TY - JOUR
T1 - Acid-Catalyzed Reactions Activate DMSO as a Reagent in Perovskite Precursor Inks
AU - Hamill, J. Clay
AU - Sorli, Jeni C.
AU - Pelczer, István
AU - Schwartz, Jeffrey
AU - Loo, Yueh Lin
N1 - Funding Information:
The authors acknowledge the financial support from the National Science Foundation through award numbers CMMI-1537011 and DMR-1420541. The latter originates from NSF’s MRSEC program that supports the Princeton Center for Complex Materials. Hamill is supported by the Department of Defense (DoD) through a National Defense Science and Engineering Graduate (NDSEG) Fellowship. The authors also acknowledge Professor Barry Rand (Princeton University, Department of Electrical Engineering) for his insightful suggestions regarding the utility of sequential precursor addition/heating experiments.
PY - 2019/3/26
Y1 - 2019/3/26
N2 - 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.
AB - 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.
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U2 - 10.1021/acs.chemmater.9b00019
DO - 10.1021/acs.chemmater.9b00019
M3 - Article
AN - SCOPUS:85063488773
SN - 0897-4756
VL - 31
SP - 2114
EP - 2120
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 6
ER -