Dielectric constant enhancement of non-fullerene acceptors via side-chain modification

2015 ◽  
Vol 51 (74) ◽  
pp. 14115-14118 ◽  
Author(s):  
Jenny E. Donaghey ◽  
Ardalan Armin ◽  
Paul L. Burn ◽  
Paul Meredith
Keyword(s):  
Dielectric Constant ◽  
Electron Acceptors ◽  
Dielectric Constants ◽  
Side Chain ◽  
Static Dielectric Constants

Substitution of alkyl solubilizing groups with short glycol chains can give non-fullerene electron acceptors with static dielectric constants of up to 9.8.

Microscopic Mechanisms for Reduced Static Dielectric Constants in Si-O-F Alloy Films

1997 ◽  
Vol 476 ◽  
Author(s):  
H. Yang ◽  
G. Lucovsky
Keyword(s):  
Dielectric Constant ◽  
Alloy System ◽  
Dielectric Constants ◽  
Force Constants ◽  
Significant Fraction ◽  
Alloy Films ◽  
Bond Stretching ◽  
Effective Charges ◽  
Static Dielectric Constants ◽  
Recent Attention

AbstractThere is considerable interest in insulators with static dielectric constants lower than SiO2; an alloy system attracting recent attention is Si-O-F. Alloying of F atoms into plasma-deposited SiO2 films leads to major changes in the SiO2 bond-stretching and -bending infrared bands accounting for a significant fraction of the reduction in the dielectric constant. These changes are explained by F induced modifications of force constants and effective charges of the neighboring Si-O-Si groups.

Chemical Bonding of Fluorine Atoms in Siof Alloys: Microscopic Mechanisms for Reductions in the Dielectric Constant Relative to SiO2

1996 ◽  
Vol 443 ◽  
Author(s):  
G. Lucovsky ◽  
H. Yang
Keyword(s):  
Molecular Structure ◽  
Dielectric Constant ◽  
Ab Initio Calculations ◽  
Infrared Absorption ◽  
Chemical Bonding ◽  
Dielectric Constants ◽  
Low Concentrations ◽  
Inductive Effects ◽  
Infrared Absorption Spectra ◽  
Static Dielectric Constants

AbstractSi-O-F alloys have static dielectric constants (εs) significantly lower than SiO2. Infrared absorption spectra provide the basis modeling the molecular structure of these alloys. Contributions of electronic and vibrational transitions to εs are discussed in terms of an empirical chemical bonding model. Ab initio calculations are then used to identify inductive effects of Si- F bonds on the properties of Si-O-Si groups that are back-bonded to the Si atom of the Si-F group. These calculations provide a theoretical framework for understanding how relatively low concentrations of F atoms produce the significant decreases in εs reported for Si-O-F alloys.

First-Principles Calculations of the Dielectric Constant for the GeO2 Films

2011 ◽  
Vol 470 ◽  
pp. 60-65 ◽  
Author(s):  
Masahiro Tamura ◽  
Jun Nakamura ◽  
Akiko Natori
Keyword(s):  
Dielectric Constant ◽  
Electric Fields ◽  
Ground State ◽  
First Principles ◽  
Rutile Phase ◽  
Dielectric Constants ◽  
Ionic Character ◽  
First Principles Calculations ◽  
External Electric Fields ◽  
Static Dielectric Constants

Dielectric properties of α-quartz and rutile-GeO2 thin-films are investigated using first-principles ground-state calculations in external electric fields. The optical and the static dielectric constants inside the films have nearly-constant values, corresponding to their bulk values, while only at the topmost surface layer the dielectric constants decrease distinctly. It has been found that the dielectric constant for the rutile-GeO2 is larger than that for the α-quartz one, which stems from the larger ionic character of the Ge-O bond for the rutile phase.

scholarly journals Comment on “investigation of dielectric constants of water in a nano-confined pore” by H. Zhu, F. Yang, Y. Zhu, A. Li, W. He, J. Huang and G. Li, RSC Adv., 2020, 10, 8628

RSC Advances ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 5179-5181
Author(s):  
Sayantan Mondal ◽  
Biman Bagchi
Keyword(s):  
Dielectric Constant ◽  
Dielectric Constants ◽  
Static Dielectric Constant ◽  
Inherent Anisotropy ◽  
Nanoconfined Water

Neglects of inherent anisotropy and distinct dielectric boundaries may lead to completely erroneous results. We demonstrate that such mistakes can give rise to gross underestimation of the static dielectric constant of cylindrically nanoconfined water.

DIELECTRIC CONSTANT AND SEEBECK COEFFICIENT FOR SEMICONDUCTORS: THERMODYNAMIC AND DFT STUDIES

2013 ◽  
Vol 12 (06) ◽  
pp. 1350057 ◽  
Author(s):  
HSIU-YA TASI ◽  
CHAOYUAN ZHU
Keyword(s):  
Boundary Condition ◽  
Dielectric Constant ◽  
Seebeck Coefficient ◽  
Gas Phase ◽  
Present Method ◽  
Dielectric Constants ◽  
Semiconductor Materials ◽  
Electronic Polarizability ◽  
Seebeck Coefficients ◽  
Good Agreement

Dielectric constants and Seebeck coefficients for semiconductor materials are studied by thermodynamic method plus ab initio quantum density functional theory (DFT). A single molecule which is formed in semiconductor material is treated in gas phase with molecular boundary condition and then electronic polarizability is directly calculated through Mulliken and atomic polar tensor (APT) density charges in the presence of the external electric field. This electronic polarizability can be converted to dielectric constant for solid material through the Clausius–Mossotti formula. Seebeck coefficient is first simulated in gas phase by thermodynamic method and then its value divided by its dielectric constant is regarded as Seebeck coefficient for solid materials. Furthermore, unit cell of semiconductor material is calculated with periodic boundary condition and its solid structure properties such as lattice constant and band gap are obtained. In this way, proper DFT function and basis set are selected to simulate electronic polarizability directly and Seebeck coefficient through chemical potential. Three semiconductor materials Mg 2 Si , β- FeSi 2 and SiGe are extensively tested by DFT method with B3LYP, BLYP and M05 functionals, and dielectric constants simulated by the present method are in good agreement with experimental values. Seebeck coefficients simulated by the present method are in reasonable good agreement with experiments and temperature dependence of Seebeck coefficients basically follows experimental results as well. The present method works much better than the conventional energy band structure theory for Seebeck coefficients of three semiconductors mentioned above. Simulation with periodic boundary condition can be generalized directly to treat with doped semiconductor in near future.

scholarly journals A note on some further determinations of the dielectric constants of organic bodies and electrolytes at very low temperatures

1898 ◽  
Vol 62 (379-387) ◽  
pp. 250-266 ◽  
Keyword(s):  
Dielectric Constant ◽  
Low Temperatures ◽  
Tuning Fork ◽  
Dielectric Constants ◽  
The Past ◽  
Method Of Measurement ◽  
The Given ◽  
Past Summer

In several previous communications we have described the investigations made by us on the dielectric constants of various frozen organic bodies and electrolytes at very low temperatures. In these researches we employed a method for the measurement of the dielectric constant which consisted in charging and discharging a condenser, having the given body as dielectric, through a galvanometer 120 times in a second by means of a tuning-fork interrupter. During the past summer we have repeated some of these determinations and used a different method of measurement and a rather higher frequency. In the experiments here described we have adopted Nernst’s method for the measurement of dielectric constants, using for this purpose the apparatus as arranged by Dr. Nernst which belongs to the Davy-Faraday Laboratory.

Static dielectric constants of the N,N-dimethylformamide/2-methoxyethanol solvent system at various temperatures

1992 ◽  
Vol 70 (12) ◽  
pp. 2895-2899 ◽  
Author(s):  
Fulvio Corradini ◽  
Luigi Marcheselli ◽  
Lorenzo Tassi ◽  
Giuseppe Tosi
Keyword(s):  
Liquid State ◽  
Specific Interaction ◽  
Solvent System ◽  
Liquid Mixtures ◽  
Dielectric Constants ◽  
Empirical Equations ◽  
Binary Liquid ◽  
Fraction Mixture ◽  
Static Dielectric Constants ◽  
Formation Of Complexes

Measurements of static dielectric constants (ε) have been made for binary liquid mixtures of N,N-dimethylformamide (DMF)/2-methoxyethanol (ME) at 19 temperatures ranging from −10 to +80 °C. Some empirical equations of the type ε = ε(T), ε = ε(X1), and ε = ε(T,X1) have been applied to check their validity. The εE values, which refer to the deviation of the dielectric constants of the binaries from the values arising from mole fraction mixture law, have been calculated. Deviations from ideal behaviour have been found to be positive at all temperatures. The positive εE values are attributed to a specific interaction between unlike molecules, which leads to the formation of complexes between DMF and ME in the liquid state. These nDMF•mME complex moieties were found to have the stoichiometric ratios 2:1, 1:1, and 1:2 in the temperature range of −10 to +80 °C.

Epitaxial Growth and Anisotropic Dielectric Properties of La-Doped Bi4Ti3O12 Thin Films

2007 ◽  
Vol 124-126 ◽  
pp. 177-180
Author(s):  
Jang Sik Lee ◽  
Q.X. Jia
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Bottom Electrode ◽  
Dielectric Constants ◽  
The Other ◽  
Field Range ◽  
Anisotropic Dielectric ◽  
Dielectric Nonlinearity ◽  
La Doped

To investigate the anisotropic dielectric properties of layer-structured bismuth-based ferroelectrics along different crystal directions, we fabricate devices along different crystal orientations using highly c-axis oriented Bi3.25La0.75Ti3O12 (BLT) thin films on (001) LaAlO3 (LAO) substrates. Experimental results have shown that the dielectric properties of the BLT films are highly anisotropic along different crystal directions. The dielectric constants (1MHz at 300 K) are 358 and 160 along [100] and [110], respectively. Dielectric nonlinearity is also detected along these crystal directions. On the other hand, a much smaller dielectric constant and no detectable dielectric nonlinearity in a field range of 0-200 kV/cm are observed for films along [001] when c-axis oriented SRO is used as the bottom electrode.

Fabrication of low dielectric constant polyimide/TiO2 nanofibers with enhanced UV-light shielding properties

2018 ◽  
Vol 31 (8) ◽  
pp. 986-995
Author(s):  
Lei Wang ◽  
Guifen Gong ◽  
Junyao Shen ◽  
Jinsong Leng
Keyword(s):  
Dielectric Constant ◽  
Light Absorption ◽  
Composite Nanofibers ◽  
Uv Light ◽  
Dielectric Constants ◽  
Low Dielectric Constant ◽  
Number Density ◽  
Tio2 Nanofibers ◽  
Low Dielectric ◽  
Mechanical Tensile

Polyimide (PI)/titanium dioxide (TiO2) composite nanofibers (NFs) with average diameters of 200–250 nm were synthesized via electrospinning. The total number density of dipoles decreased significantly, owing to the porous structures and compact interface between TiO2 NPs and PI matrix. All PI/TiO2 NFs maintain low dielectric constants and losses. For example, the dielectric constants of PI/TiO2-6% NFs are all lower than 2.6, being exposed to temperatures from 25°C to 200°C. Meantime, the dielectric losses of PI/TiO2-6% NFs are below 0.005. For ultraviolet (UV)-light shielding performance, the PI/TiO2 NFs exhibited good UV-light shielding and corresponding anti-photoaging properties. The reason can be ascribed from high UV-light absorption and scattering ability in the TiO2 NPs. The best UV-light absorption (average: 3.71) and corresponding absorption decay (15.13%) were achieved for optimized PI/TiO2-6% NFs. Other fundamental characteristics, such as the thermal stability, mechanical tensile property, and hydrophobicity, were also investigated. Such low dielectric constant PI/TiO2 composite NFs can be alternatively chosen under a longtime UV-light exposing condition.

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