Charge transfer complexes of polyenes: spectroscopic, dark and photoconductive studies

Formation of molecular charge transfer (CT) complexes of some polyenes with iodine has been confirmed by spectroscopic studies. The dark and photoconductive properties of these CT complexes have been investigated in a sandwich cell. Both the dark and photoconductivity increases by several orders of magnitude by complex formation. The measured thermal activation energy is identical for dark and photoconduction in the complexes. Similar photoconduction action spectra in pure and in iodine-complexed polyenes suggest the same photocarrier generation mechanism to be operative in both the cases. Spontaneous generation of carriers by CT interaction and their migration by trapping and detrapping mechanisms seems to be responsible for electrical conduction in the CT complexes.