Visualizing band alignment across 2D/3D perovskite heterointerfaces of solar cells with light-modulated scanning tunneling microscopy

Po Cheng Huang, Shao Ku Huang, Ting Chun Lai, Min Chuan Shih, Hung Chang Hsu, Chun Hsiang Chen, Cheng Chieh Lin, Chun Hao Chiang, Chi Ying Lin, Kazuhito Tsukagoshi, Chun Wei Chen, Ya Ping Chiu, Shiow Fon Tsay, Ying Chiao Wang

Research output: Contribution to journalArticlepeer-review

Abstract

Graded 2D perovskite capping shells with continuously upshifting valence bands, produced by tailored dimensional engineering, can effectively extract holes from 3D perovskite cores. Real-space observation of electronic structures will fully reveal the operating mechanisms of 2D/3D hybrid perovskite solar cells (PSCs). Here, for the first time, light-modulated scanning tunneling microscopy visualizes the cross-sectional band alignment across 2D (C4H9NH3)2(CH3NH3)n-1PbnI3n+1/3D CH3NH3PbI3 stacked perovskites. By systematically analyzing their electronic configuration, the mixed-dimensional perovskite band structure along the vertical 3D-to-2D direction can be spatially resolved. Remarkably, the electric field in the 2D perovskite is larger under light illumination than under dark conditions, resulting in an increase in the concentration of holes and electrons distributed in the 2D and 3D perovskites, respectively. Benefiting from this electronic reconstruction, charge recombination is suppressed, thereby significantly promoting the 2D/3D PSC performance. Moreover, our method opens an avenue for direct, local mapping of optoelectronic device energy levels.

Original languageEnglish
Article number106362
JournalNano Energy
Volume89
DOIs
Publication statusPublished - 2021 Nov
Externally publishedYes

Keywords

  • 2D/3D perovskite
  • Band mapping
  • Interface
  • Perovskite solar cells
  • Scanning tunneling microscopy

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)
  • Electrical and Electronic Engineering

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