Light emission from single self-decoupled molecules

The scanning tunneling microscope (STM), relying on the overlap of wavefunctions of a sharp tip and a conductive sample, has proven to be an ideal tool for both measurement and manipulation of objects on the nanoscale. We have extended the possibilities of conventional STM and built up an STM with a highly efficient light collection setup, which enables us to control and detect electron photon interaction on the nanoscale1. I will present an overview of our experimental techniques and recent results with regard to light emission from single molecules. Single molecule light emitting sources suffer from an intrinsic contradictoriness: To conduct, the molecular orbitals need to hybridize with the electrodes, however, to emit light, they need to be decoupled from the electrodes to prevent fluorescence quenching. This is typically achieved by inserting a thin insulating layer. We present a promising alternative, that is the functionalization of the light-emitting chromophore with a spacer group that preferentially binds to the metal and decouples the chromophore. Recently, we have provided first evidence of sharp, reproducible emission lines from such self-decoupled molecules deposited directly on the underlying metal substrate. ... mehrI will present possibilities of how to further boost the quantum efficiency of electroluminescence of individual quantum objects² and first evidence for single-photon emission from single molecules, i.e. single-photon or entangled photon nature of the emitted light.