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Analysis of Molecular Orientation in Organic Semiconducting Thin Films Using Static Dynamic Nuclear Polarization Enhanced Solid‐State NMR Spectroscopy
Author(s) -
Suzuki Katsuaki,
Kubo Shosei,
Aussenac Fabien,
Engelke Frank,
Fukushima Tatsuya,
Kaji Hironori
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201707208
Subject(s) - amorphous solid , materials science , spectroscopy , solid state nuclear magnetic resonance , nuclear magnetic resonance spectroscopy , thin film , polarization (electrochemistry) , anisotropy , chemical physics , analytical chemistry (journal) , nuclear magnetic resonance , chemistry , crystallography , nanotechnology , optics , organic chemistry , physics , quantum mechanics
Molecular orientation in amorphous organic semiconducting thin‐film devices is an important issue affecting device performance. However, to date it has not been possible to analyze the “distribution” of the orientations. Although solid‐state NMR (ssNMR) spectroscopy can provide information on the “distribution” of molecular orientations, the technique is limited because of the small amount of sample in the device and the low sensitivity of ssNMR. Here, we report the first application of dynamic nuclear polarization enhanced ssNMR (DNP‐ssNMR) spectroscopy for the orientational analysis of amorphous phenyldi(pyren‐1‐yl)phosphine oxide (POPy 2 ). The 31 P DNP‐ssNMR spectra exhibited a sufficient signal‐to‐noise ratio to quantify the distribution of molecular orientations in amorphous films: the P=O axis of the vacuum‐deposited and drop‐cast POPy 2 shows anisotropic and isotropic distribution, respectively. The different molecular orientations reflect the molecular origin of the different charge transport behaviors.