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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 24: Poster: Organic Semiconductors

CPP 24.3: Poster

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

Photophysical Characterisation of Novel Polymeric Absorber Materials for Organic Solar Cells — •Hannah Mangold¹, Ian A. Howard¹, Ralf Mauer¹, Silvia Janietz², and Frédéric Laquai¹ — ¹MPI for Polymer Research, Mainz, Germany — ²Fraunhofer IAP, Potsdam, Germany

The power conversion efficiency of organic solar cells has significantly increased in the last year as the old benchmark poly(3-hexylthiophene) (P3HT) has been surpassed by novel donor-acceptor polymers with enhanced absorption in the near-infrared region of the solar spectrum. We investigate terpolymers synthesized with different contents of dialkyl substituted diphenyl-benzopyrazine or diphenyl-thienopyrazine, which determine the optical properties of the materials, and triphenylamine units that should determine the charge transport properties of the material by acting as the hole conductor. Using ultrafast transient absorption we see that the hole indeed transfers to the triphenylamine unit, validating the approach of simplifying material property optimization by decoupling the role of light absorption and hole transport within a single polymer backbone. We achieve open circuit voltages approaching 1V and power conversion efficiencies of 3%, demonstrating the potential of this class of terpolymer. However, the inclusion of the triphenylamine unit does not enhance device performance, and based on light intensity dependent measurements, we attribute this observation to an increase in carrier trapping. Therefore, we demonstrate that it is possible to achieve independent control of light absorption and transport properties with the three monomers of a terpolymer.