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.

An investigation of the electronic properties of

Abstract: A study of the electronic properties of a polythiophene (poly(4,4 0 -dipentoxy-2,2 0 -bithiophene) as functions of the positive doping level has been carried out. The oxidative cyclic voltammogram and the electron spin resonance (ESR) spectrum show the consecutive formation of polaron and bipolaron states on increasing the doping level of the polymer. From the optical spectra it was found that the - band undergoes a blue shift with the doping. The Fermi level of the polymer was derived from the diffusion potential of the heterojunction between n-doped silicon and poly(4,4 0 -dipentoxy-2,2 0 -bithiophene). As expected for p-type inorganic semiconductors, the Fermi level was found to be pushed towards the valence band by increasing the doping level. The trend of the experimental Fermi level is in good agreement with the one calculated for a p-type semiconductor with the same doping level and bandgap as those of poly(4,4 0 -dipentoxy-2,2 0 -bithiophene).

Behavior of electroluminescent polymers with extra electron and hole under additional fields

Abstract: Much attention has been focused on the electroluminescence (EL) of polymers since the EL in polymers [1] was discovered by Cambridge University in the UK in 1990. Today the EL study of polymers has become one of the frontier subjects in the world. Being different from conventional inorganic semiconductors, the polymer is a quasi-one-dimensional system [2] and has the characteristic of low-dimensional instability. The extra electron and hole will induce the variations of both lattice structures and electronic states in low-dimensional system, leading to the bipolaron excitons [3, 4]. Recently Kersting et al. [5] and Tasch et al. [6] have observed experimentally the electric-field-induced photoluminescence (PL) quenching in electroluminescent conjugated polymers. In order to understand the PL and other optical phenomena of polymers under additional electric fields, we study the behavior of electroluminescent polymers with extra electron and hole under additional fields by the real-time dynamical methodology. Our results are compared with the relevant polymer experiments [5–7]. Electroluminescent polymers consist of carbonhydrogen atoms groups. By simplifying a carbonhydrogen atom’s group as a lattice point, we can regard an electroluminescent conjugated polymer as a finite chain of N lattice points. The electronic H of the system under an additional field will be

Efficient radical cation stabilization of PANI-ZnO and PANI-ZnO-GO composites and its optical activity

Abstract: Polyaniline (PANI) and its composites PANI-ZnO (Zinc oxide) and PANI-ZnO-GO (Graphene oxide) were successfully constructed. These materials were characterized by electron spin resonance (ESR) technique and ultraviolet visible spectrometry. The parameters such as line width, g-factor and spin concentration were deduced from ESR spectra, from the results the radical cation stabilization of PANI, PANI-ZnO and PANI-ZnO-GO composites were compared by the polaron and bipolaron formation. The absorption features obtained in the UV absorption spectra reveal the band gap of these modified PANI composites and also predicted the information of increasing and decreasing features of signal intensity and spin concentration.

Holstein dimer in many-body perturbation theory I: from polarons to bipolarons by symmetry-breaking

Abstract: strong whereas at smaller interactions only a single solution is found. The additional solutions at larger electron-phonon couplings correspond to symmetry-broken states with inhomogeneous electron densities. A comparison to exact results indicates that this symmetry breaking is strongly correlated with the formation of a bipolaron state in which the two electrons prefer to reside on the same molecule. The results further show that the Hartree and partially self-consistent Born solutions obtained by enforcing symmetry do not compare well with exact energetics, while the fully self-consistent Born approximation gives qualitatively correct behavior in the same symmetric case. This together with a presented natural occupation number analysis supports the conclusion that the fully self-consistent approximation does describe a bipolaron.