F-doped SnO2 Research Articles

Cu2 − xS films as counter-electrodes for dye solar cells with ferrocene-based liquid electrolytes

In this work, the application of hexagonal CuS nanoparticle layers as counter electrodes for dye sensitized solar cells has been studied. A fast, cheap and reliable deposition method was proposed for the one-step preparation of Cu2−xS layers on F-doped SnO2 within 30min through an ink-based technique. The electrodes prepared with our method were tested with iodine/iodide electrolyte, Co(II)/(III) bipyridine redox shuttle and Fe(II)/(III) ferrocene-based liquid electrolyte. The Cu2−xS layers showed high efficiency and stability with the ferrocene/ferrocenium redox couple, showing a fast charge recombination kinetic, low charge transfer resistance (Rct=0.73Ωcm2), reasonably high limiting current (11.8mAcm−2) and high stability in propylene carbonate.

CuxS counter electrodes in-situ prepared via the sulfidation of magnetron sputtering Cu film for quantum dot sensitized solar cells

The nanosheet-structured CuxS thin films used as counter electrodes (CEs) for CdS/CdSe quantum dot sensitized solar cells (QDSSCs) have been in situ prepared via the sulfidation of Cu nanoparticles deposited on F-doped SnO2 glass (FTO glass) substrate by magnetron sputtering method. The thickness of the deposited Cu film affects the morphology and thickness of the obtained CuxS films. The CuxS nanosheet films have good adhesion with FTO glass and the surface exhibits uniform morphology. The characteristics of QDSSCs are studied in more detail by photocurrent-voltage performance measurements, incident photon-to-current conversion efficiency (IPCE) and electrochemical impedance spectroscopy (EIS). The CuxS on FTO glass (CuxS/FTO) CEs show much higher power conversion efficiency (PCE) and IPCE than those of the Pt on FTO (Pt/FTO) CE because of their superior carrier mobility and electro-catalytic ability for the polysulfide redox reactions. Based on an optimal CuxS film thickness of 2.7 μm obtained by the sulfidation of the Cu film thickness of 300 nm on FTO, the best photovoltaic performance with PCE of 3.67% (Jsc = 16.47 mA cm−2, Voc = 0.481 V, FF = 0.46) under full one-sun illumination is achieved.

Enhanced electrocatalytic activity of electrodeposited F-doped SnO2/Cu2S electrodes for quantum dot-sensitized solar cells

Copper sulfide (Cu2S) films were deposited on F-doped SnO2 (FTO) substrates via the electrodeposition (ED) of copper (Cu) nanoparticles followed by sulfurization. The Cu nanoparticles were deposited on FTO substrates for various ED times ranging from 10 to 30 min at a constant −0.4 V. The FTO/Cu films consisted of flower-like nanoparticles comprised of randomly-clustering nanoflakes. The Cu nanoparticles electrodeposited for 10 min (FTO/Cu (10 min)) were dispersed sparsely over the FTO substrate, whereas the FTO/Cu (20 and 30 min) provided increased coverage. Unlike FTO/Cu2S (10 min), the FTO/Cu2S (20 and 30 min) consisted of vertically-standing large Cu2S nanosheets with numerous small nanosheets in between. This was attributed to the sufficient number of Cu seed nanoflakes, which not only facilitate ion transport of the redox couple but also increased the surface area, leading to significantly enhanced electrocatalytic activity. The quantum dot-sensitized solar cell (QD-SSC) with FTO/Cu2S (20 min) exhibited a significantly improved cell efficiency of 4.58%, compared to those with Pt and FTO/Cu2S (10 min). The QD-SSC with the FTO/Cu2S (30 min) showed similar cell efficiency to that with the FTO/Cu2S (20 min), despite the larger surface area because of its amorphous crystallographic structure offsetting the electrocatalytic activity.

Enhanced Efficiency of Nanoporous-layer-covered TiO2 NanotubeArrays for Front Illuminated Dye-sensitized Solar Cells

Nanoporous-layer-covered TiO2 nanotube arrays (Type II TNTs) were fabricated by two-step electrochemical anodization. For comparison, conventional TiO2 nanotube arrays (Type I TNTs) were also prepared by one-step electrochemical anodization. Types I and II TNTs were detached by selective etching and then transferred successfully to a transparent F-doped SnO2 (FTO) substrate by a sol-gel process. Both FTO/Types I and II TNTs allowed front side illumination to exhibit incident photon-to-current efficiencies (IPCEs) in the long wavelength region of 300 to 750 nm without the absorption of light by the iodine-containing electrolyte. The Type II TNT exhibited longer electron lifetime and faster charge transfer than the Type I TNT because of its relatively fewer defect states. These beneficial effects lead to a high overall energy conversion efficiency (5.32 %) of the resulting dye-sensitized solar cell. Keywords: dye-sensitized solar cell, nanotube array, electron lifetime, charge transfer, front side illumination

Reprint of “Investigations of electrochemical luminescence characteristics of ZnO/TiO2 nanotubes electrode and silica-based gel type solvents”

Abstract In this work, we suggest a simple preparation process for advanced electrochemical luminescence (ECL) cell-based on silica gel type solvents using ZnO/TiO2 nanotubes (ZnO/TNT) electrode. The ionic liquid gel solvent was prepared by adding silica nanopowder in liquid Ru(II) complex. The ZnO/TNT nanotubes were fabricated by anodic oxidation method. The ECL cell-based silica gel type on ZnO/TNT electrode is composed as F-doped SnO2 (FTO) glass/Ru(II) complex [Ru(bpy)32 +] mixed silica gel type/ZnO/TNT electrode film/FTO glass. The morphological and structural properties of ZnO/TNT electrode film were confirmed to be successful by a scanning electron microscope (SEM), X-ray diffraction and a spectral brightness analyzer. The threshold voltage at light emission start was 2.0 V for ZnO/TNT that was lower than 2.24 V for zinc oxide (ZnO), 2.25 V for TiO2 nanotube (TNT) and 2.75 V for bare FTO. The luminance and electrical properties of the ECL cell-based silica gel type with ZnO/TNT electrode were 253 cd/m2 for light intensity, 64 mA for output current, and 0.55 lm/W for ECL efficiency at 4 Vac 60 Hz. The peak intensity of the ECL cell-based silica gel type with ZnO/TNT electrode at wavelength was 622 nm which responded to dark orange color and had no effect on electrode layers. The ZnO/TNT electrode for ECL cell can increase an ECL efficiency and long lifetime stability.

Quantum dot sensitized solar cells with efficiency up to 8.7% based on heavily copper-deficient copper selenide counter electrode

Semiconductors such as sulfides have been commonly used as counter electrodes (CEs) in quantum dot sensitized solar cells (QDSCs) with high stability and catalytic activity. But the intrinsic unsatisfactory conductivity has been making researchers find alternative materials for further improving the efficiency. Here nanometer sized copper selenides substrated on F-doped SnO2 (CuxSe/FTO) are used as CE in the construction of QDSCs. Through optimizing the composition and structure variables of the CE materials, including Cu/Se ratio, film thickness, sintering temperature and time, we achieve the power conversion efficiencies up to 6.49% and 8.72% for CdSe and CdSeTe based QDSCs, respectively. Our results show that the excellent photovoltaic performance is strongly associated with the low Cu/Se molar ratio in the range of 1.20–1.38, suggesting the heavily deficient copper in CuxSe. The resultant good conductivity and electrochemical catalytic activity of the CuxSe/FTO CE have been verified by the electrochemical impedance spectroscopy, Tafel polarization and four-probe measurement results.

Influences of Sr-Incorporated TiO2 Layer on the Photovoltaic Properties of Dye-Sensitized Solar Cells.

Effects of a mixed overlayer composed of TiO2 and TiSrO3 on the performance of dye-sensitized solar cells (DSSCs) were investigated. The surface of TiO2 photoelectrode formed on F-doped SnO2 (FTO) was modified by soaking it in a TiCl4:SrCl2 mixed aqueous solution with various molar ratios and then calcining to produce the TiCl4:SrCl2-treated TiO2 photoelectrode (Ti:Sr-TiO2/FTO). The highest power conversion efficiency (PCE) was obtained from DSSC with Ti:Sr(7:3)-TiO2/FTO, which was prepared from the mixed solution with the molar ratio of 7:3 (TiOl4:SrCl2). An enhancement in short-circuit photocurrent (J(sc)) and open-circuit voltage (V(oc)) of DSSC with Ti:Sr(7:3)-TiO2/FTO was achieved, compared to those of the reference device with Ti:Sr(10:0)-TiC2/FTO (i.e., TiO2-coated TiO2/FTO). The incorporation of the mixed overlayer on the nanoporous TiO2 photoelectorde led to an improvement in the electron collection efficiency by a prolonged electron lifetime, thereby increasing the J(sc) value. The increase in V(oc) value of the device with Ti:Sr(7:3)-TiO2/FTO was due to the suppression of the charge recombination between injected electrons and I3(-) ions.

Effects of electrical and optical properties of thickness condition of ZnO nanorod array layer for efficient electrochemical luminescence cell device

In this paper, we report on electrochemical luminescence (ECL) cells with a ZnO nanorod (ZNR) layer. The investigated ECL cells were composed of F-doped SnO2 (FTO) glass/Ru(II)/ZNRs/FTO glass, which used a ZNR layer as an electrode and the Ru(II) complex [Ru(bpy)32+] as a light-emitting material. The ECL cells were fabricated by changing the thickness of ZNRs from 5 to 12.5 µm. The luminescence property of the ECL cells was strongly affected by the variation in the thickness of the ZNR layer. The threshold voltage for the light emission from the ECL cells was 2 V for 10 µm thick ZNRs, which was lower than that of the thickness of the ECL cells without a ZNR layer. Also, the intensity of luminance from the ECL cells with ZNRs was much higher than that from the ECL cells without ZNRs at the same operating voltage. The efficiency of the ECL cells without ZNRs measured at 3 V was 0.0049 lm/W, while those of the ECL cells with ZNRs were 0.0121, 0.0157, 0.0354, and 0.024 lm/W for the ZNRs layer thicknesses 5, 7.5, 10, and 12.5 µm, respectively. However, the peak light intensity at the wavelength was 623 nm which had not affected the all ZNRs thicknesses. The best lifetime of the ECL cells with these thicknesses was 40 min for ZNRs 10 µm. The use of the ZNR layer in the ECL cells significantly improves the luminescence performance.

Electric field induced metal–insulator transition in VO2 thin film based on FTO/VO2/FTO structure

A VO2 thin film has been prepared using a DC magnetron sputtering method and annealing on an F-doped SnO2 (FTO) conductive glass substrate. The FTO/VO2/FTO structure was fabricated using photolithography and a chemical etching process. The temperature dependence of the I–V hysteresis loop for the FTO/VO2/FTO structure has been analyzed. The threshold voltage decreases with increasing temperature, with a value of 9.2V at 20°C. The maximum transmission modulation value of the FTO/VO2/FTO structure is 31.4% under various temperatures and voltages. Optical modulation can be realized in the structure by applying an electric field.

Synthesis and characterization of TiO2 on ZnO-nanorod layer for high-efficiency electrochemiluminescence cell application

In this research paper, we present the fabrication of an electrochemiluminescence (ECL) cell with TiO2 on ZnO-nanorod electrodes via the dip-coating technique. The TiO2 nanoparticles coated on ZnO nanorods (TiO2-ZNRs) were grown on transparent conductive oxide (TCO) glass by the dip-coating technique. The electrode of TiO2-ZNRs for ECL cells has the structure F-doped SnO2 (FTO) glass/Ru(II) complex [Ru(bpy)32+]/TiO2-ZNRs/FTO glass. The TiO2-ZNRs were coated on FTO glass by spin-coating and dip-coating methods. The X-ray diffraction system, scanning electron microscope, and spectral brightness analyzer were used to confirm the successful formation of the structure and the morphological properties. The threshold voltage at the start of light emission was 2.25 V for TiO2-ZNRs and was lower than 3.25 V for bare FTO. The threshold voltage was l2.5 V for ZNRs. The electrical and optical properties of the TiO2-ZNRs ECL cell were 30.76 cd/m2 light intensity, 0.067 mA output current, 0.268 cd/A (at 9.67 mA/cm2) current efficiency, and 0.068 lm/W ECL efficiency at 5 V and 60 Hz. The peak intensity of the TiO2-ZNRs-based ECL cell at a wavelength of 621 nm exhibited a dark orange color and was independent of the type of electrode used. The use of TiO2-ZNRs could improve the ECL efficiency and long-lifetime stability.

α-Fe2O3 nanopillar arrays fabricated by electron beam evaporation for the photoassisted degradation of dyes with H2O2

Vertically aligned α-Fe2O3 nanopillar arrays (NPAs) were fabricated by thermally oxidizing Fe NPAs on Si, quartz and F-doped SnO2 (FTO) substrates prepared by glancing angle e-beam deposition (GLAD).

Photoconductive probing of the trap distribution in switchable interfaces.

Interfacial resistive switching features are highly dependent on the distribution of the carrier traps in the interface. However, the lack of probing seriously restricts ways of offering physical insights into its mechanism and improving interfacial resistors. In this work, we investigated a resistive switching interface that consists of Bi2S3 nano networks (BSNN) and F-doped SnO2 (FTO), uncovering the relationship between the decay of the photoconductance in BSNN and interfacial trap distribution. Based on this, we suggest a general method to probe the distribution of various interface traps. This method provides us with a new tool to study the interfacial trap distribution in an interfacial resistor, and it might also be used to understand other interface problems.

The fabrication of In2O3/In2S3/Ag nanocubes for efficient photoelectrochemical water splitting.

In this work, for the first time, a three-component In2O3/In2S3/Ag nanocomposite heterostructured photoanode is prepared on a F-doped SnO2 (FTO) glass substrate. The three-component photoanode exhibits significantly enhanced photoelectrochemical properties compared with the single-component (In2O3) and two-component (In2O3/In2S3 or In2O3/Ag) systems. Ag nanoparticles deposited on the surface of In2O3/In2S3 nanocubes can facilitate the separation of photogenerated charge carriers and enhance the absorption of visible light. In I-V curves, the In2O3/In2S3/Ag photoanode generates a remarkable photocurrent density of 8.75 mA cm(-2) (at 0 V vs. SCE), which is higher than those of the two-component In2O3/In2S3 (4.47 mA cm(-2)) and In2O3/Ag (3.50 mA cm(-2)). Furthermore, it also gives efficiency as high as 67% around 350 nm in the incident photon to electron conversion efficiency (IPCE) spectrum. These results open up a promising avenue for the design and fabrication of novel heterojunctions for photoelectrochemical water splitting.

Efficient planar Sb2S3 solar cells using a low-temperature solution-processed tin oxide electron conductor.

Efficient planar antimony sulfide (Sb2S3) heterojunction solar cells have been made using chemical bath deposited (CBD) Sb2S3 as the absorber, low-temperature solution-processed tin oxide (SnO2) as the electron conductor and poly (3-hexylthiophene) (P3HT) as the hole conductor. A solar conversion efficiency of 2.8% was obtained at 1 sun illumination using a planar device consisting of F-doped SnO2 substrate/SnO2/CBD-Sb2S3/P3HT/Au, whereas the solar cells based on a titanium dioxide (TiO2) electron conductor exhibited a power conversion efficiency of 1.9%. Compared with conventional Sb2S3 sensitized solar cells, the high-temperature processed mesoscopic TiO2 scaffold is no longer needed. More importantly, a low-temperature solution-processed SnO2 layer was introduced for electron transportation to substitute the high-temperature sintered dense blocking TiO2 layer. Our planar solar cells not only have simple geometry with fewer steps to fabricate but also show enhanced performance. The higher efficiency of planar Sb2S3 solar cell devices based on a SnO2 electron conductor is attributed to their high transparency, uniform surface, efficient electron transport properties of SnO2, suitable energy band alignment, and reduced recombination at the interface of SnO2/Sb2S3.

Preparation and Supercapacitor Properties of Porous Nickel Oxide Film

Porous Ni O film grown on the substrate of F-doped Sn O2 conductive glasses( FTO) was successfully prepared through the hydrothermal method in combination with high temperature calcination. The surface morphology,phase composition and the valence state of the obtained Ni O film were detected by SEM,TEM,XRD and XPS,respectively. The electrochemical performances were characterized by cyclic voltammetry( CV) and galvanostatic charge /discharge in the electrolyte solution of 6 mol/L KOH. These results indicate that the specific capcacitance of the Ni O electrode can reach 651. 6 F / g at a current density of 2 A / g. After1000 cycles 71. 6% of the maximum capcacitance is still remained,suggesting its excellent cycling stability and promising application as an ideal electrode material for supercapacitors.

Role of Graphene Oxide as a Sacrificial Interlayer for Enhanced Photoelectrochemical Water Oxidation of Hematite Nanorods

Photoelectrochemical cells (PECs) with a structure of F-doped SnO2 (FTO)/graphene oxide (GO)/hematite (α-Fe2O3) photoanode were fabricated, in which GO serves as a sacrificial underlayer. In contrast to low-temperature sintering carried out under a normal atmosphere, high-temperature sintering was carried out for the GO underlayer-based hematite photoanodes. The photocurrent density of the PECs with GO underlayers gradually increased as the spin speed of the FTO substrate increased. In particular, GO at a spin speed of 5000 rpm showed the highest photocurrent of 1.3 mA/cm2. The higher performance of the GO/α-Fe2O3 photoanodes was attributed to the improved FTO/α-Fe2O3 interface. When sintered at 800 °C for activation of the hematite (FTO/GO/α-Fe2O3) photoanodes, the GO layers before being decomposed act as localized hot zones at the FTO/α-Fe2O3 interface. These localized hot zones play a very crucial role in reducing the microstrain (increased crystallinity) which was confirmed from the synchrotron X-ray ...

Disposable urea biosensor based on nanoporous ZnO film fabricated from omissible polymeric substrate.

In the present study, a facile and simple fabrication method of a semiconductor based urea biosensor was reported via three steps: (i) producing a ZnO-PVA composite film by means of a polymer assisted electrodeposition of zinc oxide (ZnO) on the F-doped SnO2 conducting glass (FTO) using water soluble polyvinyl alcohol (PVA), (ii) obtaining a nanoporous ZnO film by PVA omission via a subsequent post-treatment by annealing of the ZnO-PVA film, and (iii) preparation of a FTO/ZnO/Urs biosensor by exploiting a nanoporous ZnO film as an efficient and excellent platform area for electrostatic immobilization of urease enzyme (Urs) which was forced by the difference in their isoelectric point (IEP). The characterization techniques focused on the analysis of the ZnO-PVA film surfaces before and after annealing, which had a prominent effect on the porosity of the prepared ZnO film. The surface characterization of the nanostructured ZnO film by a field emission-scanning electron microscopy (FE-SEM), exhibited a film surface area as an effective bio-sensing matrix for enzyme immobilization. The structural characterization and monitoring of the biosensor fabrication was performed using UV-Vis, Fourier Transform Infrared (FT-IR), Raman Spectroscopy, Thermogravimetric Analysis (TGA), Cyclic Voltammetry (CV), and Electrochemical Impedance Spectroscopy (EIS) techniques. The impedimetric results of the FTO/ZnO/Urs biosensor showed a high sensitivity for urea detection within 8.0-110.0mg dL(-1) with the limit of detection as 5.0mg dL(-1).

Improved Photovoltaic Properties Of Dye-Sensitized Solar Cells Using Laser Patterned F-Doped SnO2 Thin Films

Abstract We modified the surfaces of F-doped SnO2 thin films using laser patterning to improve the photovoltaic properties of dye-sensitized solar cells. To do so, we varied the laser power density and the distance between laser-patterned lines. First, we investigated three power densities. Higher densities led to higher sheet resistances owing to increases in surface roughnesses. The lowest power density increased surface roughness without electrical degradation. Next, we explored three line spacings at a fixed power density. The films with the narrowest spacing exhibited the highest power conversion efficiency (~7.00%), the highest short-circuit photocurrent density (16.28 mA/cm2), and a good fill factor (58.82%).

Photovoltammetric behavior and photoelectrochemical determination of p-phenylenediamine on CdS quantum dots and graphene hybrid film

A photoelectroactive film composed of CdS quantum dots and graphene sheets (GS) was coated on F-doped SnO2 (FTO) conducting glass for studying the electrochemical response of p-phenylenediamine (PPD) under photoirradiation. The result indicated that the cyclic voltammogram of PPD on CdS–GS hybrid film became sigmoidal in shape after exposed under visible light, due to the photoelectrocatalytic reaction. Such a photovoltammetric response was used to rapidly optimize the photoelectrocatalytic activity of hybrid films composed of different ratios of CdS to GS toward PPD. The influences of scan rate and pH on the photovoltammetric behavior of PPD on CdS–GS film revealed that although the controlled step for electrochemical process was not changed under photoirradiation, more electrons than protons might participate the photoelectrocatalytic process. Furthermore, the photoelectroactive CdS–GS hybrid film was explored for PPD determination based on the photocurrent response of film toward PPD. Under optimal conditions, the photocurrent signal on CdS–GS film was linearly proportional to the concentration of PPD ranging from 1.0×10−7 to 3.0×10−6molL−1, with a detection limit (3S/N) of 4.3×10−8molL−1. Our work based on CdS–GS hybrid film not only demonstrated a new facile photovoltammetric way to study the photoinduced electron transfer process of PPD, but also developed a sensitive photoelectrochemical strategy for PPD determination.

Electrical and Optical Properties of F-Doped SnO2 Thin Film/Ag Nanowire Double Layers

Fluorine-doped SnO2 (FTO) thin film/Ag nanowire (NW) double layers were fabricated by means of spin coating and ultrasonic spray pyrolysis. To investigate the optimum thickness of the FTO thin films when used as protection layer for Ag NWs, the deposition time of the ultrasonic spray pyrolysis process was varied at 0, 1, 3, 5, or 10 min. The structural, chemical, morphological, electrical, and optical properties of the double layers were examined using X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, the Hall effect measurement system, and UV-Vis spectrophotometry. Although pure Ag NWs formed isolated droplet-shaped Ag particles at an annealing temperature of 300 oC, Ag NWs covered by FTO thin films maintained their high-aspect-ratio morphology. As the deposition time of the FTO thin films increased, the electrical and optical properties of the double layers degraded gradually. Therefore, the double layer fabricated with FTO thin films deposited for 1 min exhibited superb sheet resistance (~14.9Ω/□), high optical transmittance (~88.6 %), the best FOM (~19.9 × 10−3 Ω−1), and excellent thermal stability at an annealing temperature of 300 oC owing to the good morphology maintenance of the Ag NWs covered by FTO thin films.