SKM 2021 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: Molecular Electronics, Hybrid and Perovskite Photovoltaics

CPP 13.8: Talk

Friday, October 1, 2021, 12:30–12:45, H3

Charge transfer dynamics across the Au/Ferrocene (aq) interface studied by a two photon pump - photovoltage probe scheme — •Manuel Bridger, Zhipeng Huang, Yujin Tong, Oscar Naranjo, Alexander Tarasevitch, Richard Kramer Campen, and Uwe Bovensiepen — University Duisburg/Essen

Photo-excitation at interfaces redistributes electrons between bulk phases on microscopic spatial and ultrafast time scales. Here we employ a two photon pump - photovoltage probe scheme to quantify the relationship of particular resonant optical transitions to interfacial charge redistribution for the case of charge transfer between a gold electrode and ferrocene self assembled monolayer in an electrochemical cell. We access vibrational and electronic excited states of ferrocene with femtosecond pulses of center wavelength 3 µ m and 400 nm respectively. Two signals are apparent: a large amplitude voltage transient at 120 ± 80 fs and a small at 4.0 ± 2.7 ps. Control experiments and comparison to similar systems probed in vacuum by 2PPE spectroscopy suggest the former is the result of charge transfer via vibronically coupled ferrocene CH vibration and hybrid ferrocene/Au electronic states and the later charge transfer via vibrationally mediated interfacial polarization. These results imply that stabilising such vibronically coupled states is a useful target for devices that rely on efficient charge transfer at solid/liquid interfaces.