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131.
二维介质型光子晶体的直线法分析 总被引:1,自引:0,他引:1
运用直线法对二维介质型光子晶体的能带结构进行分析,给出直线法中关于二维介质型光子晶体的本征方程的建立过程.同时,对不同参数的光子晶体进行计算,计算结果通过时域有限差分算法(FDTD)及已发表的数据得到了验证,并考虑不同结构的光子晶体的TE波与TM波的带隙形成情况,可为二维介质型光子晶体的设计提供参考. 相似文献
132.
Gap Functions for Equilibrium Problems 总被引:1,自引:0,他引:1
G. Mastroeni 《Journal of Global Optimization》2003,27(4):411-426
The theory of gap functions, developed in the literature for variational inequalities, is extended to a general equilibrium problem. Descent methods, with exact an inexact line-search rules, are proposed. It is shown that these methods are a generalization of the gap function algorithms for variational inequalities and optimization problems. 相似文献
133.
134.
We investigate the characteristics of Cu2O thin films deposited through the addition of N2 gas. The addition of N2 gas has remarkable effects on the phase changes, resulting in improved electrical and optical properties. An intermediate phase (6CuO·Cu2O) appears at a N2 flow rate of 1 sccm, and a Cu2O (200) phase is then preferentially grown at a higher feeding amount of N2. The optical and electrical properties of Cu2O thin films are improved with a sufficient N2 flow rate of more than 15 sccm, as confirmed through various analyses. Under this condition, a high bandgap energy of 2.58 eV and a conductivity of 1.5×10?2 S/cm are obtained. These high‐quality Cu2O thin films are expected to be applied to Cu2O‐based heterojunction solar cells and optical functional films. 相似文献
135.
A theoretical model is summarized into the shorter vector principle. It is used to predict the topological structure of wave function and the oscillation rule of energy gap in various types of finite carbon nanotubes (CNTs). The theoretical model indicates that the characteristics of the electronic states only depend on the nanotube size and its symmetry along the shorter vector direction. In this direction, the wave functions of the original 3m (or 3m/2) periodicity are also suitable for armchair, chiral and zigzag finite CNTs with the C2 (Cs), C1 and Cn point groups, respectively. Energy gaps present the oscillation with 3m (or 3m/2) or odd-even n. The first principle calculations for some prototype systems are performed. The results are consistent with the theoretical model. 相似文献
136.
The development of organic light emitting diodes (OLEDs) based on fluorescent materials has made a great progress in improving light emitting efficiency and full range colors. But it still encounters the low singlet excitons generation ratio of 25% in device. As a solution to this problem, thermally activated delayed fluorescent (TADF) materials can convert the triplet excitons to the singlet ones, thus achieve theoretically 100% exciton utilization efficiency. Up to now, the small TADF molecules have achieved great breakthrough in realizing high external quantum efficiency and full color range including blue, green, and red. While the OLED devices based on macromolecules possess the inherent advantages of simplicity and lower cost in the rapid deposition of large areas at room temperature, especially on large flexible substrates, it is still relatively difficult to realize TADF effect in macromolecules, although several reports have partially confirmed them promising candidates for practical applications. This review summarizes the recent progress in the field of TADF polymers and their device performances in OLEDs, and also gives some outlooks for the further exploration in this field at the end of this paper. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 575–584 相似文献
137.
Diketo-pyrrolo-pyrrole (DPP) is an important electron-deficient unit, and the alkylation of DPP can gives rise to good solubility of organic and polymer semiconductors in solvent. In this paper, we report our observations on the isomers of dialkyl DPP. The alkylation of DPP can take place on both the nitrogen and oxygen atoms, leading to the formation of three isomers. The presence of the isomers is evidenced by the nuclear magnetic resonance (NMR) and mass spectra. The yields of the isomers are affected by the experimental conditions, including the reaction temperature, reaction time and solvent. The isomers have different electronic structures and optical properties as revealed by the UV–Vis absorption spectroscopy, fluorescent spectroscopy, cyclic voltammetry and theoretical simulation using Gaussian 03 program with B3LYP/6-31G(d). Small molecules based on the DPP isomers with dialkylation at different sites were synthesized and investigated as donor materials of organic solar cells (OSCs). The photovoltaic performances of OSCs are consistent with the electronic structures of the DPP isomers. 相似文献
138.
We have made in-depth studies to revisit time-restricted layer-by-layer (LbL) electrostatic assembly process of a couple of organic molecules. The studies have been made in relation to electronic states of metal phthalocyanines. We show that by shortening dipping time for adsorption of the active molecules, mass adsorbed in each monolayer can be decreased and hence intermolecular spacing between the molecules can be increased. We have characterized the (sub)monolayers deposited on an electrode with scanning tunneling microscope tip to record tunneling current through the molecules. Results show that the highest occupied molecular orbitals and lowest unoccupied molecular orbitals, and also the difference between the orbitals, that is, the transport gap of the molecules in a (sub)monolayer depends on the dipping time of LbL assembly or molecule-to-molecule separation. We show that interactions between molecules in a monolayer decrease the transport gap of the metal phthalocyanines. 相似文献
139.
In this paper, we have studied two-dimensional function photonic crystals, in which the dielectric constants of medium columns are the functions of space coordinates , that can become true easily by electro-optical effect and optical kerr effect. We calculated the band gap structures of TE and TM waves, and found the TE (TM) wave band gaps of function photonic crystals are wider (narrower) than the conventional photonic crystals. For the two-dimensional function photonic crystals, when the dielectric constant functions change, the band gaps numbers, width and position should be changed, and the band gap structures of two-dimensional function photonic crystals can be adjusted flexibly, the needed band gap structures can be designed by the two-dimensional function photonic crystals, and it can be of help to design optical devices. 相似文献
140.
In this paper we study the Riesz transform on complete and connected Riemannian manifolds M with a certain spectral gap in the L2 spectrum of the Laplacian. We show that on such manifolds the Riesz transform is Lp bounded for all p∈(1,∞). This generalizes a result by Mandouvalos and Marias and extends a result by Auscher, Coulhon, Duong, and Hofmann to the case where zero is an isolated point of the L2 spectrum of the Laplacian. 相似文献