Humidity-induced degradation via grain boundaries of HC(NH2)2 PbI3 planar perovskite solar cells

Jae Sung Yun*, Jincheol Kim, Trevor Young, Robert J. Patterson, Dohyung Kim, Jan Seidel, Sean Lim, Martin A. Green, Shujuan Huang, Anita Ho-Baillie

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

103 Citations (Scopus)

Abstract

The sensitivity of organic–inorganic perovskites to environmental factors remains a major barrier for these materials to become commercially viable for photovoltaic applications. In this work, the degradation of formamidinium lead iodide (FAPbI3) perovskite in a moist environment is systematically investigated. It is shown that the level of relative humidity (RH) is important for the onset of degradation processes. Below 30% RH, the black phase of the FAPbI3 perovskite shows excellent phase stability over 90 d. Once the RH reaches 50%, degradation of the FAPbI3 perovskite occurs rapidly. Results from a Kelvin probe force microscopy study reveal that the formation of nonperovskite phases initiates at the grain boundaries and the phase transition proceeds toward the grain interiors. Also, ion migration along the grain boundaries is greatly enhanced upon degradation. A post‐thermal treatment (PTT) that removes chemical residues at the grain boundaries which effectively slows the degradation process is developed. Finally, it is demonstrated that the PTT process improves the performance and stability of the final device.
Original languageEnglish
Article number1705363
Number of pages8
JournalAdvanced Functional Materials
Volume28
Issue number11
DOIs
Publication statusPublished - 14 Mar 2018
Externally publishedYes

Keywords

  • degradation
  • formamidinium
  • humidity
  • moisture stability
  • perovskite
  • solar cells

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