Fluorine-doped Tin Oxide-coated Glass Research Articles

TiO2 nanotube formation by Ti film anodization and their transport properties for dye-sensitized solar cells

In this paper, we present the synthesis of TiO2 nanotube (NT) arrays formed by anodization of Ti film deposited on a fluorine-doped tin oxide-coated glass substrate by direct current magnetron sputtering. NH4F/ethylene glycol electrolyte was used to demonstrate the growth of stable nanotubes at room temperature. TiO2 NTs as long as 4.8 ?m with the high expansion factor to the initial sputtered Ti film (2 ?m) were obtained, showing little undesired dissolution of the metal in the electrolyte during anodization. The average pore size and wall thickness of NTs were about 70 and 30 nm, respectively. Structural investigations on the transparent NT arrays reveal the presence of anatase phase after annealing. The NTs were sensitized by the N719 complex and the resultant photoelectrodes were incorporated into dye sensitized solar cells (DSSCs). The conversion efficiency of 1.97 % was obtained under AM 1.5 illumination and the open circuit voltage, short circuit current density and the fill factor were 0.59 V, 6.71 mA/cm2 and 0.50, respectively. Investigation of the electron transport of the DSSCs by electrochemical impedance spectroscopy showed that the electron diffusion length (8.6 ?m) was higher than NTs’ height. It was also observed that the electron transport resistance measured in NT DSSC was lower compared to the reported TiO2 nanoparticle one.

Examining the effect of Zn dopant on physical properties of nanostructured SnS thin film by using electrodeposition

Undoped and Zn-doped SnS nanostructures have been successfully synthesized through an electrodeposition process by using SnCl2 and Na2S2O3 as precursors on fluorine-doped tin oxide-coated (FTO) glass substrates with different zinc concentrations. The structure, surface morphology, and the optical properties of the synthesized films are studied. The X-ray diffraction patterns of the SnS nanostructure confirm the orthorhombic structure. Scanning electron microscopy shows thin films with homogeneous and uniform surface as well, by adding Zn ions, morphology of SnS films changed from cubic to rod. Energy dispersive spectroscopy shows presence of Zn in the films. All samples are characterized by UV–Vis reflectance measurement in the wavelength range 500–1200 nm. The energy band gap values, calculated from optical measurement of reflectance, are between 1.46 and 1.49 eV, being suitable for absorbers layers in the photovoltaic applications. Eventually, studying the photocurrent responses of the nanostructures revealed that the Zn-doped SnS nanostructures exhibited better response than the undoped SnS nanostructures.

Photocurrent Properties of Undoped and Pb-Doped SnS Nanostructures Grown Using Electrodeposition Method

Nanostructured Pb-doped SnS thin films were deposited onto fluorine-doped tin oxide-coated glass substrates by electrochemical deposition. The films were characterized using different techniques to study their structural, morphological, and optical properties. The x-ray diffraction analysis indicated that the films were polycrystalline in nature and had an orthorhombic crystal structure. Scanning electron microscopy studies showed that the Pb dopant could significantly change the morphology of the nanostructures. Energy dispersive spectroscopy showed different concentrations of Pb for different morphologies. Optical measurements suggested a red shift for the band gap values from 1.46 eV to 1.40 eV with an increase in the Pb concentration. Finally, the photocurrent responses of the nanostructures were studied. The results revealed that Pb-doped SnS nanostructures exhibited better response than the undoped SnS nanostructures.

Inkjet-printed interdigitated cells for photoelectrochemical oxidation of diluted aqueous pollutants

Planar, interdigitated photoelectrochemical cells were made by inkjet printing. The electrode fingers had widths ranging from 200 to 1500 µm and were revealed by printing a positive protective polymer mask on fluorine-doped tin oxide-coated glass slides and subsequent etching. One finger family was overprinted by an ink-jettable sol–gel composition based on titanium propoxide which was then converted into TiO2 by annealing in air. An incident photon to current conversion efficiency of 0.19 was obtained at 360 nm for 200-nm-thick films. The influence of electrode geometry and titania thickness on the electrochemical properties of resulting cells is discussed in detail. Due to the interdigitated layout, photoelectrochemical response was not suffering from iR drop down to low electrolyte ionic strengths. The printed cells were used in photoelectrocatalytic degradation experiments of aqueous solutions of benzoic acid by broadband ultraviolet irradiation (UVA) and electric bias of 1 V and delivered considerable acceleration of the degradation process compared to the plain photocatalytic mode.

Effect of annealing on acid-treated WO3·H2O nanoplates and their electrochromic properties

The effect of annealing temperature on the electrochromic properties of acid-treated hydrated tungsten oxide (WO3·H2O) nanoplates is reported for the first time. Nanoplates were grown on fluorine-doped tin oxide-coated glass substrate using nitric acid, and annealing temperature was varied from 100–400°C. The as-prepared nanoplates were WO3·H2O, and these nanoplates transformed into tungsten oxide (WO3) after annealing at ≥200°C. Nanoplate thickness decreased with increasing annealing temperature from 12–55nm for the as-prepared sample to 12–40nm for the sample annealed at 400°C. WO3 nanoplates annealed at 200°C showed the best electrochromic properties with coloration efficiency of 28.64cm2C−1, high optical modulation (58%), good electrochromic cycling stability, as well as short ion insertion and extraction times of ∼9.6 and ∼5.1s, respectively.

Dramatic Enhancement in Photoresponse of β-In2S3 through Suppression of Dark Conductivity by Synthetic Control of Defect-Induced Carrier Compensation.

We report on the synthesis of dense and faceted indium sulfide (β-In2S3) nano-octahedron films on fluorine-doped tin oxide-coated glass by the hydrothermal method and their photoresponse properties in a flip chip device configuration. We have examined the temporal evolution of the phase constitution, morphology, and optoelectronic properties for films obtained after growth interruption at specific intervals. It is noted that, initially, an In(OH)3 film forms, which is gradually transformed to the β-In2S3 phase over time. In the case of the film wherein most, but not all, of In(OH)3 is consumed, an exceptionally large photoresponse (light to dark current ratio) of ∼10(4) and response time(s) (rise/fall) of ∼88/280 ms are realized. This superior performance is attributed to nearly complete carrier compensation achievable in the system under high pressure growth leading to dramatic reduction of dark conductivity. It is argued that the temporally growth-controlled equilibrium between quasi-In interstitials and cation vacancies dictates the optoelectronic properties.

Investigation of CuInS2 thin films deposited on FTO by one-pot solvothermal synthesis

CuInS2 thin films were deposited with fix different thiourea (TU) concentrations on fluorine-doped tin oxide-coated (FTO) conductive glass substrates by a facile and rapid solvothermal method. XRD analysis shows that all CuInS2 thin films crystallize in a chalcopyrite structure with a preferential orientation along (112) direction, and the average crystallize sizes of the nanoparticles are 20–50nm. The X-ray photoelectron spectroscopy (XPS) shows that the S deficiency decreases with increasing TU concentration. Surface morphology studies show the CuInS2 thin films are composed of nanoplates or sphere-like. The thicknesses of the CuInS2 thin films can be adjusted from 0.33 to 2.1μm by controlling the TU concentration. The average absorption of all CuInS2 thin films is greater than 90% in the wavelength ranging from 400 to 950nm, and the band gaps of all CuInS2 thin films are in the range of 1.52–1.90eV. As shown in room temperature photoluminescence (PL), the as-synthesized CuInS2 thin films have a near-infrared emission at 1.54eV and an orange–red emission at 1.92eV in visible spectrum.

Real-time deflection and friction force imaging by bimorph-based resonance-type high-speed scanning force microscopy in the contact mode.

We report herein an alternative high-speed scanning force microscopy method in the contact mode based on a resonance-type piezoelectric bimorph scanner. The experimental setup, the modified optical beam deflection scheme suitable for smaller cantilevers, and a high-speed control program for simultaneous data capture are described in detail. The feature of the method is that the deflection and friction force images of the sample surface can be obtained simultaneously in real time. Images of various samples (e.g., a test grating, a thin gold film, and fluorine-doped tin oxide-coated glass slides) are acquired successfully. The imaging rate is 25 frames per second, and the average scan speed reaches a value of approximately 2.5 cm/s. The method combines the advantages of both observing the dynamic processes of the sample surface and monitoring the frictional properties on the nanometer scale.PACS07.79.Lh; 07.79.Sp; 68.37.Ps

Substrate-independent and large-area synthesis of carbon nanotube thin films using ZnO nanorods as template and dopamine as carbon precursor

In this study, we introduce a method for large-area and substrate-independent synthesis of the big-inner-diameter carbon nanotube (BIDI-CNT) thin films by utilizing polydopamine (PDA) as carbon source and ZnO nanorods (NRs) as sacrificing template for the first time. ZnO NRs with hexagonal morphology were coated with PDA films via the ammonium persulfate-induced polymerization of dopamine at neutral pH for avoiding the degradation of amphoteric ZnO at alkaline pH needed by the conventional oxygen-induced polymerization of dopamine. After carbonization in N2 atmosphere at 500°C followed by ZnO removal, the hollow BIDI-CNTs with tuned wall thickness and hexagonal morphology were obtained. In addition, the obtained BIDI-CNTs were found to be N-doped. Furthermore, on the base of the outstanding substrate-independent growth properties of both ZnO NRs and PDA, the large area thin films of the N-doped BIDI-CNTs could be synthesized on various solid substrates, for instance, Al2O3, gold, fluorine-doped tin oxide-coated glass, platinum, silicon, mica, and quartz.

Langmuir-Blodgett films of self-assembled (alkylether-derivatized Zn phthalocyanine)-(C₆₀ imidazole adduct) dyad with controlled intermolecular distance for photoelectrochemical studies.

A multilayer Langmuir-Blodgett (LB) film of the self-assembled electron donor-acceptor dyad of Zn phthalocyanine, appended with four long-chain aliphatic ether peripheral substituents, and an imidazole adduct of C60 was prepared and applied as a photoactive material in a photoelectrochemical cell. Changes in the simultaneously recorded surface pressure and surface potential vs area per molecule compression isotherms for Langmuir films of the dyad and, separately, of its components helped to identify phase transitions and mutual interactions of molecules in films. The Brewster angle microscopy (BAM) imaging of the Langmuir films showed circular condensed phase domains of the dyad molecules. The determined area per molecule was lower than that estimated for the dyad and its components, separately. The multilayer LB films of the dyad were transferred onto hydrophobized fluorine-doped tin oxide-coated (FTO) glass slides under different conditions. The presence of both components in the dyad LB films was confirmed with the UV-vis spectroscopy measurements. For the LB films transferred at different surface pressures, the PM-IRRAS measurements revealed that the phthalocyanine macrocycle planes and ether moieties in films were tilted with respect to the FTO surface. The AFM imaging of the LB films indicated formation of relatively uniform dyad LB films. Then, the femtosecond transient absorption spectral studies evidenced photoinduced electron transfer in the LB film. The obtained transient signals corresponding to both Zn(TPPE)(•+) and C60im(•-) confirmed the occurrence of intramolecular electron transfer. The determined rate constants of charge separation, kcs = 2.6 × 10(11) s(-1), and charge recombination, kcr = 9.7 × 10(9) s(-1), indicated quite efficient electron transfer within the film. In the photoelectrochemical studies, either photoanodic or photocathodic current was generated depending on the applied bias potential when the dyad LB film-coated FTO was used as the working electrode and ascorbic acid or methylviologen, respectively, as the charge mediator in an aqueous solution.

Behaviour of Titanium-based Fe2O3 Photo-Anodes in Photo-Electrochemical Reactors for Water Splitting

The behaviour of titanium substrates was investigated as replacements for transparent fluorine-doped tin oxide-coated glass substrates, the low conductivity of which causes inhomogeneous spatial distributions of potential and current densities on scaling up photo-electrodes in photo-electrochemical reactors. Hence, Fe2O3 (ca. 23nm thick) was deposited by spray pyrolysis onto the titanium surface at 450°C in air, causing growth of (less photo-active) rutile by thermal oxidation, the thickness being measured as ca. 20nm by secondary ion mass spectrometry. Anodising titanium in aqueous phosphoric acid enabled ca. 12nm anatase TiO2 to be grown prior to spray pyrolysis, limiting the subsequent thermal growth of rutile, so the overall TiO2 thickness was ca. 16nm. 23nm thick Fe2O3 deposited on a 22nm TiO2 | Ti substrate after heat treatment at 500°C for 1hour was found to produced greater current densities than Fe2O3 deposited onto TEC-8 fluorine-doped tin oxide coated on glass; uv absorption by TiO2 and reflection by the titanium substrate contributed to measured photo-current densities.

Electrochemical detection of DNA damage through visible-light-induced ROS using mesoporous TiO2 microbeads

Rapid detection of DNA damage could serve as a basis for genotoxicity studies of new bio-nanoconjugations. A novel TiO2 bio-nanoconjugation, consisting of mesoporous TiO2 microbeads, dopamine (DA) and ss-DNA, was constructed on fluorine-doped tin oxide-coated glass (FTO) and used for the detection of DNA damage in the photocatalytic reaction of TiO2 under visible light. Stable mesoporous TiO2 microbead films were coated on FTO by the doctor-blade method; dopamine with oxygen containing ligands, was tightly coupled to the titanium surface prepared under phase coordination. Specific single-strands of DNA were electronically linked to TiO2 by using a dopamine bridge. DNA damage, caused by reactive oxygen species (ROS) that were photogenerated through the photocatalytic reaction, was detected with square wave voltammetry (SWV) by recording the catalytic oxidation current of [Ru(NH3)6]3+, an intercalated electroactive probe. The ability of antioxidant to protect DNA against damage in the photocatalytic reaction was also tested.

ZnO nanoneedle/H2O solid-liquid heterojunction-based self-powered ultraviolet detector

ZnO nanoneedle arrays were grown vertically on a fluorine-doped tin oxide-coated glass by hydrothermal method at a relatively low temperature. A self-powered photoelectrochemical cell-type UV detector was fabricated using the ZnO nanoneedles as the active photoanode and H2O as the electrolyte. This solid-liquid heterojunction offers an enlarged ZnO/water contact area and a direct pathway for electron transport simultaneously. By connecting this UV photodetector to an ammeter, the intensity of UV light can be quantified using the output short-circuit photocurrent without a power source. High photosensitivity, excellent spectral selectivity, and fast photoresponse at zero bias are observed in this UV detector. The self-powered behavior can be well explained by the formation of a space charge layer near the interface of the solid-liquid heterojunction, which results in a built-in potential and makes the solid-liquid heterojunction work in photovoltaic mode.

Ternary CuInS2 photoelectrodes created using the sulfurization of Cu–In metal precursors for photoelectrochemical applications

Copper indium disulfide semiconductor layers are deposited onto glass substrates or fluorine-doped tin oxide-coated glass substrates with the reactive sulfurization and the sputtering of Cu–In metal precursors. X-ray diffraction patterns and energy dispersive analysis of X-ray results reveal that the samples change from the Cu-rich tetragonal CuInS2 to the In-rich CuInS2 phase with an increase in the [In]/[In+Cu] molar ratio in the metal precursors. The thicknesses and direct band gaps of the samples, determined from surface profile measurements and transmittance and reflectance spectra, are in the ranges of 0.82–1.29μm and 1.39–1.53eV, respectively. The carrier density and mobility of samples are in the ranges of 3.29×1014–1.9×1020cm−3 and 0.58–17.41cm2/Vs, respectively. A sample with an [In]/[In+Cu] molar ratio of 0.53 has a maximum photo enhancement current density of 5.81mA/cm2 at an applied bias of 0.4V vs. an Ag/AgCl electrode in aqueous Na2S (0.35M)+K2SO3 (0.25M) solution.

Photoelectrochemical behavior of mixed ZnO and GaN (ZnO:GaN) thin films prepared by sputtering technique

Mixed zinc oxide and gallium nitride (ZnO:GaN) thin films with significantly reduced bandgaps were synthesized by using zinc oxide and gallium nitride target at 100°C followed by post-deposition annealing at 500°C in ammonia for 4h. All the films were synthesized by RF magnetron sputtering on Fluorine-doped tin oxide-coated glass. We found that mixed zinc oxide and gallium nitride (ZnO:GaN) thin films exhibited significantly reduced bandgap, as a result showed improved PEC response, compared to ZnO thin film. Furthermore, mixed zinc oxide and gallium nitride (ZnO:GaN) thin films with various bandgaps were realized by varying the O2 mass flow rate in mixed O2 and N2 chamber ambient.

Comparison of dye solar cell counter electrodes based on different carbon nanostructures

Three characteristically different carbon nanomaterials were compared and analyzed as platinum-free counter electrodes for dye solar cells: 1) single-walled carbon nanotube (SWCNT) random network films on glass, 2) aligned multi-walled carbon nanotube (MWCNT) forest films on Inconel steel and quartz, and 3) pressed carbon nanoparticle composite films on indium tin oxide-polyethylene terephtalate plastic. Results from electrochemical impedance spectroscopy and electron microscopy were discussed in terms of the catalytic activity, conductivity, thickness, transparency and flexibility of the electrode films. The SWCNT films showed reasonable catalytic performance at similar series resistance compared to platinized fluorine doped tin oxide-coated glass. The MWCNTs had similar catalytic activity, but the electrochemical performance of the films was limited by their high porosity. Carbon nanoparticle films had the lowest charge transfer resistance resulting from a combination of high catalytic activity and dense packing of the material.

UV sensor based on TiO 2 nanorod arrays on FTO thin film

Highly oriented TiO 2 nanorod arrays were fabricated directly on fluorine-doped tin oxide-coated glass (FTO) substrate by the hydrothermal method. The diameter, length, and density of the nanorods could be varied by changing the growth parameters, such as time, temperature, and initial reactant concentration. The fabricated samples were characterized with X-ray diffraction, field-emission-scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. The TiO 2 nanorod array was applied to construct photoelectric devices, by which highly sensitive and steady photocurrent responses were obtained.

Growth of nanocrystalline TiO2 films by pulsed-laser-induced liquid-deposition method and preliminary applications for dye-sensitized solar cells

A novel technique, the pulsed-laser-induced liquid-deposition (PLLD) method, has been employed to grow nanocrystalline TiO2 films on fluorine-doped tin-oxide-coated (FTO) glass substrates at room temperature. The PLLD method was implemented by directing a pulsed laser into a liquid precursor and depositing the photosynthesized nanocrystalline TiO2 on an FTO glass substrate immersed in the liquid precursor. The as-grown nanocrystalline TiO2 films were found to have a rutile crystal structure and consist of a number of flower-like TiO2 crystal units arrayed together on the FTO glass substrate. Each of the flower-like TiO2 crystal units was composed of many nanostructured TiO2 whiskers, and their building blocks were found to be bundles of TiO2 nanorods with diameter of about 5 nm. The growth of these TiO2 nanorods is highly anisotropic, with the preferential growth direction along [001]. As-grown nanocrystalline TiO2 films were annealed at 450°C in air for 30 min for the applications of dye-sensitized solar cells, and the nanostructured characteristics with good porosity were preserved after annealing. A preliminary dye-sensitized solar cell was built based on the annealed nanocrystalline TiO2 film. The results suggest that the PLLD method is a promising technique for growing nanocrystalline TiO2 films for photovoltaic applications.

Fabrication and Characterization of Transparent Super-long Titania Nanotube Arrays/FTO Electrode

Titanium film was deposited on fluorine-doped tin oxide-coated glass substrate(FTO) by electron beam evaporation(EBEAM),ultra-long titania nanotube arrays/FTO electrode was fabricated by potentiostatic anodization of the titanium film in C2H6O2+NH4F electrolyte at room temperature.The structure and the composition of the titania nanotube arrays/FTO electrode were characterized by field emission scanning electron microscope(FESEM),transmission electron microscope(TEM),X-ray photoelectron spectroscope(XPS),X-ray diffraction(XRD) and transmission spectrometer.The results show that inner diameter and length of the as-prepared titania nanotube are 43nm and 5.4μm respectively.The titania nanotube arrays/FTO transparent electrode after annealing in air is of anatase phase with length of 5μm.The transmittance of the titania nanotube arrays is 45% in visible wavelength range and an absorbance peak is observed at wavelength of 400nm.

Screening of Novel Metal Oxide Photocatalysts by Scanning Electrochemical Microscopy and Research of Their Photoelectrochemical Properties

Photocatalyst arrays of a number of metal oxides were prepared by dispensing metal precursor solutions onto fluorine-doped tin oxide-coated glass followed by annealing at 500 °C for 3 h. These were screened by scanning electrochemical microscopy with a scanning optical fiber, and the results showed that all Sn-doped Cd−In−Bi, Zn−In, and W−Cd oxide photocatalysts produced enhanced photocurrents for specific metal ratios. The products of the photoelectrochemical (PEC) reaction could be detected electrochemically by a Au ring on the optical fiber. The PEC properties of larger electrodes were investigated, and the Zn−In and W−Cd oxide photocatalysts showed a much higher photoactivity than Sn-doped Cd−In−Bi. Even without catalysts, they showed visible light response for water oxidation to oxygen.