Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: Organic Electronics and Photovoltaics - Hybrid and Organic Layer Systems

CPP 13.4: Vortrag

Montag, 12. März 2018, 15:45–16:00, C 243

Theoretical determination of the ionization potential and the electron affinity of organic semiconductors — •Susumu Yanagisawa — University of the Ryukyus

Ionization potential (IP) and electron affinity (EA) of organic semiconductors are important quantities, which are relevant to barriers for injection of charge (hole or electron). The electrostatic and electronic polarization contributions to the polarization energies for the injected charges in pentacene polymorphs were investigated with first-principles calculations. The former contribution was estimated by employing periodic slabs of the surfaces at the semi-local density functional level of theory. On the other hand, the latter was treated for the bulk systems at the many-body perturbation theory within the GW approximation. It was found that while the electronic polarization induced narrowing of the energy gap in the single crystal and the thin film phases, the electrostatic effect shifted up or down the frontier energy levels such as the highest-occupied molecular orbital- (HOMO) and the lowest-unoccupied molecular orbital-derived (LUMO) levels relative to the vacuum level, sensitively to the molecular orientation at the surface. The role of the electrostatic interaction such as the charge-permanent quadrupole interaction dominating IP and EA of the materials is discussed.