Revealing nanoscale phase separation in small-molecule photovoltaic blends by plasmonic contrast in the TEM
Revealing nanoscale phase separation in small-molecule photovoltaic blends by plasmonic contrast in the TEM
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通过 TEM 中的等离子体对比揭示小分子光伏混合物中的纳米级相分离
DOI：
10.1016/j.orgel.2012.03.008
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发表时间：
2012
影响因子：
3.2
通讯作者：
K. Fostiropoulos
中科院分区：
文献类型：
--
作者：
W. Schindler;M. Wollgarten;K. Fostiropoulos
有机给体-受体（D-A）吸收体系中相对较差的输运性质影响了有机太阳能电池（OSC）的良好前景。克服这一缺点的一个公认的关键是能够在纳米尺度上控制其体异质结（BHJ）的D-A形态。一个必要的先决条件是表征碳质材料组合的BHJ。然而，由于它们的相似性，特别是如果不是晶体，只有差对比度的图像是通过传统的透射电子显微镜（TEM）实现的。我们应用能量过滤透射电子显微镜光谱成像（EFTEM SI）研究了共蒸发酞菁锌（ZnPc）（D）和C60（A）共混层中具有化学敏感性的局部相分离。作为图像对比，我们利用纯材料的等离子体激元能量之间的显着差异（23和26 eV的ZnPc和C60，分别），记录通过电子能量损失谱。为了充分了解其结构和形态，一方面常规TEM分析允许基于晶格条纹（这里仅C60）识别适当取向的晶相。另一方面，EFTEM SI等离子体激元图揭示了独立于结晶度的两个分子相的完整横向分布。
Good prospects of organic solar cells (OSC) are dampened by relatively poor transport properties in the organic donor–acceptor (D–A) absorber system. A widely recognized key to overcome this drawback is the ability to control its D–A morphology at the bulk heterojunction (BHJ) on the nanometer scale. An essential prerequisite for this is to characterize the BHJ of the carbonaceous materials combination. However, due to their similarity, particularly if not crystalline, only poor-contrast images are achieved by conventional transmission electron microscopy (TEM). We apply energy filtered transmission electron microscopy spectrum imaging (EFTEM SI) to study local phase separation with chemical sensitivity in a co-evaporated zinc phthalocyanine (ZnPc) (D) and C60(A) blend layer. As image contrast we exploit the significant difference between the plasmon energies of the pure materials (23 and 26eV for ZnPc and C60, respectively) as recorded by electron energy loss spectroscopy. In order to fully understand its structure and morphology, on the one hand conventional TEM analysis allows to identify suitably oriented crystalline phases on the basis of lattice fringes (here only C60). On the other hand the EFTEM SI plasmon map discloses the complete lateral distribution of the two molecular phases independent of crystallinity.