Fluorine-doped Tin Oxide Conductive Glass Research Articles

Sol-gel immobilization of lipase enzyme on FTO modified with silica-zirconia and gold nanoparticles films for design of triglyceride impedimetric biosensor

A novel electrochemical sensing platform was created using the formation of a sequence of films, over a conductive fluorine-doped tin oxide glass (FTO), obtained using the sol-gel method and the dip coating technique. Firstly, thin films of silica-zirconia mixed oxides were deposited, in sequence an ionic silsesquioxane film stabilizing and controlling the size of gold nanoparticles (6.5 ± 2.4 nm) was settled, and after the lipase enzyme, obtained from Candida rugosa, was entrapped into a silica film maintaining its operational stability. The films were characterized by scanning electron microscopy (SEM) with EDX, UV–Vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The thickness of each film on the FTO glass was evaluated by optical profilometry. The presence of the enzyme on the platform was confirmed by cyclic voltammetry with the ρ-nitrophenyl palmitate method. This platform was applied successfully as a biosensor for tributyrin (TB) determination by electrochemical impedance spectroscopy EIS, showing low limit of detection (LD) of 1.86 μmol L−1 and high sensitivity of 5.37 μΩ μmol−1 L. The biosensor presented a low KMapp value of 22.69 μmol L− 1 and the Vmaxapp value of 85.57 μmol L−1 min−1 suggesting that the enzyme, immobilized with this method retained activity promoting a fast enzymatic reaction with the TB.

Experimental and theoretical study on one-step synthesis of AuAg alloy nanoparticle catalytic layer as highly stable non-enzymatic glucose sensing interface

Au-based non-enzymatic glucose sensor has excellent catalytic performance, but it is difficult to be applied to practice due to high cost. A facile method was developed to load three AuAg alloy nanoparticle catalytic layer on the fluorine-doped tin oxide conductive glass by calcination as the working electrodes for non-enzymatic glucose sensors in a single process. Scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction, and N2-adsorption–desorption were used to characterize the samples. The electrochemical properties of the electrodes were studied by cyclic voltammetry and electrochemical impedance spectroscopy methods. The Au1Ag1 catalytic layer electrode prepared achieved ultra-high detection sensitivity for glucose, and demonstrated excellent stability, maintaining ∼90 % sensitivity after 30 days of storage in room-temperature air. The adsorption properties of various AuAg substrates on glucose molecules under alkaline conditions were investigated using density functional theory. For the same AuAg substrates, the Ag sites adsorbed glucose more strongly than the Au sites. The adsorption capacity of Ag sites on the AuAg substrates is superior to that of Au sites on the Au substrates, which means that the doping of Ag improves the adsorption capacity for glucose, qualitatively supporting the experimental results. Under alkaline synthetic conditions, the AuAg alloying dramatically enhances the sensitivity and stability of the non-enzymatic glucose sensor. Meanwhile, the preparation method of the sensor is simple and the cost is low. This paper provides research ideas and theoretical support for the performance improvement and cost reduction of noble metal-based non-enzymatic glucose sensors.

Dynamic hysteresis scaling behavior in polyvinylidene fluoride-trifluoroethylene ferroelectric copolymer thin films

In this paper, we investigated the dependence of dynamic hysteresis on the electric field amplitude E0 and the frequency f in organic ferroelectric copolymer polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] thin films prepared by a spin-coating method on fluorine-doped tin oxide conductive glass. Three stages can be observed of the hysteresis area vs the field strength E0. In stage I of low E0 values, the area ⟨A⟩ dependent on E0 follows the law of ⟨A⟩∝E01.92795, whereas the diverse distribution of the area ⟨A⟩ with frequency f is found. In stage II of the intermediate E0 values, ⟨A⟩∝E0β is not applicable owing to collective contributions between 180° domain and chiral domain, while a relation of ⟨A⟩∝f−0.18636 can be deduced, a fascinating characteristic distinguishing from the nonlinear relations of the inorganics in this section. In stage III of high E0 values, the scaling law is ⟨A⟩∝f0.08447E00.49394 where the chiral domain is active. The positive β in the law of ⟨A⟩∝fαE0β illustrates that a growing number of chiral domains in P(VDF-TrFE) can keep pace with the variation of E0. Especially, the negative α in the transition zone, resembling some inorganics under low electric fields, probably indicates 180° domain reversal failing to follow with the alternating velocity of the increasing periodic electric field.

Seed layer-free hydrothermal synthesis of porous tungsten trioxide nanoflake arrays for photoelectrochemical water splitting.

The simple preparation of efficient nano-photoanodes has been a key issue in the development of photoelectrochemical water splitting. In this work, a convenient and seed layer-free hydrothermal approach has been developed to synthesize vertically aligned porous WO3 nanoflakes on a fluorine-doped tin oxide conductive glass substrate. The morphology of WO3 nanoflakes could be manipulated by changing the annealing time, which further affected the performance of WO3 nanoflakes as photoanodes. Under optimum conditions, the obtained photoanode can lead to a high photocurrent density of 2.34 mA cm−2 at 1.4 V vs. Ag/AgCl under one sun irradiation (100 mW cm−2) and an incident photon to current conversion efficiency of 60% at 300 nm. The excellent photoelectrochemical performance can be mainly attributed to the larger active surface area, single crystal structure with an optimum thickness and the exposed highly active facets.

Fabrication of Z-Scheme TiO2/SnS2/MoS2 ternary heterojunction arrays for enhanced photocatalytic and photoelectrochemical performance under visible light

In the current work, Z-scheme TiO2/SnS2/MoS2 ternary heterojunction arrays were synthesised on a fluorine-doped tin oxide conductive glass by using a facile hydrothermal technique. The microstructures, energy band structures, and photocatalytic performances of TiO2, TiO2/SnS2, and TiO2/MoS2 were investigated. The results revealed that for methylene blue, ternary TiO2/SnS2/MoS2 exhibited considerably enhanced photocatalytic efficiency (∼79%) and the optimal transient current density (∼0.92 ​mA/cm2) under visible-light irradiation; these two values were four and eight times higher than those exhibited by TiO2, respectively. The highly improved photocatalytic and photoelectrochemical performance could be attributed to the unique microstructure and band alignment of TiO2/SnS2/MoS2. These attributes can be explained as follows: (i) the large specific surface area offers numerous active sites, (ii) the modulation of the narrow-band SnS2 and MoS2 broadens visible-light response, and (iii) the Z-scheme heterojunction effectively restricts the bulk recombination and spatially separates the photogenerated electron–hole (e−–h+) pairs.

The stabilization of Ni(OH)2 by In2O3 rods and the electrochromic performance of Ni(OH)2/In2O3-rod composite porous film

In this paper, a Ni(OH)2/In2O3-rod composite film with a porous structure was prepared by hydrothermal and solvothermal techniques using fluorine-doped tin oxide conductive glass as a substrate to improve the film/substrate connection and the cycle stability of the Ni(OH)2 film. A blank Ni(OH)2 film was also prepared for comparison purposes. The morphology, microstructure, and components of the films were characterized through X-ray photoelectron spectroscope, scanning electron microscope, and X-ray diffractometer. The electrochromic performance of the films including transmittance, cyclic voltammetry, cycle stability, electrochemical impedance, and switch speed was examined. The energy level positions and band gaps of the fluorine-doped tin oxide conductive glass and In2O3 layers were calculated based on their Mott–Schottky plots and ultraviolet-visible diffuse reflectance spectra. The results show that the In2O3 rods are approximately perpendicular to the substrate. The introduction of the In2O3 rod array transition layer enhanced the film/substrate connection in addition to providing favorable conditions for the nucleation and growth of Ni(OH)2, resulting in the improved Ni(OH)2 stability and porous structure as well as electrochromic performance. The mechanism of the improvement is explained in this paper.

Bi2Se3, Bi2Te3 quantum dots-sensitized rutile TiO2 nanorod arrays for enhanced solar photoelectrocatalysis in azo dye degradation

Rutile TiO2 nanorod arrays vertically aligned on conductive fluorine-doped tin oxide glass are optimized for photocatalysis in terms of the density and diameter of nanorods by tuning the concentration of Ti precursor and reaction time during the hydrothermal process. Quantum dots (QDs) of V2VI3( V = Bi; VI = Se, Te) topographic insulators are then employed as sensitizers to enhance the visible-light response of TiO2. Electrochemical measurements show that the decoration of Bi2Se3 or Bi2Te3 significantly increases the photocurrent due to the enhanced light harvesting properties and the charge carrier separation capability mediated by the topographic isolation effect of V2VI3 QDs. Photoelectrocatalytic (PEC) activity evaluation is conducted towards the decoloration of azo dyes, including methyl orange and methylene blue under the sunlight irradiation. The elaborated Bi2Se3/TiO2 nanorod array exhibits the superior PEC performances, presenting shows great potentials in environmental remediation.

Langmuir-Blodgett-assembled monolayer zinc ferrite nanoparticle film with unique photogenerated charge carrier separation efficiency and charge transfer behavior

For figuring out the separation performance and transfer behavior of photogenerated charge carriers in porous spinel structured zinc ferrite (ZnFe2O4, ZFO) ultrathin films, novel ZFO nanoparticle films (LB-ZFO) were prepared on the fluorine-doped tin oxide conductive glass by the Langmuir-Blodgett (LB) method in this study. As illuminated by the light with the wavelength ranging from 320 nm to 440 nm, monolayer LB-ZFO film (LB-ZFO-1) showed relatively higher surface photovoltage than the 5-layered and 9-layered LB-ZFO films, which suggested the film thickness reduction facilitated the photogenerated charge carrier separation. Moreover, the LB-ZFO-1 film possessed lower flat band potential and larger space charge layer width in comparison with the 5-layered and 9-layered LB-ZFO films, further proving that stronger driving force was available for separating the photogenerated electrons and holes by reducing the film thickness. All the as-prepared LB-ZFO films exhibited the capacitor behavior because of their porous structure. The photoelectrocatalytic (PEC) activity of LB-ZFO-1 film was still low even though the electron transfer resistance at the LB-ZFO-1 film/electrolyte interface greatly decreased from 518.60 Ω to 92.56 Ω. Therefore, it suggests that the capacitor behavior existing in porous films is probably one of key factors that resulted in poor PEC activities of LB-ZFO films, which should be induced considerable attentions in future.

Characterization and electrochemical deposition of natural melanin thin films

Melanin is an important class of biological pigments because of its distinct chemical and physical properties. The electrochemical deposition of natural melanin thin films was studied using two different techniques; constant potential and cyclic voltammetry along with a deposition time of five hours. The thin films deposited electrochemically on a fluorine-doped tin oxide conductive glass substrate using the constant potential method, exhibited faster growth rate and better adhesion to the fluorine-doped tin oxide working electrodes than those deposited using the cyclic voltammetry method. The thin films deposited on the fluorine-doped tin oxide conductor glass using the constant potential method were also more homogeneous than those deposited via the cyclic voltammetry technique. The increase of film thickness is related to the increase of electrochemical deposition time. Interestingly, the electrochemical deposition using the constant potential method had the advantage of consuming less electric charge. The physical and chemical structures of the melanin thin films were characterized using ultraviolet–visible absorption spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction analysis. The ultraviolet–visible absorption spectra showed the correlation between the variation of deposition rates of melanin and the type of electrochemical technique employed as well as the thickness of the film. The average thickness of the film is 500 nm which absorb 40% of light in both type of films. The atomic force microscopy images illustrated the homogeneous deposition of the melanin molecules on the fluorine-doped tin oxide conductive glass substrate, indicating that the thickness of the thin films can be controlled. We estimated an average grain size of 14.093 Å. The ease of preparing such thin films of organic materials can open new avenues towards the use of soft conductors, in contrast to the complex preparation of industrial semiconductors.

A study on the ligand-bound Mn(II) complex

5 amino-2,4-dichlorophenol-3,5 ditertbuthylsalisylaldimine-Mn(II) complex was synthesized via the wet chemical method. The Mn(II) complex, characterized by its structural and optical properties, has been used as a sensitizer in a dye-sensitized solar cell structure by growing on TiO2 coated on fluorine-doped tin oxide conductive glass substrate. The power conversion efficiency of the TiO2/Mn (II) complex structure was calculated by current density (J) versus voltage (V) measurement. The calculated power conversion efficiency (η%) of TiO2/Mn(II) complex is %1.44. The obtained result shows that this device can be used as a promising sensitizer in solar cell application.

Effect of Intermittent Spray Pyrolysis on the Characteristics of Fluorine-Doped Tin Oxide Conductive Glass for Dye Sensitized Solar Cell

One of dye sensitized solar cell’s (DSSC) component is conductive glass, a transparent glass substrate covered with semiconductor oxide, usually fluorine-doped tin oxide (FTO). An economic and scalable method used to deposit the FTO film is spray pyrolysis. A research conducted by Fukano et al. (2004) showed that introducing intermittence in spray pyrolysis using batch atomizer improves the glass’ characteristics. This research aims to observe the effect of intermittence on spray pyrolysis method using nebulizer. A compressor nebulizer and hotplate were used, where the glass’ surface temperature reached 300oC. Transmittance, conductance, morphology and composition of the glasses produced were analyzed. Deposition time and intermittence were varied. Variation of time were 5; 7.5; 10; 16; and 39 minutes. Deposition time of 7.5 minutes showed the highest figure of merit (FOM) of 7.83×10-3 Ω-1. Intermittence was performed by turning the nebulizer off during deposition, with varying period and amount of intermittence. Periods of intermittence were varied for 10, 20, and 30 seconds, and amounts of intermittence were varied 1, 2, and 3 times. Variation of 3 intermittences at 20 seconds each resulted in the highest FOM of 19.29×10-3 Ω-1. DSSC’s efficiency built using produced conductive glass are 1.9×10-4 % and 5.5×10-4 %.

A facile method to produce TiO2 nanorods for high-efficiency dye solar cells

Highly ordered TiO2 nanorods are considered promising for photoanodes in dye-sensitized solar cells due to their high charge transfer rate of photo-generated electrons, but they often suffer from low specific area, which may lead to a low conversion efficiency. Here, we produce long vertical single-crystalline rutile TiO2-nanorod arrays on fluorine-doped tin oxide conductive glass substrates(FTO)by the hydrothermal method. To further increase the specific area, the TiO2-nanorod arrays are etched in a secondary hydrothermal process by hydrochloric acid. The etching time have a major effect on the nanorod microstructure and on the dye-sensitized solar cells efficiency. The best result is reached with 8 h of etching, which results in a record high conversion efficiency of 11.14 ± 0.12% (certified efficiency 10.3%) under full sunlight illumination (AM 1.5 G, 100 mW/cm2). The record cell has an open voltage of 0.79 V and a short current density of 21.59 mA/cm2. The proposed manufacturing approach of TiO2 nanorods is highly potential for producing high-efficiency dye-sensitized solar cells.

Current-voltage behaviors of BiFeO3/poly(vinylidene fluoride-trifluoroethylene) composite films

BiFeO3 (BFO) nanopowders (NPs) were synthesized using sol-gel method. BFO/P(VDF-TrFE) (poly(vinylidene fluoride-trifluoroethylene)) composite films were then fabricated on fluorine-doped tin oxide conductive glass substrates by solution spin-coating method. Polycrystalline phases of BFO and P(VDF-TrFE) were identified by X-ray diffraction. Field emission scanning electron microscopy showed that BFO NPs were uniformly dispersed in the P(VDF-TrFE) matrix. The conduction mechanism of BFO/P(VDF-TrFE) composite films was analyzed on account of various conduction mechanisms by analyzing the current-voltage (I-V) curves. As a result, the space charge limited conduction mechanism should be reasonable for the special I-V characteristics of the composite films. Furthermore, the space charge region of the curve mainly came from traps/defects that may be originated from imperfect crystallization of the copolymer matrix and high conductivity BFO NPs as well.

Highly efficient inverted planar perovskite solar cells from TiO2 nanoparticles modified interfaces between NiO hole transport layers and conductive glasses

It has been demonstrated that the interfaces in perovskite solar cells (PSCs) have significant influence on photovoltaic performance of PSCs. So interface engineering is very important for achieving high power conversion efficiency (PCE). However, an important interface of fluorine-doped tin oxide conductive glass (FTO)/hole transport layer (HTL) in the inverted planar PSCs is customarily missed. Here, we verify that through modification of the interface between FTO and NiO HTL with ultra-small TiO2 nanocrystals (NCs), the PCE of inverted planar PSCs can be obviously enhanced from the original 15.23% to the highest value of 16.21%. The optical transmittance spectra show that the TiO2 NCs modification has little influence on the transparency of the substrates. The PL and TRPL data reveal clearly enhanced hole-extracting speed owing to the improve coverage and quality of the NiO HTLs on TiO2 NCs-modified FTOs. These features are important reasons for the improved photovoltaic performance of the corresponding devices. This work highlights an effective way for enhancing photovoltaic performance of the inverted planar PSCs through modifying the interfaces between the transparent conductive substrates and the HTLs.

Synthesis of novel tetra (4-tritylphenoxy) substituted metallophthalocyanines and investigation of their aggregation, photovoltaic, solar cell properties

4-(4-tritylphenoxy) phthalonitrile was synthesized and characterized. Copper, zinc and cobalt phthalocyanines were obtained by reaction of 4-(4-tritylphenoxy)phthalonitrile with CuCl2, ZnCl2, CoCl2 metal salts. New compounds were characterized by using electronic absorption, nuclear magnetic resonance spectroscopy, infrared. The aggregation investigation for phthalocyanine complexes carried out in different concentrations tetrahydrofuran. Copper, cobalt and zinc phthalocyanines were used as sensitizers in dye-sensitized solar cell structures (DSSC) by growing on TiO2 coated on FTO (Fluorine doped Tin Oxide) conductive glass substrates. Current density (J) versus voltage (V) measurements were applied to investigate the photovoltaic properties of the synthesized complexes. The calculated power conversion efficiencies (η%) of the complexes using the obtained current density (J) versus voltage (V) curves show that these devices can be used as promising sensitizers in solar cell applications.

Preparation of Sb2S3 nanocrystals modified TiO2 dendritic structure with nanotubes for hybrid solar cell

Array of TiO2 dendritic structure with nanotubes was constructed on transparent conductive fluorine-doped tin oxide glass (FTO) with titanium potassium oxalate as titanium source. Sb2S3 nanocrystals were successfully deposited on the TiO2 substrate via spin-coating method. Furthermore, TiO2/Sb2S3/P3HT/PEDOT:PSS composite film was prepared by successively spin-coating P3HT and PEDOT:PSS on TiO2/Sb2S3. It was demonstrated that the modification of TiO2 dendritic structure with Sb2S3 could enhance the light absorption in the visible region. The champion hybrid solar cell assembled by TiO2/Sb2S3/P3HT/PEDOT:PSS composite film achieved a power conversion efficiency (PCE) of 1.56%.

Photoanode for solar water oxidation based on titania and hematite films

Nanostructured hematite (α-Fe2O3) film deposited on mesoporous titania (TiO2) underlayer was described as a photoanode for photoelectrochemical water splitting. Mesoporous TiO2 layers were prepared by spin coating a paste on conductive fluorine-doped tin oxide glass followed by an annealing process. Hematite film was prepared after electrochemical and annealing processes. The TiO2/Fe2O3 photoanodes achieve photocurrent densities up to 0.5 mA/cm2 at 1.23 V versus reversible hydrogen electrode. This value is greater than that for photocurrent density obtained with pristine hematite photoanode. Impedance measurements showed that prepared heterostructure TiO2/Fe2O3 contributes to diminution of electron-hole recombination process.

Effect of Few-Layered Graphene-Based CdO Nanocomposite-Enhanced Power Conversion Efficiency of Dye-Sensitized Solar Cell

A few-layered graphene (FLG)/cadmium oxide (CdO) nanocomposite was sucessfully prepared through ultrasonic-assisted synthesis. The morphology of FLG (1.0 wt.%, 2.0 wt.%, and 3.0 wt.%)/CdO nanocomposites were characterized using high-resolution transmission electron microscopy and field emission scanning electron microscopy techniques. The optical properties were studied with the help of UV–Vis diffuse reflectance spectroscopy and Raman spectroscopy, while the crystalline phases were analyzed using x-ray diffraction. The doctor blade method was used to deposit FLG/CdO nanocomposites on fluorine-doped tin oxide conductive glass substrates. The effect of FLG weight percentage (1.0 wt.%, 2.0 wt.%, and 3.0 wt.%) was studied on the power conversion efficiency of dye-sensitized solar cell applications. The photovoltaic characteristics, current density–voltage curves were measured with ruthenium (II)-based dye under air mass condition 1.5G, 100 m W m−2 of a solar simulator. The results showed that higher power conversion efficiency of 3.54% was achieved at the appropriate weight percentage of FLG (1.0 wt.%)/CdO nanocomposite, compared to the CdO and other nanocomposite working electrodes FLG (2.0 wt.%, and 3.0 wt.%)/CdO.

Fe2O3 nanothorns sensitized two-dimensional TiO2 nanosheets for highly efficient solar energy conversion

The hybrid structure of Fe2O3 nanothorns/TiO2 nanosheets photoanodes is reported in the work for the first time. Two-dimensional TiO2 nanosheets array films are grown on transparent conductive fluorine-doped tin oxide glass substrate by simple hydrothermal method. The Fe2O3 nanothorns uniformly deposited on the TiO2 backbone are prepared by chemical bath deposition followed by annealing. The phase structure, morphology and optical properties of the heterogeneous composite films are characterized by X-ray diffraction pattern, scanning electron microscopy and UV–visible spectroscopy. Different nanostructured Fe2O3/TiO2 heterostructures are also investigated by controlling the reaction time of the chemical bath deposition. The two-dimensional TiO2 nanosheets provide an extremely porous matrix and high-activity area required for deposition of Fe2O3 sensitizer. The optimal photocurrent density of Fe2O3/TiO2 film reaches 2.50mA/cm2 and the photoconversion efficiency is 1.25%, which is more than six times higher than that of bare TiO2 film (0.2%). The results indicate that the photogenerated carriers can separate and transfer more easily in Fe2O3/TiO2 films due to the type-II band structures formed at the interface between TiO2 and Fe2O3. The Fe2O3/TiO2 heterogeneous films have potential applications in photoelectrochemical solar cells or water splitting.

Mesocrystalline TiO2 nanosheet arrays with exposed {001} facets: Synthesis via topotactic transformation and applications in dye-sensitized solar cells

A facile, fluorine-free approach for synthesizing vertically aligned arrays of mesocrystalline anatase TiO2 nanosheets with highly exposed {001} facets was developed through topotactic transformation. Unique mesocrystalline {001}-faceted TiO2 nanosheet arrays vertically aligned on conductive fluorine-doped tin oxide glass were realized through topotactic conversion from single-crystalline precursor nanosheet arrays based on lattice matching between the precursor and the anatase crystals. The morphology and microstructure of the {001}-faceted TiO2 nanosheets could be readily modulated by changing the reactant concentration and annealing temperature. Owing to enhanced dye adsorption, reduced charge recombination, and enhanced light scattering arising from the exposed {001} facets, in addition to the advantageous features of low-dimensional structure arrays (e.g., fast electron transport and efficient charge collection), the obtained TiO2 nanosheet arrays exhibited superior performance when they were used as anodes for dye-sensitized solar cells (DSSCs). Particularly, {001}-faceted TiO2 nanosheet arrays ~15 μm long annealed at 500 °C showed a power conversion efficiency of 7.51%. Furthermore, a remarkable efficiency of 8.85% was achieved for a DSSC based on double-layered TiO2 nanosheet arrays ~35 μm long, which were prepared by conversion from the precursor nanoarrays produced via secondary hydrothermal growth.