Impact of low 6,13-pentacenequinone concentration on pentacene thin film growth

Thin films of pentacene (P) have been vacuum codeposited on SiO2 with low concentrations of 6,13-pentacenequinone (PQ) in order to investigate the impact on the pentacene thin film structure. Within a range of 2%-20% PQ concentration no intercalation of the compounds can be observed by means of x-ray diffraction and infrared absorption spectroscopy. The crystalline quality of the P films stays unchanged by the presence of PQ, whereas P bulk phase contributions are being suppressed at PQ concentrations >= 5%, which could be confirmed by means of atomic force microscopy. From the results the authors suggest phase-separated PQ growth as well as PQ nucleation at P grain boundaries. (c) 2007 American Institute of Physics.