Experimental observation of oxygen-related defect state in pentacene thin films

Abstract

The authors report on a metastable defect observed in pentacene thin films. The defect, which is characterized by a hole trap at Ev+0.6eV and attempt-to-escape frequency of 5×1012s−1, can be reversibly created/removed under a negative/positive bias voltage applied to the aluminum/pentacene Schottky diode at room temperature in air. Annealing the sample in vacuum at 360K removes the defect and prevents its creation by application of any bias voltage in vacuum. Considering recent calculations of defects in pentacene the authors assume that the defect is formed by replacing one of the hydrogen atoms by an oxygen atom (C22H13O).