Embedding effects on charge-transport parameters in molecular organic materials

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Accurate calculation of electronic coupling is crucial for understanding charge transport in organic materials.
• Environmental effects, such as solvent or crystal packing, significantly influence charge transport properties.
• Existing methods often struggle to incorporate these embedding effects effectively.

Purpose of the Study:

• To present a generalized tight-binding approach for calculating electronic coupling parameters.
• To explicitly include environmental "embedding effects" in the computation.
• To validate the method's performance on model systems and oligoacene crystals.

Main Methods:

• A generalized tight-binding approach is employed.
• An "embedded dimer" model is used to account for environmental influences.
• The method is applied to investigate charge (hole) transport phenomena.

Main Results:

• The generalized tight-binding method successfully determines electronic coupling parameters.
• Explicit inclusion of embedding effects is shown to be critical.
• The "energy splitting in a dimer" approximation yields reasonable results when embedding effects are properly considered, even for non-symmetric units.

Conclusions:

• The presented method offers a more accurate way to model charge transport in organic materials.
• Accounting for environmental embedding effects is essential for reliable electronic coupling calculations.
• The generalized tight-binding approach provides valuable insights into the charge transport mechanisms in organic systems.