Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 65: Poster: Organic electronics and photovoltaics (CPP; jointly with HL, O)
HL 65.5: Poster
Mittwoch, 13. März 2013, 16:30–18:30, Poster C
Low-bandgap DPP-type Polymers for OPVs: Relation between Device Performance and Photophysical Properties — •Julian Ochsmann1, Mathieu Turbiez2, Deepak Chandran3, Ian Howard1, Kwang-Sup Lee3, and Frédéric Laquai1 — 1Max Planck Institute for Polymer Research, Mainz, Germany — 2BASF, Basel, Switzerland — 3Hannam University, Seoul, Korea
Low-bandgap polymers are promising materials to serve as electron donors in the photoactive layer of bulk heterojunction solar cells. In combination with a suitable electron acceptor such as PC70BM the photoactive layer covers a broad absorption range spanning from the visible to the near-infrared spectral region leading to increased photon harvesting and thus a higher photocurrent compared to mid-bandgap polymers such as P3HT.
In this study the photovoltaic performance of several low-bandgap polymers based on the diketopyrrolopyrrole (DPP) unit was evaluated in Organic Photovoltaic Cells (OPVs) prepared with different solvent mixtures. Depending on the polymer structure and preparation conditions maximum power conversion efficiencies between 1.6 and 5 % could be reached. The photophysical properties of the photoactive layers of the OPVs were investigated by steady-state photoinduced absorption and broadband transient absorption pump-probe spectroscopy (TA) to get further insight into the exciton and polaron dynamics as well as into the efficiency-limiting mechanisms of the devices.