PHOTOPHYSICS OF FULLERENE-DOPED MACROMOLECULES: NONLINEAR ABSORBERS, DIFFRACTIVE ELEMENTS, AND SPATIAL LIGHT MODULATORS
1, , have stimulated a search for new media, which absorb the laser irradiation efficiently over broad spectral range and in wide incident energy region. The π-conjugated organic materials are promising compounds for these purposes because they allow their physical properties to be modified by doping with various impurities, including fullerenes. In the present paper the fullerene-doping effect on spectral, nonlinear optical properties, and dynamic parameters of conjugated organic systems based on 2-cyclooctylamino-5-nitropyridine, polyimide, polyaniline, etc. has been studied. A fullerene introduction in these materials has been used due to high electron affinity of fullerenes (2.6–2.7 eV) that allows the intermolecular donor-acceptor interaction to be reinforced. 4 The new charge transfer complex developed provokes new nanostructures potentials. ae This complex is of a higher excited state absorption cross-section than the ground state one. That is why, fullerene-doped systems are reverse saturable absorption materials and may be used for a sensor and eyes protection from high laser irradiation. ae Fullerene sensitization and complex formation reveal new spectral and energy ranges. The bathochromic shift is observed and new absorption band in the IR spectral range appears in the fullerene-doped materials. ae The new field gradient is formed as the charge transfer path changes (the charge is transferred from the intramolecular donor fragment not to the intramolecular acceptor one but to fullerene). As the result, the photorefractive effect is possible in these structures. The large laserinduced change in the refractive index predicts large nonlinear refraction and third order susceptibility. ae As a new way, the fullerene-doped complex influences the rotation ability of liquid crystals dipoles. The temporal characteristics of nematic LC cells have been improved at least by one order of magnitude. Experimental Materials. 3-5 % solutions of conjugated materials in 1,1,2,2– tetrachloroethane (TClE) were used. The solutions were doped with fullerenes C60 or/and C70. The fullerene concentration was varied from 0.2 wt.% to 5 wt.%. It should be noticed that fullerenes are of relatively high solubility (about 5.3 mg mL -1 ) 5 in TClE. 2-cyclooctylamino-5-nitropyridine, polyimide, polyaniline, and dispersed nematic liquid crystal compounds based on materials mentioned above were used. 2.5–5 µm thick films were spun on the glass or quarts substrates. 10-12 µm thick liquid crystal structures were prepared under condition when the refractive index of ordinary wave was coincided with the refractive index of conjugated materials. A general view of the films obtained based on the materials treated was presented in paper. 6