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Engineering of Conductive Polymer Using Simple Chemical Treatment in Silicon Nanowire-Based Hybrid Solar Cells
Published in Ming-Fa Lin, Wen-Dung Hsu, Jow-Lay Huang, Lithium-Ion Batteries and Solar Cells, 2021
Po-Hsuan Hsiao, Ilham Ramadhan Putra, Chia-Yun Chen
A further approach based on the identification of PEDOT chain conformational changes before and after EG treatment was obtained by Raman spectroscopy. As-prepared PEDOT:PSS was proclaimed consisting of intermediate structures, there are benzoid and quinoid structures in its PEDOT segments as aforecited above. The resonant structure of benzoid, which is confirming the coiled structure, will change to the quinoid arrangement as the linear or expanded coiled structure results in the conductivity enhancement mechanism. The changes of this conformational arrangement can be observed by the changes of molecules and chemical structural alteration validated by peak shifting of the spectra. The same study also revealed that the conformational change corresponds to the delocalization process of polaron to bipolaron charges over several units in PEDOT chains recognized by the electron spin resonance (ESR). A polaron is conformed as a positive charge on a unit, and a bipolaron is two positive charges delocalized over several units later; both mechanisms are known to enhance the conductivity of pristine PEDOT:PSS [28].
Competing interactions in unconventional superconductors
Published in A. S. Alexandrov, Theory of Superconductivity From Weak to Strong Coupling, 2003
Consideration of particular lattice structures shows that small inter-site bipolarons are perfectly mobile even when the electron–phonon coupling is strong and the bipolaron binding energy is large (section 4.6). Let us analyse the important case of copper-based high-Tc oxides. They are doped charged-transfer ionic insulators with narrow electron bands. Therefore, the interaction between holes can be analysed using computer simulation techniques based on a minimization of the ground-state energy of an ionic insulator with two holes, the lattice deformations and the Coulomb repulsion fully taken into account but neglecting the kinetic energy terms.
Introduction to Organic Spintronic Materials and Devices
Published in Sam-Shajing Sun, Larry R. Dalton, Introduction to Organic Electronic and Optoelectronic Materials and Devices, 2016
Bobbert et al.109 consider the effect of magnetic field on the hopping probability of a polaron from a localized state at site α to another nearest localized state at site β, which is already occupied by a like- charge polaron (Figure 30.24). In the previous section, we pointed out that oppositely charged polarons can form excitons and eventually may recombine to emit light. However, two like-charge polarons can form a bipolaron, a state where the correlation energy between the pair and the lattice deformation lowers the formation energy. The on-site charge exchange interaction requires that the bipolaron is a spin singlet. The bipolaron formation will be “spin-blocked” if two polarons have the same spin component along the common quantization axis. In addition, these polarons are exposed to a local hyperfine field produced by the adjacent nuclear spins, which can be treated as a randomly oriented classical field Bhf, The total field at a site α is then Btotal;α = B + Bhf;α, where B is the applied magnetic field (Figure 30.24). The hopping therefore occurs between energy eigenstates corresponding to the local total magnetic field directions at the two sites where the spin precession frequency is supposed to be larger than the hopping frequency. The singlet probability is now given by () P=14−1ℏ2Sα.Sβ
Synthesis of conducting water-dispersible polyaniline particles and its template-guided patterning
Published in Journal of Dispersion Science and Technology, 2022
Gopala Ram Bhadu, Jayesh C. Chaudhari, Divesh N. Srivastava
UV-Vis-NIR absorption analysis has been carried out for PANI-DBSA dispersion in water to establish the presence of PANI in the dispersion. The spectra shown in Figure 2B have been recorded over the wavelength range of 250 to 800 nm. The recorded absorption spectra show the presence of three bands in the region of 300-350 nm, 425-460 nm, and 570-750 nm. The absorption peak that appears at 350 nm is due to the excitation of the benzenoid ring (π-π* transition),[58] whereas the absorption peak at 645 nm is attributed to the quinoid ring.[59] The peaks at 450 nm and 750 nm are due to the formation of polaron/bipolaron and are the characteristic peaks of the emeraldine salt in water.[60] Therefore, FTIR and UV-Vis-NIR absorption spectra are conclusive evidence for the presence of PANI in conducting emeraldine salt form in the aqueous dispersion.
Enhanced adsorptive removal of toxic anionic dye by novel magnetic polymeric nanocomposite: optimization of process parameters
Published in Journal of Dispersion Science and Technology, 2022
Payel Das, Saimatun Nisa, Animesh Debnath, Biswajit Saha
Both MnFe2O4-PANI-NC and pure PANI comprise the polymeric structure of aniline which contains partially oxidized charge defects created during the polymerization process. Polaron and bipolaron are these two types of positive charge defects generated in the PANI structure in the polymerization process. MO dye comprises of ions in its structure and due to electrostatic force of attraction it draws attraction of the positively charged PANI. On the contrary, the intermolecular interaction like π–π dispersive interactions can happen between aromatic rings of PANI and MO dye which contributes toward the adsorption of MO dye.[34] The probable interaction mechanism is depicted in Figure 5b.
Thermoelectric materials and applications for energy harvesting power generation
Published in Science and Technology of Advanced Materials, 2018
Ioannis Petsagkourakis, Klas Tybrandt, Xavier Crispin, Isao Ohkubo, Norifusa Satoh, Takao Mori
With respect to the thermoelectric properties, an ideal conformation of the 'bipolaron network' benefits the Seebeck coefficient of the material. The Mott’s equation on thermoelectricity dictates that the Seebeck coefficient of a material is analogous to the slope of the (DOS) at the Fermi level, S ~. In a doped conducting polymer with a ‘polaron network’, the slope of the DOS at EF is close to zero and the Seebeck coefficient is expected to be small. On the contrary, for a ‘bipolaron network’, the slope of the DOS at EF is steeper and the Seebeck coefficient of the material is higher than for a polaron network. Also the crystallinity or degrees of order will have a significant impact on the DOS. With energy disorder, the DOS broadens and softens at the band edge; as a consequence, the slope of the DOS at EF decreases and the Seebeck coefficient for disordered material is low. This is why the Seebeck coefficient in conducting polymers (typically amorphous or para-crystalline) is lower than crystalline inorganic semiconductors. Consequently, proper and detailed material design is needed in order to achieve high performance thermoelectric materials [12,21,22].