Perovskite solar panels have one huge advantage over conventional silicon based solar panels — much lower cost. If the dream of inexpensive renewable power is to become a reality, perovskite solar panels may be the key. But they also have several disadvantages that researchers are struggling to overcome. The efficiency of persoskite panels is less than conventional panels, meaning less of the sunlight that strikes them is converted to electricity. They also degrade faster, are susceptible to damage from moisture, and are harder to manufacture commercially.
Researchers at the New York University School of Engineering, together with colleagues at Peking University, the University of Electronic Science and Technology of China, Yale University, and Johns Hopkins University think they have an answer to that last concern. Each perovskite solar panel is composed of several layers. One is called the electron transfer layer or ETL, which facilitates the transfer of electrons between two adjacent layers.
Until now, depositing the ETL on the surface of a panel has been done by spin casting, which involves spinning the cell and allowing centripetal force to disperse the ETL fluid over the perovskite substrate, according to a report in Science Daily. But this technique is limited to small surfaces and results in an inconsistent layer that lowers the performance of the solar cell. Spin casting does not lend itself to large scale commercial manufacturing.
The researchers chose the compound [6,6]-phenyl-C(61)-butyric acid methyl ester — popularly known as PCBM — because of its track record as an ETL material and because PCBM applied in a rough layer offers the possibility of improved conductivity, less penetrable interface contact, and enhanced light trapping. Best of all, it can be sprayed on, a process that does lend itself to commercial production. Spraying the ETL onto the panel surface results in a 30% efficiency gain compared to spin casting techniques.
“Very little research has been done on ETL options for the planar p-i-n design,” says professor André Taylor, who led the research team. “The key challenge in planar cells is, how do you actually assemble them in a way that doesn’t destroy the adjacent layers? Our approach is concise, highly reproducible, and scalable. It suggests that spray coating the PCBM ETL could have broad appeal toward improving the efficiency baseline of perovskite solar cells and providing an ideal platform for record-breaking p-i-n perovskite solar cells in the near future.”
In addition to costing less to manufacture than conventional solar panels, perovskites have the additional advantage of producing electricity from a broad range of the visible light spectrum. They aren’t as efficient or as durable as conventional panels yet, but are getting closer to commercial viability every day, thanks to research projects like this one. The National Natural Science Foundation of China (NSFC), the Foundation for Innovation Research Groups of the NSFC, the Chinese Scholarship Council, and the US National Science Foundation provided funding for the study, which was published recently in the journal Nanoscale.
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