FOTOGALVANIC EFFECT IN NEMATIC CELL DOPED BY METHIL RED
DOI:
https://doi.org/10.52575/2687-0959-2022-54-1-60–67Keywords:
azo-dye, methyl red, liquid crystal, photorefractive effectAbstract
The photovoltaic effect in a symmetrical, without orienting coatings, nematic cell with an azo-dye methyl red has been experimentally studied. It is shown that without an external electric field, under the action of light, the cell generates an electric current (∼ 10−8A/cm2), depending on the irradiation spectrum, two orders of magnitude greater than the current of a nematic cell without dye under the same irradiation conditions. The polarity of the photocurrent depends on the direction of illumination of the cell. An analysis of the temperature dependence of the photocurrent indicates a possible activation mechanism for the transfer of charge carriers with an activation energy of 0.7-2eV for different thicknesses of the nematic cell. It is assumed that there are at least two charge processes with characteristic times that differ by several orders of magnitude. The first is associated with the photoelectric effect in transparent In2O3 electrodes, while the second is due to the spatial separation of charges and is of a diffusion nature. The influence of the phase transition on the photocurrent, both in a cell with a pure nematic and in nematic cells with methyl red, is established, which is due to the appearance of a strongly scattering transition state of the liquid crystal.
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