO (indium tin oxide). However, the difference in refractive indices of ITO, substrate, and air, ITO pattern is clearly visible if there is no proper countermeasure. Most of touch screen makers and ITO substrate supplier utilize “index-matching technology” to prevent this phenomenon.Even though of the attempts to minimize visible ITO pattern in final product, there are many technical and process challenges. In this study, the causes around visible ITO pattern were investigated to understand and provide the proper countermeasures.One of the possible causes for visible ITO pattern was improper annealing process in ITO especially for film substrate. According to XPS (X-ray photoelectron spectroscopy)/ESCA (electron spectroscopy for chemical analysis) and other analysis results, ITO, which is normally deposited through sputtering, is not fully transformed to oxidized state. After aligning and adjusting annealing condition, acknowledged visible ITO pattern was disappeared.Other causes for visible patterns were also discussed in detail, and the relevant countermeasures were provided.

Improvement in External Quantum Efficiency of InGaN-Based LEDs by Micro-Textured Surface with Different Geometric Patterns

This investigation elucidates the traditional p-side-up InGaN/GaN multiple-quantum well (MQW) light-emitting diodes (LEDs) with different geometric patterns of microtextured indium-tin-oxide (ITO) surface using standard photolithography and wet chemical etching technique. The LEDs fabricated with the surface-textured ITO, concave and convex patterns, have the same forward voltage as the reference LED with planar-ITO, but provide higher light output power, increased by 7.9% and 16.3%, at 20 mA current injection, respectively. In addition, the external quantum efficiency (EQE) of LEDs were also enhanced from 18% (planar) to 19.4% and 21% (concave and convex patterned). The larger light output power and higher external quantum efficiency could be attributed to the microtextured ITO surface. With the textured ITO surface, especially the convex pattern, with light scattering effect at the ITO/air interface, photons could escape from the device more easily, thus increasing the light output power and external quantum efficiency of GaN-based LEDs at the same time.

Selective Patterning of ITO on flexible PET Substrate by 1064 nm picosecond Laser

Pulsed picosecond laser ablation of indium tin oxide (ITO) coated on flexible polyethylene terephthalate (PET) substrate has been investigated. Pulses with 355nm, 532nm and 1064nm wavelengths are performed for comparison. Laser irradiation from the front side and the back side are analyzed. The single pulse ablation threshold is found at 0.56J/cm2 from the study of the spot sizes varied according to pulse fluence. The overlap rate in multi pulses ablation of ITO layer is discussed during the scribing of lines. Optical microscopy, SEM, surface stylus and EDX analysis reveal that the ITO layer can be completely removed with little damage of the PET substrate using optimized parameters.