The synthesis and properties of solution processable phenyl cored thiophene dendrimers
作者:William J. Mitchell、Nikos Kopidakis、Garry Rumbles、David S. Ginley、Sean E. Shaheen
DOI:10.1039/b508683c
日期:——
In this paper we describe the convergent synthesis of a new class of phenyl cored thiophene dendrimers, which are promising candidates for use in organic semiconductor devices. We have prepared dendrimers with three and four dendrons around the core as well as dendrimers with 1st and 2nd generation dendrons. All the dendrimers were soluble in common organic solvents such as chloroform, THF and toluene. The structures and size properties are confirmed by a number of techniques including NMR, GPC and MALDI-TOF-MS. Decomposition was studied by TGA with initial breakdown of the hexyl surface groups followed by the aromatic core. The spectroscopic properties were studied by UV-vis and PL spectrometry which demonstrated substantial differences between the dendrimers with three and four dendrons. Optical band gaps varied between 2.34 and 2.60 eV for thin films of the dendrimers and electronic band gaps were, on average, 0.3 eV greater than the optical band gaps. The smallest band gap was measured for the dendrimer with four 2nd generation dendrons around the phenyl core. Fluorescence lifetimes of the molecules in solution ranged from 200 to 560 ps. This range in values was attributed to differences in internal conversion rates associated with varying degrees of flexibility of the extended dendrons.
在本文中,我们介绍了一种新型苯基芯噻吩树枝形分子的聚合合成方法,这种树枝形分子有望用于有机半导体器件。我们制备了核心周围有三个和四个树枝状分子的树枝状聚合物,以及有第一代和第二代树枝状分子的树枝状聚合物。所有树枝状聚合物均可溶于氯仿、四氢呋喃和甲苯等常见有机溶剂。核磁共振、气相色谱和 MALDI-TOF-MS 等多种技术证实了它们的结构和尺寸特性。通过热重分析法研究了分解情况,首先分解的是己基表面基团,然后是芳香族核心。通过紫外-可见光光谱法和聚光光谱法对光谱特性进行了研究,结果表明具有三个和四个树枝的树枝状聚合物之间存在很大差异。树枝状聚合物薄膜的光学带隙介于 2.34 和 2.60 eV 之间,电子带隙平均比光学带隙大 0.3 eV。苯核周围有四个第二代树枝状分子的树枝状聚合物的带隙最小。溶液中分子的荧光寿命从 200 到 560 ps 不等。之所以会出现这样的数值范围,是因为扩展树枝的柔韧性不同,内部转换率也不同。