ACS Appl Mater Interfaces. 2018 Aug 8;10(31):26805-26811. doi: 10.1021/acsami.8b09295. Epub 2018 Jul 27.
In this study, we demonstrate that the top surface is enriched by surfactants, tetraoctylammonium bromide, and cetylpyridinium bromide (CPB), in the sol-gel ZnO, being evidenced by the Br depth profile of electron spectroscopy for chemical analysis data. X-ray photoelectron spectroscopy results showed the formation of Zn-Br bonding due to the oxygen defects occupied by Br at the surfactant-enriched ZnO surface. The surfactant-enriched ZnO surface possessed a smoother surface and more hydrophobicity than the pristine ZnO from the experimental results of atomic force microscopy and contact angle, respectively. On the basis of ultraviolet photoelectron spectroscopy data, the work function slightly reduced due to the dipole built-up by the electrostatic force between Br and N to enhance the electron extraction ability. The improved properties benefited the power conversion efficiency (PCE) of bulk-heterojunction polymer solar cells (PSCs) by spin-coating the active layer on the surfactant-enriched ZnO surface. The inverted PSCs with the surfactant-enriched ZnO surface showed the highest PCE of 9.55% for the CPB case, in comparison with the pristine ZnO surface (8.08% PCE). This study discloses that turning the ZnO surface is easily achieved by the addition of surfactants with different molecular structures in the sol-gel ZnO for high performance polymer solar cells.
在这项研究中，我们证明了在溶胶-凝胶 ZnO 中，表面富含表面活性剂四辛基溴化铵和十六烷基溴化吡啶（CPB），这可以从化学分析电子能谱数据的 Br 深度剖析中得到证明。X 射线光电子能谱结果表明，由于表面活性剂富集的 ZnO 表面的氧缺陷被 Br 占据，形成了 Zn-Br 键合。从原子力显微镜和接触角的实验结果可以看出，表面活性剂富集的 ZnO 表面比原始 ZnO 具有更光滑的表面和更高的疏水性。基于紫外光电子能谱数据，由于 Br 和 N 之间的静电力形成的偶极子，功函数略有降低，从而增强了电子提取能力。通过在表面活性剂富集的 ZnO 表面旋涂活性层，提高的性能有益于体异质结聚合物太阳能电池（PSC）的功率转换效率（PCE）。对于 CPB 情况，具有表面活性剂富集 ZnO 表面的倒置 PSC 表现出最高的 PCE 为 9.55%，而原始 ZnO 表面为 8.08% PCE。这项研究揭示了通过在溶胶-凝胶 ZnO 中添加具有不同分子结构的表面活性剂，可以轻松实现 ZnO 表面的翻转，从而获得高性能聚合物太阳能电池。
