Flourine Doped Tin Oxide Research Articles

Fabrication and optical characterization of zinc telluride thin films using electrodeposition technique

A well adherent thin film of Zinc Telluride (ZnTe) has been deposited on Flourine doped Tin oxide glass substrates from acidic baths containing Zinc heptahydrate and Tellurium dioxide. Films of different thicknesses with their molar concentrations were obtained. A mini Schimadzu UV-VIS Spectrophotometer was used to determine the optical absorbance of the films over the wavelength range of 300-900nm at room temperature. There is a decrease in absorbance as the molar concentrations of the precursors increases; while transmittance and energy band gap shown an increase. The band gap values obtained varied between 2.10eV and 2.7eV, for as deposited films. Also, photoelectrochemical cell (PEC) measurement reveals that ZnTe thin films exhibit p-type conductivity.

Photoelectrochemical properties of gradient Ti-doped hematite thin films prepared by liquid phase deposition

Enhancing the charge transfer processes reflects a significant development in the photoelectrochemical (PEC) properties of photoanodes. One strategy to improve the charge carrier density is elemental donor doping. Engineering the donor doping into gradient doping with a negative slope of concentration from the substrate to the film's surface enhances the PEC properties effectively. Such gradient doping develops a built-in electric field that depresses the electron-hole pair recombination process. The proof of the above concept was demonstrated by preparing a gradient Ti-doped of 4-2-1%, 4-2-1-0.5%, and 4% homogeneous Ti-doped hematite thin films by the liquid phase deposition on flourine doped tin oxide (FTO) coated glass substrates. The as-prepared samples are amorphous, and they were annealed at 800 °C to ensure their crystallinity. The PEC characterizations showed that a higher level of photocurrent density was achieved for the gradient doped sample (0.37 mA.cm−2) compared to that of the 4% titanium doped sample (0.05 mA.cm−2) at 1.23 V vs. reversible hydrogen electrode (RHE). Our investigations showed that developing a built-in electric field due to gradient Ti-doping is responsible for the superior PEC properties of Ti-gradient doped samples compared to homogenously doped samples.

Building a Solar Panel for Electricity Generation in the Fabrication of Dye Sensitized Solar Cell

Dye sensitized solar cell have been fabricated since 19191 till date. In the previous year’s seven cells were fabricated and arranged in series to build a solar module for electricity generation under which 2.0 volt diode bulb was lightened. Further study was carried out here where the electrolyte was improved upon using potassium iodide with F- centre factor that enhances light harvesting but in the course of the study the fabricated DSSCs exhibited in stability due to the delay in carrying out the I-V characteristics. Three of these dye sensitized solar cells were successfully fabricated using natural dye from Laali stem bark (Isoplumbagin) dye as sensitizer, with two metallic composition titanium doxide/ Zinc oxide (TiO₂/ZnO) on Flourine doped tin oxide as the substrate which comprises of the Anode or electrode and carbon soot as the counter electrode or the cathode. These three DSSCs were arranged in series to build a solar panel. From the results obtained, Current-voltage characteristics showed that current was 0.03A and voltage 2.0 m A with power output 0.06k watt and the curve showed a forward bias pattern as with the case of a diode. From the pattern of the curve showed that the DSSCs deviated from cells that display efficiency to a diode that operates with the PN theory.

Magnesium Incorporation in n-CdTe to Produce Wide Bandgap p-Type CdTe:Mg Window Layers

In order to develop wide bandgap p-type window materials to use in graded bandgap devices, the effects of magnesium (Mg) in n-CdTe layers were explored. In this work, magnesium-incorporated cadmium telluride (CdTe:Mg) layers were electroplated using two-electrode method. The layers were deposited on glass/FTO (flourine doped tin oxide) substrates, using an aqueous solution containing Cd2+, Mg2+ and tellurium dioxide (TeO2) as the precursors. X-ray diffraction (XRD) studies indicate the reduction of crystallinity as the Mg concentration is increased in parts per million (ppm) level. Material becomes a completely amorphous layer at high Mg concentrations in the electrolytic bath. Photoelectrochemical (PEC) measurements show the gradual reduction of n-CdTe turning into p-CdTe layers when Mg concentration is increased in the electrolyte. Optical absorption measurements show the expansion of energy bandgap from CdTe bandgap (~1.48 eV) up to ~2.85 eV. The other characterisation results (energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL)) are also explored and presented together with above experimental results.

Photoelectrochemical Oxygen Evolution Reaction Activity of Amorphous Co–La Double Hydroxide-BiVO4 Fabricated by Pulse Plating Electrodeposition

Strategically integrating semiconducting films with an efficient water oxidation catalyst to reduce charge recombination and improve the photocurrent is the bottleneck in photoelectrochemical (PEC) water splitting. Amorphous catalysts, especially the mixed metal oxides/hydroxides, show better stability and activity because of their unique morphology. Facile, reproducible synthesis of these catalysts by a simple method has been problematic. In this Letter, we show for the first time the application of pulse plating to synthesize amorphous Co–La mixed double hydroxide (MDH) on BiVO4/FTO (FTO, flourine-doped tin oxide). The method provides better adhesion and uniform deposits with controlled composition and grain size and facilitates fast charge transport, while lowering the charge recombination at the interface of the electrolyte and the semiconductor. With respect to BiVO4, reduction in onset potential by 0.53 V as well as 2.7 and 33.4 times increment in photocurrent density (J) at 1.23 V and the lower potential 0.6 V, respectively, obtained by BiVO4/MDH is noteworthy. The results obtained here suggest the possibility of using BiVO4/MDH in PEC cells and photoelectrochemical diodes.

Electrodeposited copper nanoparticles: plasmon enhanced performance of TiO2 for dye sensitized solar cell

The Copper being cheap and more abundant in nature is being utilized on a large scale as an energy harvester. The present work is carried out on studies of the plasmonic effect of copper nanoparticles in dyesensitized solar cells. The copper nanoparticles were electrochemically deposited from an aqueous solution of copper sulphate on TiO2 film coated on flourine doped tin oxide (FTO). The film was kept in an aqueous “Rose Bengal” dye before and after deposition of copper nanoparticles. The incorporation of copper nanoparticles enhanced the overall power conversion efficiency of the dye sensitized solar cell. This enhancement is manifested chiefly due to increased dye loading and strongly absorbed light due to localized surface plasmon resonance of incorporated Cu nanoparticles in dye sensitized solar cell.

High efficiency bifacial Cu2ZnSnSe4 thin-film solar cells on transparent conducting oxide glass substrates

In this work, transparent conducting oxides (TCOs) have been employed as a back contact instead of Mo on Cu2ZnSnSe4 (CZTSe) thin-film solar cells in order to examine the feasibility of bifacial Cu2ZnSn(S,Se)4 (CZTSSe) solar cells based on a vacuum process. It is found that the interfacial reaction between flourine doped tin oxide (FTO) or indium tin oxide (ITO) and the CZTSe precursor is at odds with the conventional CZTSe/Mo reaction. While there is no interfacial reaction on CZTSe/FTO, indium in CZTSe/ITO was significantly diffused into the CZTSe layers; consequently, a SnO2 layer was formed on the ITO substrate. Under bifacial illumination, we achieved a power efficiency of 6.05% and 4.31% for CZTSe/FTO and CZTSe/ITO, respectively.

A Surface Photovoltage Study of Surface Defects on Co-Doped TiO2 Thin Films Deposited by Spray Pyrolysis

Surface photovoltage (SPV) spectroscopy is a powerful tool for studying electronic defects on semiconductor surfaces, at interfaces, and in bulk for a wide range of materials. Undoped and Cobalt-doped TiO2 (CTO) thin films were deposited on Crystalline Silicon (c-Si) and Flourine doped Tin oxide (SnO2:F) substrates by chemical spray pyrolysis at a substrate temperature of 400 °C. The concentration of the Co dopant in the films was determined by Rutherford backscattering spectrometry and ranged between 0 and 4.51 at %. The amplitude of the SPV signals increased proportionately with the amount of Co in the films, which was a result of the enhancement of the slow processes of charge separation and recombination. Photogenerated holes were trapped at the surface, slowing down the time response and relaxation of the samples. The surface states were effectively passivated by a thin In2S3 over-layer sprayed on top of the TiO2 and CTO films.

A Comparative Study of Nanostructured TiO2, ZnO and Bilayer TiO2/ZnO Dye-Sensitized Solar Cells

Titanium dioxide (TiO2), Zinc oxide (ZnO) and bilayer TiO2/ZnO (TZO) based cells have been developed and sensitized with five organic dyes and one cocktail dye composed of five dyes. Photovoltaic performance of TiO2 and ZnO solar cell sensitized with six dyes is compared to that of bilayer TZO cells. The forward current is found to increase with applied voltage in the range V ≤ 0.4 V, which is dominated by thermionic emission, whereas in 0.4 ≤ V ≤ 0.7 V, the current transport is due to space charge-limited current controlled by exponential trap distribution in all devices. The combined properties of the materials enhance the efficiency of composite TZO cells. TiO2 permits the formation of an energy barrier at the ZnO electrode/electrolyte interface, which reduces the back electron transfer from the conduction band of ZnO to I3 − in the electrolyte. Also, due to the TiO2 layer on the ZnO, the latter forms a compact layer between flourine-doped tin oxide (FTO)/TiO2 which benefits the fast electron transfer from TiO2 to ZnO to FTO glass. This reduces the charge recombination occurring at the ZnO/FTO interface leading to higher open circuit voltage (V oc), higher short circuit current (J sc), lower series resistance (R s), and in turn higher efficiency in TZO solar cells as compared to ZnO cells. Among the six dyes, Eosin-Y and Rose Bengal dye gave the best performance as sensitizers with TZO.

Photoelectrochemical (PEC) characterization of chemically deposited Bi 2S 3 thin films from non-aqueous medium

Bi 2S 3 thin films have been prepared by chemical bath deposition method using bismuth nitrate, Bi(NO 3) 3 and sodium thiosulphate (Na 2S 2O 3) dissolved in acetic acid and formaldehyde respectively. Films were deposited onto flourine doped tin oxide coated (FTO) glass substrates. The photoelectrochemical (PEC) cell configuration was n-Bi 2S 3/0.25 M NaOH–0.25 M Na 2S–0.25 M S/C. From the current–voltage characteristics (I–V) and capacitance–voltage (C–V) plots, it is concluded that the Bi 2S 3 films are of n-type conductivity. The photovoltaic output characteristics were used to calculate fill factor (FF) and solar conversion efficiency ( η). The low value of η may be due to high value of series resistance and interface states in the cell which are responsible for the recombination mechanism. The magnitude of band gap energy of Bi 2S 3 photoelectrode estimated from spectral response of PEC cell agrees with the magnitude obtained from optical absorption of Bi 2S 3 films. The magnitude of decay constant estimated from transient photoresponse indicated the charge transfer kinetics is of second order.

Chemical bath deposition of indium sulphide thin films: preparation and characterization

Indium sulphide (In 2S 3) thin films have been successfully deposited on different substrates under varying deposition conditions using chemical bath deposition technique. The deposition mechanism of In 2S 3 thin films from thioacetamide deposition bath has been proposed. Films have been characterized with respect to their crystalline structure, composition, optical and electrical properties by means of X-ray diffraction, TEM, EDAX, optical absorption, TRMC (time resolved microwave conductivity) and RBS. Films on glass substrates were amorphous and on FTO (flourine doped tin oxide coated) glass substrates were polycrystalline (∈ phase). The optical band gap of In 2S 3 thin film was estimated to be 2.75 eV. The as-deposited films were photoactive as evidenced by TRMC studies. The presence of oxygen in the film was detected by RBS analysis.