Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique (INRS) , 1650 Boul. Lionel-Boulet, Varennes, Quebec J3X 1S2, Canada.
Department of Electrical Engineering, École de technologie supérieure, Université du Quebec 1100 , rue Notre-Dame Ouest, Montreal, Quebec H3C 1K3, Canada.
ACS Appl Mater Interfaces. 2018 Feb 21;10(7):6498-6504. doi: 10.1021/acsami.7b17495. Epub 2018 Feb 12.
Performance of bulk heterojunction polymer solar cells (PSCs) highly relies on the morphology of the photoactive layer involving conjugated polymers and fullerene derivatives as donors and acceptors, respectively. Herein, butylamine was found to be able to optimize the morphology of the donor/acceptor (D/A) film composed of a blend of poly(3-hexylthiophene-2,5-diyl) (P3HT) and phenyl-C-butyric acid methyl ester (PCBM). Compared to the commonly used alkane dithiols and halogenated additives with high boiling points, butylamine has a much lower boiling point between 77 and 79 °C, and it is also much "greener". A specific interaction between butylamine and PCBM was demonstrated to account for the morphology improvement. Essentially, butylamine can selectively dissolve PCBM in the P3HT:PCBM blend and facilitate the diffusion of PCBM in the film fabrication processes. Atomic force microscopy and X-ray photoelectron spectroscopy investigations confirmed the formation of the P3HT-enriched top surface and the abundance of PCBM at the bottom side, i.e., the formation of vertical phase segregation, as a consequence of the specific PCBM-butylamine interaction. The D/A film with inhomogeneously distributed D and A components in the vertical film direction, with more P3HT at the hole extraction side and more PCBM at the electron extraction side, enables more efficient charge extraction in the D/A film, reflected by the largely enhanced fill factor. The power conversion efficiency of devices reached 4.03 and 4.61%, respectively, depending on the thickness of the D/A film, and these are among the best values reported for P3HT:PCBM-based devices. As compared to the devices fabricated without the introduction of butylamine under otherwise the same processing conditions, they represented 19.6 and 21.6% improvement in the efficiency, respectively. The discovery of butylamine as a new, effective additive in enhancing the performance of PSCs strongly suggests that the differential affinity of additives toward donors and acceptors likely plays a more important role in morphology optimization than their boiling point, different from what was reported previously. The finding provides useful information for realizing large-area PSC fabrication, where a "greener" additive is always preferred.
体异质结聚合物太阳能电池（PSCs）的性能高度依赖于活性层的形态，该活性层涉及分别作为供体和受体的共轭聚合物和富勒烯衍生物。本文发现，正丁胺能够优化由聚（3-己基噻吩-2,5-二基）（P3HT）和苯并[C][1,2,5]噻二唑-4,7-二酮（PCBM）共混物组成的给体/受体（D/A）膜的形态。与具有高沸点的常用烷烃二硫醇和卤化添加剂相比，正丁胺的沸点在 77 至 79°C 之间要低得多，而且也更加“环保”。证明了正丁胺与 PCBM 之间的特定相互作用是改善形态的原因。本质上，正丁胺可以选择性地溶解 P3HT:PCBM 共混物中的 PCBM，并促进 PCBM 在膜制备过程中的扩散。原子力显微镜和 X 射线光电子能谱研究证实了富 P3HT 的顶层和富含 PCBM 的底层的形成，即垂直相分离的形成，这是由于特定的 PCBM-正丁胺相互作用的结果。D/A 膜中垂直膜方向上不均匀分布的 D 和 A 成分，在空穴提取侧具有更多的 P3HT，在电子提取侧具有更多的 PCBM，使 D/A 膜中更有效地提取电荷，这反映在填充因子的大大提高上。器件的功率转换效率分别达到 4.03%和 4.61%，这取决于 D/A 膜的厚度，这是基于 P3HT:PCBM 器件报道的最佳值之一。与在相同加工条件下不引入正丁胺的器件相比，它们的效率分别提高了 19.6%和 21.6%。正丁胺作为增强 PSCs 性能的新型有效添加剂的发现强烈表明，添加剂对供体和受体的不同亲和力可能在形态优化中起着比沸点更重要的作用，这与之前的报道不同。这一发现为实现大面积 PSC 制造提供了有用的信息，在这种制造中，总是优先选择“更环保”的添加剂。
