Dynamic Evolution from Chain Disorder to Order of PTB7 Condensed State Structures under External Fields.
Dynamic Evolution from Chain Disorder to Order of PTB7 Condensed State Structures under External Fields.
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DOI：
10.1021/acsami.8b08938
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发表时间：
2018-07
影响因子：
9.5
通讯作者：
Jiaxuan Ren;Xiaona Li;Tengning Ma;B. Liu;Hao Zhang;Tao Li;D. Lu
中科院分区：
文献类型：
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作者：
Jiaxuan Ren;Xiaona Li;Tengning Ma;B. Liu;Hao Zhang;Tao Li;D. Lu
本研究通过紫外-可见吸收光谱、原子力显微镜和透射电子显微镜（TEM）研究了外场（溶剂、温度、溶液浓度和外力）对聚[[4,8-二[（2-乙基己基）氧]苯并[1,2- b:4,5- b']二噻吩-2,6-二基][3-氟-2-[（2-乙基己基）羰基]噻吩[3,4- b]噻吩二基]（PTB7）缩合态结构从无序到有序的动态演化过程的影响。发现pptb7主链在不良溶剂1,2-二氯乙烷的诱导下呈现非晶构象。然而，当温度降低时，贫溶剂的溶解度再次降低时，在非晶态构象中出现了局部有序聚集。值得注意的是，随着溶液浓度的降低或外力的增大，有序团聚体的大小进一步增大。紫外-可见吸收光谱中发现PTB7有两个主要的吸收峰；用A0 -0表示低能量吸收峰的强度，用A0-1表示高能量吸收峰的强度。采用比值R = A0-0/ A0-1表征PTB7凝聚态结构在吸收光谱中由无序到有序的动态演化。PTB7大尺寸有序聚集态的系数由非晶态的0.94提高到1.25。透射电镜也能清晰地观察到从无序到有序的动态演化过程。推测由于共聚物构象的复杂性，PTB7的凝聚态结构（无定形、局部有序聚集和大规模有序聚集）可能同时存在。该研究为基于共轭聚合物凝聚态物理的分子设计和材料合成奠定了物理基础，提高了光电子器件效率。
In this research, the effect of external fields (solvent, temperature, solution concentration, and external force) on dynamic evolution from chain disorder to order of poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2- b:4,5- b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4- b]thiophenediyl]] (PTB7) condensed state structures was explored by UV-vis absorption spectra, atomic force microscope, and transmission electron microscopy (TEM). It was found that PTB7 main chains presented amorphous conformations induced by the poor solvent 1,2-dichloroethane. However, the local ordered aggregation appeared in amorphous conformations when the solubility of the poor solvent was again lowered by reducing temperature. It is worth noting that the size of ordered aggregation was further increased with the decrease of solution concentration or increase of external force. It was found that there were two main PTB7 absorption peaks in the UV-vis absorption spectra; we denoted A0 -0 for the intensity of the lower energy absorption peak and A0-1 for the intensity of the higher energy absorption peak. The ratio R = A0-0/ A0-1 was used to characterize the dynamic evolution from disorder to order of the PTB7 condensed state structures in absorption spectra. It increased from 0.94 for PTB7 amorphous state to 1.25 for PTB7 large-size ordered aggregation. The dynamic evolution from chain disorder to order could also be distinctly observed by TEM. It was inferred that PTB7 condensed state structures (amorphous state, local ordered aggregation, and large-scale ordered aggregation) might exist simultaneously because of the complexity of copolymer conformations. This research is meaningful to establish physical basis for the molecule design and the synthesis of materials to enhance photoelectronic device efficiency based on condensed matter physics of conjugated polymer.