Showing papers by "Anvar A. Zakhidov published in 1993"
TL;DR: In this article, the photoconductivity of poly(3-alkylthiophene) was found to be remarkably enhanced upon C 60 doping, and the decay time of photoconduction became shorter.
155 citations
TL;DR: In this paper, the magnetic properties of tetrakis(dimethylamino)ethylene (TDAE) have been studied based on the measurements of the Faraday-balance magnetization and the electron-spin resonance (ESR).
Abstract: Magnetic properties of C 60 and C 70 complexes with tetrakis(dimethylamino)ethylene (TDAE) have been studied based on the measurements of the Faraday-balance magnetization and the electron-spin resonance (ESR). It has been found that both TDAE-C 60 and TDAE-C 70 possess about one radical spin per fullerene molecule. TDAE-C 60 has been confirmed to show a ferromagnetic-type transition at T c =16.7-17.5 K. Appearance of a broad and intense ESR signal below T c for TDAE-C 60 suggests that the radical spins in the magnetically ordered state are rather localized on each C 60 molecule and are ferromagnetism at temperatures above 4.5 K
86 citations
TL;DR: In this article, the photoexcited exciton-polaron (ExP) in RO-PPV is interpreted to migrate along about 100 monomer units along a polymer main chain.
Abstract: Photoluminescence has been markedly quenched and photoconductivity has been enhanced by more than one order of magnitude upon introduction of several mol% of buckminsterfullerene (C60) to poly(2,5‐dialkoxy‐p‐phenylene vinylene) (RO‐PPV), especially at excitations about 2.2 eV, corresponding to the band gap energy of RO‐PPV and also in bands at 1.8 and 3.5 eV, which correspond to optical excitation of C60 molecules, suggesting that photo‐induced charge transfer occurs between RO‐PPV and C60. On the other hand, absorption spectrum and electrical conductivity of RO‐PPV have been scarcely influenced by doping of small amount of C60, suggesting that the ground state charge transfer between C60 and RO‐PPV is not effective, contrary to the case of poly(3‐hexylthiophene). These results are discussed by taking relative electronic energy states of RO‐PPV and C60 into consideration. The photo‐excited exciton‐polaron (Ex‐P) in RO‐PPV is interpreted to migrate along about 100 monomer units along a polymer main chain i...
65 citations
TL;DR: In this article, a poly(3-alkylthiophene)/C60 junction device is provided, and its photoresponse gives evidence of the photoinduced charge transfer between poly( 3-alkythiophenes) and C60.
Abstract: A poly(3-alkylthiophene)/C60 junction device is provided. Its photoresponse gives evidence of the photoinduced charge transfer between poly(3-alkylthiophene) and C60. The photovoltaic effect in this device is observed. The current-voltage characteristics are found to depend on the wavelength of the illumination light.
45 citations
TL;DR: In this paper, the enhancement of photoconductivity in conducting polymers upon C60 doping has been observed at the photon energies corresponding to photo-excitation in both conducting polymer and C60.
Abstract: The enhancement of photoconductivity in conducting polymers upon C60 doping has been observed at the photon energies corresponding to photo-excitation in both conducting polymer and C60. In particular, the marked enhancement at 1.8 eV is attributed to the hu-t1u forbidden transition in C60. This anomalous effect is interpreted by taking the electronic energy states of both conducting polymers and C60 into consideration.
31 citations
TL;DR: In this paper, the effect of buckminsterfullerene (C 60) on poly(3-alkylthiophene) and poly(poly(3,alkyl, thiophene)-polysilicon polymers was investigated.
25 citations
TL;DR: Magnetic properties of higher fullerene (C84, C90 and C96) complexes with tetrakis (dimethylamino) ethylene (TDAE) have been first studied based on the electron spin resonance (ESR) analyses as mentioned in this paper.
23 citations
TL;DR: In this article, it was shown that the threshold of cyclic voltammetry has shifted to a higher potential in C60-doped poly(3-hexylthiophene).
Abstract: The absorption spectrum and a cyclic voltammogram for poly(3-hexylthiophene) changed upon C60 doping but those for poly(3-octadecylthiophene) did not. This suggests that C60 is an effective dopant for poly(3-hexylthiophene) in the ground state but not for poly(3-octadecylthiophene). The threshold of cyclic voltammetry has shifted to a higher potential in C60-doped poly(3-hexylthiophene). This is explained by the lowering of the valence band top due to the electron transfer from poly(3-hexylthiophene) to C60. The shift depends on alkyl chain length and decreases with alkyl chain length in accordance with the results of photoemission spectroscopy.
16 citations
TL;DR: In this paper, the effect of photoinduced charge transfer on optical absorption and photoluminescence in poly(3-hexylthiophene) was investigated and C60 was shown to be a good sensitizer for photoconductivity.
Abstract: C60 (Buckminsterfullerene) can be an acceptor dopant for poly(3-hexylthiophene), inducing marked changes in optical absorption and photoluminescence due to charge transfer from polymer to C60 upon doping. Electrical conductivity also changes to some extent upon C60 doping. In contrast, C70 is not effective as a strong dopant in poly(3-hexylthiophene). That is, the absorption spectrum does not change markedly upon C70 doping and the change in electrical conductivity is also found to be much smaller than in the case of C60 doping. However, photo-luminescence is markedly quenched upon C70 doping, just as in the case of C60 doping. These results are discussed by accounting for the difference in electronic energy states of both C60 and C70 relative to that of poly(3-hexylthiophene). The important role of photoinduced charge transfer for quenching of photoluminescence is discussed and C70 is proposed to be a good sensitizer for photoconductivity of poly(3-alkylthiophene).
13 citations
TL;DR: In this paper, the twofold increase of the siglet-oxygen luminescence intensity with excitation at 670 nm in comparison with one at 514.5 nm is observed.
11 citations
TL;DR: In this paper, the Raman scattering at 1.16 eV laser excitation has been studied in ferromagnetic TDAE-C60 and compared to that in paramagnetic tdr-C70, showing significant electron-phonon coupling of this Jahn - Teller vibrations.
TL;DR: In this article, the effect of random 13C substitution in the vibrational spectra of 12 C 60− x 13 C x was assessed through a joint experimental and theoretical study, and it was shown that the dispersion of the lower-frequency vibration is multimodal.
TL;DR: In this paper, the magnetic properties of molecular alloy complexes, TDAE-(C60)1−x(C70)x (x ≈ 0.2, 0.4 and 0.5), have been first studied based on the measurements of the Faraday-balance magnetization.
TL;DR: In this article, the degradation of superconducting (SC) state of K X C 60 upon exposure to air is a surprisingly slow (e.g. compared to n-type doped conducting polymers) and partially reversible process.
01 Jan 1993
TL;DR: In this article, the authors show that the resonance with the electronic Raman scattering (RRS) spectra shows Fano-lineshapes due to resonance with electronic continuum and the fitting of experimentally observed Hg(2) lineshapes shows the abrupt change of the Fano parameters at Tc.
Abstract: Significant spectral changes upon crossing superconducting Tc have been observed by resonant Raman scattering (RRS) (excited at 1.16 eV) in Rb3C60 and K3C60 thin films. In RRS spectra Hg (l) and Hg (2) modes clearly show Fano-lineshapes due fo resonance with electronic continuum. The electronic Raman scattering is clearly observed as a broad background (fwhm =450 cm−1) at low energy. The large linewidth observed in Hg (2) (fwhm = 60 cm−1) indicates a sizable electron-phonon coupling. Below Tc only Hg (2) mode changes dramatically its asymmetric lineshape becoming more symmetric in the superconducting phase. The fitting of experimentally observed Hg(2) lineshapes shows the abrupt change of the Fano parameters at Tc. Interband t lu tlu * transitions are suggested as a possible origin for low energy electronic excitations.
01 Jan 1993
TL;DR: In this paper, an analysis of the lattice dynamics of fullendes in the assumption of intermolecular potential consisting of the sum of the Lennard-Jones potential, Born-Mayer potential, and the Coulomb potential has been carried out.
Abstract: Raman spectra of fullendes M6C60 (M = K, Rb, Cs) in the low energy region (20-300 cm−1) at excitation by λ = 514.5 nm and 647.1 nm are studied. One of the bands (33 cm−1 in K6C60, 45 cm−1 in Rb6C60 and Cs6C60) is assigned to the librational mode of C60 molecules while other bands are due to modes corresponding to translations of predominantly metal atoms. An analysis of the lattice dynamics of fullendes in the assumption of intermolecular potential consisting of the sum of Lennard-Jones potential (for C-C intermolecular interactions), the Born-Mayer potential (for M-C interactions) and the of the Coulomb potential has been carried out.
TL;DR: Anomalous temperature dependence of the relative intensity ratio of three electron spin resonance (ESR) lines was observed in KxC60 films prepared by electrochemical doping in a solid electrolyte.
Abstract: Anomalous temperature dependence of the relative intensity ratio of three electron spin resonance (ESR) lines was observed in KxC60 films prepared by electrochemical doping in a solid electrolyte. From the ESR saturation curves of those lines measured at various temperatures, their spin-lattice relaxation times (T1) were estimated. Novel changes in the intensity among those lines with increasing microwave power can be explained by taking the difference in T1 of those lines into consideration. Under a relatively high doping condition the lowest T1 of 3.5×10-5 s was evaluated at 7.6 K.