Department of Chemistry, University of Victoria, Victoria, BC V8W 3V6, Canada.
School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.
J Am Chem Soc. 2020 Aug 5;142(31):13469-13480. doi: 10.1021/jacs.0c04975. Epub 2020 Jul 23.
The creation of organic heterojunctions from conjugated polymers on the nanoscale has attracted recent attention as a consequence of their considerable potential in optoelectronic devices. Herein, we report proof-of-concept results on a versatile synthetic strategy to access various linearly segmented nanowire heterojunctions with controlled dimensions using the seeded growth "living crystallization-driven self-assembly" method followed by a secondary crystallization step. Specifically, we describe the creation of coaxial and also segmented coaxial B-A-B and A-B-A nanowires with a solvophilic poly(ethylene glycol) (PEG) corona, an inner crystalline core that consists of poly(di--hexylfluorene) (PDHF), which functions as a donor, and an outer crystalline core of poly(3-(2'-ethylhexyl)thiophene) (P3EHT), which acts as an acceptor. The latter is present either along the entire nanowire or solely in the central or terminal segments. These assemblies were created by seeded growth of two types of π-conjugated polymeric building blocks, the triblock copolymer PDHF--P3EHT--PEG and the diblock copolymer PDHF--PEG, by using fiber-like seeds derived from either material. The nanowires with both solid-state donor and acceptor blocks exhibit Förster resonance energy transfer (FRET) from the PDHF inner core to the P3EHT outer core which was characterized by fluorescence spectroscopy and laser confocal scanning fluorescence microscopy (LCSM). The FRET in the solid-state coaxial heterojunctions with an inner PDHF core and an outer P3EHT core was enhanced relative to the directly analogous system in which the P3EHT block was solvated.
有机杂化异质结的形成源于共轭聚合物在纳米尺度上的应用，由于其在光电设备中具有巨大的潜力，因此受到了广泛关注。在此，我们报告了一种通用的合成策略的概念验证结果，该策略采用种子生长“活的结晶驱动自组装”方法，随后进行二次结晶步骤，可实现各种具有受控尺寸的线性分段纳米线异质结。具体而言，我们描述了通过溶剂化的聚（乙二醇）（PEG）冠层、由聚二-正己基芴（PDHF）组成的结晶内核（作为供体）以及聚（3-（2'-乙基己基）噻吩）（P3EHT）的结晶外核（作为受体）来创建共轴和分段共轴 B-A-B 和 A-B-A 纳米线。后者要么沿整个纳米线存在，要么仅存在于中心或末端段。这些组装体是通过两种类型的π共轭聚合物构建块，即 PDHF-P3EHT-PEG 三嵌段共聚物和 PDHF-PEG 二嵌段共聚物的种子生长来制备的，种子由源自两种材料中的纤维状种子制成。具有固态供体和受体块的纳米线表现出从 PDHF 内核到 P3EHT 外壳的Förster 共振能量转移（FRET），通过荧光光谱和激光共焦扫描荧光显微镜（LCSM）对其进行了表征。具有 PDHF 内核和 P3EHT 外壳的固态同轴异质结中的 FRET 相对于具有 P3EHT 块溶剂化的直接类似物系统得到了增强。
