Vannucchi, N.; Johansson, F. O. L.; Salvagnac, L.; Doucet, J.-B.; Ovsyannikov, R.; Giangrisostomi, E.; Silly, M. G.; Seguy, I.; Jancarik, A.; Witkowski, N.: Pentacene-like Frontier Orbitals in Angularly Fused Bisacene Spin-Coated Thin Films. The Journal of Physical Chemistry C 129 (2025), p. 17720–17726
10.1021/acs.jpcc.5c03252
Abstract:
In this paper, we unveil the electronic structure of the highest occupied and lowest excited unoccupied molecular frontier orbitals in semiconducting bisacene thin films. Thin films of angularly fused bisacenes, namely, pentaceno-pentacene, pentaceno-hexacene, and hexaceno-hexacene, are obtained after the thermal conversion of the spin-coated thin films prepared from highly concentrated ink of precursor molecules. Thus, by a combination of electron spectroscopies, namely, valence band photoemission and near-edge X-ray absorption fine structure spectroscopy, we are able to characterize the occupied and excited unoccupied density of states of the molecular frontier orbitals. We demonstrate that, under specific assumptions, it is possible to combine valence band spectra and absorption spectra relative to the Fermi level and derive the transport gap of angularly fused bisacene films relative to those of pentacene. Both the electronic structure of the frontier orbitals and the transport gap of a pentaceno-pentacene film are found alike as a pentacene film. This demonstrates that, in thin films, the delocalized character of the electrons along the angularly fused bisacene is limited to the acene subunit and adopts the pentacene electronic structure. Because of the high solubility of the bisacene precursors, it can be foreseen as a promising alternative to pentacene precursors, which exhibit poor solubility.