Campus Units

Chemistry, Ames Laboratory

Document Type

Article

Publication Version

Submitted Manuscript

Publication Date

9-18-2018

Journal or Book Title

Chemistry of Materials

DOI

10.1021/acs.chemmater.8b01899

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. 5 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 hours 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.

Comments

This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Chemistry of Materials, copyright © American Chemical Society after peer review. To access the final edited and published work see DOI: 10.1021/acs.chemmater.8b01899. Posted with permission.

Copyright Owner

American Chemical Society

Language

en

File Format

application/pdf

Published Version

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