Title

Sensitivity-Enhanced 207Pb Solid-State NMR Spectroscopy for the Rapid, Non-Destructive Characterization of Organolead Halide Perovskites

Publication Date

9-18-2018

Department

Ames Laboratory; Chemistry

Campus Units

Ames Laboratory, Chemistry

OSTI ID+

1477201

Report Number

IS-J 9762

DOI

10.1021/acs.chemmater.8b01899

Journal Title

Chemistry of Materials

Volume Number

30

Issue Number

20

First Page

7005

Last Page

7015

Abstract

Organolead halide and mixed halide perovskites (CH3NH3PbX3, CH3NH3PbX3–nYn, X and Y = Cl–, Br–, or I–) are promising materials for photovoltaics and optoelectronic devices. 207Pb solid-state NMR spectroscopy has previously been applied to characterize phase segregation and halide ion speciation in mixed halide perovskites. However, NMR spectroscopy is an insensitive technique that often requires large sample volumes and long signal averaging periods. This is especially true for mixed halide perovskites, which give rise to extremely broad 207Pb solid-state NMR spectra. Here, we quantitatively compare the sensitivity of the various solid-state NMR techniques on pure and mixed halide organolead perovskites and demonstrate that both fast MAS and DNP can provide substantial gains in NMR sensitivity for these materials. With fast MAS and proton detection, high signal-to-noise ratio two-dimensional (2D) 207Pb–1H heteronuclear correlation (HETCOR) NMR spectra can be acquired in less than half an hour from only ca. 4 μL of perovskite material. Modest relayed DNP enhancements on the order of 1 to 20 were obtained for perovskites. The cryogenic temperatures (110 K) used for DNP experiments also provide a significant boost in sensitivity. Consequently, it was possible to obtain the 207Pb solid-state NMR spectrum of a 300 nm thick model thin film of CH3NH3PbI3 in 34 h by performing solid-state NMR experiments with a sample temperature of 110 K. This result demonstrates the possibility of using NMR spectroscopy for characterization of perovskite thin films.

DOE Contract Number(s)

CHE-1253058; AC02-07CH11358

Language

en

Department of Energy Subject Categories

36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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