Photovoltaic Effects in Liquid Crystal Cells Containing Organic Dyes

Abstract

Dye sensitization on photovoltaic phenomena under visible light stimulation are described in smectic, nematic, and isotropic phases of p-cyano-p'-n-octylbiphenyl cells with a symmetrical electrode arrangement. Methyl red is used as a sensitizer. The dependence of short-circuit photocurrents on excitation light intensity, light pulse width, temperature, and the cell thickness are measured. The photocurrent consists of three components, that is, the small negative peak with a fast response, the second positive peak following after the first peak, and the third negative peak with a slow response. The second and the third components of the photocurrents cannot be observed in the solid crystalline state. Both of them decrease with an increase in the cell thickness, and their response time becomes shorter as the temperature rises. These two components are induced by the diffusion processes of the carriers produced by the light stimulation.