Performance by Fluorination
Fluorinating conjugated polymers is a widely adopted strategy to enhance the efficiency of polymer solar cells. Given the electron-withdrawing nature of fluorine, fluorination typically happens on the electron-deficient acceptor moiety of the donor-acceptor conjugated polymers.
However, in a recent paper first-authored by Dr. Qianqian Zhang in Chemistry of Materials, researchers in the You Group show that fluorinating the electron-rich thiophene units that link the donor and acceptor moieties can demonstrate a similar device efficiency-enhancing effect.
To enable this study, Dr. Zhang had to develop novel chemistry to incorporate the fluorine substituents in the electron-rich thiophene unit. As a reward, she was able to improve the device efficiency of the FTAZ polymer, 6.6%, by more than 10%, reaching 7.7% with more fluorination in the case of 4’-FT-FTAZ.