Spatially Resolved Imaging on Photocarrier Generations and Band Alignments at Perovskite/PbI2 Heterointerfaces of Perovskite Solar Cells by Light-Modulated Scanning Tunneling Microscopy

Min Chuan Shih, Shao Sian Li, Cheng Hua Hsieh, Ying Chiao Wang, Hung Duen Yang, Ya Ping Chiu, Chia Seng Chang, Chun Wei Chen

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The presence of the PbI2 passivation layers at perovskite crystal grains has been found to considerably affect the charge carrier transport behaviors and device performance of perovskite solar cells. This work demonstrates the application of a novel light-modulated scanning tunneling microscopy (LM-STM) technique to reveal the interfacial electronic structures at the heterointerfaces between CH3NH3PbI3 perovskite crystals and PbI2 passivation layers of individual perovskite grains under light illumination. Most importantly, this technique enabled the first observation of spatially resolved mapping images of photoinduced interfacial band bending of valence bands and conduction bands and the photogenerated electron and hole carriers at the heterointerfaces of perovskite crystal grains. By systematically exploring the interfacial electronic structures of individual perovskite grains, enhanced charge separation and reduced back recombination were observed when an optimal design of interfacial PbI2 passivation layers consisting of a thickness less than 20 nm at perovskite crystal grains was applied.

Original languageEnglish
Pages (from-to)1154-1160
Number of pages7
JournalNano Letters
Volume17
Issue number2
DOIs
Publication statusPublished - Feb 8 2017
Externally publishedYes

Keywords

  • heterointerface
  • PbI passivation layer
  • Perovskite-based solar cells
  • scanning tunneling spectroscopy

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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