Electron staining is generally performed prior to observing organic materials via transmission electron microscopy (TEM) to enhance image contrast. However, electron staining can deteriorate organic materials. Here, we demonstrate electrostatic potential imaging of organic materials via differential phase contrast (DPC) scanning transmission electron microscopy (STEM) without electron staining. Electrostatic potential imaging drastically increases the contrast between different materials. Phase-separated structures in a poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend that are impossible to observe using conventional STEM are clearly visualized. Furthermore, annealing behavior of the phase-separated structures is directly observed. The morphological transformations in the samples are consistent with their physical parameters, including their glass transition and melting temperatures. Our results indicate that electrostatic potential imaging is highly effective for observing organic materials.

中文翻译：

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通过微分相差扫描透射电子显微镜对有机材料中的相分离结构进行静电势成像

电子染色通常在通过透射电子显微镜 (TEM) 观察有机材料之前进行，以增强图像对比度。然而，电子染色会使有机材料变质。在这里，我们通过微分相差 (DPC) 扫描透射电子显微镜 (STEM) 展示了有机材料的静电势成像，无需电子染色。静电势成像极大地增加了不同材料之间的对比度。聚(3-己基噻吩) (P3HT) 和 [6,6]-苯基-C61-丁酸甲酯 (PCBM) 混合物中的相分离结构在使用传统 STEM 时无法观察到的结构清晰可见。此外，直接观察到相分离结构的退火行为。样品中的形态转变与其物理参数一致，包括玻璃化转变温度和熔化温度。我们的结果表明静电势成像对于观察有机材料非常有效。