Charge transfer and dipole formation at metal-organic interfaces

The rapidly developing field of organic electronics has stimulated intensive research into the fundamental electronic properties of molecular organic semiconductors and their interfaces with metal electrodes as well as insulating substrates. Theoretical and experimental studies are driven by potential applications where organic molecules constitute active materials in a wide range of electronic devices such as light-emitting diodes (LEDs), filed-effect transistors (FETs), solar cells or biosensors. The thesis is motivated by the modeling of charge injection barriers from metallic contacts into organic materials. Experiments indicate that the energy barriers of electron or hole injection are determined by the formation of an interface dipole layer localized at first molecular layer. Such barriers can be extracted by monitoring the change in the work function, produced upon the deposition of the organic layer. We calculate such work functions using density functional theory (DFT).