Fluorine-doped Indium Tin Oxide Research Articles

Unraveling the Enhanced Electrochemical Performances of Nickel Aluminum Sulfide Lattices for Overall Water Splitting and as Counter Electrode Materials for Dye-Sensitized Solar Cells

The development of a high-performance precious metal-free multifunctional electrocatalyst for overall water splitting is a promising sign for future energy research. Here, a new strategy has been followed for the synthesis of novel-structured binary metal chalcogenide electrocatalysts, such as nickel aluminum sulfide (NiAl2S4) or nickel aluminum selenide (NiAl2Se4) spinels. The new chalcogenides, NiAl2S4 or NiAl2Se4, were confirmed by different physicochemical characterizations. Using a 316 stainless steel (SSL) mesh electrode as a three-dimensional conducting substrate, the electrocatalytic overall water splitting reaction was studied. Here, NiAl2S4 spinel outperformed the other metal chalcogenide in terms of electrocatalytic activity and charge transport in the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and overall water splitting in alkaline medium. Moreover, NiAl2S4 spinel provided the finest electrocatalytic efficiencies compared to other benchmark electrocatalysts with minimized overpotentials, such as 47 or 290 mV for HER or OER, respectively, to reach the current density of 20 mA cm–2. In overall water splitting studies, a two-electrode system was formulated to show a very low potential of 1.54 V at a current density of 20 mA cm–2. Further, the prepared NiAl2S4 electrocatalyst-loaded 316 SSL electrode demonstrated excellent durability in HER, OER, and overall water splitting reactions. The obtained Faradaic efficiency was 97%, which is due to the two-dimensional sheet-like morphology of NiAl2S4, enabling a high active surface area for efficient water electrolysis. Furthermore, NiAl2S4 spinel performed well as a counter electrode (CE) material in dye-sensitized solar cells, with an efficiency of 5.02% compared to Pt (5.38%) on the fluorine-doped indium tin oxide electrode.

Bismuth oxyhalide based photo-enhanced triboelectric nanogenerators

Utilizing wide absorption characteristics of a narrow bandgap (~1.8 eV) semiconductor, we report on Bismuth Oxyiodide (BiOI) based photo-enhanced triboelectric nanogenerator (TENG). The potentiostatic deposition of tribo-positive BiOI on transparent, electrically conducting Fluorine doped Indium Tin Oxide (FTO) substrates provides a pathway to exploit concurrently the photo-enhanced charge generation and triboelectric effects. When utilized against tribo-negative polydimethylsiloxane (PDMS) films, under illumination, the BiOI/PDMS TENGs’ output was significantly enhanced, wherein an increase of 21% in output voltage, 38% in charge density (26% in short-circuit current density), and 74% in overall power density (from 0.25 Wm −2 (in dark) and 0.44 Wm −2 (under illumination)), respectively, was observed. Correspondingly, a dramatic enhancement (from ~25 mV to ~300 mV) in the average surface potential, termed as surface photovoltage (SPV), for the illuminated BiOI was observed by Kelvin Probe Force Microscopy (KPFM). For an isolated, grounded BiOI/FTO electrode, this enhanced SPV was slow-decaying (~3.5 h) and is attributed to the high dielectric constant, presence of deep surface states and traps within BiOI, and slow charge-exchange with the ambient environment. The work thus not only provides an approach for the enhancement of mechanical-to-electrical efficiency of TENGs by light absorption but can also be utilized for self-powered detection of electromagnetic radiation and photodetectors. • Potentiostatic deposition of n- type, tribo-positive Bismuth Oxyiodide (BiOI) for photo-enhanced triboelectric effect. • Under white light illumination, BiOI-PDMS TENG displays 74% increase in output power density. • Under illumination, dramatic surface photovoltage enhancement (from 25 mV to 300 mV) measured using photo-KPFM.

Unsymmetrical zinc phthalocyanines containing thiophene and amine groups as donor for bulk heterojunction solar cells.

Photovoltaic technology is an alternative resource for renewable and sustainable energy and low costs organic photovoltaic devices such as bulk-heterojunction (BHJ) solar cells, which are selective candidates for the effective conversion of solar energy into electricity. Asymmetric phthalocyanines containing electron acceptor and donor groups create high photovoltaic conversion efficiency in dye sensitized solar cells. In this study, a new unsymmetrical zinc phthalocyanine was designed and synthesized including thiophene and amine groups at peripherally positions for BHJ solar cell. The structure of the targeted compound (4) was characterized comprehensively by FT-IR, UV–Vis, 1H-NMR, and MALDI-TOF MS spectroscopies. The potential of this compound in bulk heterojunction (BHJ) photovoltaic devices as donor was also researched as function of blend ratio (blend ratio was varied from 0.5 to 4). For this purpose, a series of BHJ devices with the structure of fluorine doped indium tin oxide (FTO)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)/ ZnPc:[6,6]- phenyl-C61- butyric acid methyl ester (PCBM) blend/Al with identical thickness of ZnPc:PCBM layer were fabricated and characterized. Photo current measurements in 4 revealed that the observed photo current maximum is consistent with UV-vis spectra of the compound of 4. Preliminary studies showed that the blend ratio has a critical effect on the BHJ device performance parameters. Photovoltaic conversion efficiency of 6.14% was achieved with 4 based BHJ device.

Fully Reversible Electrically Induced Photochromic-Like Behaviour of Ag:TiO2 Thin Films

A TiO2 thin film, prepared on fluorine-doped indium tin oxide (FTO)-coated glass substrate, from commercial off-the-shelf terpinol-based paste, was used to directly adsorb Ag plasmonic nanoparticles capped with polyvinylpyrollidone (PVP) coating. The TiO2 film was sintered before the surface entrapment of Ag nanoparticles. The composite was evaluated in terms of spectroelectrochemical measurements, cyclic voltammetry as well as structural methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found that the Ag nanoparticles are effectively adsorbed on the TiO2 film, while application of controlled voltages leads to a fully reversible shift of the plasmon peak from 413 nm at oxidation inducing voltages to 440 nm at reducing voltages. This phenomenon allows for the fabrication of a simple photonic switch at either or both wavelengths. The phenomenon of the plasmon shift is due to a combination of plasmon shift related to the form and dielectric environment of the nanoparticles.

Optical and electrical investigations of rubbing assisted few-layer graphene thin film for feasibility of flexible electrode

Transparent conducting electrodes (TCEs) are key components in optoelectronic devices. The commonly used materials for this purpose are indium tin oxide (ITO) and fluorine-doped indium tin oxide (FTO). However, they have limited application for flexible optoelectronic devices due to their brittleness nature. Among various alternatives of TCE materials, graphene has been considered as a good choice owing to its extraordinary properties, such as excellent optical transparency, electrical conductivity mechanical strength along with layer stability on various substrates. In the present work, few-layer graphene (FLG) films have been deposited on flexible polyethylene terephthalate (PET) sheets by rubbing technique at room temperature. The prepared samples were characterized using Optical transparency, Raman spectroscopy, Atomic force microscopy, bending test, and sheet resistance measurements to optimize rubbing parameters. The fabricated FLG films on PET substrate exhibited a sheet resistance 400 Ω/sq. with transmittance ∼60 % indicating its promising application as a flexible transparent conducting electrode in optoelectronic devices.

Preparation of electrospun poly(acrylic acid)/multiwalled carbon nanotubes composite nanofiber for glucose detection

In this study, poly(acrylic acid) and multiwalled carbon nanotubes (PAA/MWNTs) composite nanofiber thin film was prepared on fluorine doped indium tin oxide–coated glass substrate through electrospinning method. The electrospun PAA/MWNTs nanofiber thin film was modified with layer–by–layer (LbL) self–assembled multilayers of glucose oxidase (GOD) and poly(dialyldimethylammoniumchloride) (PDADMAC) prior to employ for glucose detection. The obtained nanofiber thin film was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The prepared nanofibers thin film shows a good potential for detection of glucose at constant applied potential through an electrochemical method.

Switched photoelectrochemistry of carbon dots for split-type immunoassay

A novel and general strategy of split-type immunoassay is developed based on redox chemical reaction modulated photoelectrochemistry of carbon dots (CDs). Specifically, the photocurrent of the CDs sensitized titanium dioxide nanoparticles (TiO2 NPs) modified fluorine doped indium tin oxide (FTO) (that is the FTO/TiO2/CDs) electrode was inhibited obviously by KMnO4 due to the oxidation of surface hydroxyl groups of CDs to electron accepting carbonyls. While the inhibited photocurrent of the KMnO4 treated FTO/TiO2/CDs electrode can be restored by ascorbic acid (AA) because of the regeneration of electron donating hydroxyls to promote electron-hole separation. Take carcinoembryonic antigen (CEA) as a model analyte and alkaline phosphate (ALP) as a catalytic label tracer to hydrolyze ascorbic acid 2-phosphate (AAP) for producing AA, which greatly stimulated the photocurrent of the transducer of KMnO4 treated FTO/TiO2/CDs photoelectrode for signal output. This redox chemical reaction modulated PEC strategy enabled the separation of the immunoreaction from the photoelectrode (that is, a split-type PEC detection), eliminating potential damage of biomolecules during the PEC detection processes and leading to enhanced throughput detection as compared to conventional PEC configurations. A low detection limit of 7.0 fg/mL was achieved for CEA. This convenient, split-type PEC immunoassay with high throughput may be easily extended to other bioaffinity assays for versatile targets.

Minimizing energy losses in perovskite solar cells using plasma-treated transparent conducting layers

This study reports for increasing the efficiency of perovskite solar cells (PSCs) by modifying the surface of a fluorine-doped indium tin oxide (FTO) substrate using an atmospheric pressure plasma treatment. Surface modification of the FTO film involved several challenges, such as control of the blocking layer uniformity, removal of pinholes, and deposition of a dense layer. This strategy allows the suppression of charge recombination at the interface between the FTO substrate and hole conductor. Electrochemical impedance spectroscopy analysis showed that the plasma treatment increased the charge transfer resistance between the FTO and hole conductor from 95.1 to 351.1Ω, indicating enhanced resistance to the electron back reaction. Analyses of the open-circuit photovoltage decay revealed that modification of the surface of the FTO substrate by plasma treatment increased time constant from 6.44 ms to 13.15 ms. The effect is ascribed to suppression of the electron recombination rate. PSCs based on the newly developed electrode had 39% higher efficiency than reference devices. The obtained results provide direct evidence in favor of the developed strategy.

Synthesis, structural and optical properties of pure and rare-earth ion doped TiO2 nanowire arrays by a facile hydrothermal technique

Single crystalline pure and rare-earth metal ions (Eu3+ and Ce3+) doped TiO2 nanowire arrays were prepared on conductive fluorine doped indium tin oxide substrates by a facile hydrothermal method. Initially the conditions and parameters were optimized to prepare the high quality TiO2 nanowire arrays in the absence of organic additives. The average diameter and length of the TiO2 nanowire were found to be ~30–50nm and ~0.5–1.5μm, respectively. The formations of rutile phase structure in all the samples were confirmed by x-ray diffractometric analysis while the transmission electron microscopy confirms the single crystallinity and the maximum orientation of growth direction along [001] for the as-grown TiO2 nanowire. The optical properties of all the samples were analyzed using photoluminescence spectroscopy. The photocatalytic properties of the pure and doped TiO2 were investigated for the decomposition of organic toludine blue-O dye under ultraviolet irradiation. The result demonstrates that the Ce3+: TiO2 decomposed almost 90% of the organic dye within 80min.

All-solution-processed, transparent thin-film transistors based on metal oxides and single-walled carbon nanotubes

The fabrication of fully transparent thin-film transistor (TFT) arrays composed of metal oxides and SWCNTs was performed on a glass substrate through simple all-solution-processed, vacuum-free routes followed by thermal annealing treatments at 350 °C which is the lowest processing temperature reported to date. We adopted fluorine-doped indium tin oxide (ITO:F), stacked zirconium oxide/aluminium oxide/zirconium oxide (ZAZ), indium zinc oxide (IZO), and single-walled carbon nanotubes (SWCNTs) for gate electrodes, gate insulators, channel layers, and source/drain electrodes, respectively, which enabled the fabrication of TFT with desired-performance at a sufficiently low annealing temperature of 350 °C that is compatible with polymer substrates. The TFT fabricated with a back-gated SWCNT/IZO/ZAZ/ITO:F structure was highly transparent with a transmittance of 76.5% in the visible range and exhibited a mobility of 0.45 cm2 V−1 s−1 and an on/off current ratio of ∼106, which are comparable to those of hydrogenated amorphous silicon TFTs. These results suggest that all-solution-processed TFTs have the potential for lost-cost, fully transparent, flexible device applications.

AlGaN-based ultraviolet light-emitting diodes using fluorine-doped indium tin oxide electrodes

In this paper, improved electrical and optical properties of aluminum gallium nitride (AlGaN)-based ultraviolet light-emitting diodes using fluorine-doped indium tin oxide (F-ITO) electrodes are reported. F-doping was found to increase the work function as well as the energy bandgap of the ITO and, thereby, reduce the Shottky barrier height in contact with p-(Al)GaN. As a result, the optical transmittance increased from 79.7% to 86.9% at 380 nm, while the specific contact resistance decreased from 1.04 × 10−3 Ω·cm2 to 9.12 × 10−4 Ω·cm2 after F-doping, which led to an increase in the output power from 2.41 mW to 5.99 mW.

Solution growth of anatase TiO2 nanowires from transparent conducting glass substrates

Sol–gel reaction conditions that enable the growth of one-dimensional (1D) anatase titanium dioxide (TiO2) nanostructures from fluorine-doped indium tin oxide (FTO) substrates are described. The generation of these linear nanostructures is achieved using acetic acid (HOAc) and titanium isopropoxide (Ti(OiPr)4) in anhydrous heptane in the absence of an external bias or template. The procedure requires the functionalization of base-treated substrates with Ti-oxide nucleation sites, which serve as a foundation for the growth of linear Ti-oxide macromolecules. Calcination of these macromolecules at 450 °C under an ambient atmosphere produce uniform films of randomly oriented anatase TiO2 nanowires. The nucleation and growth processes are both acutely sensitive to the relative molar ratio (R) of HOAc to Ti(OiPr)4. Optimal surface coverage of the nucleation sites is observed when the R value utilized for the nucleation phase (denoted Ri) is equal to 1.3. The highest quality nanowire films were obtained when the R value employed during the gelation phase (denoted Rf) was held between 8.5 and 14. Characterization of the films by electron microscopy revealed a uniform film of disordered anatase TiO2 nanowires with high aspect ratios. The dimensions of the nanostructures correspond to lengths of ca. 1–10 μm and widths of 54 ± 10 nm. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) techniques demonstrate that the anatase nanowires are a linear arrangement of crystallites ranging in size from 13 to 19 nm. A systematic evaluation of how reaction conditions (e.g., solvent volume, stoichiometry of reagents, substrate base treatment) affect the generation of these TiO2 films is presented.

ZnO thin films electrodeposited in propylene carbonate under a magnetic field

Electrochemical processing of ZnO films on fluorine-doped indium tin oxide (FTO/ITO) substrate was investigated in organic propylene carbonate electrolyte solutions containing Zn(NO3)2·6H2O. Much finer and more uniform morphologies of the ZnO films were obtained in comparison with those in aqueous electrolyte solutions. The effects of superimposing a magnetic field to the ZnO films were further examined. Superimposing a magnetic field considerably influenced the transient current density in the initial stage, especially in the mass transfer controlled region at −1.5 V vs Zn wire reference electrode. It also introduced substantially no drastic influence on the microstructure in spite of the appearance of considerably significant morphological variations.