Fractional deviations in precursor stoichiometry dictate the properties, performance and stability of perovskite photovoltaic devices

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Paul Fassl - , Heidelberg University  (Author)
  • Vincent Lami - , Heidelberg University  (Author)
  • Alexandra Bausch - , Heidelberg University  (Author)
  • Zhiping Wang - , University of Oxford (Author)
  • Matthew T. Klug - , University of Oxford (Author)
  • Henry J. Snaith - , University of Oxford (Author)
  • Yana Vaynzof - , Heidelberg University  (Author)

Abstract

The last five years have witnessed remarkable progress in the field of lead halide perovskite materials and devices. Examining the existing body of literature reveals staggering inconsistencies in the reported results among different research groups with a particularly wide spread in the photovoltaic performance and stability of devices. In this work we demonstrate that fractional, quite possibly unintentional, deviations in the precursor solution stoichiometry can cause significant changes in the properties of the perovskite layer as well as in the performance and stability of perovskite photovoltaic devices. We show that while the absorbance and morphology of the layers remain largely unaffected, the surface composition and energetics, crystallinity, emission efficiency, energetic disorder and storage stability are all very sensitive to the precise stoichiometry of the precursor solution. Our results elucidate the origin of the irreproducibility and inconsistencies of reported results among different groups as well as the wide spread in device performance even within individual studies. Finally, we propose a simple experimental method to identify the exact stoichiometry of the perovskite layer that researchers can employ to confirm their experiments are performed consistently without unintentional variations in precursor stoichiometry.

Details

Original languageEnglish
Pages (from-to)3380-3391
Number of pages12
JournalEnergy and Environmental Science
Volume11
Issue number12
Publication statusPublished - Dec 2018
Peer-reviewedYes
Externally publishedYes