Conductive Indium Tin Oxide Research Articles

Thickness dependent physical and photocatalytic properties of ITO thin films prepared by reactive DC magnetron sputtering

Transparent and conducting indium tin oxide (ITO) thin films were deposited on glass substrates by reactive DC magnetron sputtering at room temperature. The effect of thickness (165–1175nm) on the physical (structural, optical, electrical) and photo catalytic properties of ITO thin films were investigated systematically. It is observed that with increasing thickness (i) the films turn from amorphous to polycrystalline with a preferential orientation along (440) direction, (ii) the average grain size and RMS roughness increases from 35nm to 100nm and 2.3nm to 8.6nm respectively, (iii) the optical band gap decreases from 3.65eV to 3.45eV and (iv) the relative density (calculated from the refractive index data) decreases. Four probe and Hall effect measurements show a low resistivity (4.5×10−4Ωcm), mobility (26cm2/Vs) and high carrier concentration (5.3×1020cm−3) values for film with a thickness 545nm. The work function of ITO films measured by Kelvin probe method varies with thickness. The photocatalytic activity (PCA) of ITO thin films was studied by the degradation of Rhodamine B in water; highest PCA is shown for the films of 545nm thickness. Present work shows that the ITO is a promising photocatalytic material for the degradation of organic compounds.

ChemInform Abstract: Preparation of Electrically Conducting Indium-Tin Oxide Thin Films by Heat Treatment of Mixed-Metal Hydroxide Dispersion Containing Polymer Binder.

ChemInform Abstract: Preparation of Electrically Conducting Indium-Tin Oxide Thin Films by Heat Treatment of Mixed-Metal Hydroxide Dispersion Containing Polymer Binder.

ChemInform Abstract: Characterization of Electrochromic Nickel Oxide Thin Films Prepared by Anodic Deposition.

Nickel oxide (NiOx) thin films have been prepared on transparent conducting indium tin oxide (ITO) substrates by anodic deposition from a nickel ammine complex solution. Electrochromic (EC) behaviour of these films was observed in a borate buffer solution at pH 10 in the potential range 0–1 V vs. Ag/AgCl; an as-prepared film (PF) was cathodically reduced to a colourless form (RF) and oxidized to a brown form (OF) by anodic polarization. Characterization of these films by low-angle incident X-ray diffraction and X-ray photoelectron spectroscopy with argon-ion (Ar+) etching revealed that the EC properties are based on the electrolytic transformation of the NiOx structure between β-NiOOH and β-Ni(OH)2, i.e. involving the redox reaction Ni3++ e ⇄ Ni2+.

Application of nanostructured ZnO films for electrochemical DNA biosensor

Nanostructured zinc oxide (nsZnO) films have been fabricated onto conducting indium–tin–oxide (ITO) coated glass plate, by cathodic electro-deposition to immobilize probe DNA specific to M. tuberculosis via physisorption based on strong electrostatic interactions between positively charged ZnO (isoelectric point = 9.5) and negatively charged DNA to detect its complementary target. Electrochemical studies reveal that the presence of nano-structured ZnO results in increased electro-active surface area for loading of DNA molecules. The DNA–nsZnO/ITO bioelectrode exhibits interesting characteristics such as detection range of 1 × 10 −6 − 1 × 10 −12 M, detection limit of 1 × 10 −12 M (complementary target) and 1 × 10 −13 M (genomic DNA), reusability of about 10 times, response time of 60s and stability of up to 4 months when kept at 4°C.

Electrochemically Assisted Deposition as a New Route to Transparent Conductive Indium Tin Oxide Films

Tin-doped indium oxide (ITO) films with Sn/In atomic ratios in the range 0−0.1 were synthesized by electrochemically assisted deposition (EAD). The process involves a fast one-step cathodic deposition of a highly crystalline In−Sn hydroxide (InSnOH) film followed by thermal conversion into ITO at 300 °C. The cathodic precipitation of InSnOH is preceded by formation of an In−Sn complex in solution. The films were characterized by field emission scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, UV−visible spectroscopy, and electrical measurements. In the Sn/In atomic ratio range 0−0.1, InSnOH and ITO films adopt the morphologies and cubic crystal structures of In(OH)3 and In2O3, respectively. The atomic environment of Sn and O atoms in the ITO films was shown to resemble that of films deposited by other techniques and commercial ITO samples made by chemical vapor deposition. Separate tin oxide/hydroxide phases were not observed by any of the characterization methods. The mor...

Conduction noise absorption by ITO thin films attached to microstrip line utilizing Ohmic loss

For the aim of wide-band noise absorbers with a special design for low frequency performance, this study proposes conductive indium-tin oxide (ITO) thin films as the absorbent materials in microstrip line. ITO thin films were deposited on the polyimide film substrates by rf magnetron cosputtering of In2O3 and Sn targets. The deposited ITO films show a typical value of electrical resistivity (∼10−4 Ω m) and sheet resistance can be controlled in the range of 20–230 Ω by variation in film thickness. Microstrip line with characteristic impedance of 50 Ω was used for determining their noise absorbing properties. It is found that there is an optimum sheet resistance of ITO films for the maximum power absorption. Reflection parameter (S11) is increased with decrease in sheet resistance due to impedance mismatch. On the while, transmission parameter (S21) is decreased with decrease in sheet resistance due to larger Ohmic loss of the ITO films. Experimental results and computational prediction show that the optimum sheet resistance is about 100 Ω. For this film, greater power absorption is predicted in the lower frequency region than ferrite thin films of high magnetic loss, which indicates that Ohmic loss is the predominant loss parameter for power absorption in the low frequency range.

Preparation and properties of transparent conductive indium-tin-oxide/polyimide substrates via a sol-gel process

High temperature, flexible and colorless indium-tin-oxide (ITO) coated plastic substrates have been prepared from a series of thermally stable, high glass transition temperature ( T g) and colorless copolyimide films. The copolyimides were synthesized from 3,3′-diaminodiphenylsulfone, 9,9′-bis(4-aminophenyl) fluorene and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride monomers. Their T gs were around 285–365 °C. The conductive ITO was synthesized by a sol-gel method, and then deposited onto the copolyimide films by a spin coating process. After thermal treatment at 300 °C under a nitrogen/hydrogen mixture gas for 24 h, the resistivity of the ITO film was 10 − 3 Ω cm, and its transmittance was 75% at the visible light region. Scanning electron microscopy and X-ray diffraction were used to observe the surface and morphology of the ITO films. UV–visible spectroscopy and the four-probe method were used to study their optical and electrical properties. The high performance ITO/plastic substrates can be used in the next generation flexible flat panel displays and solar cell.

Application of ITO/Al reflectors for increasing the efficiency of single-crystal silicon solar cells

It is shown that an increase in the efficiency and manufacturability of single-junction single-crystal silicon photoelectric converters of solar energy requires the use of a back-surface reflector based on conductive transparent indium-tin oxide (ITO) 0.25–2 µm thick. To increase the efficiency and reduce the sensitivity to the angle of light incidence on the photoreceiving surface of multijunction photoelectric converters with vertical diode cells based on single-crystal silicon, ITO/Al reflectors with an ITO layer >1 µm thick along vertical boundaries of diode cells should be fabricated. The experimental study of multijunction photoelectric converters with ITO/Al reflectors at diode cell boundaries shows the necessity of modernizing the used technology of ITO layers to achieve their theoretically calculated thickness.

Addition of aluminum to solution processed conductive indium tin oxide thin film for an oxide thin film transistor

Aluminum was added to a solution-processed conductive indium tin oxide thin film to be optimized as a channel layer for a thin film transistor (TFT). The conductive crystalline thin film becomes an amorphous semiconductor as the band gap enlarges with increasing Al content. Also, systematic variation in TFT characteristics was observed clearly, displaying transformation to a semiconductor. At the final composition of (Al2O3)0.3(In2O3)0.6(SnO2)0.1, the film channel layer exhibits a high mobility of 13.3 cm2 V−1 s−1, a high on-to-off ratio of 107 and a low subthreshold swing of 1.01 V/dec.

Solution-Processable Graphene Oxide as an Efficient Hole Transport Layer in Polymer Solar Cells

The utilization of graphene oxide (GO) thin films as the hole transport and electron blocking layer in organic photovoltaics (OPVs) is demonstrated. The incorporation of GO deposited from neutral solutions between the photoactive poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) layer and the transparent and conducting indium tin oxide (ITO) leads to a decrease in recombination of electrons and holes and leakage currents. This results in a dramatic increase in the OPV efficiencies to values that are comparable to devices fabricated with PEDOT:PSS as the hole transport layer. Our results indicate that GO could be a simple solution-processable alternative to PEDOT:PSS as the effective hole transport and electron blocking layer in OPV and light-emitting diode devices.

Template-Based Preparation of Free-Standing Semiconducting Polymeric Nanorod Arrays on Conductive Substrates

We describe the synthesis and characterization of a cross-linkable siloxane-derivatized tetraphenylbenzidine (DTMS-TPD), which was used for the fabrication of semiconducting highly ordered nanorod arrays on conductive indium tin oxide or Pt-coated substrates. The stepwise process allow fabricating of macroscopic areas of well-ordered free-standing nanorod arrays, which feature a high resistance against organic solvents, semiconducting properties and a good adhesion to the substrate. Thin films of the TPD derivate with good hole-conducting properties could be prepared by cross-linking and covalently attaching to hydroxylated substrates utilizing an initiator-free thermal curing at 160 degrees C. The nanorod arrays composed of cross-linked DTMS-TPD were fabricated by an anodic aluminum oxide (AAO) template approach. Furthermore, the nanorod arrays were investigated by a recently introduced method allowing to probe local conductivity on fragile structures. It revealed that more than 98% of the nanorods exhibit electrical conductance and consequently feature a good electrical contact to the substrate. The prepared nanorod arrays have the potential to find application in the fabrication of multilayered device architectures for building well-ordered bulk-heterojunction solar cells.

On an AlGaInP Multiple Quantum Well Light Emitting Diode with a Thin Carbon-Doped GaP Contact Layer Structure

An interesting AlGaInP multiple quantum well light emitting diode (LED) with a thin carbon-doped (C-doped) GaP contact layer and a transparent conducting indium tin oxide (ITO) film is fabricated. Moreover, LEDs with different contact layer structures are presented and compared in this work. The experimental results illustrate that the LED with a C-doped GaP contact layer exhibits a higher output power of 31.4 mW and a higher external quantum efficiency of 9%. The light output power, under dc 20 mA operation, of this LED is increased by a factor of 18% compared with conventional LEDs without the C-doped contact and ITO spreading layers. These results are mainly attributed to the improved contact property and lower optical absorption effect. In addition, the studied device shows the lower dynamic resistance , reduced leakage current , reduced wavelength shift (with 1.7 nm variation between 10 and 200 mA), and lower thermal-induced optical degradation ( during 50 mA, 220 h aging test). Therefore, the studied device shows promise in fabricating high performance AlGaInP LEDs.

“Green” electrochemical synthesis of Pt/graphene sheet nanocomposite film and its electrocatalytic property

Nanocomposite films of platinum nanoparticle-deposited expandable graphene sheet (Pt/EGS) are fabricated on conductive indium tin oxide glass electrodes via a “green” electrochemical synthetic route involving a series of electrochemical processes. The microstructure and morphology of the prepared film samples are characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, three-dimensional non-contact surface mapping, and field emission scanning electron microscopy. At the same time, the catalytic activity and stability of the Pt/EGS film for the oxidation of methanol are evaluated through cyclic voltammetry and chronoamperometry tests. The Pt nanoparticles in the Pt/EGS nanocomposite film are found to be uniformly distributed on the EGS. The as-synthesized Pt/EGS nanocomposite exhibits high catalytic activity and good stability for the oxidation of methanol, which may be attributed to its excellent electrical conductivity and the high specific surface area of the graphene sheet catalyst support.

Energy level evolution of molybdenum trioxide interlayer between indium tin oxide and organic semiconductor

The thickness dependance of molybdenum trioxide (MoO3) interlayer between conducting indium tin oxide (ITO) and chloro-aluminum pthalocyanine (AlPc-Cl) has been investigated with ultraviolet photoemission spectroscopy (UPS) and inverse photoemission spectroscopy. It was found that the MoO3 interlayer substantially increased the surface workfunction (WF). The increase was observed to saturate at 20 Å of MoO3 coverage. The increased WF results in hole accumulation and a band-bendinglike situation in the subsequently deposited AlPc-Cl. From these observations, a possible explanation is deduced for the observed reduction in series resistance by the insertion of the MoO3 insulating layer.

Growth of ITO thin films on polyimide substrate by bias sputtering

Abstract Transparent conducting indium tin oxide thin films were deposited on polyimide substrates by RF bias sputtering of ITO target. The influences of bias voltage on the structural and electrical properties of the films were investigated. In order to correlate the material characteristics with the plasma parameters during sputtering, we employed Langmuir probe and optical emission spectral studies. The films deposited onto positively biased substrates were poorly crystalline. An improvement in crystallinity was observed with increase in negative bias. The films deposited at a bias voltage of −20 V showed a preferred orientation in the [1 1 1] direction and has minimum resistivity compared to films grown at other biasing conditions. The measured plasma parameters were correlated to the film properties. The ITO films thus grown have been used as the channel layer for the fabrication of thin film transistor.

Doped Nanostructured Zinc Oxide Films Grown by Electrodeposition

ZnO thin films doped with either In or Al are n-type oxide materials of interest for application in electronic devices and thin-film solar cells. In this work, the doped ZnO films were electrodeposited at 80 degrees C from an aqueous solution on polycrystalline conductive Indium Tin Oxide covered glass substrates. The incorporation of the dopants into the ZnO film has been verified by energy dispersive X-ray spectrum, X-Ray diffraction and optical transmission analysis. The optical and surface structure properties of the ZnO doped films are strongly affected by the In and Al concentrations in the electrodeposition solution as evidenced by optical transmission and reflection measurements, and scanning electron microscopy.

Indium Tin Oxide Nanofiber Film Electrode for High Performance Dye Sensitized Solar Cells

Dye-sensitized solar cells (DSC) were fabricated using transparent and conductive indium tin oxide (ITO) nanofiber film prepared by electrospinning. Scanning electron microscope (SEM) images confirmed that the prepared films were well attached, exceptionally long, and had an average diameter of around 200 nm. We found that the maximum efficiency of the device was as high as 3.97% with the structure of a double-layer nanofiber film. It was shown that an improvement as much as 16.76% was achieved. These achievements were obtained due to a reduction in grain boundaries, to an efficient high charge collection, and to rapid electron transport.

High-efficiency flexible white organic light-emitting diodes

A high-efficiency flexible white organic light-emitting diode (OLED) was fabricated using effective device structure on high glass-transition plastic substrate with a thin silicon dioxide pre-coat and highly conductive indium tin oxide (ITO) deposited by radio frequency magnetron sputtering at elevated temperature. Sputtering ITO at 200 °C on a 150 A SiO2-modified polyethersulfone yielded a high power efficiency of 6.5 lm/W at 800 cd m−2 and a maximum external quantum efficiency of 3.2% with a pure-white emission of (0.321, 0.339). Besides device structure, the power efficiency of the flexible OLEDs depends strongly on the conductivity of ITO, which in turn depends on its surface topology, which can be most effectively improved by adding a SiO2 pre-coat of optimal thickness.

Spray-deposited CuInSe2 nanocrystal photovoltaics

Photovoltaic devices (PVs) were fabricated by spray-coating an ink of copper indium diselenide (CIS) nanocrystals as the light-absorbing layer. Without high-temperature post-deposition annealing, PVs were made on glass and plastic substrates with power conversion efficiencies of up to 1.9% and 1.1%, respectively, under AM1.5 illumination. The mild processing conditions also enabled fabrication of alternative device structures that are not compatible with conventional high-temperature PV processing, including substrate and superstrate designs, and devices with transparent back contacts of conducting indium tin oxide (ITO) and plastic substrates. Device performance is observed to be limited by poor charge extraction from the nanocrystal films, with the highest efficiencies being obtained from PVs with relatively thin absorber layers. To improve light absorption without sacrificing internal quantum efficiency, stacked PVs were fabricated, which exhibited improved short-circuit current and power conversion efficiency compared to stand-alone single junction devices.

Influence of pH value on structure and optical properties of electrodeposited PbS thin films

PbS thin films were prepared on transparent conductive indium tin oxide glass substrates using a constant voltage cathodic electrodeposition method. The influence of solution pH on the phase compositions, surface morphologies and optical properties of the as deposited films was investigated. Results show that cubic PbS thin films with oriented growth along (111) and (200) direction can be obtained at pH=2.4, deposition voltage of 3 V, following deposition for 20 min with EDTA added as a complexing agent. The as deposited thin films exhibit a dense surface morphology. The compressive stress and optical bandgap of the PbS thin films first decrease and then increase with increasing pH value, and the bandgap of the thin films is calculated to be 0.38–0.39 eV.