Thin organic layers for photography and electronic devices

The dye sensitization in photography is achieved by thin layers of J-aggregated dyes on silver halide grains. Studies by Yoshihara et al. with picosecond and femtosecond spectroscopies have indicated that the migration of excitons in the dye layers plays important roles in their charge separation to inject electrons into the grains. Studies by Seki et al. with ultraviolet photoelectron spectroscopy have revealed that the electronic structure of the interface between dye layers and a substrate is characterized by the fact that the vacuum level of the former is lowered with respect to that of the latter by the electric double layer formed at the interface, and that this characteristic structure is generally valid for the interfaces between organic layers and substrates. Hanna et al. have confirmed the formation of such an electronic double layer at the interfaces between a liquid crystalline organic semiconductor and electrodes by analyzing the current voltage characteristics.