TiCl4 Aqueous Solution Research Articles

Carbon fibers decorated with TiO2 nanoparticles for photocatalytic degradation of methylene blue dye

This report demonstrates the development of carbon fibers (CFs) decorated with TiO2 nanoparticles (NPs) as an efficient photocatalyst for the photocatalytic degradation of methylene blue (MB) as a model dye. Carbon fibers were produced by carbonization of polyacrylonitrile fibers, previously produced by centrifugal spinning. Subsequently, the CFs were decorated with TiO2 NPs (CFs@TiO2) by tailored soaking protocol using aqueous TiCl4 solution with different concentrations (0.025, 0.05, 0.1, and 0.2 M). SEM analyses revealed that soaking in TiCl4 produced a smooth, conformal, continuous TiO2 nanoparticulate coating with thickness increasing from 40.4 ± 21.2 to 257.9 ± 63.9 nm with increasing TiCl4 concentration. X-ray diffraction and Raman spectroscopy confirmed the anatase nature of TiO2. Photocatalytic decomposition rates of MB were assessed under UV light illumination for all CFs@TiO2 samples, and it was revealed that the lowest amount of TiO2 NP on C yielded the highest rates. The synergistic interaction between CFs and TiO2 NPs with a uniform morphology and a well-crystalline anatase structure, present in an optimal amount of fiber bodies, is the key reason for the remarkable photocatalytic performance. This work shows that C fibers decorated with an optimal amount of TiO2 NPs have a great potential as an effective photocatalytic material.

Low-Temperature Processed Brookite Interfacial Modification for Perovskite Solar Cells with Improved Performance.

The scaffold layer plays an important role in transporting electrons and preventing carrier recombination in mesoporous perovskite solar cells (PSCs), so the engineering of the interface between the scaffold layer and the light absorption layer has attracted widespread concern. In this work, vertically grown TiO2 nanorods (NRs) as scaffold layers are fabricated and further treated with TiCl4 aqueous solution. It can be found that a thin brookite TiO2 nanoparticle (NP) layer is formed by the chemical bath deposition (CBD) method on the surface of every rutile NR with a low annealing temperature (150 °C), which is beneficial for the infiltration and growth of perovskite. The PSC based on the TiO2 NR/brookite NP structure shows the best power conversion of 15.2%, which is 56.37% higher than that of the PSC based on bare NRs (9.72%). This complex structure presents an improved pore filling fraction and better carrier transport capability with less trap-assisted carrier recombination. In addition, low-annealing-temperature-formed brookite NPs possess a more suitable edge potential for electrons to transport from the perovskite layer to the electron collection layer when compared with high-annealing-temperature-formed anatase NPs. The brookite phase TiO2 fabricated at a low temperature presents great potential for flexible PSCs.

Impact of TiO2/Graphene-Oxide coated on quartz crystal resonator on the sensing performance of NH3, N2 and ethanol at room temperature

Gas sensors based on Quartz Crystal Resonator device coated with TiO2/Graphene-Oxide (GO) films were fabricated to sense ethanol, ammonia, and nitrogen at room temperature. TiO2 nanostructures, as gas sensing film, were fabricated by drop casting TiCl4 aqueous solution with different concentrations, and analyzed by SEM, TEM, XRD and profilometer. Exposed to the above mentioned gases, the responses of the sensors, Δf, were measured. Sensor with 55 nm TiO2 film shows higher response to N2 and 100 ppm concentration of ethanol and NH3 than the others, due to larger surface area of the film, which are 635, 334, and 528 Hz, respectively. To improve the response further, TiO2/GO film is prepared, the response of which for N2 and 100 ppm concentration of ethanol and NH3 increased significantly to 848, -360 and 740 Hz, respectively. Sensing mechanisms are based on changing in mass and elasticity properties of the device. High response, simple and low cost preparation and room temperature operation are the main advantages of these sensors making them attractive for future applications.

Ultrafast synthesis of anatase TiO2 microspheres doped with rare-earth by one-step microwave method

Using a one-step microwave method without any further calcination, various rare-earth (Re) ions doped anatase titania microspheres were synthesized successfully in less than 10 min. TiCl4 aqueous solution and rare-earth salt solution are used as reactant, and ethanol was used as solvent. Anatase titania microspheres doped with rare-earth ions including Ce(IV), Sm(III), Tm(III) and Tb(III) were obtained without using any template or surfactant. The scanning electron microscopy images show that the particles have well-defined spherical shapes with a relatively narrow size distribution. X-ray diffraction and Raman spectra demonstrate the crystalline phase of the particles to be anatase. The energy-dispersive spectroscopy spectra and elemental mapping identify rare earth elementals distribute in the microspheres uniformly. The valence state of rare-earth in the samples was determined by X-ray photoelectron spectroscopy spectra. The studies provide a super-rapid method to prepare rare earth doped crystalline TiO2 microspheres, which are useful materials for optical, biological and environmental applications.

Effect of pH on the Formation of Amorphous TiO2 Complexes and TiO2 Anatase during the Pyrolysis of an Aqueous TiCl4 Solution

The titanium dioxide (TiO2) nanostructures resulted by the pyrolysis of titanium tetrachloride (TiCl4) at a low temperature of 80 °C were found to be a mixture of amorphous TiO2 complexes and anatase nanostructures, whose ratio depends on the pH of the pyrolysis medium. At a low pH level, the resulting TiO2 nanostructures are predominantly anatase and gradually shift to amorphous TiO2 complexes as the pH level increases. Moreover, the amorphous TiO2 complexes can convert back to anatase nanostructures by a post-heating treatment, and can then transform to rutile with elevating temperature. Amongst the TiO2 nanostructures recovered from the amorphous TiO2 complexes, anatase appears to be the most effective photocatalyst in the decomposition of methylene blue.

A STUDY OF TiO2 COATING STRUCTURE ON SURFACES OF MERANTI WOOD (SHOREA SP) AS A PHOTOCATALYST IN PEAT WATER PURIFICATION

Coating of TiO2 made on the surface of meranti wood acts as a photocatalyst which is a semiconductor that plays a role in the process of absorbing UV light to degrade humic acid in peat water. Making a thin layer of TiO2 by Soaking meranti wood that has been cut with a size of 30mm x 30mm x 2mm into aqueous solution of TiCl4 and HCl with a ratio of 1: 1 at a temperature of 80 ° C for 1 hour. Before coating the wood with TiO2 the meranti wood is first cleaned and soaked for 2 hours in 0.5 mmol / l surfactant sodium dodecyl sulfate (SDS Sigma Aldrich) at a temperature of 80°C to obtain hydrophobic properties. meranti wood with a thin layer of TiO2 is used as a base on the peat water purification reactor. The analysis carried out was XRD to see TiO2 crystals formed, SEM and EDS to see TiO2 deposited on wood surfaces and wood pores. Analysis on peat water obtained a pH of 6.78 which means that the acid content in the water was mostly degraded, COD of 15 mg / l which had entered the class 2 water standard.

Low temperature synthesis of anatase TiO2 nanocrystals using an organic-inorganic gel precursor

The purpose of this research was to establish a novel approach to synthesize nano-crystalline anatase TiO2 powder through a low temperature solution process and extracting TiO2 from the solution via freeze-drying procedure. The amorphous TiO2 precursors were first prepared using an aqueous TiCl4 solution and N, N-dimethylformamide as a TiO2 structure directing agent at 40 °C. The freeze-drying treatment of the DMF-derived amorphous Ti(IV) gel precursors produced organic–inorganic hybrids, including crystallized tiny TiO2 particles. The size, shape, and crystal phase of the TiO2 particles were determined by using transmission electron microscopy and X-ray diffraction. Most notably, anatase TiO2 nanocrystals were successfully obtained at less than near-room temperature. Furthermore, a sintering process of the gel precursors at 500 °C produced anatase TiO2 nanoparticles with three-dimensional network morphology. The resulting nanoparticles were found to have approximate grain sizes of 30–50 nm, with the organic-inorganic gel supporting the crystallization as a template.

Photoelectrochemical Cathodic Protection Effect of Bi2S3/TiO2 nanorod Array Composite Film for Stainless Steel

TiO2 nanomaterials have long been a topic of interest for applications in various fields due to their special photoelectrochemical properties. However, there are some problems for practical applications of a pure TiO2 film. TiO2 can only be excited by ultraviolet light and its photoelectric conversion efficiency is low due to the high electron-hole recombination rate. In order to overcome these problems, many methods have been developed to modify TiO2 films for improving their photoelectrochemical properties. In this work, we fabricated a Bi2S3 modified rutile TiO2 nanorod array film on FTO conductive glass for achieving a good photoelectrochemical cathodic protection effect on 403 stainless steel (403SS) in a NaCl solution. A single crystalline rutile TiO2 nanorod array film was prepared by a typical hydrothermal reaction method. A FTO substrate (10 mm × 15 mm × 2.2 mm) was immersed in a TiCl4 solution and thermally treated in an electric oven at 70 ℃ for 30 min. After that, the FTO specimen was annealed at 550 ℃ in air for 1 h. Then the specimen with the TiO2 seed layer was immersed a mixed aqueous solution of TiCl4 and HCl, and heated in an electric oven at 150 ℃ for 10 h. Bi2S3 nanoparticles was prepared on the TiO2 film by a typical chemical bath deposition method. The TiO2 film sample was alternately immersed in the Bi(NO3)3 ethylene glycol solution and the Na2S aqueous solution for 1 min. After each immersion, the film sample was dried at 80 ℃ for 5 min. This operation cycle was repeated for 15 times. Finally, the film sample was annealed at 240 ℃ for 4 h in a N2 atmosphere. The prepared films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and their photoelectrochemical properties and photocathodic protection effects were investigated. The results indicated that the prepared TiO2 film was composed of the nanorod array. The TiO2 in the film was highly crystallized and agreed well with the rutile phase, and Bi2S3 nanoparticles were successfully deposited on the TiO2 film. The photoresponse of the Bi2S3/TiO2 composite film was extended into the visible light region, and its photoelectrochemical properties were enhanced. Under white light illumination, the Bi2S3/TiO2 composite film as a photoanode could make the potential of 403SS in a 0.5 M NaCl solution decrease by 695 mV (relative to its corrosion potential), showing a more effective photoelectrochemical cathodic protection effect than the pure rutile TiO2 nanorod film, which is of significance for environmentally friendly corrosion control of metals. This work was supported by the National Natural Science Foundation of China (Nos. 21573182, and 21173177).

TiO2 Passivation Layer on ZnO Hollow Microspheres for Quantum Dots Sensitized Solar Cells with Improved Light Harvesting and Electron Collection.

Light harvesting and electron recombination are essential factors that influence photovoltaic performance of quantum dots sensitized solar cells (QDSSCs). ZnO hollow microspheres (HMS) as architectures in QDSSCs are beneficial in improving light scattering, facilitating the enhancement of light harvesting efficiency. However, this advantage is greatly weakened by defects located at the surface of ZnO HMS. Therefore, we prepared a composite hollow microsphere structure consisting of ZnO HMS coated by TiO2 layer that is obtained by immersing ZnO HMS architectures in TiCl4 aqueous solution. This TiO2-passivated ZnO HMS architecture is designed to yield good light harvesting, reduced charge recombination, and longer electron lifetime. As a result, the power conversion efficiency (PCE) of QDSSC reaches to 3.16% with an optimal thickness of TiO2 passivation layer, which is much higher when compared to 1.54% for QDSSC based on bare ZnO HMS.

Tri-functionalized TiO Cl4-2 accessory layer to boost efficiency of hole-free, all-inorganic perovskite solar cells

Tin dioxide (SnO2) is generally regarded as a promising electron-transporting layer (ETL) for state-of-the-art perovskite solar cells (PSCs), however, the ubiquitous oxygen-vacancy-related defects at SnO2 surface and the large energy difference between conduction band of SnO2 and perovskite layer undoubtedly cause severe charge carrier recombination, resulting in sluggish charge extraction efficiency and non-negligible open-circuit voltage (Voc) loss. Herein, a chlorine-containing TiOxCl4-2x accessory layer is fabricated by immersing SnO2 layer into the TiCl4 aqueous solution to passivate the surface oxygen-vacancy-related defects of SnO2 layer and to set an intermediate energy level at ETL/perovskite interface in all-inorganic cesium lead tri-bromine (CsPbBr3) PSCs. Furthermore, the TiOxCl4-2x layer also improves the infiltration of SnO2 layer surface toward perovskite precursor for high-quality perovskite film. Finally, the hole-free, all-inorganic CsPbBr3 PSC with a structure of FTO/SnO2/TiOxCl4-2x/Cs0.91Rb0.09PbBr3/carbon achieves a champion efficiency of 10.44% with a Voc as high as 1.629 V in comparison to 8.31% for control device. Moreover, the optimized solar cell presents good stability in 80% humidity in air.

Effect of Ag/rGO on the Optical Properties of Plasmon-Modified SnO2 Composite and Its Application in Self-Powered UV Photodetector

A facile hydrothermal method was employed to synthesize silver–reduced graphene oxide (Ag/rGO) plasmon-modified SnO2 composite, by incorporating Ag–reduced graphene oxide (Ag/rGO) into SnO2 nanorods as a photoanode for assembling a self-powered ultraviolet photodetector (UVPD). The as-synthesized samples were investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and UV visible spectrophotometer. The as-prepared Ag/rGO films show enhanced light absorption attributed to the localized surface plasmon resonance (LSPR). The optimized 1.0 wt.% Ag/rGO incorporated into SnO2-based UVPD exhibits a significant photocurrent response due to the enhanced absorption light and effective suppression of charge recombination. This UVPD demonstrates a high performance, with photocurrent density reaching 0.29 mAcm−2 compared to the SnO2-based device with 0.16 mAcm−2. This device also exhibits a high on:off ratio of 195 and fast response time, which are superior to that of the free-modified one. In addition, the UVPD based on plasmon-modified SnO2 photoanode treated with TiCl4-aqueous solution has attained a higher photocurrent with a maximum value reaching 5.4 mAcm−2, making this device favorable in ultraviolet detection.

Effects of TiCl4 post-treatment on the performance of hole transport material-free, screen printable mesoscopic perovskite solar cells with carbon electrode

The prevention of current leakage in perovskite solar cells is an effective method for improving performance of devices. In this work, we treated a surface of TiO2 compact layer by the way of hydrolyzing TiCl4 aqueous solution and have investigated the influence of TiCl4 post-treatment on the performance of hole transport material-free, screen printable mesoscopic perovskite solar cells with carbon electrode. The device, which fabricated by TiO2 compact layer post-treated with TiCl4 aqueous solution for 50 min, has achieved highest device performance, with a short-circuit current density of 23.28 mA cm−2, an open circuit voltage of 0.98 V, a fill factor of 0.65 and the power conversion efficiency of 14.83%. The improved device performance is attributed to inhibition of charge recombination at the fluorine-doped tin oxide/perovskite interface and improvement of charge transport ability of the TiO2 compact layer by TiCl4 post-treatment.

The Role of Thickness Control and Interface Modification in Assembling Efficient Planar Perovskite Solar Cells.

Perovskite solar cells (PSCs) have achieved tremendous success within just a decade. This success is critically dependent upon compositional engineering, morphology control of perovskite layer, or contingent upon high-temperature annealed mesoporous TiO2, but quantitative analysis of the role of facile TiCl4 treatment and thickness control of the compact TiO2 layer has not been satisfactorily undertaken. Herein, we report the facile thickness control and post-treatment of the electron transport TiO2 layer to produce highly efficient planar PSCs. TiCl4 treatment of TiO2 layer could remove the surface trap and decrease the charge recombination in the prepared solar cells. Introduction of ethanol into the TiCl4 aqueous solution led to further improved open-circuit voltage and short-circuit current density of the related devices, thus giving rise to enhanced power conversion efficiency (PCE). After the optimal TiCl4 treatment, PCE of 16.42% was achieved for PSCs with TiCl4 aqueous solution-treated TiO2 and 19.24% for PSCs with TiCl4 aqueous/ethanol solution-treated TiO2, respectively. This work sheds light on the promising potential of simple planar PSCs without complicated compositional engineering and avoiding the deposition and optimization of the mesoporous scaffold layer.

Effects of Chemical Bath-Deposited TiO2 Compact Layer on the Performance of the Fully Screen-Printable Hole-Transport Material-Free Mesoscopic Perovskite Solar Cells with a Carbon Electrode

The optimization of a compact layer in perovskite solar cells (PSCs) strongly influences the device performance. In this work, we prepared a TiO2 compact layer through simple hydrolysis of aqueous TiCl4 solution and have investigated the influence of the TiO2 compact layer on the performance of the fully screen-printable hole-transport material (HTM)-free PSCs with a carbon electrode. The PSC prepared from the TiO2 compact layer made by hydrolyzing TiCl4 precursor solution for 70 min achieved the highest device performance, with a short-circuit current density of 20.01 mA cm−2, an open-circuit voltage of 0.96 V, a fill factor of 0.60 and a power conversion efficiency of 11.53%. Cyclic voltammetry, steady-state photoluminescence spectroscopy and electrochemical impedance spectroscopy were performed to study the charge transfer process in the device. The obtained results suggest that the compact layer in the solar cell structure without HTM plays a decisive role. The improved device performance was attributed to the increase of the charge transport ability and a charge recombination resistance in the TiO2 compact layer.

Ultrafast Synthesis of Urchin-Like Rutile TiO₂ by Single-Step Microwave-Assisted Method.

The preparations of crystal titanium dioxide (TiO2) are often time-consuming multistep processes involving high temperature. Rapid and efficient methods to obtain TiO2 with anatase or rutile phase are desirable. In this paper, we describe an ultrafast single-step method to obtain urchin-like rutile TiO2 particles via microwave irradiation. In the procedure, TiCl4 aqueous solution was used as a reactant and toluene was used as a solvent. It takes only a few minutes without any further heat treatment. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). The effect of temperature, irradiation time and the ratio of precursor to solvent on the morphology and crystal structure were studied. The results show urchin-like rutile TiO2 with high stability is formed after only 5 min microwave irradiation at 135 °C.

(Invited) Interface Modification for Efficient Charge Transfer in Perovskite Solar Cells

Power conversion efficiencies of the perovskite solar cells (PSCs) are drastically increased in this 5 years. PSCs without a mesoporous TiO2 layer, planar-type cells, commonly obtained poorer cell performance as compared to cells with a porous TiO2 layer, owing to inefficient electron transfer from the perovskite layer to the compact TiO2 layer in the former case. The matching of the conduction band edge (CBE) levels of perovskite and the compact TiO2 layer is thus essential for enhancing solar cell performance. In this work, we discussed about the interface between perovskite and electron transport layer (ETL) to improve the performance of the PSCs with adjustment of the CBE levels for reducing the energy loss at the material interfaces in the PSCs. The CBE levels were evaluated with the electrochemical methods. The chemical bath treatment with TiCl4 (TiCl4 treatment) for the compact TiO2 layer to increase the performance of PSC has been reported. The effect of the TiCl4 treatment was considered as the cause of the wettability increases of the precursor solution of the perovskite on TiO2 compact layer and the efficient charge transport from perovskite layer to TiO2 layer. However, TiCl4 treatment may change the CBE potentials. The adjustment of the CBE potentials will be important issue to obtain the low barrier potentials for electron transfer from perovskite to TiO2 compact layers. To study the effect of the TiCl4 treatment on the CBE potentials, we prepared the electrochemical cells with the iodide and tri-iodide redox electrolyte and treated substrate with TiCl4 aqueous solution and the relation between open circuit voltages ( V oc) and the electron density in TiO2 layer of the cells were measured with the charge extraction methods. The V oc as the quasi CBE potential was negatively shifted with the TiCl4 treatment but positively shifted with heating after TiCl4 treatment. We compared the PSCs performance as the different heating temperature at 150 °C, 300 °C, and 450 °C of the TiCl4 treated compact TiO2 layers. The Voc was decreased and the short circuit current was increased with increasing the temperature. The highest PCE was obtained with the heating at 300 °C.

Low-Temperature Soft-Cover-Assisted Hydrolysis Deposition of Large-Scale TiO2 Layer for Efficient Perovskite Solar Modules

Perovskite solar cells with TiO2 electron transport layers exhibit power conversion efficiency (PCE) as high as 22.7% in single cells. However, the preparation process of the TiO2 layer is adopted by an unscalable method or requires high-temperature sintering, which precludes its potential use for mass production of flexible devices. In this study, a scalable low-temperature soft-cover-assisted hydrolysis (SAH) method is presented, where the precursor solution is sandwiched between a soft cover and preheated substrate to form a closed hydrolysis environment. Compact homogeneous TiO2 films with a needle-like structure were obtained after the hydrolysis of a TiCl4 aqueous solution. Moreover, by careful optimization of the TiO2 fabrication conditions, a high PCE of 14.01% could be achieved for a solar module (4 × 4 cm2) prepared using the SAH method. This method provides a novel approach for the efficient scale-up of the low-temperature TiO2 film growth for industrial applications.

Boosting efficiency of planar heterojunction perovskite solar cells by a low temperature TiCl4 treatment

It is well known that electron transport layer (ETL) plays an indispensable role in the planar heterojunction perovskite solar cells (PSCs). TiO2 is widely used as an ETL material due to its excellent transport properties, however, the presence of defects in the TiO2 layer diminishes the power conversion efficiency (PCE) of the devices. Herein, we introduce a method of low-temperature TiCl4 treatment to deposit a TiOx layer on the surface of TiO2 film, which can effectively passivate trap states at the TiO2 surface. Moreover, the treating process is optimized to be 30[Formula: see text]min using a 40[Formula: see text]mM TiCl4 aqueous solution. Benefiting from this, we obtain the champion device with the highest PCE of 18.47%, which is mainly due to the reduction of surface defects and the deposition of the well-crystallized perovskite films. Besides, the modified PSCs exhibit an average PCE of 17.59%, which is much better than the control devices.

Influence of the concentration of TiCl4 solution used for post-treatment on mesoporous TiO2 layers in hybrid lead halide perovskite solar cells

Abstract The influence of the concentration of a TiCl4 aqueous solution used for post-treatment on the device performance of MAPbI3-xClx perovskite solar cells is investigated. All cell parameters increase after treatment by TiCl4 up to the concentration of 100 mM. The enhancement in the fill factor is mainly attributed to the decrease in the series resistance of the treated cells, which is verified via photovoltaic and electrochemical impedance spectroscopy (EIS) measurements. Moreover, more efficient transport and suppressed recombination of charges in the treated cells are observed via EIS and photoluminescence quenching experiments, leading to an increase in the short circuit current density of the treated cells. As a result, a maximum efficiency of 15.6% is achieved for the cell post-treated with 100 mM TiCl4 solution, which is 1.25 times greater than that of the untreated cell, 12.4%.

Photovoltaic Performance of TiO2 Dye Sensitized Solae Cells Coated with ZnO

Dye-sensitized solar cells (DSSCs) are one of the most promising alternative renewable energy sources, which have attracted much attention due to their high conversion efficiency, simple manufacturing process, low production cost, and non-toxicity. TiO2 nanostructures have been mostly used in DSSCs because of their unique photovoltaic and photochemical properties. Mainly, they can provide high surface area for efficient dye adsorption and diffusion pathway for charge transfer processes. Recently, many efforts have been done to improve the conversion efficiency of nanostructured TiO2 photoanodes. One of the promising approaches to enhance the performance of TiO2 -based DSSCs is the suppression of recombination reactions at the TiO2 /dye/electrolyte interfaces. Due to a wide direct band gap (3.37 eV) and the large excitation binding energy (60 meV) of ZnO nanostructures, they have been supposed to be an appropriate inherent barrier layer between the photoelectrode and electrolyte in TiO2 -based DSSCs. In the present work, the sol gel dip coating method was adopted for the deposition of ZnO films on TiO2 NPs. This is a very versatile and simple technique, that does not need any vacuum system of sophisticated instrumentation. F-doped SnO2 conducting glass (FTO) was used as substrates. They were cleaned under ultrasonic treatment (5 min in acetone, 5 min in alcohol), rinsed with double distilled water, and finally treated for 2 min in a 45% nitric acid solution prior to drying in nitrogen atmosphere, and used to make both the working and counter electrodes. A 2M aqueous TiCl4 solution was obtained by dilution of concentrated TiCl4 (Across chemicals) with pre-cooled distilled water solvent in an ice bath and kept in refrigerator. Doctor Blade technique was acquired to deposit TiO2 paste on FTO layers. The coated electrodes were annealed gradually under airflow in programmed heating steps. ZnO films were deposited on the TiO2 NPs by the following procedure: 1 mM of zinc nitrate (AR, Emerck) was dissolved in ethanol (solution A). 1 ml of this solution A was diluted diluted 10 times to obtain 1x 10-4 M solution (solution B), 1 ml of this solution B was durther diluted ten times to obtain 1 x 10-5 M solution (solution C), 1 ml of solution C was diluted ten times to obtain 1 x 10-6 M solution. (solution D). 30 ml of above solutions were separately taken in a 50 ml beaker kept at 75°C, prior to dipping the TiO2 NPs, the pH of the four solutions was adjusted to 9 by NH4OH. Four separate coated TiO2 NPs were dipped individually in the above four Zn2+ solutions. The dipping time was kept constant at 30s. For Dynamic light scattering experiments (DLS), ZnO films were coated under identical conditions on clean glass substrates with the above solutions. The films were withdrawn from the solutions after 30 min and washed with ethanol and dried at room temperature. These four films were further heated in air at 350°C for ZnO formation. Dynamic light scattering (DLS) method was used to study the particle size distribution of the ZnO nanostrures on TiO2. Fig.2 shows the distribution, It is observed that the particle size increases with increase of Zn2+ concentration from 10-5 M to 10-3 M. The slight improvement of VOC and Jsc values obtained after ZnO coating, indicates the effect of ZnO. The effect of ZnO NPs shifts the Fermi level of TiO2 NPs [16] provides extra traps on TiO2 nanoporous structure to capture the carriers and reduce the rate of recombination reactions. In fact, the deposition of the appropriate amount of ZnO NPs could act as charge trapping to capture the carriers, which resulted in suppressing the recombination reactions and subsequently enhancing the JSC values. For further characterization of TiO2/ZnO DSSC, the incident photo-to-current conversion efficiency (IPCE) or externalquantum efficiency (EQE) test was performed.