Rate-determining process in MISIM photocells for optoelectronic conversion using photo-induced pure polarization current without carrier transfer across interfaces

Recently, we proposed a [metal|insulator|semiconductor|insulator|metal] (MISIM) photocell, as a novel architecture for high-speed organic photodetectors. The electric polarization in the S layer, induced by modulated light illumination, propagates into the outside circuit as a polarization current through the I layers, without any carrier transfer across the interfaces. In the present work, we examined the MISIM photocells consisting of zinc-phthalocyanine(ZnPc)-C60 bilayers for the S layer and Parylene C for the two I layers, to understand the fundamental aspects of the MISIM photocells, such as current polarity and modulation-frequency dependence. It was found that, in such devices, the current polarity was primarily determined by the polarization in the S layer, which was induced by the donor–acceptor charge-transfer upon illumination. Furthermore, the ON and OFF current, which appeared in the periods of illumination-on and -off, respectively, exhibited significantly different dependence on the modulation frequency. This was well-explained by an imbalance between a quick polarization in the S layer during illumination and its slow relaxation in the dark

Fluorination induced electronic effects on Pt(II) square-planar complex of o-phenylenediimine ligand

A novel complex [Pt(C6F4(NH)2)2] (2), formed by a Pt(ii) cation bound to two molecules of the tetrafluorinated 1,2-phenylenediimine ligand, has been synthesized and characterized by electrochemical and XRD measurements, UV-vis-NIR spectroscopy as well as by DFT and TD-DFT calculations. The effect induced by the fluorine atoms has been highlighted by comparison with the corresponding Ni (1H) and Pt (2H) hydrogenated complexes. The cyclic voltammetry data show that the reduction and the oxidation processes of 2 are easier and more difficult (by about 0.5 V), respectively, compared to those of 1H and 2H, suggesting that the electron withdrawing ability of the fluorine atoms lowers the energy level of both the HOMO and the LUMO. UV-vis-NIR measurements are similar for all the three complexes, indicating similar HOMO-LUMO gaps and that the effects of fluorination on the frontier orbitals are roughly the same. Moreover, polymorphism in the powder form of 2 has been highlighted by XRD measurements while the film presents only one phase. Furthermore, this complex shows a field-effect for n-type carriers. All the experimental results are also supported by the calculations, which show the role played by the fluorine atoms in the electronic structure of 2

Analyses of integrated EPID images for on-treatment quality assurance to account for interfractional variations in volumetric modulated arc therapy

Purpose: To investigate the effects of interfractional variation, such as anatomical changes and setup errors, on dose delivery during treatment for prostate cancer (PC) and head and neck cancer (HNC) by courses of volumetric modulated arc therapy (VMAT) aided by on‐treatment electronic portal imaging device (EPID) images. Methods: Seven patients with PC and 20 patients with HNC who had received VMAT participated in this study. After obtaining photon fluence at the position of the EPID for each treatment arc from on‐treatment integrated EPID images, we calculated the differences between the fluence for the first fraction and each subsequent fraction for each arc. The passing rates were investigated based on a tolerance level of 3% of the maximum fluence during the treatment courses and the correlations between the passing rates and anatomical changes. Results: In PC, the median and lowest passing rates were 99.8% and 95.2%, respectively. No correlations between passing rates and interfractional variation were found. In HNC, the median passing rate of all fractions was 93.0%, and the lowest passing rate was 79.6% during the 35th fraction. Spearman’s correlation coefficients between the passing rates and changes in weight or neck volume were − 0.77 and − 0.74, respectively. Conclusions: Analyses of the on‐treatment EPID images facilitates estimates of the interfractional anatomical variation in HNC patients during VMAT and thus improves assessments of the need for re‐planning or adaptive strategies and the timing thereof

Electrochemical deposition of highly-conducting metal dithiolene films

Electrochemical deposition has been used to prepare a thin film of neutral 4′,4-(3-alkyl)-thiophene-5′,5-hydogen-nickel and copper dithiolenes (Ni–C2, Cu–C2).</p

Single-component reflecting objective for low-temperature spectroscopy in the entire visible region

A single-component reflecting objective was constructed for low-temperature spectroscopy with optimal imaging and transmission properties at all visible wavelengths. The performance of the objective immersed in superfluid helium at a temperature of 1.5 K was tested by comparing dark-field images of uncolored polymer beads taken at wavelengths of 400 and 800 nm. Under conditions optimized for imaging at both wavelengths, the size of the image i

Noticias

The <i>K</i>₄ structure was theoretically predicted for trivalent chemical species, such as sp² carbon. However, since attempts to synthesize the <i>K</i>₄ carbon have not succeeded, this allotrope has been regarded as a crystal form that might not exist in nature. In the present work, we carried out electrochemical crystallization of the radical anion salts of a triangular molecule, naphthalene diimide (NDI)-Δ, using various electrolytes. X-ray crystal analysis of the obtained crystals revealed the <i>K</i>₄ structure, which was formed by the unique intermolecular π overlap directed toward three directions from the triangular-shape NDI-Δ radical anions. Electron paramagnetic resonance and static magnetic measurements confirmed the radical anion state of NDI-Δ and indicated an antiferromagnetic intermolecular interaction with the Weiss constant of θ = −10 K. The band structure calculation suggested characteristic features of the present material, such as a metallic ground state, Dirac cones, and flat bands