作者:Amparo Ruiz-Carretero、Taner Aytun、Carson J. Bruns、Christina J. Newcomb、Wei-Wen Tsai、Samuel I. Stupp
DOI:10.1039/c3ta12411h
日期:——
Organic photovoltaic device efficiencies can be greatly improved by controlling the morphology of donor and acceptor domains in the active layer. Connectivity within donor and acceptor domains is of key importance in order to direct charge carriers efficiently to the electrodes. We report here on self-assembly pathways leading towards optimal morphology of solar cell active layers, using as the donor a hairpin-shaped molecule containing a trans-1,2-diamidocyclohexane core and two arms of diketopyrrolopyrrole conjugated segments, and a C71 fullerene derivative as the electron acceptor. Self-assembly of the donor molecule is driven by the synergistic action of hydrogen bonds and π–π stacking, and under proper conditions this results in the formation of long supramolecular nanowires that enhance charge transport and device efficiencies. We found that a stepwise cooling process with minimal stirring of solutions is necessary to create by self-assembly robust wires that are not disrupted when acceptor molecules are added. The efficiencies of devices created by this process can be 400-fold greater than those of devices formed by simple mixing of donor and acceptor molecules. The synergistic action of hydrogen bonds and π stacking in donor molecules that create long nanowires by self-assembly results in devices that are 54% more efficient than those built with analogous donor molecules containing only the conjugated structure.
通过控制有源层中施主域和受主域的形态可以大大提高有机光伏器件的效率。为了将电荷载流子有效地引导至电极,供体和受体域内的连接性至关重要。我们在这里报告了导致太阳能电池活性层最佳形态的自组装途径,使用包含反式1,2-二酰氨基环己烷核心和两个二酮吡咯并吡咯共轭片段臂的发夹形分子以及C71富勒烯衍生物作为供体作为电子受体。供体分子的自组装是由氢键和π-π堆积的协同作用驱动的,在适当的条件下,这会导致形成长的超分子纳米线,从而增强电荷传输和器件效率。我们发现,要通过自组装坚固的导线来创建在添加受体分子时不会被破坏的导线,需要采用最小限度搅拌溶液的逐步冷却过程。通过该过程创建的器件的效率可以比通过供体和受体分子简单混合形成的器件高 400 倍。供体分子中氢键和 π 堆积的协同作用通过自组装产生长纳米线,使得器件比仅包含共轭结构的类似供体分子构建的器件效率高 54%。