Unraveling the Surface State of Photovoltaic Perovskite Thin Film

Rui Wang, Jingjing Xue, Xihan Chen, Canglang Yao, Zhao Kui Wang, Marc H. Weber, Aaron H. Rose, Selbi Nuryyeva, Jiahui Zhu, Tianyi Huang, Yepin Zhao, Shaun Tan, Matthew C. Beard, Yanfa Yan, Kai Zhu, Yang Yang

Research output: Contribution to journalArticlepeer-review

21 Scopus Citations


Recently, most of the highly efficient perovskite optoelectronic devices have been reported to employ effective surface passivation strategies, further confirming the significance of surface states in regulating their device performance. Therefore, an in-depth understanding and a systematic approach toward comprehensive investigations on perovskite surface states are urgently required. Here, we present methodical studies toward understanding the surface states in perovskite thin films utilizing a molecular “positively charged defect indicator” strategy. In formamidinium (FA)-methylammonium (MA) mixed-cation perovskite thin films, a nonuniform distribution of cations is uncovered with FA cations being close to the top and MA close to the bottom of the film, which leads to unique surface defect energetics. Antisite FAI was found to become a dominant deep trap on the surface of this system. As a result, a surface recombination velocity as low as 20 cm/s was achieved in such FA-based perovskite photovoltaic devices.

Original languageAmerican English
Pages (from-to)2417-2428
Number of pages12
Issue number7
StatePublished - 7 Jul 2021

Bibliographical note

Publisher Copyright:
© 2021 Elsevier Inc.

NREL Publication Number

  • NREL/JA-5900-79381


  • cation distribution
  • defect identification
  • MAP3: Understanding
  • mixed-cation perovskite
  • perovskite solar cell
  • surface states


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