Effects of industrial interest have been detected in investigations on the dark conductivity and photoconductivity of dyes. For example, it was found that organic dyes can be used in the same way as inorganic photoconductors in vidicon television pickup tubes for the reproduction of images. Among other things, pointers were obtained to the formation of rectifying and photoelectrically sensitive pn junctions, to relatively high thermoelectromotive forces of doped and polymeric dyes, to the possibility of use in reprography, and to a high catalytic activity connected with the conductivity, which is already being utilized in fuel cells.