High efficiency solar cells, longer-lasting light bulbs, and thermoelectric energy harvesting - these are just some of the end goals of the work Silvija Gradečak is doing at MIT, developing the use of nanomaterials for light harvesting and energy conversion.
According to Gradečak, the nano-scale dimensions can be used to fine-tune the behaviour of photons, electrons and protons, thus designing nanoscale components and controlling their performance and properties.
For instance, by modifying the composition and size of nanomaterials, the energy band gap of a semiconductor can be changed, enabling photons of different energies to be absorbed into a nanostructured solar cell.
Silvija Gradeèak, photo: M. Scott Brauer
The solar cells created by Gradečak can absorb a range of wavelengths, and are made of different nanomaterials such as graphene, nanoparticles and nanowires. These novel solar cells are lightweight, flexible and transparent and can be utilized not just on fixed flat surfaces but also on moving or curved surfaces like clothing and cars.
Nanowire LEDs boost efficiency
Gradečak is also working on a project to develop new light-emitting diodes. She believes that nanowire LEDs could be more efficient and last longer than the conventional type. The nanowires can be grown on different substrates, and are also less expensive than present technology.
She is presently developing a device that can emit blue, green and red light in varying ratios, by using nanotechnology to tune the band gap of the semiconductor material, and therefore the wavelength of the emitted light.
Energy from waste heat
Buildings, power stations and car engines generate large amounts of heat energy that is un-harnessed. Gradečak is working on thermoelectric devices to capture that heat and use it to generate additional electricity. For example, in a car, the heat captured from the engine could be used to power the vehicle's electrical systems.
Nanotechnology is being used to enhance devices in a multitude of fields. Research such as that being carried out at MIT is crucial, to translate our increasing understanding of nanomaterials into macroscale benefits.