FTO-coated Glass Substrates Research Articles

Investigation of TiO2 thin films as a cathodic material for electrochromic display devices

Titanium dioxide is a preferred material in many fields of applications and is also used as one of best electrochromic display (ECD) candidates due to its chemical stability. Electrochromic devices are innovative, low-cost and low energy consumption for using as displays. In this work, electrochromic, morphological, structural, and some optical properties of tandem structures were comprehensively investigated. The mean thicknesses of the samples were measured as 86 and 120 nm on ITO- and FTO-coated glass substrates, respectively. The chronoamperometry test was performed to determine some electrochromic properties of the ECD. It was observed that the amounts of ions intercalated/de-intercalated from the coated TiO2 layer were almost equal to each other. According to the chronocoulometric analysis, the superior reversibility and coloration efficiency of the assembled ECD were found to be 83% and 26 cm2/C, respectively, onto ITO substrates. Higher reversibility is revealed in thinner films, which is consistent with the obtained thickness results. In a similar manner, highest coloration efficiency obtained for our ECD has demonstrated good contact between the TiO2-deposited layer and the ITO-coated glass substrate. Also, the highest porosity was reached by taking the highest coloration efficiency value into account. Moreover, coloration efficiencies and ΔT ratios are changed due to the interlayer transparent conductive oxide layers. Raman spectroscopy measurement reveals the anatase phase of TiO2 films on both substrates. Another important finding is related to the defect structures of the TiO2 phase. TiO2, TiO3 and TiO4 mixed phases show the lower coloration efficiency according to the TiO2 phase, for the first time. TiO3 and TiO4 phases were grown by using the FTO-coated glass substrate. Comparing results with reports has shown that our investigated design and technology for ECD applications are good candidates for such applications.

Synthesis and optoelectronic properties of Cu3VSe4 nanocrystals.

The ternary chalcogenide Cu3VSe4 (CVSe) with sulvanite structure has been theoretically predicted to be a promising candidate for photovoltaic applications due to its suitable bandgap for solar absorption and the relatively earth-abundant elements in its composition. To realize the absorber layer via an inexpensive route, printed thin-films could be fabricated from dispersions of nano-sized Cu3VSe4 precursors. Herein, cubic Cu3VSe4 nanocrystals were successfully synthesized via a hot-injection method. Similar with reported Cu3VS4 nanocrystals, Cu3VSe4 nanocrystals with cubic structure exhibit three absorption bands in the UV-Visible range indicative of a potential intermediate bandgap existence. A thin film fabricated by depositing the nanoparticles Cu3VSe4 on FTO coated glass substrate, exhibited a p-type behavior and a photocurrent of ~ 4 μA/cm2 when measured in an electrochemical cell setting. This first demonstration of photocurrent exhibited by a CVSe nanocrystals thin film signifies a promising potential in photovoltaic applications.

Investigations on copper zinc tin sulfide thin films grown through nebulizer assisted spray pyrolysis technique

An attempt is made in this work to synthesize the nontoxic Cu2ZnSnS4 (CZTS) thin film on FTO coated glass substrates through aerosol assisted nebulizer spray pyrolysis technique at different annealing temperatures for photovoltaic energy conversion. The deposited thin film is further used to form a heterojunction interface with a cadmium sulfide layer to fabricate a solar cell with Glass/FTO/CdS/CZTS/Ag superstrate structure to reveal its photovoltaic application. Various characterization techniques are utilized to study its inherent properties. X-ray diffraction (XRD) is employed to investigate the structural parameters such as crystallite size, microstrain and dislocation density which shows a preferential peak for (112) plane around 28.5° confirming the formation of kesterite CZTS. Raman measurements establish the peak for CZTS at 336 cm−1 and confirm the absence of parasitic secondary phases for an excitation wavelength of 488 nm. Scanning electron microscope and atomic force microscope used to examine the surface morphology and roughness of the films reveal a good surface morphology with a grain size of 555.9 nm and roughness of 123.7 nm for an annealing temperature of 350°C. The bandgap of the deposited CZTS films is found to be around 1.5 eV. The I-V characteristics of CZTS seem to be better for the 350°C annealed film. The performance of the optimized CZTS absorber layer is tested by forming a solar cell structure. The devised solar cell exhibited an open circuit voltage of 213 mV and a short circuit current density of 490 μA cm−2 with a conversion efficiency of 0.68% substantiating the usage of the prepared film as an absorber for photovoltaic conversion.

Electrodeposition of Cu2o/MoS2 Thin Films on Fto Substrate As a Heterojunction Photoelectrochemical Cell for Water Splitting

The layered structure MoS2, an n-type conductor (bandgap of 1.9-2 eV), can be excited under irradiation with visible light. However, its valence band energy (-4.2 eV) is closed to the minimum energy required to reduce water into hydrogen (- 4.2 eV at pH = 7). The p-type semiconductor Cu2O (a bandgap of 2 eV) has a valence band energy of - 4.0 eV, higher than that of MoS2 and therefore has potentially as photocatalytic for water splitting. In this work, the heterojunction of Cu2O/MoS2 is prepared on a conductive FTO-coated glass substrate by electrodeposition methods. We conduct initially the MoS2 thin film on FTO by cyclic voltammetry (CV). Then, the Cu2O thin film is deposited on the MoS2/FTO thin film by double-potential pulse chronoamperometric (DPPC) to form a p-n junction Cu2O/MoS2/FTO photo-electrode which play an anodic role in a photoelectrochemical cell. The structure, morphology and composition of heterojunction electrode are characterized by powder X-ray diffraction, SEM, TEM, IR, Raman spectroscopy, electrochemical impedance spectroscopy (EIS). The optical properties are determined by UV-VIS spectroscopy and Photoluminescence (PL) spectroscopy. The photoelectrochemically catalytic activity of the electrodes is performed in dark condition and light condition with 1.5 AM from a solar simulator system by Linear-sweep voltammograms and Transient photocurrent-time methods. The H2-generation yield is evaluated by gas chromatography. The effect of the structure and the composition of the Cu2O/MoS2 thin films on the kinetics and mechanism of the photoelectrochemical water splitting is also considered.

Vertically Aligned Al-Doped ZnO Nanowire Arrays as Efficient Photoanode for Dye-Sensitized Solar Cells

In this communication, we report on the synthesis of vertically aligned aluminium (Al)-doped ZnO (ZnO:Al) nanowire (NW) thin films on FTO-coated glass substrates and their use as photoanode in dye-sensitized solar cells (DSSC). Very thin Al layers (∼3 nm, ∼6 nm and ∼10 nm) were deposited onto chemically synthesized ZnO nanowire film by electron-beam evaporation. The films were then subjected to rapid thermal annealing to incorporate different amounts of Al (∼0.98 at.%, 1.94 at.% and ∼2.89 at.%) into the ZnO nanowires. Optical, microstructural and compositional study of the films confirmed the growth of highly transparent and well-aligned ZnO:Al nanowires with a hexagonal crystal structure. The basic DSSC structure was fabricated using both undoped ZnO nanowire and ZnO:Al nanowire thin films as photoanode. In both cases, commercially available N3 dye was used as a photosensitizer, iodide/tri-iodide solution as electrolyte and FTO-coated glass as counter electrode. A significant increase in short-circuit current was observed, from 1.3 mA cm−2 for the pristine ZnO nanowire film-based DSSC to 4.4 mA cm−2 for the ZnO:Al (2.89 at.%) nanowire film-based DSSC. The overall power conversion efficiency (PCE) was also found to increase from 0.13% (for pristine ZnO nanowire thin film) to 0.49% for the ZnO:Al thin film-based DSSC.

Effects of Ag doping on compact TiO2 thin films synthesized via one-step sol–gel route and deposited by spin coating technique

In this paper, we present a novel one-step, easy and cost-effective method for the synthesis of Ag-doped TiO2 sol and deposition of its compact thin films by spin coating technique. The effects of dopant quantity (0–5% by weight) on structural, morphological, optical and electrical properties of TiO2 thin films have been investigated and reported. The X-ray Diffraction (XRD) spectra revealed single anatase phase having no secondary phases. The scanning electron microscopy (SEM) showed pinholes-free/compact thin films composed of spherical nanoparticles where the particle size has been demonstrated to decrease with increasing Ag doping. The atomic force microscopy (AFM) confirmed smooth and compact TiO2 thin films, however, the surface roughness tends to grow with increasing the dopant quantity. The X-ray fluorescence spectroscopy (XRF) revealed the presence of Ag mass percentage in the relevant samples, which has been demonstrated to grow with increasing the amount of dopant. The UV–Vis spectroscopy concluded the bandgap reduction of pure anatase phase of TiO2 (3.38 eV) as the Ag doping reaches to its maximum value of 5% (3.18 eV). Spectroscopic Ellipsometry has been employed to determine the thickness of thin films which was found to be in the range of ~ 100 nm, while electrical properties have been measured through DC-Hall Effect technique. It was found that the conductivity of thin films improved from 5.74 × 10–2 to 2.72 × 10–1 Ω−1 cm−1 on glass while on FTO-coated glass substrates, a higher value of 1.51 × 104 Ω−1 cm−1 was achieved.

Two-dimensional BN-doped ZnO thin-film deposition by a thermionic vacuum arc system

Graphene is an interesting two-dimensional dopant for the electronic, electrochemical, and optoelectronic devices due to its high electron mobility, high electrical, and thermal conductivity, and high optical transparency. Another graphene-like material is boron nitride (BN). h-BN shares similar lattice structure with graphene and many physical properties except large bandgap. In this study, optical, morphological, and structural properties of the two-dimensional BN-doped ZnO thin films have been investigated with various techniques such as UV–Vis spectroscopy, field emission scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. Two-dimensional BN-doped ZnO thin films were produced onto glass, indium tin oxide-coated glass, and fluorine tin oxide-coated glass using by a Thermionic Vacuum Arc (TVA) deposition technique. The results show that the substrate effect causes the different growth mechanisms for the two-dimensional BN-doped ZnO thin films. It is found that bandgap of ZnO changed drastically and bandgaps of the deposited thin films were found to be 3.96 eV, 3.97 eV, 4.05 eV for two-dimensional BN-doped ZnO thin films deposited onto glass, ITO-coated glass, and FTO-coated glass substrates, respectively. According to the Raman spectra, BN crystal orientations are in hexagonal form in ZnO crystal.

Heterojunction Solar cell(NiPcTs/CdS)organic/inorganic

In the present study, thin films of organic semiconductors Nickel PhthalocyanineTetrasulfonic Acid Tetrasodium Salt (NiPcTs) and inorganic semiconductor (CdS) prepared from the mixing of liquids for thesetwomaterials with different size ratios by the spin coating method on pre-patterned (Fluorine-doped Tin Oxide) FTO coated glass substrates and then the manufacture of solar cells. The properties of solar cells the study through the optical properties (absorption spectra, absorption coefficient, power gap) and electrical characteristics (continuous onductivity, Hall Effect and cell efficiency measurements) and Was obtainedThe efficiency of a multiple solar cell ranging from (0.16-13.2 %)

Fabrication and TCAD simulation of TiO2 nanorods electron transport layer based perovskite solar cells

Abstract This paper reports Pd/PTAA/hybrid perovskite (CH3NH3PbI3)/TiO2 nanorods (TNRs) based solar cell grown on a FTO coated glass substrate. The TNRs-layer, synthesized by low-cost hydrothermal process, acts as the electron transport layer (ETL) while the PTAA acts as the hole transport layer (HTL) in the device. The solar cells with different TNRs thickness are fabricated and characterized for the optimized performance parameters namely the short circuit current density (JSC), open circuit voltage (VOC), fill factor (FF), and power conversion efficiency (PCE). The Solar Cell Capacitance Simulator-One Dimensional (SCAPS-1D) is used to simulate the proposed solar cell structure for validating our experimental results. The effects of thickness variation of ETL on the solar cell parameters have been investigated by solving the drift-diffusion model. The measurements show that the efficiency of the solar cell is decreased with increased ETL thickness which is attributed to higher trap sites in the active layer and ETL. The optimized maximum efficiency of 15.04% is obtained for ETL thickness of 500 nm. The simulated results also show close similarity with the experimental results with an efficiency of 15.69%.

Highly efficient 3D-ZnO nanosheet photoelectrodes for solar-driven water splitting: Chalcogenide nanoparticle sensitization and mathematical modeling

Three-dimensional (3D) zinc oxide nanosheets (ZnO-NS), assembled on the FTO coated glass substrates after chemical treatment, have been achieved via a simple yet effective chemical bath deposition technique. The exploration of chalcogenide nanoparticle sensitization on ZnO-NS thin-film photoanodes led us to a spectacular enhancement in the photoelectrochemical conversion efficiency for solar-driven water splitting process as compared to the bare 3D-ZnO-NS. The maximum incident photon-to-charge carrier efficiency of bare 3D-ZnO-NS has been enhanced by approximately four folds as a result of cadmium sulfide (CdS) and cadmium selenide (CdSe) sensitization and the efficiency value have reached to 51% at 550 nm. Besides, the maximum charge injection and charge separation efficiencies of the ZnO–CdSe electrodes have been calculated as 93% and 64%, respectively. Numerical examination of the optical absorption and electrical field distribution has been performed via the finite-difference time-domain (FDTD) method in order to investigate the basis of the enhancement in the photoelectrochemical efficiencies of the 3D-ZnO-NS photoelectrodes. FDTD numerical simulation proved that the accumulation of rectangular 2D-nanosheets of ZnO in 3D-microspherical forms enhanced the light absorption significantly. Moreover, FDTD results also verified that the optical absorption of the ZnO electrodes has been extended from ultraviolet to visible region via CdS and CdSe nanoparticle deposition.

Synthesis and characterization of CoFe2O4 thin films for solar absorber application

Spinel oxides synthetized by the electrochemical route can be used in different technological areas. In the present work, cobalt ferrite (CoFe2O4) thin films were deposited from sulfate bath on FTO-coated glass substrate by linear sweep voltammetry technique (LSV). We have investigated the effect of applied magnetic field B (AMF B) up to 0.5 T on the electrochemical response, the crystallographic texture, the morphology, the semiconductor type and the optical properties of the elaborated films. The structural and compositional analysis confirmed the synthesis of a well-crystallized CoFe2O4 with a good stoichiometry after an annealing treatment at 500 °C. Moreover, the CoFe2O4 films exhibited a p-type semiconductor as confirmed by the photo-electrochemical and Mott-Schottky tests. In addition, an increasing in the absorbance in the visible-UV region is observed under AMF B. Consequently, the magneto-electrodeposited CoFe2O4 thin films have a direct band gap energy of 1.5 eV.

Investigation of spray pyrolyzed copper oxide as a photocathode in photoelectrochemical energy conversion

Herein we report, the development of nanostructured copper oxide thin films over glass and FTO-coated glass substrates by spray pyrolysis technique. Tenorite CuO thin films having closed packed two-dimensional assembly of nanostructures have been successfully deposited by spraying aqueous copper nitrate solution. The spray rate was maintained at ∼1–1.5 ml/min and the substrate temperature range were maintained around 300 °C to 350 °C. The effect of precursor concentration variation was investigated and the physical properties of the developed CuO was studied by different characterization techniques like FE-SEM, X-Ray Diffraction Spectroscopy and UV–vis spectroscopy. It was clearly observed from the obtained results that the droplet size distribution and the surface morphology could be easily controlled by changing the precursor concentration and deposition temperature. The photoelectrochemical (PEC) performance of the optimized cupric oxide film was further studied. The spray deposited CuO having indirect bandgap of 1.59 eV as estimated from the Tauc’s plot with a predominant (1 1 1) plane exhibited photocurrent of ∼1 mA/cm2 vs RHE under AM 1.5 solar radiation in the neutral electrolyte. Here, the influence of precursor concentration, electrolyte variation and role of electron scavenging agent on PEC performance of spray deposited CuO thin films were investigated.

A highly sensitive poly(chrysoidine G)-gold nanoparticle composite based nitrite sensor for food safety applications.

This work demonstrated the development of conducting poly(chrysoidine G) (PCG)-gold nanoparticle (AuNP)-modified fluorine-doped tin oxide (F : SnO2, FTO) film-coated glass electrodes for the sensitive electrochemical detection of nitrite (NO2-). The homogeneously distributed PCG nanoparticle layer was deposited onto the FTO electrode by cyclic voltammetry sweeping. AuNPs were then anchored onto the PCG/FTO electrode by the chemical reduction of pre-adsorbed Au3+ ions. The as-prepared AuNP/PCG/FTO electrode exhibited excellent electrocatalytic activity for the oxidation of NO2- with high sensitivity (approximately 0.63 μA cm-2μM-1) and a low limit of detection (0.095 μM), which is relevant within the normal concentration range of NO2- in human bodily fluids. The AuNP/PCG/FTO sensor showed sufficient reproducibility, repeatability, low interference, and strong recovery for NO2- detection in food samples. These results indicate that the AuNP/PCG nanocomposites have immense potential for the electrochemical detection of other biologically important compounds.

Fabrication of n-In6Se7:Sn/p-CuInSe2 heterojunction diode on FTO coated glass substrates using reactive evaporation technique

The heterojunction diode using Sn doped In6Se7 and CuInSe2 thin films are fabricated on FTO coated glass substrates using reactive evaporation technique. The structure of CuInSe2 film is studied using XRD analysis and the film exhibits polycrystalline nature. XPS result confirms that the prepared sample is nearly stoichiometric. The I–V measurements of FTO/n-In6Se7:Sn/p-CuInSe2/Ag heterojunction diode, in dark condition, shows rectification behavior. The knee voltage and ideality factor of the diode are observed to be 1.52 V, 3.09 V and 5.57, 16.16 respectively when the Sn dopant concentration varied from 0.47 at% to 1.57 at%. The absence of photoresponse from the diodes under illumination condition is explained using the energy band structure of the heterojunction.

Broadband photosensing using p-type cupric oxide nanorods/conducting polymer Schottky junction

Broadband photosensing properties has been demonstrated using p-type CuO nanorods/conducting polymer poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) Schottky junction. CuO nanorods have been grown on FTO coated glass substrate by low cost hydrothermal technique. Schottky junction device was fabricated by spin coating the polymer layer on top of the nanorods. The rectifying property and diode parameters of the device have been investigated using current-voltage measurements. The build in potential at the nanorods/polymer junction was studied using Kelvin Probe Force Microscopy (KPFM). The photodetector parameters such as transient decay time (τ), rise and fall time, external quantum efficiency (EQE), responsivity and detectivity have been studied in details. Such metal oxide semiconductor/polymer heterojunction device demonstrated broadband photoresponse (300–700 nm) with highest EQE ~67.5% and responsivity ~0.3A/W at 560 nm under 0.5 V reverse bias.

Thermal sintering of printable copper for enhanced conductivity of FTO coated glass substrates

Copper inks potentially provide a cost effective replacement to silver for printed electronic circuits. In glass based applications such as PV or smart glass, it can provide a means of conductivity enhancement or additional functionality. Three inks consisting of a mixture of nano and micro copper particles were systematically studied to examine the relationship between sintering temperature, sintering time and gaseous environment on the electrical qualities of the sintered printed films deposited on FTO coated glass. There is a definite interaction between the particulate nature of the ink, the sintering conditions and the conductive properties of the film. Films containing only nano-particles provide the most conductive films with optimum sintering conditions of temperatures of 225 °C for 60 min. The inclusion of micro particles increased the ideal sintering temperature but lowered the sintering time. An ink containing an equal mixture of nano and micro particles exhibited the lowest performance and this could be attributed to partial oxidation of the nano-particles along the conductive path, which occurs as a result of the presence of the micro particles.

Tungsten doping effect on V2O5 thin film electrochromic performance

Electrochromic W-doped V2O5 thin films have been deposited on FTO-coated glass substrates by RF magnetron sputtering. The structural, morphological, optical and electrochromic properties of films deposited with various tungsten concentrations were studied. The increase of the doping content induces an amorphization of the films, which contributes to an enhanced cycling performance. High W doping (resulting in WO3) values exhibit high coloration efficiency of ∼ 41 cm2 C−1at 560 nm and large transmittance modulation of 76.9% at 560 nm. Both WO3 and V2O5 are electrochromic materials with very good properties, hence their combination is of interest from both technological and fundamental perspectives.

Characterization of electrodeposited ZnTe thin films

ZnTe thin films were deposited on FTO-coated glass substrates by a low-cost, easy and simple electrodeposition method. The grown layers of ZnTe have been characterized by photoelectrochemical cell (PEC) measurement for determining carrier type, UV–visible spectrophotometer for optical characterization, X-ray diffraction (XRD) for structural analysis and scanning electron microscopy (SEM) for the surface morphology. An annealing effect of the as-deposited thin films has also been investigated. PEC measurements of ZnTe film showed p type electrical conductivity. Optical measurement showed that ZnTe films have very high transmittance in the UV–visible region; moderate transmittance in the visible range; and moderate to lower transmittance in the visible–infrared region and have higher absorbance in the middle of the visible region to near-infrared region. Band gap values are estimated to vary from 2.3 to 1.90 eV for the ZnTe films deposited at different conditions. Band gap of ZnTe films is observed to decrease when the films are annealed at different temperatures in nitrogen environment. From the XRD and SEM study, ZnTe films are found to be polycrystalline with (111) preferential orientation of the cubic structure and appeared dense crack-free surfaces with regular granular-shaped grains without any cauliflower-like appearance. After annealing the as-deposited film transmittance, absorbance and intensity in XRD pattern are observed to increase and a good ZnTe crystal structure is observed to form. The values of average crystallite size are estimated to be 22.82 nm and 30.82 nm for as-deposited and annealed ZnTe films, respectively.

Simultaneous improvement of piezoelectric and magnetic properties in diamagnetic ion modified BiFeO3 film

Multiferroic BiFeO3 (BFO) and Bi0.97Y0.03Fe0.95Sc0.05O3 (BYFSO) films were fabricated on FTO coated glass substrate using sol-gel spin-coating technique. Y–Sc co-doping induces the structural distortion without changing the crystal structure (rhombohedral: R3c) of BFO. The electrical and magnetic properties of co-doped film may tuned due to increase in grain and particles size. The high dielectric constant (εr=290) and low loss (tanδ=0.084) indicates the improved insulating properties in BYFSO film. Increase in oxygen vacancy concentration in BYFSO film is explained with leakage current density, which follows Ohmic-SCLC conduction mechanism. Switching of 1800 domains into non-1800 (maximum 710 and 1090 type) ensures improved ferrolectric and piezoelectric properties in BYFSO film. The magnetic properties enhance significantly with saturation magnetization (Ms), remanent magnetization (Mr) are 9.45 emu/cm3, 6.154 emu/cm3 respectively at coercive (Hc) field of 0.822 kOe. Room temperature multiferroic BYFSO film with improved insulating and magnetic properties may be useful for non-volatile RRAM memory application.

Al dopant-dependent third-order nonlinear optical parameters in ZnO thin films under CW Nd: YAG laser irradiation

Structural, morphological and optical properties of Al-doped ZnO thin films synthesized by the spray pyrolysis method on the FTO-coated glass substrate are investigated in this study. The measurements were carried out on a series of films with various contents of Al dopant from 0 up to 4% of Al/ZnO ratios. 2-D and 3-D atomic force microscopy images revealed that the Al content has a considerable influence on the surface morphology and roughness of thin films so that the grain size and surface roughness of the films decreased with increasing the Al contents. Room temperature PL spectra revealed UV as well as defect emission peaks which experienced a slight blue shift with Al/ZnO ratios increasing from 1 to 4%. Measurements of nonlinear optical properties of Al-doped ZnO thin films were performed using a CW Nd: YAG laser at 532 nm by the Z-scan technique. It was demonstrated that the Al-doped ZnO thin films have a negative nonlinearity can be related to the thermal effects. The optical limiting measurements confirmed that undoped and Al-doped ZnO thin films are good candidates for optical limiter devices at 532 nm wavelength of lasers. The effects of defect states on the nonlinearity of thin films are also investigated in this work.