Imaging 0.36 nm Lattice Planes in Conjugated Polymers by Minimizing Beam Damage
Imaging 0.36 nm Lattice Planes in Conjugated Polymers by Minimizing Beam Damage
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DOI：
10.1021/acs.macromol.0c01082
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发表时间：
2020-10-13
期刊：
影响因子：
5.5
通讯作者：
Gomez, Enrique D.
中科院分区：
文献类型：
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作者：
Kuei, Brooke;Bator, Carol;Gomez, Enrique D.
透射电子显微镜能以0.5埃的分辨率分辨材料的原子结构。然而，软质材料的高分辨率透射电子显微镜（HRTEM）受到光束损伤的限制。我们在一系列共轭聚合物中表征了损伤，包括聚（3-己基噻吩-2,5-二基）（P3HT）、聚（3-十二烷基噻吩-2,5-二基）（P3DDT）和聚[（5,6-二氟-2,1,3-苯并噻吩-4,7-二基）-alt-(3,3 ' '-二（2-辛基十二烷基）-2,2'；5“,2”;5 ‘，2 -季噻吩-5,5 ’' -二基)](PffBT4T-2OD)，通过监测电子衍射峰随剂量率、光束湮没和温度的衰减。我们还测量了低损耗电子能谱随剂量率的衰减。这些损伤实验表明，共轭聚合物中束损伤的主要机制是电离产生的反应物质的扩散，可能是侧链。阐明辐射效应的机理描述，可以使成像方案的损害最小化，这使得3.6埃pi-pi堆叠在溶液处理的共轭聚合物（PffBT4T-2OD）的直接成像成为可能，将这类材料的最先进的分辨率提高了一个数量级。
Transmission electron microscopy can resolve the atomic structure of materials with 0.5 angstrom resolution. High-resolution transmission electron microscopy (HRTEM) of soft materials, however, is limited by beam damage. We characterized damage in a series of conjugated polymers comprising poly(3-hexylthiophene-2,5-diyl) (P3HT), poly(3-dodecylthiophene-2,5-diyl) (P3DDT), and poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3"'-di(2-octyldodecyl)-2,2';5',2 '';5 '',2 -quaterthiophene-5,5"'-diyl)] (PffBT4T-2OD) by monitoring the decay of electron diffraction peaks as a function of dose rate, beam blanking, and temperature. We also measured the decay of low-loss electron energy-loss spectra as a function of dose rate. These damage experiments suggest that the dominant mechanism of beam damage in conjugated polymers is the diffusion of a reacting species generated from ionization, likely of side chains. Elucidating a mechanistic description of radiation effects leads to imaging protocols that can minimize damage, which enables the direct imaging of 3.6 angstrom pi-pi stacking in a solution-processed conjugated polymer (PffBT4T-2OD), improving state-of-the-art resolution of this class of materials by an order of magnitude.