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161.
The Influence of Charge Transport and Recombination on the Performance of Dye‐Sensitized Solar Cells
Mingkui Wang Dr. Peter Chen Robin Humphry‐Baker Dr. Shaik M. Zakeeruddin Dr. Michael Grätzel Prof. Dr. 《Chemphyschem》2009,10(1):290-299
Electrochemical impedance spectroscopy (EIS) and transient voltage decay measurements are applied to compare the performance of dye sensitized solar cells (DSCs) using organic electrolytes, ionic liquids and organic‐hole conductors as hole transport materials (HTM). Nano‐crystalline titania films sensitized by the same heteroleptic ruthenium complex NaRu(4‐carboxylic acid‐4′‐carboxylate) (4,4′‐dinonyl‐2,2′‐bipyridyl)(NCS)2 , coded Z‐907Na are employed as working electrodes. The influence of the nature of the HTM on the photovoltaic figures of merit, that is, the open circuit voltage, short circuit photocurrent and fill factor is evaluated. In order to derive the electron lifetime, as well as the electron diffusion coefficient and charge collection efficiency, EIS measurements are performed in the dark and under illumination corresponding to realistic photovoltaic operating conditions of these mesoscopic solar cells. A theoretical model is established to interpret the frequency response off the impedance under open circuit conditions, which is conceptually similar to photovoltage transient decay measurements. Important information on factors that govern the dynamics of electron transport within the nanocrystalline TiO2 film and charge recombination across the dye sensitized heterojunction is obtained. 相似文献
162.
Constructing a mutant strain of single gene disruption is the basis for the study of gene function and metabolomics. Systematic
and complete genome sequencing is the basis of genetic manipulation. In the case of a little knowledge about the Streptomyces lydicus genome and the speculation that polyketide synthases (type I) might be responsible for the polyketide side chain biosynthesis
of streptolydigin, a 588-bp fragment was amplified by polymerase chain reaction (PCR) according to the homology existing in
the same functional genes among Streptomyces. A mutant strain of this gene was constructed by single crossover homologous recombination. The results of sequence analysis
as well as the metabolite analysis of the mutant and the original strain by liquid chromatography/mass spectroscopy indicated
that this fragment was part of type II thioesterase (TE) gene, which was required for streptolydigin biosynthesis like other
type II TEs function in related antibiotics biosynthesis. Furthermore, targeted gene manipulation based on PCR was a powerful
tool for studying gene function and metabolomics, especially when little was known about the genomic sequence of streptomyces. 相似文献
163.
High temperature materials are necessary for the design of primary heat shields for future reusable space vehicles re-entering atmospheric planet at hypersonic velocity. During the re-entry phase on earth, one of the most important phenomena occurring on the heat shield is the recombination of atomic oxygen and this phenomenon is more or less catalyzed by the material of the heat shield. PM 1000 is planned to be use on the EXPERT capsule to study in real conditions its catalycity. Before the flight, it is necessary to perform measurements on ground test facility. Experimental data of the recombination coefficient of atomic oxygen under air plasma flow were obtained in the diffusion reactor MESOX on pre-oxidized PM 1000, for two total pressures 300 and 1000 Pa in the temperature range (850-1650 K) using actinometry and optical emission spectroscopy. In this investigation, the evolution of the recombination coefficient is dependent of temperature, pressure level and also of the chemical composition of the surface leading to one order of magnitude for a given temperature. The recombination coefficient is increasing with temperature and also dependent on the static pressure. The surface change due to the plasma exposure is inspected with SEM, XRD and XPS. As chromium oxide is the main part of the oxide layer formed during the oxidation in air plasma conditions, a sintered Cr2O3 sample was elaborated from powders to compare the data of the recombination coefficient obtained on PM 1000. Pre- and post-test analyses on the several materials were carried out using SEM, WDS, XRD and XPS. 相似文献
164.
The kinetics of inhibited oxidation of lipids was studied by computer simulation to evaluate the contributions of the recombination/disproportionation
of inhibitor radicals and chain transfer to retardation effects. The influence of inhibitor regeneration on the induction
periods and inhibited oxidation rate was demonstrated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1915–1920, October, 1999. 相似文献
165.
S. V. Koshevaya M. Tecpoyotl-T E. A. Gutiérrez-D M. Hayakawa V. V. Grimalsky 《International Journal of Infrared and Millimeter Waves》1999,20(11):1925-1932
Theoretical and experimental analysis has been performed for surface oriented silicon plasma-based p,i,n structures used to control high power level, broadband devices. It is shown that these structures are very promising for their use as modulators in the millimeter and submillimeter wave range. 相似文献
166.
Luis V.A. Scalvi Fábio R. Messias A.E. Souza M. Siu Li C.V. Santilli S.H. Pulcinelli 《Journal of Sol-Gel Science and Technology》1998,13(1-3):793-798
Thin films of undoped and Sb-doped SnO2 have been prepared by a sol-gel dip-coating technique. For the high doping level (2–3 mol% Sb) n-type degenerate conduction is expected, however, measurements of resistance as a function of temperature show that doped samples exhibit strong electron trapping, with capture levels at 39 and 81 meV. Heating in a vacuum and irradiation with UV monochromatic light (305 nm) improves the electrical characteristics, decreasing the carrier capture at low temperature. This suggests an oxygen related level, which can be eliminated by a photodesorption process. Absorption spectral dependence indicates an indirect bandgap transition with Eg 3.5 eV. Current-voltage characteristics indicate a thermionic emission mechanism through interfacial states. 相似文献
167.
Jerome Perrin Jacques Méot Jean-Marie Siéfert Jacques Schmitt 《Plasma Chemistry and Plasma Processing》1990,10(4):571-587
NF3 plasma etching is used for dry cleaning of reactors after plasma-enhanced chemical vapor deposition of hydrogenated amorphous silicon from SiH4. The NF3 plasma chemistry, in a closed isothermal plasma box with silicon coated walls, is analyzed by mass spectrometry of gases. Silicon is etched as SiF4 by F atoms produced in the NF3 dissociation into F+NF2, or 2F+NF. The NF radicals recombine as N2 +2F whereas the long-lived NF2 radicals do not react with Si, but recombine as N2F4 This is the main limitation (or fluorine conversion into SiF4. The pressure increase at the end point of etching is attributed to the sudden increase of F atom concentration in the gas phase and the consequent recombination q( F atoms as F2. 相似文献
168.
The excitation of B4.3C with an Ar-laser () yields a photoluminescence spectrum between about 1.56 and 1.58 eV with its main maximum at 1.563 eV and a weaker maximum at 1.572 eV. It is attributed to the indirect-allowed recombination of free excitons. 相似文献
169.
The method of absolute calibration of the TALIF signal of atomic nitrogen by NO titration in the afterglow of a flow tube reactor has been analyzed using TALIF and emission spectroscopy. An increase in production of atomic nitrogen at titration beginning and an asymmetric parabolic curve for emission of NObands have been observed. Of three possible explanations of these effects the model of wall recombination was favored: it led to fitted wall recombination coefficients referring to wall loss factors, which where in the same dimension as literature values and was able to simulate a hysteresis effect, which has been observed experimentally. According to the observations the titration end point cannot be used to determine the atomic nitrogen density in the afterglow before any NO has been added into the system as the titer produces part of this density itself. But for absolute calibration purposes referring to the wall recombination model the linear decrease of the TALIF signal with increasing titer concentration can still be used as straight line of calibration. Only a correction of the calibration factor by a factor of 0.59 for 5 mbar titrations has to be taken into account as the titer shows wall interaction not only in a catalytic way, but is partly consumed. 相似文献
170.