Acid-Catalyzed Reactions Activate DMSO as a Reagent in Perovskite Precursor Inks

J. Clay Hamill, Jeni C. Sorli, István Pelczer, Jeffrey Schwartz, Yueh Lin Loo

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Proton transfer from methylammonium (CH3NH3+) to dimethylsulfoxide (DMSO), a common Lewis-base solvent, initiates the production of ammonium (NH4+) and dimethylammonium ([CH3]2NH2+). We propose two parallel reaction pathways initiated by this proton transfer. Using DMSO-d6 to elucidate reaction schemes, we demonstrate that protonation is followed either by methyl group transfer between the resulting CH3NH2 and residual CH3NH3+, or by transmethylation to CH3NH2 from DMSOH+. The former reaction yields NH4+ and (CH3)2NH2+ and is the dominant pathway at processing relevant temperatures; the latter yields (CH3)2NH2+ in addition to methylsulfonic acid and dimethylsulfide. In the preparation of hybrid organic-inorganic perovskite (HOIP) thin films for photovoltaic applications, the substitution of CH3NH3+ with NH4+ and (CH3)2NH2+ in the HOIP crystal results in deviations from the tetragonal structure expected of phase-pure CH3NH3PbI3, with a deleterious effect on the absorptivity of the resulting films. These results emphasize the importance of elucidating the under-appreciated precursor/solvent reactivity, the products of which, when incorporated into the solid state, can have profound effects on HOIP composition and structure, with a commensurate impact on macroscopic properties and device performance.

Original languageEnglish (US)
Pages (from-to)2114-2120
Number of pages7
JournalChemistry of Materials
Volume31
Issue number6
DOIs
StatePublished - Mar 26 2019

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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