Researchers at the University of California, Los Angeles (UCLA) have used an antioxidant known as L-glutathione as an interlayer in an organic PV cell to prevent oxidation of other materials. The efficiency of the cell is 13.5% and the average visible transmittance is 21.5%. Researchers said it is suitable for solar greenhouses.
“We already founded a startup to scale up the production of these organic solar cells for industrial use,” researcher Minhuan Wang said. pv magazine.
The new device has L-glutathione antioxidant as a reducing intermediate layer. This facilitates charge transfer between the cell’s zinc oxide (ZnO) layer and a photoactive layer made of a non-fullerene acceptor known as PM6:Y6, the researchers said “Achieving sustainability in greenhouses by integrating stable semi-transparent organic photovoltaics”, which was published recently The sustainability of nature.
They built the cell from a substrate made of glass and indium tin oxide (ITO), a new intermediate layer, a photoactive layer, hole Transport layer made of molybdenum trioxide (MoO3) and silver (Ag) metal contact.
“TlG molecule can effectively nullify both large defects in the ZnO film and weaken the carrier combinationnation at the interface,” the researchers said, referring to the passivating effect of the interlayer. “The LG molecule prevents charge transfer from the ZnO surface to O 2 , preventing the formation of a superoxide molecule.”
According to their observations, the new intermediate layer has two different functions. On the one hand, it acts as a passivating agent and on the other hand, it dampens the formation of superoxide, which is usually triggered by oxygen vacancy on the ZnO surface.
“Suppressed Superoxide and Hydroxide Radical Generation led in particular to an improvement in the stability of the encapsulated function semi-transparent OPV devices with a PM6/Y6 photoactive layer,” the US group said. “Devices equipped with the LG interlayer retained more than 84% initial efficiency after 1,008 hours of continuous exposuresio.”
With the addition of the intermediate layer, the efficiency of the cells also improved – from 11.6% to 13.5% – as the short-circuit current density improves 20.5 to 22.2 mA cm−2. “Furthermore, due to the strong reducibility of the lG molecule, radical production is reduced,” the researchers said.
They also tested the growth of common crops such as wheat, mung beans and broccoli in a setup with a transparent glass roof with segments of inorganic solar cells and in a setup with a roof made entirely of semi-transparent organic solar cells.
“The yield of the greenhouse with the organic solar roof increased more than the yield of the standard greenhouse,” they noted, noting that the L-glutathione layer blocked ultraviolet rays, which are harmful to plant growth, as well as infrared rays, which can cause greenhouses to overheat.
“We didn’t expect organic solar cells to outperform a conventional glass-roofed greenhouse,” said co-author Yepin Zhao. “But we repeated the experiments several times with the same results, and after further research and analysis, we discovered that plants do not need as much sunlight to grow as we first thought.”