Berlin 2015 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 26: Organic Electronics and Photovoltaics: OPV I (joint session CPP, HL, TT)

CPP 26.1: Invited Talk

Tuesday, March 17, 2015, 14:00–14:30, C 130

Ultrafast Coherent Charge Transfer in Solar Cells and Artificial Light Harvesting Systems — •Christoph Lienau¹, Ephraim Sommer¹, Antonietta de Sio¹, Ralf Vogelgesang¹, Margherita Maiuri², Giulio Cerullo², Angel Rubio³, Carlo A. Rozzi⁴, and Elisa Molinari⁴ — ¹Carl von Ossietzky University, Oldenburg, Germany — ²Politecnico di Milano, Milano, Italy — ³Universidad del País Vasco, San Sebastian, Spain — ⁴Dipartimento di Scienze Fisiche, Modena, Italy

To elucidate the fundamental microscopic processes in solar energy conversion, we have recently combined coherent femtosecond spectroscopy and first-principles quantum dynamics simulations [1,2] and have used this approach to explore the primary photoinduced electronic charge transfer in two prototypical structures: (i) a carotene-porphyrin-fullerene triad, an elementary component for an artificial light harvesting system [2] and (ii) a polymer:fullerene blend as a model for an organic solar cell [1].

Our results provide strong evidence that in both systems, at room temperature, the driving mechanism of the primary step within the current generation cycle is a quantum-correlated wavelike motion of electrons and nuclei on a timescale of few tens of femtoseconds. They suggest that the strong coupling between electronic and vibrational degrees of freedom is of key importance for the dynamics and yield of the charge separation process. Here, I will discuss our most recent experimental and theoretical findings. [1] S. M. Falke et al., Science 344, 6187 (2014). [2] C. A. Rozzi et al., Nature Comm. 4, 1602 (2013)