The next generation of solar photovoltaics is upon us. But first new solar materials like perovskite crystals and other organics must be able to catch up with the conventional thin-film and silicon crystalline technologies that are already being used. But there are thousands if not millions of compounds that could yield the next great solar cell. To that end the National Institute of Standards and Technology (NIST) and the Naval Research Laboratory have developed a new means of testing materials to more quickly determine which mixes are likely to prover the best for creating the next generation of solar cells.
"We'd like to give companies and manufacturers an alternative to trial and error," said NIST research chemist Ted Heilweil. "It takes a long time to develop photovoltaic materials for market. Screening them using our method would be much faster,” he asserted.
The team published its in Nature Communications online on July 16. To test the method, the researchers used a number of mixedorganic molecules and polymers that are already understood.
The team published its in Nature Communications online on July 16. To test the method, the researchers used a number of mixedorganic molecules and polymers that are already understood.
The new method uses off-the-shelf laser technology and helps bypass the need to construct prototype cells. The method uses ultrafast lasers to probe a candidate material's abilities directly, without developing electric contacts. The researchers found that combining the first laser with a second laser that’s close to the microwave spectrum, they could mimic the sun with visible light pulses and measure its reaction with the second laser. “When the sample absorbs these ‘terahertz’ waves, its properties change in easily detectable ways,” NIST said.
"We looked at small organics and polymers that people in the solar industry have been using as benchmarks, and we saw the same relative behavior with our terahertz measurements," Heilweil said. "We're pretty confident that our method can tell you what is useful to know."
Organic solar cells are of particular interest for the solar industry because they are lower cost and can be physically flexible, opening up new avenues for creating solar panels and arrays, from solar-powered windows to clothes and more.
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