Scientists Turn Light Into Electrical Current Using a Golden Nanoscale System
University of Pennsylvania researchers have shown the feasibility of the transduction of optical radiation in a molecular circuit into electrical current. The process uses type of system which uses an array of nano-sized molecules of gold. This system creates plasmons on the molecular surfaces which induce and project electrical currents across molecules in response to electromagnetic waves. This process is very similar to photovoltaic cells, but on a much smaller scale.
This discovery might bring us more efficient energy harvesting using the nano-sized self-powered circuit, using sunlight. Newly developed biosensors have been created using surface plasmons, using light activation. These light-activated Plasmon circuits may also be able to be used in computer data storage system, representing data as wavelengths of light.
Fabrication, testing strategies and analysis derived from this development program may lead to a completely new set of devices using Plasmon-controlled single molecules, due to the fact that molecular compounds exhibit a wide range of electrical and optical properties. These devices could lead to new optoelectronic and energy-harvesting devices.
The team responsible for this breakthrough at the Nano/Bio Interface Center was led by Dawn Bonnel, who is a professor of materials science at the University of Pennsylvania as well as the director of the Center. This group fabricated a variety of light sensitive gold nanoparticles. The group then linked these particles on a glass substrate. Energy efficiency was increased by factors of between 400 and 200 per cent by determining the optimal spacing between molecules on the substrate. This minimized spacing between particles, when coupled with optical radiation is what induces the excitation of conductive electrons, or plasmons. These plasmons ride the surfaces of the particles, focusing light on the molecular junctions. This plasmon effect is what is responsible for the incredible efficiency increase.
Energy efficiency was increased by factors of between 400 and 200 per cent by determining the optimal spacing between molecules on the substrate
Very large electromagnetic fields are generated between the particles between optimally coupled nanoparticles with plasmon generating state. This electromagnetic field is captured by the gold nanoparticles. This causes particles to to couple to one another. This creates a percolative path across opposing electrodes. Researchers state that efficiency enhancement factors in the thousands can result when these systems are fully tuned and optimized.
The team responsible for this groundbreaking discovery was composed of researchers from Duke University, the University of Maryland and the University of Pennsylvania. Team members included Bonnell, Sanjini Nanayakkara, David Conklin and TaeHon Park of the Departments of Engineering, Chemistry and Materials and Applied Sciences at Penn. Parag Banerjee represented the Departments of Materials Science and Engineering at Maryland and Michael J Therien came from Duke’s Chemistry Department. A number of energy related foundations, as well as the Department of Energy supported this research. Click here to read the full text of the article.
