Sunday, March 30, 2014 — “However, if you continue to mix the layers, you get a uniform batter with less purity, which decreases solar cell performance as the charges recombine and are lost due to too much mixing.
“What we find is that in real devices the structure is similar to making swirls with different sized forks using a combination of big or small motions. This creates two length scales that can have different degrees of batter uniformity, leading to complex tradeoffs between size, purity and performance. Our task now is to understand these tradeoffs and find out how to engineer solar cells that take advantage of them.”
The paper, titled “Quantification of Nano- and Mesoscale Phase Separation and Relation to Donor and Acceptor Quantum Efficiency, Jsc, and FF in Polymer:Fullerene Solar Cells,” appears in Advanced Materials (DOI: 10.1002/adma.201400216). The research was funded by the U.S. Department of Energy, Office of Science, Basic Energy Science and the Chinese Ministry of Science and Technology.