Chemical Engineering Department and Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing-Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, Taiwan, 30013, Republic of China.
ACS Appl Mater Interfaces. 2013 Jul 24;5(14):6665-71. doi: 10.1021/am401430h. Epub 2013 Jul 8.
We present a novel idea for overcoming the drawback of poor contact between the ZnO cathode and active layer interface in an inverted polymer solar cell (i-PSC), simply by incorporating an electron-acceptor self-assembled monolayer (SAM)--tetrafluoroterephthalic acid (TFTPA)--on the ZnO cathode surface to create an electron-poor surface of TFTPA on ZnO. The TFTPA molecules on ZnO are anchored on the ZnO surface by reacting its carboxyl groups with hydroxyl groups on the ZnO surface, such that the tetrafluoroterephthalate moieties lay on the surface with plane-on electron-poor benzene rings acting as positive charge centers. Upon coating a layer of fullerenes on top of it, the fullerene molecules can be physically adsorbed by Coulombic interaction and facilitate a promoted electron collection from the bulk. The active layer is composed of the mid bandgap polymer poly(3-hexylthiophene) (P3HT) or low bandgap polymer, poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl) carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7), as the donor and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the acceptor. Significant enhancement in power conversion efficiency (PCE) was observed for the devices with the active layer P3HT:PC61BM (or PC71BM) by promoting from 3.20 to 4.03% (or from 3.27 to 4.04%) and with the active layer PTB7:PC71BM from 6.03 to 6.90%. This method should be also applicable to other types of active layer.
我们提出了一种新的想法，通过在倒置聚合物太阳能电池（i-PSC）的 ZnO 阴极表面上简单地掺入电子受体自组装单层（SAM）-四氟对苯二甲酸（TFTPA）-来克服 ZnO 阴极与活性层界面之间接触不良的缺点，在 ZnO 上形成 TFTPA 的电子贫乏表面。TFTPA 分子通过其羧基与 ZnO 表面上的羟基反应而锚定在 ZnO 表面上，使得四氟对苯二甲酸部分位于表面上，带有平面电子贫苯环作为正电荷中心。在其顶部涂覆一层富勒烯后，富勒烯分子可以通过库仑相互作用被物理吸附，并促进从本体中收集电子。活性层由中带隙聚合物聚（3-己基噻吩）（P3HT）或低带隙聚合物聚[[4,8-双[(2-乙基己基)氧基]苯并[1,2-b:4,5-b']二噻吩-2,6-二基][3-氟-2-[(2-乙基己基)羰基]噻吩[3,4-b]噻吩二基]]（PTB7）组成，作为供体和[6,6]-苯基-C61-丁酸甲酯（PC61BM）或[6,6]-苯基-C71-丁酸甲酯（PC71BM）作为受体。通过从 3.20%提高到 4.03%（或从 3.27%提高到 4.04%），用 P3HT:PC61BM（或 PC71BM）作为活性层的器件的功率转换效率（PCE）得到了显著提高，用 PTB7:PC71BM 作为活性层的器件的 PCE 从 6.03%提高到 6.90%。这种方法也应该适用于其他类型的活性层。
