Fluoride-doped Tin Oxide Research Articles

Electrospun TiO2 nanofiber based hierarchical photoanode for efficient dye-sensitized solar cells

The development of effective photoanode materials with hierarchical architecture provides a promising scheme to fabricate efficient energy conversion devices. In this manuscript, we report the synthesis of a novel hierarchical nanorod-branched TiO2 nanofiber non-woven fabric film and its photoelectric performance as photoanode material for dye-sensitized solar cells (DSSCs) is investigated. The synthesis process involves transferring electrospun TiO2 nanofibers film completely to the surface of fluoride-doped tin oxide (FTO) glass substrate first, and a followed hydrothermal treatment to grow hierarchical TiO2 nanorod branches. The photovoltaic tests reveal that the DSSCs based on such hierarchical photoelectrode exhibit an impressive power conversion efficiency (η) of 6.26% under AM 1.5G one sun illumination with greatly improved short-circuit current density (Jsc) compared to pristine TiO2 nanofibers film. The enhanced efficiency is a direct consequence of the synergistic effect of improved light harvesting efficiency induced by high dye loading and superior broadband light scattering effect and fast charge transport of composite structure, which are characterized in detail by UV–vis diffuse reflectance spectra, electrochemical impedance spectra (EIS), open-circuit voltage-decay (OCVD) measurement, intensity-modulated photocurrent/photovoltage spectroscopy (IMPS/IMVS). These results indicate the electrospun non-woven fabric films based nanomaterials can work as excellent photoelectrode candidates for DSSCs, or other photoelectric applications.

Fluorine-doped tin oxide films by spray pyrolysis using vacuum within nozzle

Fluoride-doped tin oxide films on glass substrate were prepared from NH4F-doped SnCl2 precursor by spray pyrolysis with ceramic heater as heat source, it insert in reactor and creating a vacuum into nozzle. They were characterized by scanning electron microscopy, UV-Vis spectroscopy, measurement of electrical resistance and X-ray diffraction. The results showed that the fluoride-doped tin oxide films demonstrate potential as materials for photovoltaic applications.

Electrospun carbon nanofibers with surface-attached platinum nanoparticles as cost-effective and efficient counter electrode for dye-sensitized solar cells

Dye-sensitized solar cells (DSCs) have attracted incredible attention in recent years as relatively inexpensive alternative to silicon solar cells. Conventionally, a transparent fluoride-doped tin oxide (FTO) conductive glass with a thin layer coating of platinum (Pt) is used as counter electrode in DSCs. The widespread use of Pt as counter electrode in DSCs is due to its catalytic capability for I3- reduction in electrolyte. However, Pt is costly and can be affected by the corrosive nature of I-/I3- redox couple, which makes it a less desirable candidate for use in industrial scale manufacturing. In this study, carbon nanofibers with surface-attached Pt nanoparticles were prepared by stabilization and carbonization of electrospun polyacrylonitrile (PAN) nanofibers and subsequent controllable Pt nanoparticle growth on the obtained carbon nanofiber surface through redox reaction. The hierarchical carbon nanofibers with surface-attached Pt nanoparticles (ECNFs-PtNPs) were then employed as cost-effective counter electrode in DSCs. The effects of size, morphology, and loading of Pt nanoparticles on performance of DSCs were investigated. Compared to conventional counter electrode, the counter electrode that was made of ECNFs-PtNPs exhibited larger open circuit voltage (Voc). The DSCs that were made with ECNFs-PtNPs counter electrode demonstrated excellent solar energy conversion efficiencies in the range of 7% to 8%.

Fabrication and Optoelectronic Properties of Fluoride Tin Oxides/Porous Silicon/p-Silicon Heterojunction

In this paper, formation of a nanostructure semi transparence fluoride tin oxides (FTO) by spray pyrolysis technique on porous silicon PS layer. Porous silicon PS layer was prepared by anodization of p-type silicon wafers to fabricate of the UV- Visible Fluoride-doped tin oxide /Porous silicon /p-Si heterojunction photodetector. Optical properties of FTO thin films were measured. The optical band gap of 3.77 eV for SnO2:film was deduced. From (I-V) and (C-V) measurements, the barrier height for FTO/PS diode was of 0.77 eV, and the built in voltage , which was of 0.95 V. External quantum efficiency was 55 % at 500 nm which corresponding to peak responsivity of 1.15 A/W at 1 V bias. The PS band gap in the vicinity of PS/c-Si heterojunction was 1.38 eV.

Fabrication and Optoelectronic Properties of Fluoride Tin Oxides/Porous Silicon/p-Silicon Heterojunction

In this paper, formation of a nanostructure semi transparence fluoride tin oxides (FTO) by spray pyrolysis technique on porous silicon PS layer. Porous silicon PS layer was prepared by anodization of p-type silicon wafers to fabricate of the UV- Visible Fluoride-doped tin oxide /Porous silicon /p-Si heterojunction photodetector. Optical properties of FTO thin films were measured. The optical band gap of 3.77 eV for SnO2:film was deduced. From (I-V) and (C-V) measurements, the barrier height for FTO/PS diode was of 0.77 eV, and the built in voltage , which was of 0.95 V. External quantum efficiency was 55 % at 500 nm which corresponding to peak responsivity of 1.15 A/W at 1 V bias. The PS band gap in the vicinity of PS/c-Si heterojunction was 1.38 eV.

Infiltration of Spiro-MeOTAD hole transporting material into nanotubular TiO2 electrode for solid-state dye-sensitized solar cells

TiO2 nanotubes grown by anodic oxidation of Ti thin film deposited on conducting transparent fluoride-doped tin oxide (FTO) substrate were used as a unique geometrically organized template to study the infiltration of Spiro-MeOTAD hole transporting material (HTM) inside straight pores. The TiO2 nanotube (TNT) array electrode was compared with a mesoporous one in terms of loading with an organic dye of high extinction coefficient. It was shown that it is possible to build a working solid state dye sensitized solar cell device with such a combination of materials and its performance was compared with a device in which the solid state HTM was replaced by a liquid state electrolyte.

Formation and properties of cadmium sulfide buffer layer for CIGS solar cells grown using hot plate bath deposition

In the present study, cadmium sulfide (CdS) thin films were deposited on different substrates [soda glass, fluoride doped tin oxide, and tin doped indium oxide (ITO) coated glass] by a hot plate method. To control the thickness and the reproducibility of the sample production, the thin films were coated at different temperatures and deposition times. The CdS thin films were heated at 400 °C in air and forming gas (FG) atmosphere to investigate the effect of the annealing temperatures. The thickness of the samples, measured by ellipsometry, could be controlled by the deposition time and temperature of the hot plate. The phase formation and structural properties of CdS thin films were studied by X-ray diffraction and scanning electron microscopy, whereas the optical properties were obtained by UV–vis spectroscopy. A hexagonal crystal structure was observed for CdS thin films and the crystallinity improved upon annealing. The structural and optical properties of CdS thin films were also enhanced by annealing at 400 °C in FG atmosphere (95 % N2, 5 % H2). The optical band gap was changed from 2.25 to 2.40 eV at different annealing temperatures and gas atmospheres. A higher electrical conductivity, for the sample annealed at FG, was noticed. The samples deposited on ITO and annealed in FG atmosphere showed the best structural and electrical properties compared to the other samples. CdS thin films can be widely used for application as a buffer layer for copper–indium–gallium–selenide solar cells.

Preparation of Fluoride-Doped Tin Oxide Films on Soda–Lime Glass Substrates by Atomized Spray Pyrolysis Technique and Their Subsequent Use in Dye-Sensitized Solar Cells

The development of a novel method for the fabrication of low-cost, transparent, conducting glass (F–-doped SnO2 layer on soda–lime glass, FTO) by a specially developed atomized spray pyrolysis tech...

Preparation of polyaniline/TiO2 nanocomposite film with good adhesion behavior for dye‐sensitized solar cell application

In this study, novel Polyaniline (PAni)/TiO2 nanocomposites were applied on fluoride‐doped tin oxide (FTO) glass to act as an efficient counter electrode in dye‐sensitized solar cell (DSSC) application. PAni/TiO2 nanocomposites were synthesized via chemical oxidation process using di‐2‐ethylhexylsulfosuccinate sodium salt (NaDEHS) as dopant. The nanocomposites were characterized using fourier transform infrared and ultraviolet‐visible spectrometers. In the application of PAni as the counter electrode in the solar cell, the film showed poor adhesion on the FTO glass. Palm oil‐based alkyd was introduced into the nanocomposite mixture to improve the adhesion of the film. The findings in the work show that strong adhesion of PAni on FTO glasses has led to higher incident photon to current conversion efficiency (IPCE) in solar cell. The short circuit current (Jsc), Voc (open circuit voltage), and IPCE of the resulted PAni/TiO2 counter electrode with good adhesion in DSSC are 15.8 mA/cm2, 670 mV, and 3.0%, respectively. POLYM. COMPOS., 34:1884–1891, 2013. © 2013 Society of Plastics Engineers

Water Oxidation and Oxygen Monitoring by Cobalt-Modified Fluorine-Doped Tin Oxide Electrodes

Electrocatalytic water oxidation occurs at fluoride-doped tin oxide (FTO) electrodes that have been surface-modified by addition of Co(II). On the basis of X-ray photoelectron spectroscopy and transmission electron microscopy measurements, the active surface site appears to be a single site or small-molecule assembly bound as Co(II), with no evidence for cobalt oxide film or cluster formation. On the basis of cyclic voltammetry measurements, surface-bound Co(II) undergoes a pH-dependent 1e(-)/1H(+) oxidation to Co(III), which is followed by pH-dependent catalytic water oxidation. O2 reduction at FTO occurs at -0.33 V vs NHE, allowing for in situ detection of oxygen as it is formed by water oxidation on the surface. Controlled-potential electrolysis at 1.61 V vs NHE at pH 7.2 resulted in sustained water oxidation catalysis at a current density of 0.16 mA/cm(2) with 29,000 turnovers per site over an electrolysis period of 2 h. The turnover frequency for oxygen production per Co site was 4 s(-1) at an overpotential of 800 mV at pH 7.2. Initial experiments with Co(II) on a mesoporous, high-surface-area nanoFTO electrode increased the current density by a factor of ~5.

How to combine electrochromic and electrocatalytic applications with the low degradation rate of electrodeposited tungsten oxides

Vanadium- and molybdenum-doped as well as undoped oxotungstate films electrodeposited on fluoride doped tin oxide (FTO) from peroxide-free solutions are considered as mediator electrocatalysts for inorganic anions reduction (by the example of IO3−). The most risky aspect related to oxide degradation is addressed in electrochromic and voltammetric experiments. Potential-dependent optical absorption (300–1100nm spectral range), coloration–decoloration kinetics, and capacity of the films are studied. Two-step coloration mechanism is ascertained, and the optimal wavelength (1100nm) is chosen for further monitoring of the film redox state in the course of stability tests. The comparison of cycling stability in 0.5 and 2.0M H2SO4 in terms of capacity and coloration efficiency indicates the change of film degradation mechanism from dissolution to mechanical peeling with increase of acidity. The latter mechanism is shown to be less important for the film stability.

Kinetics-controlled growth of aligned mesocrystalline SnO2 nanorod arrays for lithium-ion batteries with superior rate performance

A general method for facile kinetics-controlled growth of aligned arrays of mesocrystalline SnO2 nanorods on arbitrary substrates has been developed by adjusting supersaturation in a unique ternary solvent system comprising acetic acid, ethanol, and water. The hydrolysis processes of Sn(IV) as well as the nucleation and growth of SnO2 crystals were carefully controlled in the mixed solvents, leading to an exclusively heterogeneous nucleation on a substrate and the subsequent growth into mesocrystalline nanorod arrays. In particular, aligned arrays of hierarchically structured, [001]-oriented mesocrystalline SnO2 nanorods with four {110} lateral facets can be readily grown on Ti foil, as well as many other inert substrates such as fluoride-doped tin oxide (FTO), Si, graphite, and polytetrafluoroethylene (Teflon). Due to the unique combination of the mesocrystalline structure and the one-dimensional nanoarray structure, the obtained mesocrystalline SnO2 nanorod arrays grown on metallic Ti substrate exhibited an excellent rate performance with a high initial Coulombic efficiency of 65.6% and a reversible capacity of 720 mA·h/g at a charge/discharge rate of 10 C (namely, 7,820 mA/g) when used as an anode material for lithium-ion batteries.

Influence of fluoride-doped tin oxide interlayer on Ni–Sb–SnO2/Ti electrodes

In the present work, fluoride-doped tin oxide (FTO) as an interlayer was introduced into nickel and antimony co-doped tin dioxide coated titanium electrodes to investigate the influence of FTO interlayer on the structural properties and lifetime performance of the electrodes. Scanning electron microscopy and X-ray diffraction techniques were used to characterize the morphology and crystal structure of the electrodes with or without FTO interlayer. The electrode surface became smoother with FTO interlayer introduced while the crystallite size reduced. Electrochemical impedance spectroscopy was also adopted to analyze the electrodes’ electrochemical behavior. With FTO interlayer introduced, the formation of titanium dioxide-insulating layer on the titanium substrate was significantly retarded during the anodic process. The accelerated lifetime tests presented that the lifetime of the electrodes with proper FTO interlayer was six times longer than that without FTO interlayer. The mechanisms for the electrodes’ lifetime enhancement with FTO interlayer were discussed.

Chemically grown vertically aligned 1D ZnO nanorods with CdS coating for efficient quantum dot sensitized solar cells (QDSSC): a controlled synthesis route

In the present article, vertically aligned ZnO nanorod arrays were synthesized by an aqueous chemical growth (ACG) route on a fluoride doped tin oxide (FTO) coated glass substrate. These nanorods were further sensitized with cadmium sulfide (CdS) quantum dots (QDs) by a successive ionic layer adsorption and reaction (SILAR) technique. The synthesized CdS coated ZnO nanorods were characterized for their structural and morphological properties with X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM). Finally, prepared CdS coated 1D ZnO photoelectrodes were tested for their photoelectrochemical performance. Our results show that the sample deposited after 40 SILAR cycles shows 5.61 mA cm(-2) short current density (JSC) with η = 1.61% power conversion efficiency.

Facile assembly of an efficient CoOxwater oxidation electrocatalyst from Co-containing polyoxotitanate nanocages

Cobalt-containing polyoxotitanates (TiCo) are excellent precursors for the simple and scalable preparation of Nocera-type CoOx water-oxidation electrocatalysts. The TiCo cages serve as a reservoir for cobalt ions in a titania matrix on fluoride-doped tin oxide electrodes, and form, in situ, the active CoOx catalyst for O2 evolution with high stability in phosphate buffer in pH neutral water.

High performance dye-sensitized solar cells (DSSCs) achieved via electrophoretic technique by optimizing of photoelectrode properties

This paper describes a simple method utilizing electrophoretic deposition (EPD) of commercial P25 nanoparticles (NPs) films on fluoride-doped tin oxide (FTO) substrate. In this process, voltage and the number of deposition cycles are well controlled to achieve TiO2 film thickness of around 1.5–26μm, without any mechanical compression processing. The experimental results indicate that the TiO2 film thickness plays an important role as the photoelectrode in DSSCs because it adsorbs a large number of dye molecules which are responsible for electrons supply. Furthermore, it was found that effects of the bulk traps and surface states within the TiO2 films on the recombination of the photo-injected electrons (electron–hole pairs) strongly depend on the TiO2 electrode annealing temperature. Finally, a DSSC with a 24μm thick TiO2 film and annealed at 500°C produced the highest conversion efficiency (η=6.56%, ISC=16.4, VOC=0.72, FF=0.55) with an incident solar energy of 100mW/cm2.

Electrode-assisted catalytic water oxidation by a flavin derivative

The success of solar fuel technology relies on the development of efficient catalysts that can oxidize or reduce water. All molecular water-oxidation catalysts reported thus far are transition-metal complexes, however, here we report catalytic water oxidation to give oxygen by a fully organic compound, the N(5)-ethylflavinium ion, Et-Fl(+). Evolution of oxygen was detected during bulk electrolysis of aqueous Et-Fl(+) solutions at several potentials above +1.9V versus normal hydrogen electrode. The catalysis was found to occur on glassy carbon and platinum working electrodes, but no catalysis was observed on fluoride-doped tin-oxide electrodes. Based on spectroelectrochemical results and preliminary calculations with density functional theory, one possible mechanistic route is proposed in which the oxygen evolution occurs from a peroxide intermediate formed between the oxidized flavin pseudobase and the oxidized carbon electrode. These findings offer an organic alternative to the traditional water-oxidation catalysts based on transition metals.

Band gap engineering of TiO2 nanostructure-based dye solar cells (DSCs) fabricated via electrophoresis

This work describes a simple method utilizing electrophoretic deposition (EPD) as versatile technique to deposit of commercial TiO2 (P25) nanopartcles (NPs) films on the fluoride-doped tin oxide (FTO) substrate. The main goal of this study is investigating the effects of surface treatment on the properties of nanoporous P25 electrodes in order to efficiently control and optimize the main fabrication step of the dye-sensitized solar cells (DSSCs). In order to increase of the electron transfer efficiency in DSSC, post-treatment of P25 films using TiCl4 has been carried out. As a result, cell efficiencies were improved about 40%. Solar cells based on a core–shell structure, including a ZnO as shell and a P25 as core, have been investigated. Results demonstrated that ZnO/P25 film electrode was enable to enhance of short-circuit photocurrent density (JSC) and consequently solar conversion efficiency for a DSSC by 10%, compared to those of a DSSC containing a bare P25 film electrode. The results were attributed to increase the concentration of free electrons in the conduction band (CB) of P25.

The anodized crystalline WO3 nanoporous network with enhanced electrochromic properties

We demonstrate that a three dimensional (3D) crystalline tungsten trioxide (WO(3)) nanoporous network, directly grown on a transparent conductive oxide (TCO) substrate, is a suitable working electrode material for high performance electrochromic devices. This nanostructure, with achievable thicknesses of up to 2 μm, is prepared at room temperature by the electrochemical anodization of a RF-sputtered tungsten film deposited on a fluoride doped tin oxide (FTO) conductive glass, under low applied anodic voltages and mild chemical dissolution conditions. For the crystalline nanoporous network with thicknesses ranging from 0.6 to 1 μm, impressive coloration efficiencies of up to 141.5 cm(2) C(-1) are achieved by applying a low coloration voltage of -0.25 V. It is also observed that there is no significant degradation of the electrochromic properties of the porous film after 2000 continuous coloration-bleaching cycles. The remarkable electrochromic characteristics of this crystalline and nanoporous WO(3) are mainly ascribed to the combination of a large surface area, facilitating increased intercalation of protons, as well as excellent continuous and directional paths for charge transfer and proton migration in the highly crystalline material.

Electrodeposited CuInS2Using Dodecylbenzene Sulphonic Acid As a Suspending Agent for Thin Film Solar Cell

CulnS<sub >2</sub> thin films were electrochemically deposited onto fluoride-doped tin oxide (FTO) substrate in presence of dodecylbenzene sulphonic acid to adjust pH of the solution and as a suspending agent for the sulfur. Cyclic voltammetry and chronoamperometry were carried out to determine the optimum pH. The composition, crystallinity, and optical properties of the compounds synthesized were studied by energy dispersive X-ray (EDX), X-ray diffraction, and UV-Visible spectra. It was found that the increasing of pH shifts the electrodeposited voltage toward more negative and lowers the deposition current. It was concluded that CuInS<sub >2</sub> with atomic stoichiometric ratio was prepared at pH equal to 1.5 and 150&#x2009;ml of 0.1&#x2009;M sodium thiosulphate, 5&#x2009;ml of 0.1&#x2009;M indium chloride, and 5&#x2009;ml of 0.1&#x2009;M cupper chloride. The energy gaps were calculated to be 1.95 and 2.2&#x2009;eV for CuInS<sub >2</sub> prepared at 1.5 and 2.5 of pH, respectively. It was found that <svg style="vertical-align:-3.22281pt;width:18.299999px;" id="M1" height="14.35" version="1.1" viewBox="0 0 18.299999 14.35" width="18.299999" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,14.35)"> <g transform="translate(72,-60.52)"> <text transform="matrix(1,0,0,-1,-71.95,63.79)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝐽</tspan> </text> <text transform="matrix(1,0,0,-1,-65.2,60.66)"> <tspan style="font-size: 8.75px; " x="0" y="0">s</tspan> <tspan style="font-size: 8.75px; " x="3.4045279" y="0">c</tspan> </text> </g> </g> </svg>, <svg style="vertical-align:-3.22281pt;width:20.0625px;" id="M2" height="14.35" version="1.1" viewBox="0 0 20.0625 14.35" width="20.0625" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,14.35)"> <g transform="translate(72,-60.52)"> <text transform="matrix(1,0,0,-1,-71.95,63.79)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑉</tspan> </text> <text transform="matrix(1,0,0,-1,-64.76,60.66)"> <tspan style="font-size: 8.75px; " x="0" y="0">o</tspan> <tspan style="font-size: 8.75px; " x="4.3759999" y="0">c</tspan> </text> </g> </g> </svg>, and <svg style="vertical-align:-2.29482pt;width:7.9375px;" id="M3" height="9.875" version="1.1" viewBox="0 0 7.9375 9.875" width="7.9375" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,9.875)"> <g transform="translate(72,-64.1)"> <text transform="matrix(1,0,0,-1,-71.95,66.44)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝜂</tspan> </text> </g> </g> </svg> are <svg style="vertical-align:-0.3135pt;width:73.637497px;" id="M4" height="14.375" version="1.1" viewBox="0 0 73.637497 14.375" width="73.637497" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,14.375)"> <g transform="translate(72,-60.5)"> <text transform="matrix(1,0,0,-1,-71.95,60.86)"> <tspan style="font-size: 12.50px; " x="0" y="0">1</tspan> <tspan style="font-size: 12.50px; " x="6.2515001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="9.3772497" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="15.62875" y="0">2</tspan> <tspan style="font-size: 12.50px; " x="24.655916" y="0">×</tspan> <tspan style="font-size: 12.50px; " x="35.433502" y="0">1</tspan> <tspan style="font-size: 12.50px; " x="41.685001" y="0">0</tspan> </text> <text transform="matrix(1,0,0,-1,-24.01,66.03)"> <tspan style="font-size: 8.75px; " x="0" y="0">−</tspan> <tspan style="font-size: 8.75px; " x="5.99512" y="0">4</tspan> </text> </g> </g> </svg>&#x2009;A/cm<sup >2</sup>, 0.52&#x2009;V, and <svg style="vertical-align:-0.3135pt;width:65.824997px;" id="M5" height="14.375" version="1.1" viewBox="0 0 65.824997 14.375" width="65.824997" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,14.375)"> <g transform="translate(72,-60.5)"> <text transform="matrix(1,0,0,-1,-71.95,60.86)"> <tspan style="font-size: 12.50px; " x="0" y="0">1</tspan> <tspan style="font-size: 12.50px; " x="6.2515001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="9.3772497" y="0">3</tspan> <tspan style="font-size: 12.50px; " x="18.404415" y="0">×</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">1</tspan> <tspan style="font-size: 12.50px; " x="35.433502" y="0">0</tspan> </text> <text transform="matrix(1,0,0,-1,-30.26,66.03)"> <tspan style="font-size: 8.75px; " x="0" y="0">−</tspan> <tspan style="font-size: 8.75px; " x="5.99512" y="0">2</tspan> </text> </g> </g> </svg>&#x25;, respectively, for FTO/CuInS<sub >2</sub>/ZnO/FTO heterojunction solar cell.