Pentacene Excitons in Strong Electric Fields.
Klaus KuhnkeVolodymyr TurkowskiAlexander KabakchievTheresa LutzTalat S RahmanKlaus KernPublished in: Chemphyschem : a European journal of chemical physics and physical chemistry (2018)
Electroluminescence spectroscopy of organic semiconductors in the junction of a scanning tunneling microscope (STM) provides access to the polarizability of neutral excited states in a well-characterized molecular geometry. We study the Stark shift of the self-trapped lowest singlet exciton at 1.6 eV in a pentacene nanocrystal. Combination of density functional theory (DFT) and time-dependent DFT (TDDFT) with experiment allows for assignment of the observation to a charge-transfer (CT) exciton. Its charge separation is perpendicular to the applied field, as the measured polarizability is moderate and the electric field in the STM junction is strong enough to dissociate a CT exciton polarized parallel to the applied field. The calculated electric-field-induced anisotropy of the exciton potential energy surface will also be of relevance to photovoltaic applications.
Keyphrases
- density functional theory
- energy transfer
- molecular dynamics
- image quality
- computed tomography
- contrast enhanced
- dual energy
- high resolution
- quantum dots
- single molecule
- magnetic resonance imaging
- solar cells
- high intensity
- high glucose
- diabetic rats
- molecular docking
- human health
- solid state
- endothelial cells
- crystal structure