Nanoscale Domain Imaging of All-Polymer Organic Solar Cells by Photo-Induced Force Microscopy
Nanoscale Domain Imaging of All-Polymer Organic Solar Cells by Photo-Induced Force Microscopy
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DOI：
10.1021/acsnano.7b07865
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发表时间：
2018-02-01
期刊：
影响因子：
17.1
通讯作者：
Bao, Zhenan
中科院分区：
文献类型：
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作者：
Gu, Kevin L.;Zhou, Yan;Bao, Zhenan
有机太阳能电池中本体异质结层的快速纳米级成像对于高性能器件的持续开发至关重要。不幸的是，隧道电子显微镜 (TEM) 和原子力显微镜 (AFM) 等常用成像技术存在重大缺陷。例如，根据相差或地形特征假设域同一性可能会导致不准确的形态学结论。在这里，我们展示了一种称为光诱导力显微镜（PiFM）的技术，用于对具有纳米级化学特异性的有机太阳能电池本体异质结进行成像。 PiFM 是一种相对较新的扫描探针显微镜技术，它将 AFM 尖端与可调谐红外激光相结合，以诱导偶极子进行化学成像。将 AFM 的纳米分辨率与调谐红外激光的化学特异性相结合，我们能够在分辨率接近 10 nm 的全聚合物本体异质结模型中空间映射供体和受体域。将 PiFM 图像的域尺寸与共振软 X 射线散射的整体平均结果进行比较，表明具有极好的定量一致性。此外，我们证明，在我们的全聚合物系统中，MM 形貌、MM 相和 PiFM 显示出较差的相关性，这突出表明需要超越标准 AFM 来表征本体异质结的形态。
Rapid nanoscale imaging of the bulk hetero-junction layer in organic solar cells is essential to the continued development of high-performance devices. Unfortunately, commonly used imaging techniques such as tunneling electron microscopy (TEM) and atomic force microscopy (AFM) suffer from significant drawbacks. For instance, assuming domain identity from phase contrast or topographical features can lead to inaccurate morphological conclusions. Here we demonstrate a technique known as photo-induced force microscopy (PiFM) for imaging organic solar cell bulk heterojunctions with nanoscale chemical specificity. PiFM is a relatively recent scanning probe microscopy technique that combines an AFM tip with a tunable infrared laser to induce a dipole for chemical imaging. Coupling the nanometer resolution of AFM with the chemical specificity of a tuned IR laser, we are able to spatially map the donor and acceptor domains in a model all-polymer bulk heterojunction with resolution approaching 10 nm. Domain size from PiFM images is compared to bulk-averaged results from resonant soft X-ray scattering, indicating excellent quantitative agreement. Further, we demonstrate that in our all-polymer system, the MM topography, MM phase, and PiFM show poor correlation, highlighting the need to move beyond standard AFM for morphology characterization of bulk heterojunctions.