ECOLE · Electrical control of picoCavity enhanced mOlecule-Light intEractions

Controlling and engineering light matter interactions at ever smaller scales is an ambitious research enterprise that has fostered the field of plasmonics, leading to improved molecular sensing, monitoring of chemical reactions at the single molecule level and the exploration of new phenomena such as room-temperature strong coupling. One of the most powerful and prolific approaches has been to engineer plasmonic gap cavities with (sub) nanometric gaps yielding high field enhancements. At such small scales, the displacements of one or few atoms leads to an additional, highly localized field enhancement, termed picocavity, that allows for example to robustly detect SERS signals stemming from a single molecule by boosting its signal more than 1000 times.In Ecole I will equip such small plasmonic gap nanocavities with electrical connections. First, I will achieve electrical control over the formation and dynamics of picocavities, making them a more reliable sensing tool and testing current hypotheses about their microscopic nature and formation mechanisms. Subsequently I will use this increase enhancement to study the electron-phonon coupling in a molecular junction. Looking at the influence of strong optical resonances and drive on the the electron transport and phonon generation, allowing to reach non-classical states. Third, I will then demonstrate electrically driven mid-IR upconversion from a molecular junction, where the incoming excites vibrations of fluorescent molecules and thereby triggers overbias electroluminescence. This paves the way for a new all electrical detection scheme of mid-IR radiation, with a more scalable and potentially cheaper approach than current technology, enabling to integrate the advantages and promises of the mid-IR technology in a larger range of products and applications.