Chinese researchers have pushed organic solar cell efficiency to 20.4%, according to a new study in the journal Joule. Specifically, the team at China’s Ningbo Institute of Materials Technology and Engineering achieved this with molecular locking. Their cells also kept more than 85% of their output after 2,000 hours of nonstop use.
Organic solar cells use carbon-based materials instead of traditional silicon to convert sunlight into power. Because of this, they are lighter, more flexible, and can even be see-through. However, the bond between their layers and electrodes tends to weaken under heat and sunlight. As a result, the layers peel apart, and the cell fails. For this reason, producing these cells at a large scale has remained difficult.
To fix this, the team first placed an ultra-thin layer of indium chloride between the electrode and the film. After heating, this layer triggers a chemical reaction that locks the film firmly to the electrode. The process then forms a tight network of bonds that holds everything in place. In other words, the technique glues the cell together at a molecular level so the layers stay put.
Because the layers now stay locked, the small-area lab cells reached 20.4% power conversion efficiency. The team then scaled up to a module measuring 15.6 square centimeters. That larger module also hit 18.8% efficiency, which the researchers describe as a record. In short, the technique works at both small and large scales, which matters for mass production.
Prof. LIU Quan of the Chinese Academy of Sciences led the research at NIMTE. The team then published the study in Joule on October 21.
“We scaled the technique to large-area modules with an aperture area of 15.6 cm2, reaching a record active-area PCE of 18.8%,” said Prof. LIU Quan, corresponding author of the study.
According to the researchers, the technique could one day serve as a universal platform for mass-producing organic solar panels. Traditional silicon panels currently reach 20% to 25% efficiency, but they are heavy and rigid. By contrast, organic cells stay light and flexible, so they could cover buildings, car roofs, and smartwatch screens. The National Natural Science Foundation of China also funded the work.
You can read the research paper here.