Complete description of ionization energy and electron affinity in organic solids : Determining contributions from electronic polarization, energy band dispersion, and molecular orientation

Ionization energy and electron affinity in organic solids are understood in terms of a single molecule perturbedby solid-state effects such as polarization energy, band dispersion, and molecular orientation as primary factors.However, no work has been done to determine the individual contributions experimentally. In this work, theelectron affinities of thin films of pentacene and perfluoropentacene with different molecular orientations aredetermined to a precision of 0.1 eV using low-energy inverse photoemission spectroscopy. Based on the preciselydetermined electron affinities in the solid state together with the corresponding data of the ionization energiesand other energy parameters, we quantitatively evaluate the contribution of these effects. It turns out that thebandwidth as well as the polarization energy contributes to the ionization energy and electron affinity in the solidstate while the effect of the surface dipole is at most a few eV and does not vary with the molecular orientation.As a result, we conclude that the molecular orientation dependence of the ionization energy and electron affinityof organic solids originates from the orientation-dependent polarization energy in the film.

https://opac.ll.chiba-u.jp/da/curator/100079/

https://opac.ll.chiba-u.jp/da/curator/100079/PhysRevB_92_075145.pdf

American Physical Society

Journal Article

10980121

AA11187113

Physical review. B

92

075145

2015-08-31

https://doi.org/10.1103/PhysRevB.92.075145

eng

http://journals.aps.org/prb/abstract/10.1103/PhysRevB.92.075145

publisher

(C)2015 American Physical Society