Transparent Fluorine-doped Tin Oxide Research Articles

A transparent electrode with water-oxidizing activity

Hydrogen production by water splitting is a promising method to store energy. Water-oxidation reaction is a bottleneck in water-splitting systems. Herein, a mononuclear nickel(II) phosphine complex with 1,2-bis(dicyclohexylphosphino)ethane ligand, was synthesized and characterized by X-ray crystallography method. The water-oxidizing catalyst under the electrochemical condition was studied. The role of Ni compound for the water-oxidation reaction on the surface of fluorine-doped tin oxide as one of the true catalysts was investigated by the electrochemical methods and Scanning Electron Microscopy coupled with Energy Dispersive X-ray (SEM/EDX) Spectroscopy. The big ligand around the Ni ion causes a very small size of Ni-based particles on the surface of the electrode, which are the active catalysts for the water-oxidation reaction. Such small nanosized Ni-based compounds are transparent and have no effect on the transparency of the obtained fluorine-doped tin oxide. Thus, it is a promising method to synthesize a transparent fluorine-doped tin oxide with water-oxidizing activity.

Electrode plate-culture methods for colony isolation of exoelectrogens from anode microbiomes

Exoelectrogens play central roles in microbial fuel cells and other bioelectrochemical systems (BESs), yet their physiological diversity remains largely elusive due to the lack of efficient methods for the isolation from naturally occurring microbiomes. The present study developed an electrode plate-culture (EPC) method that facilitates selective colony formation by exoelectrogens and used it for isolating them from an exoelectrogenic microbiome enriched from paddy-field soil. In an EPC device, the surface of solidified agarose medium was spread with a suspension of a microbiome and covered with a transparent fluorine doped tin oxide (FTO) electrode (poised at 0 V vs. the standard hydrogen electrode) that served as the sole electron acceptor. The medium contained acetate as the major growth substrate and Coomassie Brilliant Blue as a dye for visualizing colonies under FTO. It was shown that colonies successfully appeared under FTO in association with current generation. Analyses of 16S rRNA gene sequences of colonies indicated that they were affiliated with genera Citrobacter, Geobacter and others. Among them, Citrobacter and Geobacter isolates were found to be exoelectrogenic in pure-culture BESs. These results demonstrate the utility of the EPC method for colony isolation of exoelectrogens.

ZnO-Assisted Growth of CH3NH3PbI3- xCl x Film and Efficient Planar Perovskite Solar Cells with a TiO2/ZnO/C60 Electron Transport Trilayer.

Appropriate electron transport layers (ETL) are essential in perovskite solar cells (PSCs) with high power conversion efficiency (PCE). Herein, a TiO2/ZnO/C60 trilayer fabricated on a transparent fluorine-doped tin oxide (FTO) glass substrate is used as a compound ETL in planar PSCs. The trilayer shows positive effects on both perovskite synthesis and device performance. The ZnO layer assists growth of CH3NH3PbI3- xCl x ( x ≈ 0) annealed at a lower temperature and with a shorter time, which is due to a more rapid and easier decomposition of the intermediate CH3NH3PbCl3 phase in the growth of CH3NH3PbI3- xCl x. All three materials in the trilayer are important for obtaining PSCs with a high PCE. ZnO is critical for enhancing the open circuit voltage by ensuring proper energy alignment with the TiO2 and C60 layers. C60 enhances carrier extraction from the CH3NH3PbI3- xCl x layer. TiO2 eliminates charge recombination at the FTO surface and ensures efficient electron collection. The best-performing PSC based on the TiO2/ZnO/C60 electron transport trilayer features a PCE of 18.63% with a fill factor of 79.12%. These findings help develop an understanding of the effects of ZnO-containing ETLs on perovskite film synthesis and show promise for the future development of high-performance PSCs with compound ETLs.

Assembly of CdSe Quantum Dots onto TiO2 Flower-rod Films for Quantum Dot-sensitized Solar Cell Applications

A hierarchical double-layered TiO2 flower-rod structure composed of three-dimensional (3D) TiO2 flowers and one-dimensional (1D) nanorods on transparent fluorine-doped tin oxide (FTO) conducting glass has been synthesized by a facile hydrothermal method and was applied as photoanode in CdSe quantum dots sensitized solar cells (QDSSCs). The 3D TiO2 flowers with the increased surface areas can adsorb more QDs, which reinforce the absorption of light; meanwhile 1D TiO2 nanorods beneath the flowers offer a direct electrical pathway for photogenerated electrons, accelerating the electron transfer rate. The effect of coating cycles of QDs on the photovoltaic performance was investigated by successive ionic layer adsorption reaction (SILAR) cycles. The best power conversion efficiency of solar cell based on flower-rod structure with 12 SILAR cycles of CdSe QDs can reached to 1.98% under one sun illumination (AM 1.5G, 100 mW/cm2).

Broadband Light Absorption and Efficient Charge Separation Using a Light Scattering Layer with Mixed Cavities for High-Performance Perovskite Photovoltaic Cells with Stability.

CH3 NH3 PbI3 is one of the promising light sensitizers for perovskite photovoltaic cells, but a thick layer is required to enhance light absorption in the long-wavelength regime ranging from PbI2 absorption edge (500 nm) to its optical band-gap edge (780 nm) in visible light. Meanwhile, the thick perovskite layer suppresses visible-light absorption in the short wavelengths below 500 nm and charge extraction capability of electron-hole pairs produced upon light absorption. Herein, we find that a new light scattering layer with the mixed cavities of sizes in 100 and 200 nm between transparent fluorine-doped tin oxide and mesoporous titanium dioxide electron transport layer enables full absorption of short-wavelength photons (λ < 500 nm) to the perovskite along with enhanced absorption of long-wavelength photons (500 nm < λ < 780 nm). Moreover, the light-driven electric field is proven to allow efficient charge extraction upon light absorption, thereby leading to the increased photocurrent density as well as the fill factor prompted by the slow recombination rate. Additionally, the photocurrent density of the cell with a light scattering layer of mixed cavities is stabilized due to suppressed charge accumulation. Consequently, this work provides a new route to realize broadband light harvesting of visible light for high-performance perovskite photovoltaic cells.

Hydrothermal growth of nanorod arrays and in situ conversion to nanotube arrays for highly efficient Ag-sensitized photocatalyst

TiO2 nanorod arrays (NRAs) were hydrothermally grown on transparent fluorine-doped tin oxide (FTO) substrates, and were converted into nanotubes (NTAs) by hydrothermally in situ etching. Ag nanoparticles (NPLs) were sensitized on the NRAs and NTAs by a simple photodeposition approach (products were denoted as Ag-TiO2 NRAs and NTAs). The Ag-TiO2 NTAs samples possessed a large specific surface area (116 m2 g-1) with Ag NPLs homogeneously dispersed among the TiO2 NTAs. The Ag-TiO2 NTAs exhibited significantly enhanced photocatalytic activities (98.8%) in degradation of methyl orange (MO) compared to Ag-TiO2 NRAs (92.6%), TiO2 NTAs (86.2%), and NRAs (81.7%). The enhanced photocatalytic activities can be attributed to the large specific surface area of TiO2 NTAs and strong surface plasmon resonance (SPR) of Ag NPLs. In addition, Ag-TiO2 NTAs showed easy recovery feature in the recovery process and high durability in the recycling test, which was expected to be an efficient and practical photocatalyst used for waste water treatment.

Two Electrode Collector-Generator Method for the Detection of Electrochemically or Photoelectrochemically Produced O2.

A dual working electrode technique for the in situ production and quantification of electrochemically or photoelectrochemically produced O2 is described. This technique, termed a collector-generator cell, utilizes a transparent fluorine doped tin oxide electrode to sense O2. This setup is specifically designed for detecting O2 in dye sensitized photoelectrosynthesis cells.

Preparation, characterization and electronic properties of fluorine-doped tin oxide films

Tin oxide (SnO2) and fluorine doped tin oxide (FTO) films were prepared on glass substrates by sol-gel spin-coating using SnCl4 and NH4F precursors. Fluorine doping concentration was fixed at 4 at% and 20 at% by controlling precursor sol composition. Films exhibited the tetragonal rutile-type crystal structure regardless of fluorine concentration. Uniform and highly transparent FTO films, with more than 85% of optical transmittance, were obtained by annealing at 600 °C. Florine doping of films was verified by analyzing the valence band region obtained by XPS. It was found that the fluorine doping affects the shape of valence band of SnO2 films. In addition, it was observed that the band gap of SnO2 is reduced as well as the Fermi level is upward shifted by the effect of fluorine doping.

Hierarchical three-dimensional branched hematite nanorod arrays with enhanced mid-visible light absorption for high-efficiency photoelectrochemical water splitting.

Herein, we presented hierarchical three-dimensional (3D) branched hematite nanorod arrays (NAs) on transparent fluorine-doped tin oxide (FTO) conductive glass substrates, which exhibited high PEC water splitting performance due to the enhancement of mid-visible light harvesting as well as charge separation and transfer. The introduction of a TiO2 underlayer made the as-prepared 3D branched hematite NAs achieve a photocurrent density of 0.61 mA cm(-2) at 1.23 V vs. reversible hydrogen electrode (RHE) without high-temperature activation.

Study of dielectric relaxation processes in printable zinc oxide films on transparent substrates

AC impedance spectroscopic measurements have been performed on sol–gel derived zinc oxide (ZnO) films on transparent fluorine-doped tin oxide coated glass substrates in the frequency range 10−2 to 106 Hz over the temperature range −185 to +25 °C (88–298 K). The relaxation behaviour of the nanocrystal line ZnO thin film can be described in terms of the Debye model giving an interpretation of the semi-circular relaxation phenomenon within the given temperature range. Two different relaxation times were obtained from impedance (Z) and electric modulus (M) studies of the devices and the multiple hopping of charge carriers between trap sites in grain and grain-boundary regions is believed to be responsible for charge transport. The values of activation energies for trap levels obtained from AC conductivity study are 0.0153 and 0.0487 eV which are close to the activation energies obtained from DC electrical measurement for temperature region between 88 and 178 K and 179 and 298 K, respectively.

Pulsed Electrodeposition of Gold Nanoparticles on Fluorine-Doped Tin Oxide Glass and Absorption-Based Surface Plasmon Resonance Evaluation

Synthesis and immobilization of Au nanoparticles (AuNPs) was performed on transparent fluorine-doped tin oxide (FTO) substrate by pulse electrodeposition method. The method was cost effective, simple and capable of producing nanoparticles strongly attached to the substrate. Effects of several influencing factors such as duty cycle, pulse frequency, current density, solution concentration, deposition period and annealing procedure on the optical properties of AuNPs-FTO electrode were investigated. AuNPs-FTO electrodes were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and UV-Vis absorption analysis. Controllability of the plasmon absorption of the electrodeposited film by tuning of the electrodeposition conditions and thermal annealing procedure was important achievements helpful to the progress of the AuNP film applications in the tunable localized surface plasmon resonance spectroscopy (LSPR) manufacturing industry.

Blacking FTO by strongly cathodic polarization with enhanced photocurrent

Transparent fluorine-doped tin oxide (TFTO) coating on quartz glass is widely used as substrate in photoelectrochemistry for solar energy transformation, sensing and so on. We observed that the TFTO could become blackish by strongly cathodic polarization. Characterization of the black FTO (BFTO) by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy revealed that part of SnO2 on the TFTO was reduced into metal Sn nanoparticles during the cathodic polarization. The BFTO greatly increased solar absorption and enhanced photocurrent responses in comparison with TFTO. It might be necessary to take caution in photoelectrochemical measurements while the FTO is strongly cathodically polarized.

Enhanced photoelectrochemical performance of CdSe/CdS/TiO2 nanorod arrays solar cell with a PbS underlayer

Vertically oriented single-crystalline one-dimensional (1D) TiO2 nanorod arrays film with high aspect ratio was synthesized directly on transparent fluorine-doped tin oxide conducting glass substrate by a facile two-step hydrothermal process. When used in CdSe/CdS/PbS quantum dots sensitized solar cells (QDSSCs), the 1D ordered TiO2 nanorods with the increased internal surface areas can adsorb more QDs, which enhanced the ability of light absorption. Moreover, 1D ordered TiO2 nanorods can also offer a direct electrical pathway for photogenerated electrons, accelerating the electrons transfer rate. In addition, the introduction of PbS as underlayer in CdSe/CdS/TiO2 system can extend the optical absorption range, which greatly raised the utilization of the solar energy. The incident photon to current conversion efficiency of the CdSe/CdS/PbS/TiO2 nanorods solar cell reached to 52 %, which is higher than that of CdSe/CdS/TiO2 nanorods solar cell, indicating that the better light harvesting ability could be obtained by the introduction of PbS QDs. The power conversion efficiency of CdSe/CdS/PbS/TiO2 nanorods solar cell can reach to 2.56 % under one sun illumination (AM 1.5 G, 100 mW/cm2), which is greatly higher than that of CdSe/CdS/TiO2 nanorods solar cell (1.73 %).

Dye-Sensitized Solar Cells Using Dyes Extracted from Flowers, Leaves, Parks, and Roots of Three Trees

In this paper, eleven natural dyes were collected from three trees and used as photosensitizers for dye sensitized solar cells (DSSCs). The cells were fabricated using TiO 2 as a semiconducting layer deposited on transparent fluorine doped tin oxide (FTO) conductive glass using doctor blade method. The absorption spectra of the extracts were performed in the spectral range from 400 nm to 750 nm. The J-V characteristic curves of all fabricated cells were measured and analyzed. The parameters related to the solar cell performance were determined. Moreover, the impedance spectroscopy of the cell with the best performance was investigated.

Ti-doped hematite thin films for efficient water splitting

Uniform Ti-doped hematite thin films were deposited on transparent fluorine-doped tin oxide FTO coated glasses using a pulsed laser deposition method. An influence of dopant concentration on the photoelectrochemical characteristics was examined under water splitting. Photocurrent measurements indicated that 3 mol% of Ti atoms was optimal dopant concentration in hematite films produced by this method. The maximum photocurrent density of un-doped and 3 mol% Ti-doped Fe2O3 photoelectrodes was 0.67 and 1.64 mA/cm2 at 1.23 V versus RHE, respectively. The incorporation of Ti atoms into hematite photoelectrodes was found to drastically enhance the water splitting performance.

Synthesis of hierarchical TiO2 flower-rod and application in CdSe/CdS co-sensitized solar cell

A hierarchical double-layered TiO2 flower-rod structure composed of three-dimensional (3D) TiO2 flowers and one-dimensional (1D) nanorods on transparent fluorine-doped tin oxide (FTO) conducting glass has been synthesized by a facile hydrothermal method. The possible formation mechanism of the hierarchical architecture is also proposed. When used in CdSe/CdS quantum dots co-sensitized solar cells (QDSSCs), the 1D ordered rutile nanorods at bottom can accelerate the electron transfer rate by providing direct electrical pathway for photogenerated electrons, while the 3D flowers formed on the top of nanorods can increase the adsorption of QDs due to the enlarged areas, and can also be used as a scattering layer. The performance of the CdSe/CdS/TiO2 flower-rod solar cell can achieve a short-circuit current density (Jsc) of 13.46 mA cm−2, and a open-circuit voltage (Voc) of 0.42 V, with a maximum power conversion efficiency of 2.31% under one sun illumination (AM 1.5 G, 100 mW cm−2), which is greatly higher than that of CdSe/CdS/TiO2 nanorod solar cell (1.63%).

Preparation of Layered Double Hydroxide and its Graphene Composite Films as Electrodes for Photoelectrochemical Cells

Visible-light responsive photoanodes for water splitting into hydrogen and oxygen were fabricated via NiTi-layered double hydroxide (NiTi-LDH, [Ni1-xTix(OH)2]2x+(An-)2x/n・mH2O]) and NiTi-LDH/graphene composite prepared by homogeneous precipitation methods. The NiTi-LDH and NiTi-LDH/graphene films were formed on transparent fluorine-doped tin oxide (FTO) glass substrates by electrophoretic deposition (EPD). The EPD films showed the pattern of hydrotalcite structure under x-ray diffraction, indicating that NiTi-LDH has been deposited on FTO by EPD without degradation. NiTi-LDH powder was obtained from formic acid intercalated LDH by homogeneous precipitation in formamide with hexamethylenetetramine, and NiTi-LDH/graphene composite was obtained from graphene and NiTi-LDH aqueous suspension with urea. The formed NiTi-LDH and NiTi-LDH/graphene composite films have different morphologies. Both NiTi-LDH and NiTi-LDH/graphene films prepared showed photovoltage of 15-55 mV under visible-light irradiation. Their photoelectrochemical properties were affected by the film morphology.

Enhanced photoelectrochemical performance of CdSe/Mn-CdS/TiO2 nanorod arrays solar cell

Abstract Vertically oriented single-crystalline one-dimensional TiO2 nanorod arrays was synthesized directly on transparent fluorine-doped tin oxide (FTO) conducting glass substrate by a facile hydrothermal method and was applied as photoanode in CdSe/Mn-doped CdS quantum dots sensitized solar cells (QDSSCs). The effect of coating cycles of QDs on the photovoltaic performance was investigated to find the optimal combination is 10 cycles of Mn-doped CdS and 9 cycles of CdSe, the CdSe(9)/Mn-CdS(10)/TiO2 solar cell exhibited the best performance due to the complementary effect in the light absorption of Mn-doped CdS and CdSe QDs. The power conversion efficiency of CdSe(9)/Mn-CdS(10)/TiO2 solar cell reached to 2.40% under one sun illumination (AM 1.5 G, 100 mW/cm2), which was 46.34% higher than that of CdSe(9)/CdS(10)/TiO2 solar cell without doping of Mn (1.64%).

Mn-doped CdS quantum dots sensitized hierarchical TiO2 flower-rod for solar cell application

Abstract A double-layered TiO2 film which three dimensional (3D) flowers grown on highly ordered self-assembled one dimensional (1D) TiO2 nanorods was synthesized directly on transparent fluorine-doped tin oxide (FTO) conducting glass substrate by a facile hydrothermal method and was applied as photoanode in Mn-doped CdS quantum dots sensitized solar cells (QDSSCs). The 3D TiO2 flowers with the increased surface areas can adsorb more QDs, which increased the absorption of light; meanwhile 1D TiO2 nanorods beneath the flowers offered a direct electrical pathway for photogenerated electrons, accelerating the electron transfer rate. A typical type II band alignment which can effectively separate photogenerated excitons and reduce recombination of electrons and holes was constructed by Mn-doped CdS QDs and TiO2 flower-rod. The incident photon-to-current conversion efficiency (IPCE) of the Mn-doped CdS/TiO2 flower-rod solar cell reached to 40% with the polysulfide electrolyte filled in the solar cell. The power conversion efficiency (PCE) of 1.09% was obtained with the Mn-doped CdS/TiO2 flower-rod solar cell under one sun illumination (AM 1.5G, 100 mW/cm2), which is 105.7% higher than that of the CdS/TiO2 nanorod solar cell (0.53%).

Fabrication of a CuInS2photoelectrode using a single-step electrodeposition with controlled calcination atmosphere

n-type CuInS2 thin films were fabricated by a one-step electrodeposition of Cu/In/S precursors on a transparent fluorine-doped tin oxide (FTO) substrate followed by calcination in a mixture of N2 and H2 at 500 °C without the need of toxic H2S gas for sulfurization. The analyses of structural and optical properties revealed that tetragonal chalcopyrite CuInS2 thin films were obtained when heat treated in a mixture of 8% H2 and 92% N2; whereas calcination in pure N2 resulted in the formation of CuInS2 with a considerable amount of In2O3 and CuxS impurities. The synthesized n-CuInS2 thin film has an optical bandgap of 1.3 eV with the conduction band at ca. −1.2 V vs. Ag/AgCl at pH 6.5. The heat treatment in a mixture of H2 and N2 provided a reducing atmosphere to suppress the oxide formation of the electrodeposited Cu/In/S elements. It also increased the donor density of CuInS2 sixfold by increasing the density of the sulfur vacancies (known to be electron donors) at the grain surface. As a result of the improved purity and increased donor density, the hydrogen treated CuInS2 thin film yielded a photocurrent density of ∼8 mA cm−2 at 0.5 V vs. Ag/AgCl in 0.25 M Na2S and 0.35 M Na2SO3 under visible light illumination, which is a fourfold enhancement as compared to that obtained from the CuInS2 film calcined in pure N2.