Department of Chemistry and The James Franck Institute, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States.
J Am Chem Soc. 2011 Feb 16;133(6):1885-94. doi: 10.1021/ja108601g. Epub 2011 Jan 25.
Herein, we describe the synthesis of fluorinated polythienothiophene-co-benzodithiophenes (PTBFs) and the characterization of their physical properties, especially their performance in solar cells. Fluorination of the polymer backbone lowered both the HOMO and LUMO energy levels and simultaneously widened the energy bandgap of the polymer (0.1-0.2 eV). Incorporation of fluorine into the various positions of the polymer backbone significantly affected the solar cells' power conversion efficiency from 2.3% to 7.2%. Detailed studies revealed that the polymer containing mono-fluorinated thienothiophene gave the best solar cell performance. Perfluorination of the polymer backbone led to poor compatibility with PC(71)BM molecules, thus poor solar energy conversion efficiency. This is possibly due to the enhanced self-organization properties of the polymer chains and the fluorophobicity effect. Furthermore, it was found that perfluorination of the polymer backbone resulted in poor photochemical stability against singlet oxygen attack. Theoretical studies indicated that the internal polarization caused enhancement of the negative charge density on thienothiophene rings, which rendered them vulnerable to [2+4] cycloaddition reaction with singlet oxygen.
在此，我们描述了氟化聚噻吩并噻吩-co-苯并二噻吩（PTBFs）的合成及其物理性质的表征，特别是其在太阳能电池中的性能。聚合物主链的氟化降低了 HOMO 和 LUMO 能级，同时拓宽了聚合物的能带隙（0.1-0.2 eV）。氟原子在聚合物主链的不同位置的引入显著影响了太阳能电池的功率转换效率，从 2.3%提高到 7.2%。详细的研究表明，含有单氟化噻吩并噻吩的聚合物给出了最佳的太阳能电池性能。聚合物主链的全氟化导致与 PC（71）BM 分子的相容性较差，因此太阳能转换效率较差。这可能是由于聚合物链的自组织性质增强和疏氟性效应所致。此外，还发现聚合物主链的全氟化导致对单线态氧攻击的光化学稳定性较差。理论研究表明，内部极化导致噻吩并噻吩环上负电荷密度增强，使其容易与单线态氧发生[2+4]环加成反应。
