Ionization Energies, Electron Affinities, Bandgaps, Exciton Binding Energies, and Polarization Energies of Orientation-Controlled Picene, [6]-Phenacene, and [7]-Phenacene Thin Films
Year: 2026
Type: article
Abstract: Phenacenes, in which benzene rings are fused in a zigzag manner, are chemically robust π-conjugated hydrocarbons of interest for organic electronic applications and superconductivity. However, quantitative electronic parameters of phenacene thin films remain limited compared with those of acenes. Here, we determine the ionization energies (IEs), electron affinities (EAs), bandgaps, exciton binding energies, and polarization energies of orientation-controlled thin films of picene, [6]-phenacene, and [7]-phenacene using ultraviolet photoelectron spectroscopy and low-energy inverse photoelectron spectroscopy. The energy parameters depend only weakly on molecular size. In contrast, both IE and EA exhibit large orientation-dependent shifts of approximately 1 eV: lying films show IEs of 6.28–6.42 eV and EAs of 2.20–2.39 eV, whereas standing films show IEs of 5.54–5.74 eV and EAs of 1.46–1.73 eV. Nevertheless, the bandgaps of approximately 4 eV and exciton binding energies of approximately 1 eV remain nearly independent of molecular size and orientation. Analysis of polarization energies shows that the induction term is nearly orientation independent, whereas the electrostatic term strongly depends on orientation and originates primarily from molecular quadrupole moments. These results identify molecular orientation as a key factor governing frontier energy levels in phenacene thin films.
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Awards: Elucidation of electron conduction mechanisms in organic semiconductors to overcome the limitations of n-type properties of organic semiconductors, Precise and quick prediction of electron conduction levels in organic semiconductors using machine learning, Advanced measurement for unveiling hierarchical quasiparticles towards renovating molecular materials research, Elucidate the electronic functions at organic semiconductor interfaces by means of a precise electronic state evaluation
OpenAlex ID: W7204805490