Impact of potassium doping on the electronic structure of tetracene and pentacene: An electron energy-loss study.
We report the doping induced changes of the electronic structure of tetracene and pentacene probed by electron energy-loss spectroscopy in transmission. A comparison between the dynamic response of undoped and potassium-intercalated tetracene and pentacene emphasizes the appearance of a new excitation feature in the former gap upon potassium addition. Interestingly, the momentum dependency of this new excitation shows a negative dispersion. Moreover, the analysis of the C 1s and K 2p core-level excitation results in a significantly lower doping level compared to potassium doped picene, a recently discovered superconductor. Therefore, the present electronic structure investigations open a new pathway to better understand the exceptional differences between acenes and phenacene and their divergent behavior upon alkali doping.
Center for Free-Electron Laser Science / DESY, Notkestraße 85, D-22607 Hamburg, Germany.
Friedrich
F
Roth
IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany.
Martin
M
Knupfer