Organic solar cells with a big leap towards practical use
The right materials for the construction of purely organic solar cells have long been known. Behind the not quite catchy name Y6-SMA lies a large molecule of hydrocarbons, nitrogen, fluorine, sulphur and oxygen.
There are no rare earths, silicon or other metals. And yet the efficiency in laboratory tests is currently 19 percent. Industrially manufactured solar cells do not perform much better.
The biggest problem with this design is its short service life. So far, the durability, which is measured by when the efficiency drops to less than 80 percent of the initial value, has not been convincing. At best, just under 1,000 hours were achieved, which would not be a year even in not very sunny regions.
With a new, seemingly contradictory concept, a research team from the University of Hong Kong has succeeded in multiplying this value - almost to the level of practical solar technology.
The separation between the molecules that emit electrons and those that absorb electrons, which leads to the necessary voltage and thus the generation of electricity, is eliminated in the organic solar cells presented here. Instead, the molecules are interwoven.
This intermixing takes place at the molecular level, resulting in a structure in the nanometer range. In subsequent tests with pulsed laser light, a typical procedure for testing the durability of photoelectronics, the original value for the service life was increased from 1,000 to 25,000 hours.
This means that the efficiency would still be 80 percent after around 10 years and more. Of course, these are still laboratory tests, but the mere fact of having constructed a solar module from organic compounds that is close to current technology should have made the field of research much more interesting.
In the end, it will lead to a compostable solar cell that can be disposed of with garden waste after 20 years of operation. A dream of the future, but at least there would be no supply bottlenecks for the widely used elements.
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