Our research activities—from theoretical analysis, to fundamental research, to material and device development—have a broader impact on energy and sustainability, typically by enabling new types of future devices that require less energy to operate, or that are used for energy production or storage.
Electronics and Optoelectronics
The development of ultra-wide bandgap semiconductors, typically III-Nitrides, is important towards superior optoelectronic and electronic devices in fields such as power electronics used in the electrical grid, and also towards new classes of more light emitters.
Several other fundamental investigations have relevance for solar energy harvesting with new materials such as lightweight organic systems, or for energy storage and new types of batteries. As an example, research pursued by the Reichmanis group focuses on active materials for lithium-ion electrodes that can have up to 10 times the charge capacity of the graphite electrodes used in current systems, like high-capacity magnetite and silicon anodes, while also exploring flexible electrodes and polymer electrolytes.
Fundamental investigations on excitons in organic materials contribute to progress in the area of solar energy harvesting through organic systems that may have a shorter lifetime or slightly lower efficiency, but would compensate for this by environmentally cheap to produce, by being lightweight, but the ability the ability of rolling out large sheets of energy-collecting plastic. The Biaggio group is investigating how photon absorption in molecular organic semiconductors can lead to two long-lived triplet excitons that are then easier to convert into photovoltaic current.
Even for photovoltaics systems based on conventional materials, like silicon, it is possible to lower the energy and cost required to manufacture them by controlling interfaces and directing electron flow. One way to do that is studied in the research group of Nick Strandwitz, and it consists of using atomic layer-deposited (ALD) tunnel barriers, which are so thin that electrons can tunnel through them, and can lead to silicon photovoltaic cells made with a combination of ALD tunnel barriers and metal oxides that selectively transport electrons with specific energies.
Developments in optics and photonics have already contributed to an enormous amount of energy savings by allowing to transmit information via photons in optical fibers instead of using expensive to produce and operate copper cables. In addition, the future possibility of using photons for data processing will also contribute to energy savings. This ranges from the development of all-optical switches in which optical waves can perform operations on bits transported by other optical waves, to the ability to quickly move information from the electronic to the optical domain, where it can be transmitted without losses in fibers and optical waveguides, a technology that promises to save a lot of energy in data centers when connecting the multiple cores of computer clusters.
Work on using small organic molecules to add active photonics functionality to passive integrated optics circuits such as the silicon photonics platform is being done in Biaggio’s group, in the context of exploring the appeal of small molecules for practical nonlinear optics. One are of research focuses on developing a flexible way to systematically and reproducibly add electro-optic modulation functionality to passive integrated optical circuit elements, which can be done by depositing an organic molecular glass that is then electrically poled. Such systems would help enable an ultrafast transfer of data from the electrical to the optical domain, which can cut down on the energy consumed in data centers where data is sent back and forth between different processors using copper cable, requiring active cooling.