14 DAY TRIAL // University of Michigan (U-M) Department of Electrical Engineering and Computer Science professor Jay Guo and his team announce the development of a new type of screen pixel. The device also contains a solar cell, and could easily be used to boost the energy efficiency of electrical devices. At first, the scientists want to include this technology in cell phones, smartphones and e-readers, but long-term plans call for it to be applied to laptop, tablet and computer screens. The pixels could also be used to create billboards that recycle a lot of the energy used to power them up.
An interesting and unusual application would be to use them to create decorative solar panels, which would fulfill the dual function of looking pretty and producing electricity from sunlight. Details of the work appear in the latest issue of the esteemed scientific journal ACS Nano.
The pixels are, in effect, nothing more than reflective photovoltaic color filter devices, which are perfectly capable of absorbing photons and releasing electrons. The flow of electrons can then be channeled through wires to make electricity.
In modern electronic displays, as little as 8 percent of the entire amount of light generated behind the screen reaches the user’s eyes. The remaining 92 percent is absorbed by a wide variety of polarizers, color filters, and similar devices.
“This absorbed light is totally wasted. It becomes heat. You can feel it if you put your hand close to a monitor. Why not try to harvest some of this energy?” Guo says of the reasons that drove him and his team to create the new technology.
At this point, his new pixels can only convert 2 percent of that 92 percent wasted light into electricity, but refining the technology could result in higher conversion efficiency rates. Even so, the amount of harvested energy is enough to make a difference in small electronic devices today.
The filter the U-M group developed is a mere 200 nanometers thick, which makes it about 100 times thinner than traditional colorant-based filters. It was created by adding organic semiconductor solar cells to an elegant and ultra-thin color filter, the team says.
The ACS Nano paper is called “Photonic Color Filters Integrated with Organic Solar Cells for Energy Harvesting.” At this point, the university is moving to patent the innovation. After this is done, the technology will most likely be awarded to a commercial entity for future development.