MendoCoastCurrent, October 23, 2008
A new hybrid inorganic/organic material could usher in solar cells that absorb all solar wavelengths. Researchers have created a new material that overcomes two of the major obstacles to solar power: it absorbs all the energy contained in sunlight, and generates electrons in a way that makes them easier to capture.
Ohio State University chemists and their colleagues combined electrically conductive plastic with metals including molybdenum and titanium to create the hybrid material.
This new material is the first that can absorb all the energy contained in visible light at once.
The new polymer could also enable much more efficient charge separation since electrons dislodged by light in the material remain free much longer than in conventional solar cells used in solar powered battery chargers.
The inorganic/organic hybrid polymer material can be made into polymer blends that can “absorb essentially across the entire solar spectrum–they go from about 300 nanometers down to about 10,000 nanometers,” said professor Malcolm Chisholm of Ohio State University.
Solar materials work by using incident light to boost the energy of electrons, thereby separating then from the hull of atoms in the material. They can then be harvested to generate electricity.
However, separated electrons fall back into their host atoms if not collected quickly. Usually, solar materials either fluoresce (called singlet emisson) or phosphoresce (triplet emission). The new hybrid material does both, further increasing potential efficiency.
“The materials we have made show both singlet and triplet emissions,” said Chisholm. “The singlet state lasts a relatively long time, in the region of about 10 pico seconds; the triplet lasts a lot longer–up to a 100 or so microseconds, which should be good for separating the electrons and the hull.”
At this point, the material is years from commercial development, but he added that this experiment provides a proof of concept — that hybrid solar cell materials such as this one can offer unusual properties.
The project was funded by the National Science Foundation and Ohio State’s Institute for Materials Research.
Chisholm is working with Arthur J. Epstein, Distinguished University Professor of chemistry and physics; Paul Berger, professor of electrical and computer engineering and physics; and Nitin Padture, professor of materials science and engineering to develop the material further. That work is part of the Advanced Materials Initiative, one Ohio State’s Targeted Investment in Excellence (TIE) programs.