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.
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TL;DR: In this article, double holes in anatase TiO${}_{2}$ prefer binding with each other, to form an O-O dimer after large structural distortion, which pushes the hole states upward into the conduction band and traps the holes.
Abstract: Rather than being free carriers or separated single-hole polarons, double holes in anatase TiO${}_{2}$ prefer binding with each other, to form an O-O dimer after large structural distortion. This pushes the hole states upward into the conduction band and traps the holes. Similar double-hole-induced O-O dimerization (a bipolaron) exists also in other transition metal oxides (TMOs) such as V${}_{2}$O${}_{5}$ and MoO${}_{3}$, which have the highest valence bands composed mainly of O 2p states, loose lattices, and short O-O distances. Since the dimerization can happen in impurity-free TMO lattices, independent of any extrinsic dopant, it acts as an intrinsic and general limit to the p-type conductivity in these TMOs.
27 citations
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TL;DR: A new mechanism for the formation of doped polyaniline is presented, which allows for the rationalization of the experimentally observed equilibrium between polaron and bipolaron defects in emeraldine salt.
Abstract: A new mechanism for the formation of doped polyaniline is presented. Besides providing suitable structural and spectroscopic parameters, the new mechanism allows for the rationalization of the experimentally observed equilibrium between polaron and bipolaron defects in emeraldine salt. The magnetic behavior and the “metallic island” model for conduction in doped polyaniline are also theoretically supported by the new proposal.
27 citations
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30 May 1985-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: In this paper, a series of experiments demonstrate that solitons are the important excitations in trans-(CH) x and that the properties of these nonlinear excitations can be directly studied during photoexcitation or after doping.
Abstract: The results of a series of experiments demonstrate that solitons are the important excitations in trans -(CH) x and that the properties of these nonlinear excitations can be directly studied during photoexcitation or after doping. The importance of these concepts in the more general context of conducting polymers is addressed. Although the twofold degenerate ground state of trans -(CH) x is quite special, the relevant concepts have been generalized to confined soliton pairs (bipolarons). Experimental results that demonstrate electron-hole symmetry and weak confinement in polythiophene make this polyheterocycle a nearly ideal example of a model system in which the ground-state degeneracy has been lifted. In the dilute doping regime, in situ absorption spectroscopy data (during electrochemical doping) strongly suggest charge storage via bipolarons with confinement parameter γ ≈ 0.1–0.2. These results on polythiophene demonstrate that a quantitative fundamental understanding is possible even for relatively complex systems.
26 citations
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TL;DR: In this article, the one-dimensional spectral function of the Holstein-Hubbard bipolaron in one dimension was studied using cluster perturbation theory together with the Lanczos method, which allows one to calculate the spectrum at continuous wave vectors and thereby to investigate the dispersion and the spectral weight of quasiparticle features.
Abstract: The one-electron spectral function of the Holstein-Hubbard bipolaron in one dimension is studied using cluster perturbation theory together with the Lanczos method. In contrast to other approaches, this allows one to calculate the spectrum at continuous wave vectors and thereby to investigate the dispersion and the spectral weight of quasiparticle features. The formation of polarons and bipolarons, and their manifestation in the spectral properties of the system, is studied for the cases of intermediate and large phonon frequencies, with and without Coulomb repulsion. A good agreement is found with the most accurate calculations of the bipolaron band dispersion available. Pronounced deviations of the bipolaron band structure from a simple tight-binding band are observed, which can be attributed to next-nearest-neighbor hopping processes.
26 citations
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TL;DR: In this paper, a structural, optical and dielectric studies on micro-crystals of Oxypeucedanin (C16H14O5) isolated from the roots of plant Prangos pabularia (Mir et al. 2014) were carried out, and the obtained trend in frequency exponent with frequency (ω) indicates that the universal dynamic response is followed by this compound.
Abstract: Recently, we carried out structural, optical and dielectric studies on micro-crystals of Oxypeucedanin (C16H14O5), isolated from the roots of plant Prangos pabularia (Mir et al. (2014) [3,4]). The obtained trend in frequency exponent (s) with frequency (ω) indicates that the universal dynamic response is followed by this compound. From optical absorption spectroscopy, the optical band gap (Eg) was estimated around 3.76 eV and system is showing indirect allowed transition. Using Eg in certain relation of s, a close value of s (as much close obtained by fitting ac conductivity) was obtained. This method was further used for other similar systems and again same trend was obtained. So a general conclusion was made that the high transmitting wide band insulators or semiconductors may follow bipolaron hopping transport mechanism.
26 citations