Organic/inorganic hybrid materials: challenges for ab initio methodology.

CONSPECTUS: Organic/inorganic hybrid structures are most exciting since one can expect new properties that are absent in either of their building blocks. They open new perspectives toward the design and tailoring of materials with desired features and functions. Prerequisite for real progress is, however, the in-depth understanding of what happens on the atomic and electronic scale.

Optical absorption in degenerately doped semiconductors: Mott transition or Mahan excitons?

Electron doping turns semiconductors conductive even when they have wide fundamental band gaps. The degenerate electron gas in the lowest conduction-band states, e.g.

Characteristics of small- and large-polaron motion in organic crystals.

Based on a generalized theory of charge transport in organic crystals we investigate the motion of polarons of arbitrary size. Within this theory, we analyze the influence of characteristic electronic, vibronic, and thermal energies and their role for the transport regimes. The polaron bandwidth is identified as the central temperature-dependent quantity.

Charge transport in guanine-based materials.

Temperature-induced dynamic disorder is one of the great unknowns in charge transport through DNA and DNA-related systems. Using guanine crystals as a model system, we studied the temperature dependence and anisotropy of charge-carrier (hole) transport in guanine-based materials. Employing the Kubo formalism, we calculated the hole mobilities with ab initio DFT material parameters.