Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 50: Organic Electronics and Photovoltaics III - Organic Photovoltaics

CPP 50.2: Vortrag

Donnerstag, 4. April 2019, 09:45–10:00, H18

The charge transfer state in organic solar cells: contribution of static disorder and molecular reorganisation — •Clemens Göhler and Carsten Deibel — Institut für Physik, Technische Universität Chemnitz, 09126 Chemnitz, Germany

Solar cells from organic semiconductors use an active layer consisting of a heterogeneous blend of electron acceptor and donor materials, such as fullerenes and conjugated polymers. The donor HOMO and acceptor LUMO level in these heterojunctions form an additional charge transfer (CT) state, which can be detected with electro-optical spectroscopy methods.

Molecular properties of donor copolymers, such as molecular weight, defects, or stoichiometry, are crucial to the solar cells performance - predominantly by affecting short circuit current and fill factor. Their impact upon the open circuit voltage, which is connected to the CT states energy, might not be as distinct. They are, however, affecting the CT states energetic distribution, which can be described as a convolution of its molecular reorganisation energy and the amount of energetic disorder. We are able to unravel both contributions using temperature dependent sub-gap photocurrent spectroscopy to contribute to a deeper understanding of the CT states role in solar cell performance.