Researchers at Ohio State University have accidentally discovered a new solar cell material capable of absorbing all of the sun’s visible light energy. The material is comprised of a hybrid of plastics, molybdenum and titanium. The team discovered it not only fluoresces (as most solar cells do), but also phosphoresces. Electrons in a phosphorescent state remain at a place where they can be “siphoned off” as electricity over 7 million times longer than those generated in a fluorescent state. This combination of materials also utilizes the entire visible spectrum of light energy, translating into a theoretical potential of almost 100% efficiency. Commercial products are still years away, but this foundational work may well pave the way for a truly renewable form of clean, global energy.
Traditional solar cell materials use a property called fluorescence to gather electricity. Energy from the sun strikes whatever material they are made of resulting in a momentary “dislodging” of electrons into an excited state. The excited electrons exist due to a property called fluorescence. They last only a dozen or so picoseconds (trillionths of a second) in this state, which is also called a “singlet state.” The many picosecond dwell there is fairly typical among traditional solar cell material in use today.
The new material, which was accidentally discovered using supercomputers to determine possible theoretical molecular configurations, causes not only fluorescing electrons in the singlet state to be created, but also phosphorescing electrons in what’s called a “triplet state.”
These triplet state electrons remain in their excited state of phosphorescence for scores of microseconds (up to about 200 microseconds, or 0.0002 seconds). With such a long lasting state of free electron flow, their ability to be captured is theoretically significantly greater than existing technologies.
And if the research team’s current efforts (of using only a few molecules of the hybrid materials suspended in a liquid solution) can be extended into practical real-world scales, then products yielding nearly 100% solar efficiency may soon be achievable.