3 years ago

Interfacial Electron Injection Probed by a Substrate-Specific Excitonic Signature

Interfacial Electron Injection Probed by a Substrate-Specific Excitonic Signature
Gerald Auböck, Enrico Pomarico, Thomas Rossi, Malte Oppermann, Majed Chergui, Tania Palmieri, Edoardo Baldini
Ultrafast interfacial electron transfer in sensitized solar cells has mostly been probed by visible-to-terahertz radiation, which is sensitive to the free carriers in the conduction band of the semiconductor substrate. Here, we demonstrate the use of deep-ultraviolet continuum pulses to probe the interfacial electron transfer, by detecting a specific excitonic transition in both N719-sensitized anatase TiO2 and wurtzite ZnO nanoparticles. Our results are compared to those obtained on bare nanoparticles upon above-gap excitation. We show that the signal upon electron injection from the N719 dye into TiO2 is dominated by long-range Coulomb screening of the final states of the excitonic transitions, whereas in sensitized ZnO it is dominated by phase-space filling. The present approach offers a possible route to detecting interfacial electron transfer in a broad class of systems, including other transition metal oxides or sensitizers.

Publisher URL: http://dx.doi.org/10.1021/jacs.7b06322

DOI: 10.1021/jacs.7b06322

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