Analysis of Molecular Orientation in Organic Semiconducting Thin Films Using Static Dynamic Nuclear Polarization Enhanced Solid‐State NMR Spectroscopy

Abstract

Molecular orientation in amorphous organic semiconducting thin-film devices is an important issue affecting device performance.However,todate it has not been possible to analyzet he "distribution" of the orientations.A lthough solid-state NMR (ssNMR) spectroscopycan provideinformation on the "distribution" of molecular orientations,t he technique is limited because of the small amount of sample in the device and the low sensitivity of ssNMR. Here,wereport the first application of dynamic nuclear polarization enhanced ssNMR (DNP-ssNMR) spectroscopyf or the orientational analysis of amorphous phenyldi(pyren-1-yl)phosphine oxide (POPy 2 ). The 31 PD NP-ssNMR spectra exhibited as ufficient signal-to-noise ratio to quantify the distribution of molecular orientations in amorphous films:the P=Oaxis of the vacuumdeposited and drop-cast POPy 2 shows anisotropic and isotropic distribution, respectively.T he different molecular orientations reflect the molecular origin of the different charge transport behaviors.

Noise Reduction in Solid-State NMR Spectra Using Principal Component Analysis

“…To resolve this, various techniques have been developed that use high field magnets, cryogenic detection systems, , and paramagnetic dopants to reduce the longitudinal relaxation time ( T 1 ) . In addition, 1 H indirect detection, − nonuniform sampling, and dynamic nuclear polarization − methods have been developed to enhance the sensitivity.…”