Electroluminescence from Nanoscale Gaps and Single-Molecule Junctions.
Presented By: Angela Lyn Paoletta
Abstract:
The term “electroluminescence” refers to light emission resulting from the application of an electrical bias. Electron tunneling across a biased, nanoscale junction can serve as the excitation source for photon emission. This effect is also mediated by the plasmonic environment of the junction, where a strong local field can enhance light emission by orders of magnitude.
This defense presents measurements of electroluminescence from nanoscale gaps and single-molecule junctions. These measurements are made possible by a custom light emission detection system coupled to a scanning tunneling microscope break junction (STM-BJ) instrument. Conductance and light emission data are obtained simultaneously for thousands of junctions. Three studies will be presented. The first detangles how gap size, electrical bias, and emission wavelength affect plasmonic enhancement in Au tunnel junctions. Next, light emission data from molecular junctions will be used to estimate finite-frequency shot noise and uncover critical information about transmission characteristics. Finally, I will present one of the first examples of single-molecule strong light-matter coupling in an electroluminescent system, substantiated by spectroscopy data.
This defense will greatly expand on existing knowledge of plasmonic phenomena, particularly in relation to electroluminescent devices, and lay a strong foundation for single- molecule spectroscopy studies using the STM-BJ technique.
