Ohio State University research leader Professor Malcolm Chisholm at the Department of Chemistry and two noted researchers at the National Taiwan University Department of Chemistry have their new photovoltaic solar material research published by the Proceedings of the National Academy of Science.

Malcolm Chisholm

Malcolm Chisholm

The excitement is about a synthesized electrically conductive plastic combined with metals including molybdenum and titanium forming up a new hybrid solar collector material. The claims are astonishing and will trigger your skepticism – some reports claim Professor Chisholm expects near 100% efficiency.

The Ohio State team explored an unreported number of different molecular configurations on a computer at the Ohio Supercomputer Center. Then the colleagues at National Taiwan University synthesized the molecules of the new material in a liquid solution, measured the frequencies of light the molecules absorbed, and also measured the length of time that excited electrons remained free in the molecules.

They saw something very unusual. The molecules didn’t just fluoresce as some solar cell materials do. They phosphoresced as well. Both luminous effects are caused by a material absorbing and emitting energy, but phosphorescence lasts much longer.

Current solar cell materials make 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 electron activity only lasts a dozen or so picoseconds (trillionths of a second) in this state, which is also called a “singlet state.” The many picosecond dwell period is fairly typical among traditional solar cell materials in use today.

But phosphorescing electrons exist 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) when the molecules were deposited in a thin film, similar to how they might be arranged in an actual solar cell. With such a long lasting state of free electron flow, their ability to be captured is theoretically significantly greater than existing technologies.

Electrons in a phosphorescent state remain at a place where they can be “siphoned off” as electricity over a theoretical 7 million times longer dwell period than those generated in a fluorescent state. This combination of materials is also claimed to utilize the entire visible spectrum of light energy, translating into a theoretical potential of almost 100% efficiency.

That’s sensational – now can it be pushed to engineering a cell and grow to volume?

Only a few molecules were created through a joint effort of the OSU team and the team from the National Taiwan University. They synthesized enough of the material to carry out preliminary tests. And while these early findings are truly remarkable, there are still more on the horizon.

Chisholm said, “This long-lived excited state should allow us to better manipulate charge separation.” The material may be years from commercial development, but Professor Chisholm added that this experiment provided a proof of concept — that hybrid solar cell materials such as this one can offer unusual properties.

This may be only the first solar sensation from material modeling in supercomputers. Supercomputers are enabling an entirely new area of material research. Scientists don’t have to physically create samples of every possible material in the lab, and then test and document everything they learn about it. Now they can set up a series of parameters and instruct a supercomputer to find the one that best matches their desires, wants and wishes. Such computations often takes many days or even weeks for each trial material, but it’s more economical, feasible and far faster than making and testing each pre-worked out human idea.

Materials analysis that supercomputers carry out is only as good as software is properly designed, and the machine is powerful. Faster computers are allowing research teams to develop better, improved and more comprehensive software driven models for materials research.

This is just a first spark of what’s coming.


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