Plasmonic enhancement of single-molecule charge-transport and optoelectronic response.


Recent advancements in nanoscience have enabled the reliable and reproducible wiring of molecules into electrical circuits. A single molecule can be sandwiched between two nanoelectrodes (a “molecular junction”) and an electrical current can be driven through, enabling the assessment of their optoelectronic properties and charge transport efficiency at the smallest scale possible. Different molecules give junctions with different electrical behaviour, and significant research efforts have contributed to the development of single-molecule transistors, single-molecule mechanosensitive resistors and even single-molecule light sources.

The two metallic electrodes, while an integral part of the final single-molecule device, are a somewhat understudied component. Progress in nanofabrication and break-junction techniques have now enabled the fabrication of electrodes of well-defined shape, with precision down to 10nm – an ideal scale to control the plasmonic properties of the final device. For instance, the presence of notches on the nanoelectrode gives rise to interference patterns and formation of standing waves, that allow a fine control on the electrically-induced localised surface plasmon resonance. Matching its energy to the levels of the molecule would give rise to plasmon-enhanced transport and emission, resulting in more efficient molecular devices.

In this project, we want to systematically study how the charge transport (i.e. conductance) and photonic behaviour (i.e. light-emission) of single-molecule junctions are altered by the nanoelectrode shape. The research programme will entail contribution from device modelling (using FDTD methods), nanofabrication (using thermal scanning probe lithography techniques, tSPL) and optoelectronic measurements (using bespoke mechanically-controlled break-junction equipment, MCBJ).

As part of the studentship the successful candidate will:

·      Design nanoelectrodes and computationally model their plasmonic properties.

·      Nanofabricate nanoelectrodes using tSPL techniques.

·      Fabricate molecular devices with MCBJ techniques and asses their optoelectronic behaviour.

·      Contribute to the activities of a diverse research group operating at the chemistry/physics interface

·      Gain interdisciplinary experience by being involved in our collaborative network with partners from all corners of the world.

Given the wide interdisciplinarity of the project, it will suit candidates with backgrounds in either chemistry, physics, or material science, with a keen interest in nanotechnology. The successful candidate will also be given opportunities to acquire further skills in chemical synthesis, instrument design/development, data analysis (e.g. coding), scanning probe microscopy, or electrochemistry.

More information about the research, and further useful references can be found at Informal enquiries are also encouraged and should be addressed to Dr. Andrea Vezzoli ().

Some teaching duties may be required. In your online application form please quote reference number: CCPR080