scispace - formally typeset
Search or ask a question
Topic

Bipolaron

About: Bipolaron is a research topic. Over the lifetime, 1335 publications have been published within this topic receiving 29154 citations. The topic is also known as: bipolarons.


Papers
More filters
Book ChapterDOI
01 Jan 2009
TL;DR: In this paper, an experiment has been made in order to study the impact of SWNTs in in-situ chemically polymerized PANi-SWNTs composites, where the SWNT surface plays a role of nucleation sites for PANi growth.
Abstract: An experiment has been made in order to study the impact of SWNTs in in-situ chemically polymerized PANi-SWNTs composites It is found that the SWNTs surface plays a role of nucleation sites for PANi growth The presence of SWNTs enhances the degree of polymerization and increase the conductivity (polaron or bipolaron lattice) of PANi When radiated by a near-infrared laser (1064 nm) the dried materials emit strong fluorescent bands in mid-infrared region which are assumed to be the transitions from the π-orbital (highest occupied molecular orbital) to polaron and bipolaron lower levels The bands are speculated to arise from charge transfer interactions between the PANi and SWNTs, which brings new polaron and bipolaron levels into the band gap of PANi The PANi-SWNTs also exhibits an improvement in NH3 gas sensing characterization in comparison to neat SWNTs and PANi The results are interpreted as a modification in the chemical and electronic structure of PANi

2 citations

Journal ArticleDOI
TL;DR: In this paper , the potential of pair interaction for the singlet states of polarons was carried out in the region intermediate coupling, and the variational functions have been selected in the form of a multiparameter system of Gaussian functions with exponentially correlated multipliers.
Abstract: Abstract Polarons and bipolarons in two-dimensional (2 D) crystals with a simple conduction band are considered in the work. A study of the potential of pair interaction for the singlet states of polarons was carried out in the region intermediate coupling. The effective functional of exchange-coupled pair of polarons was obtained by the Buimistrov-Pekar method. Variational calculations of the singlet states energies were carried out taking into account the direct dependence of the wave function of the system on the interelectron distance. The variational functions have been selected in the form of a multiparameter system of Gaussian functions with exponentially correlated multipliers. The region of existence of a two-dimensional bipolaron was determined as a function of the crystal parameters. It has been shown that a single-center configuration (a configuration similar to a two-dimensional helium atom) is stable. The minimum corresponding to the two-center configuration (“polaron molecule”) is secondary extremum that disappears when the electronic correlations associated with the direct dependence of the wave function of the system on the distance between electrons are taken into account. The main energy minimum corresponds to single-center configuration. The study of the fulfillment of the virial theorem for polaron and bipolaron functionals was carried out. The results of variational calculations were compared with the calculations performed by other authors. Two-center configuration of a 2D bipolaron is unstable. The only minimum corresponds to a one-center 2D bipolaron. Exchange energy of two 2D polarons is antiferromagnetic.

2 citations

Posted Content
TL;DR: In this article, the authors derived the Nernst coefficient and the Thermoelectric power for the cuprates in the bipolaronic model and showed an interesting interference term due to the triplet and singlet bipolaron and polaron current flow.
Abstract: An understanding of high temperature superconductivity clearly requires the nature of its normal state, however the normal state of the cuprates is poorly understood. One possible explanation is the bipolaronic model where mobile, heavily phonon-dressed holes (polarons) are paired in real space. The ground state is made up of intersite singlet bipolarons where excitations can be made to triplet bipolaron and polaron bands. Based on this model I derive the Nernst coefficient and the Thermoelectric power for the cuprates. The Nernst coefficient shows an interesting interference term due to the triplet and singlet bipolaron and polaron current flow. The interference remains even when the scattering rate is independent of energy.

2 citations

Journal ArticleDOI
TL;DR: The structural and spectroscopic properties of the three possible regioisomers generated from the σ-dimerisation of 3′-styryl substituted terthiophene have been investigated theoretically using density functional theory calculations as mentioned in this paper.
Abstract: The structural and spectroscopic properties of the three possible regioisomers generated from the σ-dimerisation of 3′-styryl substituted terthiophene have been investigated theoretically using density functional theory calculations. The calculated geometries on the neutral species show that the thiophene chain is only slightly altered between isomers, however upon oxidation to the polaron or bipolaron species the bonding in the thiophene chain is sensitive to the regioisomerisation. The structural distortion caused by the polaron is confined between the substituents in the case of the HH isomer (where the substituents point towards the σ-link); this is not the case for the other two regioisomers. The calculated Raman spectra of the neutral species are similar for the three isomers, however, distinct spectral differences are predicted when the isomers are oxidised. For both the neutral and oxidised species the correlation of experimental and calculated spectra is superior for the HH isomer.

2 citations

Book ChapterDOI
01 Jan 1990
TL;DR: In this paper, a new model for PANi is proposed and the structure of the chromophore giving rise to PANi absorption at ca. 3eV is consistent with a simple p-di-substituted phenylene moiety, whereas that of the absorption at 1.6 eV is inconsistent with a mixed benizonoid/quinoid radical (eg. a semiquinone moiety).
Abstract: Thin films of polyaniline (PANi) prepared electrochemically can readily be investigated insitu. In this way, both the oxidation state and level of protonation can be precisely controlled. Insitu UV/VIS/NIR and Resonance Raman spectra are presented here. These results show that the usual polaron/bipolaron models applied to other conducting polymers are not consistent in the case of PANi. The structures of the chromaphores associated with the observed ‘dopant’ induced optical absorptions in PANi are quite different, which is inconsistent with polaron theory. Resonance Raman spectra show that the structure of the chromophore giving rise to absorption at ca. 3eV is that of a simple p-di-substituted phenylene moiety, whereas that of the absorption at ca. 1.6 eV is consistent with a mixed benizonoid/quinoid radical (eg. a semiquinone moiety). In both cases the chromophores are localised. Therefore a new model for PANi is proposed.

2 citations


Network Information
Related Topics (5)
Band gap
86.8K papers, 2.2M citations
87% related
Magnetization
107.8K papers, 1.9M citations
86% related
Quantum dot
76.7K papers, 1.9M citations
85% related
Electron
111.1K papers, 2.1M citations
83% related
Amorphous solid
117K papers, 2.2M citations
83% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202316
202229
202127
202023
201920
201833