Resonance Raman spectroscopy is used to extract vibrational dynamics information and charge transfer interactions between conjugated polymer donor and various electron acceptor molecules used in organic solar cells. A key element for obtaining this information is the appearance of resolved overtone transitions (up to three harmonics) which are rarely observed in this class of materials. These features encode vibrational dynamics and geometry changes in the excited state and we use time-dependent wavepacket simulations to analyze resonance Raman intensities. Mode-specific vibrational displacements are sensitive to donor/acceptor interactions as well as the packing and conformational characteristics of the polymer. Vibrational coherence timescales are also sensitive to acceptor concentration and interactions with the polymer donor. This information is usually difficult to obtain from conventional ultrafast spectroscopic studies of polymer charge transfer complexes and photoinduced charge transfer dynamics.

Uncovering vibrational dynamics and charge transfer interactions with resonance Raman spectroscopy

246th National Meeting (2013)

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