Laboratory of Materials and Interface Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Het Kranenveld 14, Postbus 513, 5600 MB, Eindhoven, the Netherlands.; Center for Multiscale Electron Microscopy, Eindhoven University of Technology, Het Kranenveld 14, Postbus 513, 5600 MB, Eindhoven, the Netherlands; Institute for Complex Molecular Systems, Eindhoven University of Technology, De Zaale, 5612 AJ Eindhoven, the Netherlands.
Materials & Structural Analysis, Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG, Eindhoven, the Netherlands.
Ultramicroscopy. 2020 Jan;208:112855. doi: 10.1016/j.ultramic.2019.112855. Epub 2019 Oct 10.
The performance stability of organic photovoltaics (OPVs) is largely determined by their nanoscale morphology and composition and is highly dependent on the interaction with oxygen and water from air. Low-dose cryo-(S)TEM techniques, in combination with OPV donor-acceptor model systems, can be used to assess oxygen- and water-uptake in the donor, acceptor and their interface. By determining a materials dependent critical electron dose from the decay of the oxygen K-edge intensity in Electron Energy Loss Spectra, we reliably measured oxygen- and water-uptake minimizing and correcting electron beam effects. With measurements below the dose limit the capability of STEM-EDX, EFTEM and STEM-EELS techniques are compared to qualitatively and quantitatively measure oxygen and water uptake in these OPV model systems. Here we demonstrate that oxygen and water is mainly taken up in acceptor-rich regions, and that specific oxygen uptake at the donor-acceptor interphase does not occur. STEM-EELS is shown to be the best suitable technique, enabling quantification of the local oxygen concentration in OPV model systems.
有机光伏（OPV）的性能稳定性在很大程度上取决于其纳米级形态和组成，并且高度依赖于与空气中氧气和水的相互作用。低剂量冷冻（S）TEM 技术与 OPV 给体-受体模型系统相结合，可用于评估给体、受体及其界面中氧气和水的吸收。通过确定电子能量损失谱中氧 K 边强度衰减的材料相关临界电子剂量，我们可靠地测量了最小化和校正电子束效应的氧气和水吸收。在低于剂量限制的测量条件下，将 STEM-EDX、EFTEM 和 STEM-EELS 技术的能力进行比较，以定性和定量测量这些 OPV 模型系统中的氧气和水吸收。在这里，我们证明氧气和水主要被吸收在富受体区域，并且在给体-受体界面处不会发生特定的氧气吸收。STEM-EELS 被证明是最合适的技术，能够定量测量 OPV 模型系统中的局部氧浓度。
