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 dissertation 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.
Chapter 1 discusses molecular optoelectronics, a field at the intersection of plasmonic phenomena and molecular electronics, and introduces the STM-BJ technique for measuring molecular junctions. Chapter 2 describes the light emission detection setup that is operated in tandem with the STM-BJ instrument. Chapter 3 presents a study of Au tunnel junctions. This lays the groundwork for the plasmonics at play in these electroluminescent systems, detangling how gap size, electrical bias, and emission wavelength affect plasmonic enhancement.
In Chapters 4 and 5, Au-molecule-Au junctions are investigated in some of the first experimental studies of single-molecule electroluminescence at ambient conditions. Chapter 4 uses light emission data from molecular junctions to estimate finite-frequency shot noise and uncover critical information about transmission characteristics. Chapter 5 presents one of the first examples of single-molecule strong light-matter coupling in an electroluminescent system, substantiated by spectroscopy data.
This dissertation greatly expands on existing knowledge of plasmonic phenomena, particularly in relation to electroluminescent devices. Furthermore, it lays a strong foundation for single-molecule spectroscopy studies using the STM-BJ technique.
| Identifer | oai:union.ndltd.org:columbia.edu/oai:academiccommons.columbia.edu:10.7916/m2yy-kh14 |
| Date | January 2024 |
| Creators | Paoletta, Angela Lyn |
| Source Sets | Columbia University |
| Language | English |
| Detected Language | English |
| Type | Theses |
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