Electronic structure: delocalisation length and triplet routes

Electronic structure is the second crucial factor determining the efficiency of organic semiconductors, be it due to energy level matching of donor and acceptor materials in organic solar cells and organic light-emitting diodes or due to determining the transport properties for charges. Hence, a detailed understanding of the electronic structure on a molecular scale is of paramount importance.

Due to its molecular resolution, EPR spectroscopy provides unique insights into the electronic structure of organic semiconductors, including but not limited to revealing the role of donor and acceptor moieties in push–pull systems, the repeat unit in terms of electronic structure, factors determining exciton delocalisation length, and the origin of triplet states often encountered in these materials.

Which part in a push–pull system dominates the electronic structure?

• method: TREPR @ X-Band, 80 K

• method: quantum-chemical calculations (DFT, …) for calculating spin densities

• preparation: (frozen) solution

• analysis: fitting of triplet spectra

What is the repeat unit of a polymer in terms of its electronic structure?

• method: TREPR @ X-Band, 80 K

• method: quantum-chemical calculations (DFT, …) for calculating spin densities

• preparation: (frozen) solution

• analysis: fitting of triplet spectra

How are triplet states created? What is their origin?

• method: TREPR @ X-Band, 80 K with variable excitation wavelengths

• method: quantum-chemical calculations (DFT, …) for calculating spin densities

• preparation: (frozen) solution

• analysis: fitting of triplet spectra

Which parameters affect the exciton delocalisation length?

• method: TREPR @ X-Band, 80 K

• method: quantum-chemical calculations (DFT, …) for calculating spin densities

• preparation: (frozen) solution

• analysis: fitting of triplet spectra