| AVS 62nd International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Tuesday Sessions |
| Session NS+EN+SS-TuA |
| Session: | Nanophotonics, Plasmonics, and Energy |
| Presenter: | Pablo Merino Mateo, Max-Planck-Institut für Festkörperforschung, Germany |
| Authors: | P. Merino Mateo, Max-Planck-Institut für Festkörperforschung, Germany C. Grosse, Max-Planck-Institut für Festkörperforschung, Germany A. Rosławska, Max-Planck-Institut für Festkörperforschung, Germany K. Kuhnke, Max-Planck-Institut für Festkörperforschung, Germany K. Kern, Max-Planck-Institut für Festkörperforschung, Germany |
| Correspondent: | Click to Email |
Electron-hole pair (exciton) creation and annihilation by charges are crucial processes for technologies relying on efficient charge-exciton-photon conversion. Photoluminescence has been instrumental for this purpose with near-field techniques approaching 20 nm spatial resolution. However, molecular resolution is still out of reach and individual charge carriers cannot be addressed with these methods. In the present contribution we show how to overcome these limitations by using scanning tunneling microscopy (STM) to inject current at the atomic scale and Hanbury Brown-Twiss (HBT) interferometry to measure photon correlations in far-field electroluminescence.
Quantum systems like molecules or quantum dots cannot emit two photons at the same time which results in an antibunching of the emitted photon train and a dip in the photon-photon correlation function. Such single photon emitters are key elements for quantum cryptography and their miniaturization to the nanoscale would be desirable. This requires reproducible emitter separations typically below the optical diffraction limit and has imposed strong limitations on suitable structures and materials.
Using our HBT-STM setup on localized trap states in C60 multilayers we were able to study single photon emission at the ultimate molecular scale. Controlled injection allows us to generate excitons in C60 and probe them with charges one by one. We demonstrate electrically driven single photon emission and determine exciton lifetimes in the picosecond range. Monitoring lifetime shortening and luminescence saturation for increasing carrier injection rates provides access to charge-exciton annihilation dynamics with Ångstrom spatial resolution. Comparison with theory reveals exciton quenching efficiencies close to unity. Our approach introduces a unique way to study single quasi-particle dynamics on the ultimate molecular scale.