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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 24: Poster: Organic Semiconductors

CPP 24.4: Poster

Mittwoch, 28. März 2012, 11:00–13:00, Poster A

Photophysical investigation of core-enlarged rylene dyes for solid state dye-sensitized solar cells — •Yoojin Kim, Michael Meister, Ian A. Howard, Belinda Nölscher, Glauco Battagliarin, Denis Andrienko, Chen Li, Klaus Müllen, and Frédéric Laquai — MPI for Polymer Research Mainz

Perylene derivatives used as sensitizers in solid state dye-sensitized solar cells have attracted a lot of interest owing to their high molar extinction coefficients and broad absorption spectra. However, their absorbance is limited to the visible spectral region. By enlarging the perylene core with additional naphthalene units, the absorption can be extended to the near infrared region. However, devices employing such core-enlarged rylene dyes and an anhydride as anchoring group do not necessarily show higher efficiencies. In this study, the photophysical properties of rylene films in device structures are examined using quasi steady-state photoinduced absorption (PIA) and time-resolved photoluminescence spectroscopy. In presence of the hole transporter Spiro-MeOTAD, we observe a Stark effect in the PIA that suggests a change in the direction of the dipole moment unfavorable for charge separation. This change most probably originates from ring opening of the anhydride group during adsorption to the metal oxide, which is also supported by first-principles (TD-DFT, B3LYP) calculations. However, we note that moderate charge generation and regeneration of the dyes are still observed. By relating our results to solar cell performance we point out the factors which reduce the performance after the spectral response is extended to the infrared region.