Improved performance in dye-sensitized solar cells employing TiO2 photoelectrodes coated with metal hydroxides

The performance of dye-sensitized solar cells (DSCs) was compared before and after processing the TiO(2) electrodes by minute-order electrochemical reactions with metal nitrates, where the metals were Mg, Zn, Al, and La, in 2-propanol. An overcoating of metal hydroxide was formed without the need for a sintering process, and magnesium hydroxide was found to give the largest improvement in photovoltage, fill factor, and eventually overall conversion efficiency of the DSCs. To analyze the nature of the improvement, the diffusion coefficient (D) and electron lifetime (tau) were determined. While little influence of overcoating on D was seen, a correlation between the increase in tau and V(oc) was observed for the metals examined here. The remarkable improvement in the electron lifetime of the DSCs suggests that an overcoating with magnesium hydroxide species function as the blocking layers at the fluorine-doped tin oxide and TiO(2) interfaces, thus contributing to the suppression of electron leakage, i.e., recombination processes between unidirectional transporting electrons and poly-iodides such as tri-iodide in the processed TiO(2) photoelectrode systems. The increase in V(oc) can be explained by the increased electron density caused by the increase in electron lifetime.     

Ion current generation in the field ion microscope: I. dynamic approach

The numbers of gas particles arriving at unit tip surface in unit time from a field free region are derived as functions of velocity components for a spherical tip. It is shown that a considerable fraction of the gas particles arrives at the tip having large tangential velocities. The simple model of collision of a particle with a metal surface is used and the trajectories and rebounds of particles are tracked. The principal method to calculate the total ion current is shown. The capture probability of particles by the dipole attraction potential is shown to increase when the tip temperature is lowered, the field strength is increased, the mass ratio of the gas atom to the metal atom increases and the gas temperature is lowered.     

Ion current generation in the field ion microscope: II. quasi-static approach

The field ion current is calculated for helium on tungsten, for various fields, and for various values of tip temperature and gas temperature on the basis of the balance equation developed by Van Eekelen. The expression of ion current by rate constants for ionization and for escape, the total supply and the capture probability is derived. The behaviour of ion current as a function of other parameters is discussed in the light of these equilibrium properties of the system. Field adsorption effects are also considered. The increase of the mass ratio of the gas atom to the metal atom causes the increase of ion current even if ionization probability is decreased by the field adsorption. Anomalous features of the field ion image at 4.2 K are discussed.     

Demonstration for a two-axis interferometric tilt sensor in KAGRA

Recently, a folded Mach–Zehnder interferometer with homodyne in- and quadrature-phase detection was proposed as a high-precision, wide-dynamic range tilt sensor. By way of a practical application and to validate actual performance, two-axis tilt sensors were developed and installed for one mirror of the input mode cleaner cavity in KAGRA, the large-scale cryogenic gravitational-wave telescope in Kamioka, Gifu, Japan. Building on previous work, we have demonstrated that the two-axis tilt sensor has properly sensed the tilt angle changes of the mirror motion with high precision and without calibration. Compared with our initial angular sensor, an optical lever, which is calibrated by using the interferometer tilt sensor, we found that both sensors showed actual tilt motions of the mirror at low frequencies, and the two-axis interferometer sensor has a better sensitivity at higher frequencies.     

Influence of oxygen vacancies on optical properties of anatase TiO2 thin films

This paper presents an investigation into the relaxation process of photo-excited carriers in anatase TiO₂ thin films, in which the concentration of oxygen vacancy is controlled by annealing at various temperatures in an oxygen atmosphere. The influence of oxygen vacancies on absorption spectra, photoluminescence (PL) spectra, and PL decay dynamics are discussed.     

Optical properties of polymer blends composed of poly(methyl methacrylate) and ethylene–vinyl acetate copolymer

Optical properties for immiscible polymer blends composed of poly(methyl methacrylate), PMMA, and ethylene–vinyl acetate copolymer (EVA) are studied employing various EVA samples with different vinyl acetate contents. PMMA/EVA shows transparency at room temperature when the difference in refractive index between both phases is small. The light transmittance, however, decreases with increasing the ambient temperature. This phenomenon is attributed to the difference in the volume expansion ratio, leading to the difference in refractive index, between PMMA and EVA. It is found that addition of tricresyl phosphate, TCP, improves the transparency and its temperature dependence. As a result, a ternary PMMA/EVA/TCP blend shows high level of transparency in the wide temperature range, although it has apparent phase separated morphology.     

Spatial-carrier phase-shifting digital holography utilizing spatial frequency analysis for the correction of the phase-shift error

We propose a single-shot digital holography in which the complex amplitude distribution is obtained by spatial-carrier phase-shifting (SCPS) interferometry and the correction of the inherent phase-shift error occurred in this interferometry. The 0th order diffraction wave and the conjugate image are removed by phase-shifting interferometry and Fourier transform technique, respectively. The inherent error is corrected in the spatial frequency domain. The proposed technique does not require an iteration process to remove the unwanted images and has an advantage in the field of view in comparison to a conventional SCPS technique.     

Synthesis of heterocyclic compounds using amidines as their ene‐1,1‐diamine tautomers. II. Synthesis of 2,3‐dihydropyridine, 3,4‐dihydropyridine and 3,4‐dihydropyrrol‐2‐one derivatives by the reaction of amidines with α, β‐unsaturated carbonyl compounds

N‐t‐Butylacetamidines 1 on heating with methyl vinyl ketone, acrolein or crotonaldehyde gave the 2,3‐dihydropyridine derivatives 4,5 or 6 via N‐alkylation of the acetamidines 1 . Reaction of amidines 1 with phenyl 1‐propenyl ketone, benzalacetone or chalcone gave 3,4‐dihydropyridine derivatives 8, 9 or 10 . These were obtained by C‐alkylation, achieved by Michael addition of the acetamidines 1 as their N,C‐tautomers ene‐1,1‐diamines 1 ′ to α,β‐unsaturated carbonyl compounds, and subsequent cyclodehydration of adducts. Reaction of 1 with ethyl 3‐benzoylacrylate gave 3,4‐dihydropyrrol‐2‐one derivatives 13 .     

Synthesis of Heterocyclic Compounds Using Amidines as Their Ene-1,1-diamine Tautomers,IV: Synthesis of N-Bridged Heterocycles 1,2,3,4-Tetrahydropyrido[1,2-a]pyrimidin-6-ones and Methyl 1,2,3,4-Tetrahydropyrrolo[1,2-a]pyrimidin-7-ylideneacetates

2-Benzyl-1,4,5,6-tetrahydropyrimidines 1 (as ene-1,1-diamine N,C-tautomers) in diglyme reacted with ethyl benzoylacetate at 160 °C in an oil bath to give 1,2,3,4-tetrahydropyrido[1,2-a]pyrimidin-6-ones 3 and with dimethyl acetylenedicarboxylate in methanol at room temperature, leading to methyl 1,2,3,4-tetrahydropyrrolo[1,2-a]pyrimidin-7-ylideneacetates 5, respectively.