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.

A one-dimensional model of superconductivity for A3C60 (A=K, Rb, Cs)

Abstract: Superconductivity is analyzed in a body-centered orthorhombic crystal structure of A 3 C 60 , where A=K, Rb, Cs and a model is proposed. The model is based on a characteristic chain of A elements that can be identified in the crystal structure and it is found that a bipolaron mechanism through these atoms, not the C 60 , is responsible for the occurrence of superconductivity. The later merely acts as the supporting skeleton. A qualitative discussion on the consequences of the model is also provided.

Interfaces between poly(9,9-dioctylfluorene) and alkali metals as affected by molecular weight and oxygen

Abstract: The electronic structure of poly(9,9-dioctylfluorene)(PFO) in different molecular weights coated with alkali metals (K and Cs) has been studied by x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). No significant differences on the electronic structures were observed for all combinations of alkali metals and PFO in different molecular weights. These metals led to low injection barrier at the K/PFO or Cs/PFO interfaces and induced bipolaron gap states in the PFO. With increasing coverage of the alkali metals, the bipolaron states and the highest-occupied molecular orbitals gradually broadened, and the two shake-up peaks of Cls XPS peaks associated with the lowest-unoccupied molecular orbitals of PFO also broadened and greatly diminished. Upon slight oxygen exposure, the two bipolaron states disappeared and the deformed features in the UPS and XPS spectra were partially recovered.

Thermodynamic and kinetic aspects of charge transfer inside conducting polymer films

Abstract: A new variant of the theory of charging processes for electroactive polymer films on electrode surfaces was recently developed for conducting polymers containing cation-radicals (polarons) of identical sizes Compared with the previously proposed models, the new approach explicitly takes into account the polaron charge delocalization over several monomer units of a polymer chain Although the obtained theoretical predictions appeared to be in a qualitative agreement with experimental results, it has not been explored earlier whether the developed approach is consistent with thermodynamic principles With that in mind, we complete the previously derived expressions for fluxes of charged quasi-particles and then treat them within the framework of the non-equilibrium thermodynamics As a result, it has been established in the limit of the quasi-reversible character of charging/discharging processes that such a treatment allows one to achieve complete accordance of these expressions with thermodynamic requirements This confirms validity of the previous predictions and, at the same time, creates premises for treating the electrochemical properties of more complicated systems than those considered in this paper In parallel to these general conclusions, we have calculated quasi-equilibrium voltammetry curves of electrodes modified with polymer films containing polaron and bipolaron charge carriers of equal sizes A primary comparison of such calculated curves with experimental ones confirms their qualitative agreement