Tight binding models accurately predict band structures for copolymer semiconductors

2020 ◽  
Vol 22 (35) ◽  
pp. 19659-19671 ◽  
Author(s):  
Prithvi Tipirneni ◽  
Vishal Jindal ◽  
Michael J. Janik ◽  
Scott T. Milner
Keyword(s):  
Conjugated Polymers ◽  
Organic Photovoltaics ◽  
Tight Binding ◽  
Band Gaps ◽  
Active Materials ◽  
Band Structures ◽  
Wide Range ◽  
Binding Models

Conjugated polymers possess a wide range of desirable properties including accessible band gaps, plasticity, tunability, mechanical flexibility and synthetic versatility, making them attractive as active materials in organic photovoltaics (OPVs).

Band Structures of Carbon Nanotubes with Nanoscale Periodic Pores Depending on their Circumferences

2003 ◽  
Vol 02 (01n02) ◽  
pp. 109-116
Author(s):  
Hiroyuki Takeda ◽  
Katsumi Yoshino
Keyword(s):  
Carbon Nanotubes ◽  
Tight Binding ◽  
Band Gaps ◽  
Band Structures ◽  
Electronic Band ◽  
Tight Binding Approximation ◽  
One Dimensional ◽  
Flat Bands ◽  
Porous Graphite ◽  
Electronic Band Structures

We theoretically evaluate the electronic band structures in carbon nanotubes with nanoscale periodic pores with a tight-binding approximation of π electrons, and demonstrate that band gaps of the carbon nanotubes with nanoscale periodic pores differ significantly from those of conventional carbon nanotubes. The band gaps of the carbon nanotubes with nanoscale periodic pores depend strongly on the size of pores and inter-pore distances. In some carbon nanotubes with nanoscale periodic pores, band gaps are constant as a function of their circumferences. In other ones, band gaps have the exact periodicity of three as a function of their circumferences. Those behaviors can be explained by taking properties of nanoscale periodic porous graphite into consideration. In some carbon nanotubes with relatively large nanoscale periodic pores, flat bands appear, which may cause singular properties about magnetism in one-dimensional porous carbon nanotubes.

scholarly journals Sensors and sensor arrays based on conjugated polymers and carbon nanotubes

2002 ◽  
Vol 74 (9) ◽  
pp. 1753-1772 ◽  
Author(s):  
Liming Dai ◽  
Prabhu Soundarrajan ◽  
Taehyung Kim
Keyword(s):  
Carbon Nanotubes ◽  
Conjugated Polymers ◽  
Excited States ◽  
Sensor Arrays ◽  
Glucose Sensors ◽  
Mechanical And Thermal Properties ◽  
Active Materials ◽  
Wide Range ◽  
Pros And Cons ◽  
Potential Use

The need for cheaper, faster, and more accurate measurements has been a driving force for the development of new sensing devices. As is well known, the electrical conductivity of conjugated polymers can be reliably regulated over a wide range through interactions with electron acceptors and donors. This, together with the fast optical dynamics (either in the ground or excited states) of most conjugated polymers, has made conjugated polymers very attractive as transducer-active materials. On the other hand, the unusual electronic, mechanical, and thermal properties of carbon nanotubes have also led to their potential use in a wide range of devices, including sensors. In particular, the ability of carbon nanotubes and their derivatives to operate as gas and glucose sensors has been recently demonstrated. This article provides a status review on the research and development of sensors and sensor arrays based on conjugated polymers and carbon nanotubes. The unique features characteristic of most reported sensing transduction modes related to conjugated polymers and carbon nanotubes are discussed, along with their pros and cons.

scholarly journals Dynamical transitions in aperiodically kicked tight-binding models

2021 ◽  
Vol 103 (13) ◽  
Author(s):  
Vikram Ravindranath ◽  
M. S. Santhanam
Keyword(s):  
Tight Binding ◽  
Binding Models

Beyond two-center tight binding: Models for Mg and Zr

2020 ◽  
Vol 4 (11) ◽  
Author(s):  
R. M. Fogarty ◽  
J. Smutna ◽  
M. R. Wenman ◽  
A. P. Horsfield
Keyword(s):  
Tight Binding ◽  
Binding Models

scholarly journals The Band-Gap Studies of Short-Period CdO/MgO Superlattices

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Ewa Przeździecka ◽  
P. Strąk ◽  
A. Wierzbicka ◽  
A. Adhikari ◽  
A. Lysak ◽  
...  
Keyword(s):  
Band Gap ◽  
Layer Thickness ◽  
Energy Gap ◽  
Band Gaps ◽  
Short Period ◽  
Wide Range ◽  
Salt Structure ◽  
Short Period Superlattices ◽  
Direct Band ◽  
Sublayer Thickness

AbstractTrends in the behavior of band gaps in short-period superlattices (SLs) composed of CdO and MgO layers were analyzed experimentally and theoretically for several thicknesses of CdO sublayers. The optical properties of the SLs were investigated by means of transmittance measurements at room temperature in the wavelength range 200–700 nm. The direct band gap of {CdO/MgO} SLs were tuned from 2.6 to 6 eV by varying the thickness of CdO from 1 to 12 monolayers while maintaining the same MgO layer thickness of 4 monolayers. Obtained values of direct and indirect band gaps are higher than those theoretically calculated by an ab initio method, but follow the same trend. X-ray measurements confirmed the presence of a rock salt structure in the SLs. Two oriented structures (111 and 100) grown on c- and r-oriented sapphire substrates were obtained. The measured lattice parameters increase with CdO layer thickness, and the experimental data are in agreement with the calculated results. This new kind of SL structure may be suitable for use in visible, UV and deep UV optoelectronics, especially because the energy gap can be precisely controlled over a wide range by modulating the sublayer thickness in the superlattices.

scholarly journals Topological reduction of tight-binding models on branched networks

2002 ◽  
Vol 65 (5) ◽  
Author(s):  
P. Buonsante ◽  
R. Burioni ◽  
D. Cassi
Keyword(s):  
Tight Binding ◽  
Binding Models

scholarly journals METAL–INSULATOR TRANSITIONS IN TETRAHEDRAL SEMICONDUCTORS UNDER LATTICE CHANGE

2004 ◽  
Vol 18 (07) ◽  
pp. 975-988
Author(s):  
SHAILESH SHUKLA ◽  
DEEPAK KUMAR ◽  
NITYA NATH SHUKLA ◽  
RAJENDRA PRASAD
Keyword(s):  
Dielectric Constant ◽  
Fermi Surface ◽  
Lattice Constant ◽  
Critical Behavior ◽  
Tight Binding ◽  
Metal Insulator ◽  
Wide Range ◽  
Insulating Phase ◽  
Tetrahedral Semiconductors ◽  
Lattice Compression

Although most insulators are expected to undergo insulator to metal transition on lattice compression, tetrahedral semiconductors Si, GaAs and InSb can become metallic on compression as well as by expansion. We focus on the transition by expansion which is rather peculiar; in all cases the direct gap at Γ point closes on expansion and thereafter a zero-gap state persists over a wide range of lattice constant. The solids become metallic at an expansion of 13% to 15% when an electron Fermi surface around L-point and a hole Fermi surface at Γ-point develop. We provide an understanding of this behavior in terms of arguments based on symmetry and simple tight-binding considerations. We also report results on the critical behavior of conductivity in the metal phase and the static dielectric constant in the insulating phase and find common behavior. We consider the possibility of excitonic phases and distortions which might intervene between insulating and metallic phases.

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