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[en] An inverted bulk heterojunction organic photovoltaic device based on blend of conjugated polymers and fullerenes derivatives with Cs2CO3/PVDF composites as an electron transporting layer. The entire device structure ((Cs2CO3/PVDF)/P3HT: PCBM/V2O5/Al) has been fabricated using spin coating method and the final metal contact was made using thermal evaporation technique. The mol % of Cs2CO3: PVDF ratio and the spin rate of electron transport and P3HT:PCBM was subjected to be varied and its device performance were evaluated using solar simulator under one sun condition. The physio-chemical characterizations such as UV-Visible, FTIR, PL, XRD, FESEM and AFM were performed for all the materials used in the device fabrications. By varying the spin rate of conjugated polymers/fullerene blends it may helps in scaling up of self-organized molecules of an active layer. Also the variation of spin rate will plays a role in the surface roughness of the film and thereby contributing enhancing the photo-conversion efficiency of fabricated devices. The device fabricated with optimized conditions under ambient atmosphere exhibits efficiency of 1.8 % with JSC of 5.8 mA/cm2 and VOC of 0.57 V. The performance of the device can be enhanced further by controlling exposure of electrode materials. (author)
[en] This paper presents investigations on the post-blue Violet Stimulated Luminescence (VSL) signal in quartz and aims at describing several characteristics of this signal. It is shown that the post-blue VSL signal induced by a stimulation at 405 nm after a preheat treatment at 260 °C for 10 s can be described by three first-order components. The first component (VSL1) is naturally bleachable and reaches a low residual level (around 11 Gy for the sample analyzed in this study). Furthermore, solar simulator experiments allow to demonstrate that this component is characterized by a high bleaching decay rate. The origin of the signal was investigated through TL experiments which suggest that the post-blue VSL signal is mainly associated with traps thermally stimulated at 375 °C. Additional results about the measurement parameters (temperature of stimulation, normalization process, preheat temperature) are also reported and discussed. - Highlights: • The post-blue VSL signal can be described by three first-order components. • The first component VSL1 is naturally bleachable and reaches a low residual level. • The post-blue VSL1 signal originates from the temperature region between 370 and 390 °C
[en] In this paper, the dependence of dose recovery tests on the different bleaching light sources (blue-LEDs, solar simulator, natural sunlight) is investigated with a variety of sedimentary quartz samples, selected so that their OSL signals are dominated by the fast OSL component. We observed that when long solar simulator bleaching was applied, various known doses were underestimated in an SAR-based dose recovery test. However, when blue-LEDs and short solar simulator bleaching were used (10 s and 60 s) the known doses were accurately recovered. In repeated measurement of the OSL signals induced by the same regeneration and test dose, we observed a considerable increase in quartz OSL sensitivity during or after the first OSL measurement when long solar simulator bleaching was used; this seems to provide a possible explanation for the observed underestimation of the laboratory known doses. A series of experimental results using a sample from a modern aeolian dune surface shows that there are no subsequent sensitivity changes when the naturally zeroed samples are bleached with sunlight for long time. It seems that there is a dependence of the sensitivity change on the amount of dose administered before solar simulator bleaching and on the light intensity of solar simulator. When small doses were given to the naturally zeroed sample, the sensitivity change during or after the first OSL measurement was not significant. However, when a considerable amount of beta dose (∼4000 Gy) is administered to the sample, a clear sensitivity change during or after the first OSL measurement (∼20%) was observed. Such a sensitivity change was not observed when the bleaching light intensity of solar simulator was reduced by increasing the distance between samples and the UV lamp. Our results show that, at least for the samples described here, the outcomes of dose recovery experiments are dependent on the bleaching conditions.
[en] Sulfonamides are the second most widely used group of veterinary antibiotics which are often detected in the environment. They are eliminated from freshwaters mainly through photochemical degradation. The toxicity of sulfadimethoxine (SDM) was evaluated with the use of Lemna minor before and after 1- and 4-h irradiation in a SunTest CPS+ solar simulator. Eight endpoints consisting of: number and total area of fronds, fresh weight, chlorophylls a and b, carotenoids, activity of catalase and guaiacol peroxidase, and protein content were determined. The total frond area and chlorophyll b content were the most sensitive endpoints with EC50 of 478 and 554 μg L−1, respectively. The activity of guaiacol peroxidase and catalase increased at SDM concentrations higher than 125 and 500 μg L−1, respectively. The SDM photodegradation rate for first order kinetics and the half-life were 0.259 h−1 and 2.67 h, respectively. The results show that the toxicity of irradiated solutions was caused by SDM only, and the photoproducts appeared to be either non-toxic or much less toxic to L. minor than the parent compound. To study the recovery potential of L. minor, after 7 days exposure in SDM solutions, the plants were transferred to fresh medium and incubated for the next 7 days. L. minor has the ability to regenerate, but a 7-day recovery phase is not sufficient for it to return to an optimal physiological state.
[en] Here we report the results of dose recovery experiments carried out on fine-grained quartz from a Holocene sample in Chinese loess. Optical bleaching prior to giving a 9.35 Gy dose in the laboratory was carried out using artificial light sources, namely blue light emitting diodes (LEDs) and a solar simulator, followed by more than 24 h storage at room temperature. Stimulating the quartz with blue LEDs at room temperature resulted in overestimation of the recovered dose, whereas using the same stimulation time at temperatures above 150 deg. C resulted in the correct value for the recovered dose. Exposure to the solar simulator for times less than 200 min resulted in overestimation of the dose, whereas progressive underestimation was found for longer bleaching times. When doses of up 5333 Gy were given ahead of a 200 min exposure to the solar simulator, the dose recovered depended upon the magnitude of the previous dose, thus questioning the general application of a simple dose recovery experiment. - Highlights: → Dose recovery experiments are affected by type of light and duration of bleaching. → Dose given prior to optical bleaching affects dose recovered. → Sensitivity change depends upon magnitude of previous dose.
[en] Monodisperse nanocrystals of a new wurtzite phase of Cu2CoSnS4 (CCTS) have been synthesized using a simple solution-based method. The wurtzite CCTS nanocrystals grow in the shape of nanorods with an average length of 32 ± 2.0 and width of 16 ± 1.5 nm. The more stable stannite phase of CCTS has also been synthesized by increasing the reaction temperature or by a post-high-temperature annealing process. The band gap of wurtzite CCTS nanocrystals is determined to be 1.58 eV. Thin films prepared from the nanocrystal suspension display photoresponse behaviour with white light from a solar simulator, suggesting the potential use of CCTS as an active layer in low-cost thin-film solar cells. (paper)
[en] The hypothesis that sunglass ultraviolet (UV) protection can degrade with Sun exposure has never been proven experimentally. No sunglasses standards take into account UV transmittance changes after long Sun exposure. We selected 12 sunglass lenses and measured transmittance values from 280 nm to 780 nm. After 50 hours of exposure, new transmittance measurements were taken and transmittance variations inferior to 0.2% were observed. The exposition continues longer and more lenses will be tested to obtain conclusive results. We hope to obtain experimental data to confirm UV protection loss hypothesis and obtain a relation between Sun and solar simulator exposition (paper)
[en] The upgrade of a large area xenon lamp pulsed solar simulator to a 1500X pulsed solar simulator is presented in detail. Spectral match, spatial non-uniformity and temporal instability are analyzed according to the existing international standards, resulting in a Class CAA solar simulator: ongoing improvements to meet Class AAA requirements are discussed. The procedure for the calibration of a set of c-Si reference cells equipped with neutral density filters for calibrated measurements at high intensity is also presented. The paper finally highlights the importance of the spectral match to the standard AM1.5d (direct beam) spectrum over a wider range than described in the available standards for solar simulator classification
[en] The evaluation and assessment of the performance of photovoltaic (PV) cells in terms of measurable parameters requires the measurement of the current as a function of voltage, temperature, intensity, wind speed and spectrum. Most noticeable of all these parameters in the PV conversion efficiency η, defined as the maximum electrical power Pmax produced by the PV cell divided by the incident photon power Pin which is measured with respect to standard test conditions (Sc). These conditions refer to the spectrum (AM 1.5), solar radiation intensity (1000 Wm-2), cell temperature (25 ± 2 degree C) and wind speed (2 mph). Tests under STC are carried out in the laboratory at a controlled environment. There have been several studies that analyze uncertainties in the laboratory measurement of solar cell efficiencies using different solar simulators and their transference to operational situations. Our preliminary results demonstrate that the short circuit current (ISC) of the solar cell decreases when irradiance is less than 1000 Wm-2 irrespective of the working temperature of the cell
[en] It has been known for a long time that the precise characterization of multi-junction solar cells demands spectrally tunable solar simulators. The calibration of innovative multi-junction solar cells for CPV applications now requires tunable solar simulators which provide high irradiation levels. This paper describes the commissioning and calibration of a flash-based four-lamp simulator to be used for the measurement of multi-junction solar cells with up to four subcells under concentrated light