Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 77: Organic electronics and photovoltaics IV (CPP, jointly with DS, HL, O)

HL 77.4: Talk

Thursday, March 14, 2013, 10:30–10:45, H34

Diffusion limited charge generation from fullerene excitons in low bandgap polymer solar cells — •Clare Dyer-Smith, Ian Howard, and Frédéric Laquai — Max Planck Institut für Polymerforschung, Mainz, Germany

Organic solar cells with high power conversion efficiencies have been realised in recent years by the use of low bandgap polymers in combination with C70-based electron acceptors to provide good absorption coverage across the entire solar emission spectrum. Diffusion-limited charge generation from fullerene excitons has been observed in such blends, including the high-performance PTB7:PC70BM blend system which is the subject of the present study. We characterise the diffusion-limited charge generation from fullerene excitons in this system using transient absorption and photoluminescence spectroscopy. Fitting to a simple exciton quenching model allows us to determine the size of fullerene domains in the blend, showing quantitatively how blend morphology limits device performance, and allowing us to identify selection criteria for the optimum blend morphology in devices based upon light-absorbing fullerene acceptors.