Dresden 2011 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 12: Organic Semiconductors II: Solar Cells B (jointly with HL, DS)

CPP 12.8: Vortrag

Dienstag, 15. März 2011, 12:30–12:45, ZEU 222

Triplet Excitons and Cations in dicyanovinyl end-capped quaterthiophenes with varying side chain length — •Christian Koerner¹, Hannah Ziehlke¹, Roland Fitzner², Egon Reinold², Peter Bäuerle², Karl Leo¹, and Moritz Riede¹ — ¹Institut für Angewandte Photophysik, Technische Universität Dresden — ²Institut für Organische Chemie II und Neue Materialien, Universität Ulm

Dicyanovinyl end-capped oligothiophenes (DCV-nT) are highly suitable for systematical investigations of energy and charge transfer processes in donor-acceptor blends because of the tunability of electronic and morphological properties by varying e.g. length of backbone or side chains. Moreover, it has been shown to work well as absorber in small molecule organic solar cells (OSC) achieving up to 5.2% power conversion efficiency (PCE) for DCV-5T in a bulk heterojunction (BHJ) device¹.

We use photoinduced absorption spectroscopy (PIA) to probe the long-living (µs-ms) excited states (triplet excitons, cations) after photoexcitation of DCV-nT:C₆₀ blends. With PIA, their generation and recombination behaviour can be investigated. Here, we report our results obtained on a series of DCV-4Ts with varying side chains from none to methyl side chains which supposedly mainly influences the morphology of the thin film. We complement our studies by exploring the potential of these materials as absorber layer in planar and BHJ solar cells. For example, DCV-4T without side chains gives an open circuit voltage of 1V and PCEs of 1.9% in a BHJ solar cell with C₆₀.

¹ Fitzner et al., Adv. Func. Mat., accepted