Electric field assisted charge carrier photogeneration in poly(spirobifluorene-co-benzothiadiazole)

• Published in: The Journal of chemical physics Vol. 133; no. 16; p. 164904
• Main Authors: Devizis, A, Serbenta, A, Peckus, D, Thiessen, A, Alle, R, Meerholz, K, Hertel, D, Gulbinas, V
• Format: Journal Article
• Language: English
• Published: United States 28.10.2010
• ISSN: 1089-7690
• DOI: 10.1063/1.3493589

The dynamics of charge carrier generation in poly(spirobifluorene-co-benzothiadiazole) was investigated by electric field-induced fluorescence quenching and differential absorption measurements. Three different time domains of carrier generation have been identified: an ultrafast phase, a subnanosecond phase, and an entire lifetime phase. The charge generation efficiencies during the first and second phases were found to be almost independent of temperature, being about 25% and 10%, respectively, at an applied electric field of 1.3×10(6) V/cm, while the generation efficiency during the third phase increases from 2% at 80 K to 10% at room temperature. The results of transient spectroscopy measurements and quantum chemical calculations suggest an intramolecular charge transfer for about 1 ps from the alkoxy-substituted fluorene side group to the benzothiadiazole subunit of the main chain. The formation and evolution of the resulting charge transfer states determine the way of charge carrier generation.