Degradation of Highly Alloyed Metal Halide Perovskite Precursor Inks: Mechanism and Storage Solutions

Benjia Dou, Lance M. Wheeler, Jeffrey A. Christians, David T. Moore, Steven P. Harvey, Joseph J. Berry, Frank S. Barnes, Sean E. Shaheen, Maikel F.A.M. Van Hest

Research output: Contribution to journalArticlepeer-review

77 Scopus Citations

Abstract

Whereas the promise of metal halide perovskite (MHP) photovoltaics (PV) is that they can combine high efficiency with solution-processability, the chemistry occurring in precursor inks is largely unexplored. Herein, we investigate the degradation of MHP solutions based on the most widely used solvents, dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). For the MHP inks studied, which contain formamidinium (FA+), methylammonium (MA+), cesium (Cs+), lead (Pb2+), bromide (Br-), and iodide (I-), dramatic compositional changes are observed following storage of the inks in nitrogen in the dark. We show that hydrolysis of DMF in the precursor solution forms dimethylammonium formate, which subsequently incorporates into the MHP film to compromise the ability of Cs+ and MA+ to stabilize FA+-based MHP. The changes in solution chemistry lead to a modification of the perovskite film stoichiometry, band gap, and structure. The solid precursor salts are stable when ball-milled into a powder, allowing for the storage of large quantities of stoichiometric precursor materials.

Original languageAmerican English
Pages (from-to)979-985
Number of pages7
JournalACS Energy Letters
Volume3
Issue number4
DOIs
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 American Chemical Society.

NREL Publication Number

  • NREL/JA-5K00-71274

Keywords

  • degradation
  • efficiency
  • metal halide perovskite
  • photovoltaics

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