Gigahertz Frame Rate Imaging of Charge-Injection Dynamics in a Molecular Light Source

7 pags., 4 figs.Light sources on the scale of single molecules can be addressed and characterized at their proper sub-nanometer scale by scanning tunneling microscopy-induced luminescence (STML). Such a source can be driven by defined short charge pulses while the luminescence is detected with sub-nanosecond resolution. We introduce an approach to concurrently image the molecular emitter, which is based on an individual defect, with its local environment along with its luminescence dynamics at a resolution of a billion frames per second. The observed dynamics can be assigned to the single electron capture occurring in the low-nanosecond regime. While the emitter's location on the surface remains fixed, the scanning of the tip modifies the energy landscape for charge injection into the defect. The principle of measurement is extendable to fundamental processes beyond charge transfer, like exciton diffusion.A. Rosławska acknowledges support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement 771850) and the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement 894434. P. Merino acknowledges support from the A.v. Humboldt Foundation, the ERC Synergy Program (grant ERC-2013-SYG-610256, Nanocosmos), Spanish MINECO (MAT2017-85089-C2-1-R), and the “Comunidad de Madrid” for its support to the FotoArt-CM Project S2018/NMT-4367 through the Program of R&D activities between research groups in Technologies 2013, cofinanced by European Structural Funds