Effect Of UV Light Irradiation Research Articles

Effect of UV light irradiation on the In2O3 nanoparticle films synthesis by the sparking method

Sparking method has been demonstrated as a powerful method in nanoparticles synthesis. In this research, we proposed a UV light irradiation strategy to enhance the nanoparticle fabrication technique. The sparking method was performed under UV light irradiation without heat treatment for In2O3 nanoparticle films preparation. The results showed that UV light can effect on properties of In2O3 nanoparticle films as a function of light intensity. The mechanism was proposed based on photoelectric effect. Under UV light irradiation, the In2O3 nanoparticles aggregated and accumulated faster and efficiency of adhesion between particles during their collisions was improved. Additionally, the band gap energy of In2O3 decreased with increasing the intensity of UV light irradiation.

The effect of UV light irradiation on the gas-sensing properties of the quartz crystal microbalance sensor combined with ZnO film

The effect of UV light irradiation on the gas-sensing properties of the quartz crystal microbalance sensor combined with ZnO film

Effect of UV-Light Irradiation on Charge-Accumulation States in PTzBT Polymer Solar Cells

Ternary polymer solar cells based on a polymer PTzBT have received a lot of attention because their power conversion efficiency (PCE) and thermal stability have been greatly improved by adding a small amount of an oligomer ITIC. However, the charge-accumulation states of the PTzBT ternary polymer solar cells have not yet been completely clarified. Here, we report electron spin resonance (ESR) spectroscopy of the PTzBT ternary polymer solar cells to investigate the charge-accumulation states from a microscopic viewpoint with examining the effect of UV-light irradiation. We observed a slight increase in the ESR intensity of the PTzBT cells and layered film samples under simulated solar irradiation with a UV-cut filter. Multiple signals were observed in the PTzBT cells under solar irradiation when the UV-cut filter was removed. Interestingly, no decrease was observed in the ESR signal of ZnO under solar irradiation with the UV-cut filter, although holes in ZnO in the PTzBT cells are known to decrease under solar irradiation. These findings will contribute to a deep understanding of the material properties of polymer solar cells.

Effect of UV, pH and solvent on the photophysical properties of novel xanthylium fluorophore in solid and liquid state

The current work describes the comparative study of the photophysical properties of new series of xanthylium fluorophore in different organic solvents, the effect of pH, and the effects of UV light irradiation and stability. The designed molecule plays a significant role in the stability. We disclosed the synthesized molecule's stability from UV–Vis, fluorescence, theoretical studies, the molecule sensitivity to solvent polarity, and pH due to its structural nature. The decrease in absorbance and fluorescence intensity with UV–visible light irradiation for the solid and liquid samples were studied. The dye discoloration rate was estimated. The mechanism for the same has been explored, and the information is given in detail. The electrostatic potential, surface mapping analysis, and the stability of the synthesized dye molecules were studied theoretically and compared with the experimental outcome. The stability study and other factors allowed us to predict the suitable application of the synthesized xanthylium fluorophore.

Effect of UV light irradiation, pH and concentration on the dye sequestration efficiency of anionic surfactant based self-assembled aqueous mesophases

Lyotropic lamellar phases are prepared by using the varying concentration of sodium dodecyl sulfate: water (SDS: W) and then doped with methyl blue dye (0.01 wt.%). Textural analysis confirms that the addition of the dye does not perturb the lamellar patterns. Dye molecules may self-assembled over the lamellar aqueous interface in an ordered fashion. Lyotropic lamellar phases are explored for methyl blue sequestration/adsorption under the influence of UV irradiation (125 W and λ=365 nm). No structural phase change in lyotropic systems has been observed after UV irradiation. However, visual blue to colourless transition and continuous suppression of adsorption intensity has been seen for the dye-doped system. About 97–99% sequestration efficiency is noted for these lyotropic systems within 60 min in alkaline pH (8–9). Sequestration/ adsorption of dye could be the result of electrostatic interactions amidst N+ and O− of dye and anionic surfactant SDS. Such interactions alter one of the double bonds of one NH group of methyl blue permanently, hence, disrupts the molecular planarity of the dye molecule and could be a cause of dye sequestration. The effect of varying pH has also been discussed. Studied systems could be seen as an economic and efficient adsorbent for water and impurity purification applications.

Effects of UV light irradiation on fluctuation enhanced gas sensing by carbon nanotube networks

The exceptionally large active surface-to-volume ratio of carbon nanotubes makes it an appealing candidate for gas sensing applications. Here, we studied the DC and low-frequency noise characteristics of a randomly oriented network of carbon nanotubes under NO2 gas atmosphere at two different wavelengths of the UV light-emitting diodes. The UV irradiation allowed to sense lower concentrations of NO2 (at least 1 ppm) compared to dark conditions. Our experimental studies confirmed that the flicker noise of resistance fluctuations under UV irradiation significantly enhanced the sensing characteristics of nanotube networks at low concentrations. We observed a dominating 1/f-like noise component below 1 kHz. The sensitivity of nanotube networks was higher for shorter wavelength, whereas drift in the resistance was smaller for longer wavelength. The measurements under the NO2 gas atmosphere revealed a remarkable reduction in DC resistance drift of the nanotube network between consecutive cycles of gas sensing. This phenomenon was explained via absorption-desorption of NO2 gas molecules on nanotubes surface. Since small concentrations of NO2 pose a threat to the ecosystem, these results might play a significant role in the development of sensitive nanotubes-based photo-activated gas sensors.

Effects of UV light irradiation on color changes in thermally modified rubber wood based on FTIR

To evaluate the effects of chemical changes during thermal modification on the resistance of wood against photodegradation, heat-treated specimens of rubber wood (Hevea brasiliensis) were exposed to ultraviolet light for 384 h. The color changes in the exposed wood surfaces were analyzed using a colorimeter; the chemical changes were monitored using Fourier-transform infrared spectroscopy (FTIR). The photoweathering performances of rubber wood treated at 155 °C for 2 h, 155 °C for 6 h, and 185 °C for 2 h were similar to that of untreated wood, as the lignin did not undergo profound chemical transformation under mild modification conditions. However, compared to untreated rubber wood, the photoaging performances of rubber wood treated at 185 °C for 6 h and 215 °C for 2 h were notably changed. The transformation process was confirmed by FTIR. A good linear relationship between color change and lignin degradation was observed after mild, but not severe, heat treatment. The concentration of carbonyl groups in the wood specimens generally increased during photoaging, although not all samples showed a good correlation between color change and the concentration of carbonyl groups. Only the photochromic performance of wood changed notably when lignin was extensively modified under severe heat-treatment conditions.

UV-illuminated chemical bath deposition of CdS buffer layer for CIGSSe solar cells

In this paper, we compare the performance of Cu(In,Ga)(S,Se)2 (CIGSSe) thin film solar cells with a CdS buffer layer grown by chemical bath deposition (CBD) with UV irradiation of 365 nm or 254 nm at an output power of 8 W. The effects of UV light irradiation on the CBD-CdS thin film deposition mechanism were investigated through chemical and electro-optical studies. UV light irradiation during the solution process promotes the hydrolysis of thiourea, thereby inhibiting the formation of the intermediate products being developed on the reaction pathways and decreasing the solution pH. Therefore, the efficiency of the CdS/CIGSSe solar cells was improved because of the increased elemental ratio of S/(S + O) in the CdS thin film. This very simple and effective approach can be used to control the S/O ratio of the CdS thin film fabricated by the CBD process without artificially controlling the process temperature, solution pH or concentration.

UV response on dielectric properties of nano nematic liquid crystal

Abstract In this work, we investigate the effect of UV light irradiation on the dielectric parameters of nematic liquid crystal (5CB) and ZnO nanoparticles dispersed liquid crystal. With addition of nanoparticles in nematic LC are promising new materials for a variety of application in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however we optimize the properties of liquid crystal and understand how the UV light irradiation interact the nanoparticles and LC molecules in dispersed/doped LC. The dielectric permittivity and loss factor have discussed the pure nematic LC and dispersed/doped system after, during and before UV light exposure. The dielectric relaxation spectroscopy was carried out in the frequency range 100 Hz–10 MHz in the nematic mesophase range.

Fungicidal Effects of Ultraviolet Light (254 nm) Irradiation on Contaminated Museum Packing and Storing Materials

In storage of modern museums, collections are packed and stored with acid-free paper-based materials for keeping safe and stable conditions. Direct contact of fungal contaminated packing and storing materials with the collections is concerned about expanding of infection in storage facilities. In this study, fungicidal effects of UV light irradiation on the materials such as archival board and Japanese tissue paper contaminated with Penicilliun commune and Chaetomium globosum were tested. The analyzed materials were divided into two groups; Group 1 was examined with 20 μl of spore suspensions of fungi (106 cfu/ml) ; and Group 2 was tested on Czapek- Dox agar medium modified without sugar and inoculated with 100 μl of the spore suspensions of fungi (106 cfu/ml) . Six doses of UV irradiation were examined on Group 1 and five doses on Group 2 in addition to control. The assessment was done by using 1) adenosine triphosphate (ATP) bioluminescence assay and double staining to determine the cell viability; 2) observation under light microscope to evaluate morphophysiological change of tested fungi (spores and hyphae) . Because of the thinness and high transparency of tissue paper, UV irradiations were highly efficient to fungicide its fungal contamination compared with archival board. In spite of the high resistance of C. globosum spores, the rate of growth was slow, and with a little amount of perithecia or fruiting bodies and a high amount of ycelium (which damaged rapidly through UV irradiation) . This may be due to a low relative humidity of the incubation environment. Minimum dosage of UV irradiation with fungicidal effectiveness against all fungal contamination was estimated as 118 J/cm2.

Effect of UV-light irradiation on phase diagram of lyotropic chromonic liquid crystal

We demonstrate that the phase diagram of a Lyotropic Chromonic Liquid Crystal (LCLC) is affected by ultraviolet (UV) light irradiation. UV-irradiation induces a phase transition from the nematic (N) to isotropic (I) state at a fixed temperature. Birefringence measured in-situ decreases under irradiation, until the moment when the isotropic phase starts to nucleate and the initial homogeneous nematic transforms into a biphasic state. On further irradiation the birefringence of the N fraction of the biphasic I-N state increases revealing redistribution of the composition components between the two coexisting phases. The efficiency of the irradiation-induced changes depends on the orientation of the chromonic aggregates w.r.t. the polarization of UV light. Changes of the birefringence are noticeably higher for light polarization perpendicular to the nematic director. The effect can be understood as a photo-induced weakening of the face-to-face molecular attraction within the chromonic aggregates and the resulting shortening of these aggregates.

Effect of UV light irradiation on the dielectric behaviour of liquid crystal/nano composite

ABSTRACTIn this work, we investigate the effect of UV light irradiation on the dielectric parameters of the nematic liquid crystal (5CB) containing dispersed ZnO nanoparticles. With addition of nanoparticles, nematic LC's are promising new materials for a variety of applications in energy harvesting, displays and photonics including the liquid crystal laser. To realize many applications, however one must optimize the properties of liquid crystal and understand how UV light irradiation interacts with the nanoparticles and LC molecules in dispersed/doped LC. The dielectric permittivity and loss factor are discussed for the pure nematic LC and dispersed/doped system after, during and before UV light exposure. Dielectric relaxation spectroscopy was carried out in the frequency range 100 Hz-10 MHz in the nematic mesophase.

Engineered nanoparticles of titanium dioxide (TIO2): Uptake and biological effects in a sea bass cell line

With the rapid development of nanotechnology there has been a corresponding increase in the application of titanium dioxide nanoparticles (TiO2-NPs) in various consumer and industrial products, consequently their potential health hazards and environmental effects are considered an aspect of great concern.In the present study, in order to assess the impact of TiO2-NPs in the marine environment, the biological effects of TiO2-NPs on a sea bass cell line (DLEC) were investigated. Cells were exposed for 24 h to different concentrations of TiO2-NPs (1, 8, 40, 200 and 1000 μg/ml) or co-exposed with CdCl2 (Cd). The effects of UV light irradiation were also investigated in cells treated with TiO2-NPs and/or Cd. The internalization of TiO2-NPs and the morphological cell modifications induced by the treatments were examined by transmission and scanning electron microscopy, this latter coupled with energy dispersive X-ray spectroscopy (EDS) for particle element detection. In addition, the effects of controlled exposures were studied evaluating the cytotoxicity, the DNA damage and the expression of inflammatory genes.Our study indicates that TiO2-NPs were localized on the cell surface mainly as agglomerates revealed by EDS analysis and that they were uptaken by the cells inducing morphological changes. Photoactivation of TiO2-NPs and/or co-exposure with Cd affects ATP levels and it contributes to induce acute cellular toxicity in DLEC cells dependent on Ti concentration. The inflammatory potential and the DNA damage, this latter displayed through a caspase-3 independent apoptotic process, were also demonstrated.Overall our data suggest that the interaction of TiO2-NPs with marine water contaminants, such as cadmium, and the UV irradiation, may be an additional threat to marine organisms.

Formulation and physiochemical study of α-tocopherol based oil in water nanoemulsion stabilized with non toxic, biodegradable surfactant: Sodium stearoyl lactate

The unique properties such as high optical clarity, stability and enhanced bioavailability of nanoemulsion make them useful for food, cosmetic and pharmaceutical industries. In this work, sodium stearoyl lactate and Tween 80 surfactants were collectively used to fabricate alpha tocopherol based oil in water nanoemulsion using high energy ultrasonication method. The spherical nature of pure and drug loaded nanoemulsion has been confirmed with transmission electron microscopy (TEM). The influence of pH, dilution, surfactant concentration and ionic strength on average particle size of pure and nutraceutical (benzylisothiocyanate and curcumin) encapsulated emulsion was examined. The prepared emulsion exhibited good stability up to 90days in salt solution (50–200mM) and different pH conditions. The cumulative release % of benzylisothiocyanate and curcumin was found to be 50.29% in 36h and 89.15% in 150h respectively. The antioxidant activity of pure, benzylisothiocyanate, curcumin and cocktail (benzylisothiocyanate and curcumin) nanoemulsion was calculated with 2,2-diphenyl-1-picrylhydrazyl radical. The IC50 value of different antioxidant showed that benzylisothiocyanate nanoemulsion acted as better antioxidant as compared to pure and curcumin encapsulated nanoemulsion. Also the cell viability of pure nanoemulsion was found to be 24% on hep G2 cell. The effect of UV light irradiation on curcumin and benzylisothiocyanate stability was carried out in different solvent conditions (water/ethanol and nanoemulsion). The degradation of curcumin by the impact of UV light was successfully controlled by trapping in NEm.

Effect of ultraviolet light irradiation and ion collision on the quality of multilayer graphene prepared by microwave surface-wave plasma chemical vapor deposition

We successfully synthesized graphene by microwave surface-wave plasma chemical vapor deposition (CVD) and investigated the effect of UV light and ion collision from the plasma exposure during graphene synthesis. The graphene obtained here was multilayer graphene consisting of approximately 5 layers according to cross-sectional transmission electron microscopy results. The quality of the graphene was compared between the case where UV light was irradiated from the plasma and the case where the UV light was blocked by a grid-inserted CVD configuration. Quality was evaluated by Raman scattering spectroscopy. There were more defects in the graphene prepared with irradiation of UV light than with blocking of UV light. Furthermore, we investigated the effects of ion collisions that occurred in the plasma, but they had no effect on graphene quality. These results suggest that during graphene synthesis, UV light from the plasma affects its crystallinity. The electrical conductivity, optical transmittance and mobility of the transferred graphene films were measured to clarify the effects of UV light irradiation.

(Invited) Long Term Stability of Antimony Sulfide-Based Hybrid Solar Cells

Recently various materials such as antimony sulfide (Sb2S3),1,2) antimony selenide,3) lead sulfide,4) cadmium selenide,5) lead-halogen perovskite6-8) have been applied for organic-inorganic hybrid solar cells. Among these materials, Sb2S3 has much attraction for photovoltaics in terms of appropriate bandgap, high absorption coefficient, low toxicity, and abundance. Sb2S3 has been prepared by chemical bath deposition, atomic layer deposition, complex-decomposition method, and so on and applied as the thin film for solar cell, which has been attained the power conversion efficiency (PCE) of 7.5%.1) Although Sb2S3-based solar cell seems to be stable in air,2) stability test under the accelerated conditions has not yet been reported. In addition, various materials such as SnO2, TiO2, or ZnO have been utilized as an electron transporting layer (ETL) and polythiophenes, 2,2’,7,7’-tetrakis(N,N-di-p-methoxyphenylamine)-9,9’-spirobifluorene, ZnPc, CuSCN, MoO3, or NiO have been used as a hole transporting layer (HTL) of the Sb2S3 based solar cells, however, optimization of the combinations of ETL and HTL in terms of the durability has also not yet been explored. In this context, we prepared Sb2S3-based solar cells with TiO2 or ZnO nanoparticles for ETL in addition to poly(3-hexylthiophene)-2,5-diyl (P3HT)/ (3, 4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS), ZnPc, or MoO3 for HTL and compared their photovoltaic properties with encapsulation by using glass and UV cut-off films under JIS C8938 conditions of 1 sun at 63 °C at a relative humidity (RH) of 50%. Among these hybrid solar cells, combination with ZnPc and TiO2 has the highest durability with keeping the relative power conversion efficiency of 90% after the stability test under 1 sun at 63 °C at a RH of 50% for 500 h. In order to investigate the effect of UV light irradiation, another durability test of glass-ITO/TiO2/Sb2S3/ZnPC/Au without UV cut filter was performed The photovoltaic performance was completely maintained for 3 d with UV cut filter, however it has almost been lost without the cut filter after 3 d. Decolorization was observed after the irradiation without the UV cut filter though the decolorization did not occur with the filter. Once the TiO2 layer was removed from the cell, described as glass-ITO/ Sb2S3/ZnPC/Au, there was no decolorization even when without using the UV cut filter. In this context, anatase TiO2 nanoparticles in this case act as the photocatalyst during the UV light irradiation to oxidize and decompose Sb2S3, which resulted in the above decolorization of the cells. Therefore, effective suppression of the photoactivation of TiO2 through UV light irradiation by using cut filter is essential to realize the long term stability and promising further extension for optimization of the photovoltaic performance. J. A. Chang, J. H. Rhee, S. H. Im, Y. H. Lee, H. J. Kim, S. I. Seok, M. K. Nazeeruddin, and M. Graetzel, Nano Lett., 2010, 10, 2609–2612.Y. C. Choi, D. U. Lee, J. H. Noh, E. K. Kim, and S. I. Seok, Adv. Funct. Mater. 2014, 24, 3587-3592.N. Guijarro, T.Lutz, T.Lana-Villarreal, F. O’Mahony, R. Gomez, and S. A. Haque, J. Phys. Chem.Lett., 2012, 3, 1351-1356.H. Wang, T. Kubo, J. Nakazaki, T. Kinoshita, and H. Segawa, J. Phys. Chem. Lett. 2013, 4, 2455-2460.P. K. Santra and P. V. Kamat, J. Am. Chem. Soc., 2012, 134, 2508-2511.A. Kojima, K. Teshima, Y. Shirai, T. Miyasaka, J. Am. Chem. Soc., 2009, 131, 6050-6051.M. M. Lee, J. Teuscher, T. Miyasaka, T. N. Murakami, H. J. Snaith, Science, 2012, 338, 643-647.W. S. Yang, J. H. Noh, N. J. Jeon, Y. C. Kim, S. Ryu, J. Seo, S. I. Seok, Science, 2015, 348, 1234-1237.

Synthesis and characterization of RF sputtered WO3/TiO2 bilayers

Abstract Ultra-thin WO3/TiO2 bilayer thin films with various amounts of WO3 materials were deposited on glass substrates using RF reactive magnetron sputtering in an attempt to enhance the photocatalytic activity and/or photoinduced hydrophilic conversion of titania-based materials. AFM images reveal changes in surface morphology on increasing WO3 film thickness. Core level and valence band XPS spectra suggest band gap narrowing with the increase of tungsten atomic concentration in the bilayer structure. Both hydrophilic conversion and the photocatalytic activity of the surface were quantified via contact angle measurements. The latter process involved monitoring the contact angle changes induced by the decomposition of an additional oleic acid overlayer, as an effect of UV light irradiation. All the investigated samples exhibit similar photocatalytic features and close values for the hydrophilic conversion rates.

CO2 gas detection properties of a TIO2/Al2O3 heterostructure under UV light irradiation

Al/TiO2/p-Si and Al/TİO2/Al2O3/p-Si samples were prepared using the atomic layer deposition method (ALD) and their gas sensing properties were investigated. The electrical properties of the samples were studied using a two probe method in the temperature range 25–230 °C and at room temperature UV conditions. The TiO2/Al2O3 heterojunction sample exhibited an excellent gas sensing response to CO2 gas at room temperature and improved the effect of UV light irradiation. The results showed that heterostructures helped to improve the gas sensor properties, affected the sensing at room temperature and thus guided the design of photocatalysts. The TiO2/Al2O3 heterojunction prepared using this method can be used as a material for semiconductor gas sensors detecting poisonous gases like CO2 at room temperature with high sensitivity and selectivity.

Wood Surface Protection against Artificial Weathering with Vegetable Seed Oils

Effects of UV-light irradiation and water spray on the mechanical strength and surface characteristics of untreated and pretreated Scots pine sapwood samples were studied. The specimens were treated with parsley seed oil, pomegranate seed oil, linseed seed oil, nigella seed oil, canola oil, sesame seed oil, and soybean oil. The compositional changes and surface properties of the weathered samples were characterized by Fourier transform infrared (FTIR-ATR) spectroscopy and color and surface roughness measurements. The results showed that all vegetable oils provided lower color changes than the control group after 600 h of exposure in a weathering test cycle. The least color change was found on the Scots pine surface pretreated with pomegranate seed oil. The vegetable oil treatment retarded the surface lignin degradation during weathering, indicating that the surface roughness values of pine wood treated with vegetable oils decreased with irradiation over time compared with those of control samples. The effect of artificial weathering on mechanical strength was determined with a compression strength test. It was observed that the compression strength values of Scots pine samples treated with vegetable oils was higher than that of untreated samples after 600 h of weathering exposure.

Effect of UV light irradiation on photovoltaic characteristics of inverted polymer solar cells containing sol–gel zinc oxide electron collection layer

An inverted organic bulk-heterojunction solar cell containing a zinc oxide (ZnO) based electron collection layer with a structure of ITO/ZnO/[6,6]-phenyl C61 butyric acid methyl ester (PCBM): regioregular poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxylenethiophene): poly(4-styrene sulfonic acid)/Au (ZnO cell) was fabricated. We examined the relationship between the heating temperature of the ZnO layer and the device performance under irradiation by simulated sunlight while cutting the UV light. The effects of the UV light contained in simulated sunlight were investigated by photocurrent–voltage (I–V) and alternating current impedance spectroscopy (IS) measurements. When the ZnO cells were irradiated with simulated sunlight, they exhibited a maximum power conversion efficiency (PCE) of over 3%, which hardly varied with the heating temperature of ZnO layers treated at 250°C, 350°C, and 450°C. In contrast, when the ZnO cells were irradiated with simulated sunlight without UV content, their photovoltaic characteristics were very different. In the case of the cell with ZnO prepared by heating at 250°C, PCE of 2.7% was maintained even under continuous irradiation with simulated sunlight without UV. However, for the cells with ZnO prepared by heating at 350°C and 450°C, the shapes of the I–V curves changed with the UV-cut light irradiation time, accompanying an increase in their series resistance. Overall, after UV-cut light irradiation for 1h, the PCE of the cell with ZnO prepared by heating at 350°C decreased to 1.80%, while that of the cell with ZnO prepared by heating at 450°C fell to 1.35%. The photo IS investigations suggested that this performance change was responsible for the formation of charge-trapping sites at the ZnO/PCBM:P3HT interface which act as recombination centers for photo-produced charges in the PCBM:P3HT layer.