Research Projects


Single-Molecule Electronic Devices


The electronics industry has revolutionized society in the last 50 years. The advent of electronic devices has affected practically every aspect of human life from art and culture to energy and health-care. The engine of that success has been the miniaturization of electronic devices, which has allowed increases in speed and reliability while decreasing costs. However, this paradigm is now facing real physical limits to its continued advancement. As conventional electronics devices are scaled down, their bulk properties are compromised, and both the efficacy and efficiency of transistors are affected. To overcome this issue it is necessary to engineer the growth and assembly of atomic and molecular building blocks to develop complex materials with tailored electrical properties from the bottom-up. Much success has been achieved in these areas, and we are working to demonstrate and integrate a variety of single-molecule devices that operate based on quantum-mechanical principles, and mimic the properties of conventional transistors, diodes, and wires.


Charge Transport in Bio-Molecules

In addition to its primary role as the carrier of genetic information, DNA has recently emerged as an important material for nanotechnology. Its exceptional self-assembly capabilities have enabled the development of nanostructured systems with unparalleled nanoscale precision and it has been suggested that these electronic properties may be involved in biological processes such as signaling or oxidative damage recognition or repair. The combination of these unique structural and electronic properties also make DNA a promising molecule for applications in molecular electronics. Because of this incredible promise we are working to understand the electronic properties of this important class of molecules. Moreover, reliable, efficient, and inexpensive detection and species-level identification of microorganisms including bacteria, viruses, and fungi is a grand challenge for advancing biological sciences and health-care in the 21st century. Because the conductance of oligonucleotides is sensitive to length, sequence, and single-base mismatches, single-molecule electronic detection of oligonucleotides provides a unique opportunity for identifying a specific microbe in situ.


2-Dimensional Molecule-Nanoparticle Hybrid Arrays

Molecule-nanoparticle hybrid materials are unique composite systems with tunable, chemical, optical, and electrical properties. Interest in these ‘meta-material’ systems arises from their potential as controllable artificial solids, and the novelty and promise of building bottom-up materials. The wide-variety of potential applications for these systems include molecule-based sensing, photonics, plasmonics, stress sensing, biomedical devices, electronics, and others. Moreover, from a fundamental standpoint, these systems provide a platform for studying unique nanoscale behavior, including the crossover between macroscopic and nanoscale electronic transport phenomena, and thin-film optical properties.These systems provide a unique opportunity to study the evolution of molecular electronic devices from the bottom-up. Although incredible progress has been made in the development of single-molecule devices, and single-molecule transistors, diodes, and wires have all been demonstrated, it has not been possible to demonstrate that these devices can be integrated into larger systems to create integrated circuits, or to precisely control the electronic or energy conversion properties of the resultant composite material. Therefore, we are using these systems as a test-bed to explore the evolution of the electronic properties of molecular-scale devices from the single-molecule level up toward large-scale, composite systems.


Transport and Energy Conversion at the Atomic-Scale

Molecules represent a unique class of materials which are inherently quantum mechanical in nature, can be designed and constructed with atomic-level precision, are natural 1-dimensional (1D) transport devices, and possess unique opportunities for device fabrication, function, and implementation. Despite the plethora of exciting attributes of these systems, many of the investigations of the electronic properties of molecular systems has focused on mimicking the functions of conventional semiconductor devices such as diodes, and wires. Alternatively, exploiting the distinctive properties of molecules could lead to the development of novel devices with unparalleled functions or paradigms of operation. However, the development of novel, molecular-scale, electronic, spintronic, plasmonic, or phononic devices requires a thorough understanding of the transport processes involved in these systems, and the complex interplay between the optical, electrical, thermal, and mechanical domains at the atomic scale. To understand these processes we are working to develop novel spectroscopic tools and techniques that allow us to understand this behavior.