Shallow Iodine Defects Accelerate the Degradation of α-Phase Formamidinium Perovskite

Shaun Tan, Ilhan Yavuz*, Marc H. Weber, Tianyi Huang, Chung Hao Chen, Rui Wang, Hao Cheng Wang, Jeong Hoon Ko, Selbi Nuryyeva, Jingjing Xue, Yepin Zhao, Kung-Hwa Wei, Jin Wook Lee, Yang Yang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Shallow defects, by definition, do not constitute non-radiative recombination centers and are, therefore, mostly benign and of less importance in inorganic covalent semiconductors, such as silicon or gallium arsenide. Perhaps, for this reason, shallow defects have received comparatively less attention from the metal halide perovskite community. In this work, we observed through systematic experimental and computational studies that shallow iodine interstitial defects (Ii) can be unintentionally generated during commonly used surface treatments for state-of-the-art perovskite solar cells (PSCs). Although shallow and, thus, not particularly detrimental to initial device performance, Ii aggravates the phase instability of FAPbI3 perovskites to accelerate its degradation. A universal strategy is proposed to resolve this issue to significantly elongate the operational lifetime of PSCs.

Original languageEnglish
Pages (from-to)2426-2442
Number of pages17
Issue number11
StatePublished - 18 Nov 2020


  • defects
  • formamidinium
  • iodine interstitial
  • iodine vacancy
  • passivation
  • perovskite
  • shallow defects
  • stability
  • surface treatment
  • trifluoroacetate

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