Structure of p-Sexiphenyl Nanocrystallites in ZnO Revealed by High-Resolution Transmission Electron Microscopy

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• 作者：Holm Kirmse ; Mino Sparenberg ; Anton Zykov ; Sergey Sadofev ; Stefan Kowarik ; Sylke Blumstengel
• 刊名：Crystal Growth & Design
• 出版年：2016
• 出版时间：May 4, 2016
• 年：2016
• 卷：16
• 期：5
• 页码：2789-2794
• 全文大小：413K
• 年卷期：0
• ISSN：1528-7505

文摘

The structure of para-sexiphenyl (6P) nanocrystallites embedded in ZnO single crystals is resolved by cross-sectional high-resolution transmission electron microscopy (HRTEM) combined with image contrast simulations and X-ray diffraction measurements. The hybrid structures are prepared by subsequent physical vapor deposition of 6P on ZnO(1010) templates followed by overgrowth with ZnO. Application of ultramicrotomy for HRTEM specimen preparation and imaging under different focus conditions provides direct access to the atomic and molecular structure of the hybrid interface and the organic inclusion. The hybrid stacks reveal a high structural perfection. The 6P nanocrystallites maintain a structure as in the bulk crystal. Individual 6P lattice planes can be traced up to the lateral and top interfaces with ZnO, indicating that all interfaces are defined on an atomic/molecular level. Further evaluation of the HRTEM images reveals peculiarities of 6P growth on ZnO(1010). The common 6P β-phase coexists here with the rarely reported γ-phase. The ZnO surface structure induces two mirror-symmetric in-plane preferential orientations of the 6P nanocrystallites. The ZnO surface topography, on the other hand, is critical for the structural perfection of 6P. Although conformal growth is observed, ZnO step edges induce characteristic stacking faults in 6P nanocrystallites.