Inverted organic solar cells with solvothermal synthesized vanadium-doped TiO2 thin films as efficient electron transport layer

We investigated the effects of using different thicknesses of pure and vanadium-doped thin films of TiO2 as the electron transport layer in the inverted configuration of organic photovoltaic cells based on poly（3-hexylthiophene） P3HT：[6-6] phenyl-（6） butyric acid methyl ester（PCBM）. 1% vanadium-doped TiO2nanoparticles were synthesized via the solvothermal method. Crystalline structure, morphology, and optical properties of pure and vanadium-doped TiO2 thin films were studied by different techniques such as x-ray diffraction, scanning electron microscopy, transmittance electron microscopy, and UV–visible transmission spectrum. The doctor blade method which is compatible with roll-2-roll printing was used for deposition of pure and vanadium-doped TiO2 thin films with thicknesses of 30 nm and 60 nm. The final results revealed that the best thickness of TiO2 thin films for our fabricated cells was 30 nm. The cell with vanadium-doped TiO2 thin film showed slightly higher power conversion efficiency and great Jsc of 10.7 mA/cm^2 compared with its pure counterpart. In the cells using 60 nm pure and vanadium-doped TiO2 layers, the cell using the doped layer showed much higher efficiency. It is remarkable that the external quantum efficiency of vanadium-doped TiO2 thin film was better in all wavelengths.

Influence of Annealing on X-Ray Radiation Sensing Properties of TiO2 Thin Film

A recent study shows that the titanium dioxide （TiO2） thin film synthesised by a chemical bath deposition technique is a very useful material for the X-ray radiation sensor. In this work, we reported the influence of annealing on the X-ray radiation detection sensitivity of the TiO2 film. The films were annealed at 333 K, 363K, 393K, 473 K, and 573K for 1 hour. Structural analyses showed that the microstrain and dislocation density decreased whereas the average crystallite size increased with annealing. The band gap of the films also decreased from 3.26eV to 3.10eV after annealing. The I-V characteristics record under the dark condition and under the X-ray irradiation showed that the conductivity increased with annealing. The influence of annealing on the detection sensitivity was negligible if the bias voltage applied across the films was low （within 0.2V - 1.0V）. At higher bias voltage （〉1.0V）, the contribution of electrons excited by X-ray became less significant which affected the detection sensitivity.

Properties of TiO_2 Thin Films Prepared by Magnetron Sputtering

With rapid progressive application of TiO2 thin films, magnetron sputtering becomes a very interesting method to prepare such multi-functional thin films. This paper focuses on influences of various deposition processes and deposition rate on the structures and properties of TiO2 thin films. Anatase, rutile or amorphous TiO2 films with various crystalline structures and different photocatalytic, optical and electrical properties can be produced by varying sputtering gases, substrate temperature, annealing process, deposition rate and the characteristics of magnetron sputtering. This may in turn affect the functions of TiO2 films in many applications. Furthermore, TiO2-based composites films can overcome many limitations and improve the properties of TiO2 films.

A Novel Multi-Tube Photoreactor with UV Light and Immobilized TiO_2 Thin Film for Water Treatment

A novel multi-tube photoreactor with 0.0188m3 valid reaction volume was constructed in pilot-scale. This rectangular reactor consisted of 13 regularly distributed silica glass tubes coating with TiO2 thin film photo-catalyst. Total active area of TiO2 thin film is 0.3916m2. The ratio of surface area to volume achieves 20.8m-1. Photocatalytic experiment of phenol red demonstrates that the apparent reaction rate constant (k) is 0.074 65 h-1 and 0.16502h-1 for reaction system with and without micro-bubbles mixing. The corresponding apparent quantum efficiency (a) is 8.1771 X 10-7g.J-1 and 4.9036 x 10-7g-J-1, respectively. COD value of reactant could decrease to 17mg.L-1 and high performance liquid chromatography (HPLC) only shows two absorption peaks in 24 h pho-tocatalytic process time, so this photoreactor has good photomineralization effect. Experimental results reveal that photocatalytic destruction of organics is possible by using the multi-tube photoreactor.

OPTICAL CHARACTERIZATION OF TiO_2 THIN FILM ON SILICON SUBSTRATE DEPOSITED BY DC REACTIVE MAGNETRON SPUTTERING

TiO2 thin film has attracted considerable attention in recent years, due to its different refractive index and transparency with amorphous and different crysta ls in the visible and near-infrared wavelength region, high dielectric constant, wide band gap, high wear resistance and stability, etc, for which make it being used in many fields. This paper aims to investigate the optical characterizatio n of thin film TiO2 on silicon wafer. The TiO2 thin films were prepared by DC re active magnetron sputtering process from Ti target. The reflectivity of the film s was measured by UV-3101PC, and the index of refraction (n) and extinction coef ficient (k) were measured by n & k Analyzer 1200.

Nanostructure Study of TiO2 Films Prepared by Dip Coating Process

The microstructure properties of the sol-gel derived TiO2 films were studied by the atomic force microscopy (AFM). The films were prepared by dip coating process. The optical properties of the films were explained on the basis of the microstructure of the films.

Effect of initial precursor concentration on TiO_2 thin film nanostructures prepared by PCVD system

TiO2 thin film was prepared on Si substrate by plasma chemical vapor deposition （PCVD） system and the morphologies of ZiO2 thin film were controlled by adjusting the initial precursor concentration. As the initial titanium tetra-isopropoxide （TTIP） concentration increases in PCVD reactor, the shapes of TiO2 particles generated in PCVD reactor change from the spherical small-sized particles around 20 nm and spherical large-sized particles around 60 nm to aggregate particles around 100 nm. The TiO2 particles with different shapes deposit on the substrate and become the main building blocks of resulting TiO2 thin film. We observed the TiO2 thin film with smooth morphology at low initial TTIP concentration, granular morphology at medium initial TTIP concentration, and columnar morphology at high initial TTIP concentration. It is proposed that we can prepare the TiO2 thin film with controlled morphologies in one-step process just by adjusting the initial precursor concentration in PCVD .

STUDY ON PHOTOCATALYTIC MECHANISM OF SOL-GEL-DERIVED Pb-DOPED TiO_2 THIN FILMS

Pb-doped TiO2 photocatalytic thin films were prepared on a soda-lime glass substrate via sol-gel method using TiO2 sol solution containing lead and characterized by X-ray photoelectron spectroscopy (XPS). The results showed that besides oxides of Ti(IV) there is a certain amount of oxides of To(?) and Ti(?) and Pb exists in the forms of PbTiO3 and PbO. The photocatalytic activity of the Pb-doped TiO2 films was evaluated by the photocatalytic decolorization of aqueous methyl orange and photocatalytic mechanism mas also analyzed.

Low Temperature Coating of Anatase Thin Films on Silica Glass Fibers by Liquid Phase Deposition

Uniform crystalline TiO2 thin films were coated on silica glass fibers by liquid phase deposition from aqueous solution of ammonium hexafluorotitanate at low temperature. TiO2 thin films and nanopowders were prepared by adding H3BO3 into （NH4）2TiF6 solution supersaturated with anatase nano-crystalline TiO2 at 40 ℃. The effects of the deposition conditions on the surface morphology, section morphology, thickness of the deposited TiO2 thin films were investigated. The results indicate that the growth rate and particle size of the thin films were controlled by both the deposition conditions and the amount of anatase nano-crystalline TiO2.

Surface Microstructure Characterization of Sol-gel Derived Porous TiO_2 Thin Films

Porous TiO2 thin films were prepared from alkoxide solutions with and without polyethylene glycol (PEG) by sol-get route on soda lime glass, and were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that TiO2 film prepared from precursor solution without PEG is composed of spherical particles of about 100 nm and several nanometer mesoporous pores. With the increase of the amount of PEG added to the precursor solution, the diameter and the depth of the pores in the resultant films increas on the decomposition of PEG during heat-treatment, which lead to them increase of the surface roughness of the films. XRD and TEM results show that the single anatase phase is precipitated and there are some orientation effects in (101) direction.

Effect of Heat-treatment on Crystalline Phase and UV Absorption of 60CeO_2-40TiO_2 Thin Films by Magnetron Sputtering

60CeO2-40TiO2 thin films were deposited on soda-lime silicate glass substrates by R.F. magnetron sputtering. The effects of heat-treatment on the UV-absorption of the thin films were studied on the 60CeO2-40TiO2 thin film with the largest UV cut-off wavelength. The sample films with CeO2：TiO2=60：40 were heated at 773 K, 873 K, 973 K for 30 min. These films are characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and X-ray photoelectron spectroscopy and spectrometer （XPS）. XRD analysis proves that the addition of TiO2 to CeO2 changed the crystalline state of CeO2. But the UV absorption effect of CeO2-TiO2 films with CeO2 crystallite phase is inferior to that of the amorphous phase CeO2-TiO2 films. XPS analysis also indicates that the amorphous phase CeO2-TiO2 films have the most Ce3＋ content in these films. Amorphous phase and crystalline phase of the CeO2-TiO2 films have different effects on UV absorption of the thin films.

Extraction of optical constants and thickness of nanometre scale TiO2 film

TiO2 thin films were deposited on glass substrates by sputtering in a conventional rf magnetron sputtering system. X-ray diffraction pattern and transmission spectrum were measured. The curves of refraction index and extinction coefficient distributions as well as the thickness of films calculated from transmission spectrum were obtained. The optimization problem was also solved using a method based on a constrained nonlinear programming algorithm.

Preparation of Ag-doped TiO_2 Thin Film by Sol-gel Method

The Ag-TiO2 thin film has been prepared on glass substrate by sol-gel process . The structure and properties of the materials were studied by DTA , XRD, and EPR. The photocatalytic activity was examined by the photocatalytic degradation of dichlorophos. The analysis results indicate that the photocatalytic activity of the Ag-TiO2 thin film is higher than that of pure TiO2 thin film. It is also influenced by the content of anatase and heating temperature . The ESR result shows that the Ag-TiO2 thin film has more hydroxide radicals than pure TiO2 thin film after illuminated by UV light.

Effect of substrate temperature on structural properties and photocatalytic activity of TiO_2 thin films

Titanium dioxide (TiO2) films with anatase structure were prepared on quartz glass substrates by pulse laser ablating titanium (99.99%) target under oxygen pressure of 10 Pa at substrate temperature of 500-800 ℃. The structural properties of the films were characterized by X-ray diffractometry(XRD), X-ray photoelectron spectroscopy(XPS) and field emission scan electron microscopy(FESEM). The results show that, as the substrate temperature is increased from 600 ℃ to 800 ℃, the anatase structure of the films changes from random growth to (211)-oriented growth. The absorption edge tested by UV-Vis Spectrometer has a blue shift. The photocatalytic activity of the films was tested on the degradation of methyl orange. It is found that the film with random growth structure exhibits better photo-degradation efficiency than that with (211)-oriented growth structure.

Preparation and Properties of Ag-TiO_2 Thin Films on Glass Substrates

Ag TiO 2 thin films were prepared on glasses.The morphology and structure of Ag TiO 2 films were investigated by XRD, SEM and FT IR.The photocatalytic and hydrophilic properties of Ag TiO 2 thin films were also evaluated by examining photocatalytic degradation dichlorophos under sunlight illumination and the change of contact angle respectively.The research results show that the Ag TiO 2 thin film is mainly composed of 20-100nm Ag and TiO 2 particles.The Ag TiO 2 thin films possess a super hydrophilic ability and higher photocatalytic activity than that of pure TiO 2 thin film.

Study on UV Shielding TiO_2 Thin Film Prepared by Sol-Gel Method

Titanium dioxide (TiO_2) thin films were prepared on microscopes slides by sol-gel and dip-coating processes from specially formulated sols.The results show that there exists anatase and rutile structure of TiO_2 when heat treatment temperature is 450℃,and at 800℃,TiO_2 particle size is of below 100 nm and rutile structure is presented.In the range of 360 nm～400 nm the transmittance of TiO_2 sol increases with the increasing of the concentration of Ti(OC_4H_9)_4 in ethanol solution. The transmittance of TiO_2 films with various number of the layer is measured to be 0% below 320 nm,and the three-layer TiO_2 film is of the best UV resistance in the range of 320 nm～400 nm.