Impact of fluorinated end groups on the properties of acceptor–donor–acceptor type oligothiophenes for solution-processed photovoltaic cells
作者:Guangrui He、Xiangjian Wan、Zhi Li、Qian Zhang、Guankui Long、Yongsheng Liu、Yanhui Hou、Mingtao Zhang、Yongsheng Chen
DOI:10.1039/c3tc31709a
日期:——
Two new oligothiophene derivatives with the acceptorâdonorâacceptor structure incorporating fluorinated alkyl cyanoacetate units as the terminal acceptor groups, DCAE7T-F1 and DCAO7T-F7, have been designed and synthesized for solution-processable BHJ solar cells. The impacts of these fluorinated end groups on the optical absorption, solubility, electrochemical properties, morphology, surface energy, film forming ability, mobility and solar cell performance were studied. We found that as the fluorinated alkyl length increased, the surface energy decreased and the lipophobicity increased. Due to its high lipophobic property and a problem with its wettability, DCAO7T-F7 was not able to produce a uniform film by spin coating. A power conversion efficiency (PCE) of 2.26% was achieved with an open-circuit voltage (Voc) of 0.83 V, short circuit current (Jsc) of 5.55 mA cmâ2 and fill factor (FF) of 0.50 for DCAE7T-F1 based solar cells. The low Jsc suggests that controlling the film morphology and molecular assembly is essential for the performance of these fluorinated small molecules.
我们设计并合成了两种新的低聚噻吩衍生物,即 DCAE7T-F1 和 DCAO7T-F7,它们具有受体-单体-受体结构,以氟化烷基氰基乙酸酯单元作为末端受体基团,可用于溶液可处理 BHJ 太阳能电池。研究了这些含氟末端基团对光吸收、溶解性、电化学性能、形貌、表面能、成膜能力、迁移率和太阳能电池性能的影响。我们发现,随着氟化烷基长度的增加,表面能降低,疏油性增加。由于 DCAO7T-F7 具有较高的疏脂性和润湿性,因此无法通过旋涂产生均匀的薄膜。基于 DCAE7T-F1 的太阳能电池的功率转换效率(PCE)为 2.26%,开路电压(Voc)为 0.83 V,短路电流(Jsc)为 5.55 mA cmâ2 ,填充因子(FF)为 0.50。低Jsc表明,控制薄膜形态和分子组装对这些含氟小分子的性能至关重要。