Photoconductivity of sublimated rubrene films during oxidation. The magnetic field effect

The mechanism of carrier generation in sublimated rubrene films in the course of their oxidation is investigated. The technique of the simultaneous measurement of photoconductivity and fluorescence of the samples and their variation in magnetic fields up to 3 kOe is employed. The excited states whose deactivation leads to both, fluorescence and carrier generation in unoxidized films are found to be rubrene singlet excited molecules 1M1 and in films exposed to air, excited complexes of 1M1 with O2 molecules and with transannular rubrene peroxide molecules MO2. The probability of carrier generation in the interaction of 1N1 with O2 is higher than with MO2. The existence is shown of an efficient channel of generation of triplet rubrene excitons, associated with the deactivation of excited triplet complexes of rubrene with MO2. The influence is investigated of variations in the crystalline structure of films on the behaviour of photoconductivity.