Abstract

The ultrafast electronic dynamics of microcrystalline pentacene films is investigated by pump probe spectroscopy with 30 fs time resolution. These films are very promising systems for organic transistors and the dynamics of electronic excitations have a strong impact on the performance of such devices. The nature of the photoexcited species is discussed controversially in literature [1,2] and our pump probe experiments should resolve this discussion. The films are optically excited by 24 fs pulses from a noncollinearly phase matched optical parametric amplifier (NOPA) at 670 run in the lowest electronic absorption band. The subsequent spectral evolution of the absorption is measured between 480 nm and 750 nm with a white light continuum generated in a 3 mm thick sapphire substrate or with compressed pulses from a second NOPA for a better time resolution.

© 2007 IEEE