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Title: Methylammonium lead iodide grain boundaries exhibit depth-dependent electrical properties

In this paper, the nanoscale through-film and lateral photo-response and conductivity of large-grained methylammonium lead iodide (MAPbI 3) thin films are studied. In perovskite solar cells (PSC), these films result in efficiencies >17%. The grain boundaries (GBs) show high resistance at the top surface of the film, and act as an impediment to photocurrent collection. However, lower resistance pathways between grains exist below the top surface of the film, indicating that there exists a depth-dependent resistance of GBs (R GB(z)). Furthermore, lateral conductivity measurements indicate that R GB(z) exhibits GB-to-GB heterogeneity. These results indicate that increased photocurrent collection along GBs is not a prerequisite for high-efficiency PSCs. Rather, better control of depth-dependent GB electrical properties, and an improvement in the homogeneity of the GB-to-GB electrical properties, must be managed to enable further improvements in PSC efficiency. Finally, these results refute the implicit assumption seen in the literature that the electrical properties of GBs, as measured at the top surface of the perovskite film, necessarily reflect the electrical properties of GBs within the thickness of the film.
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [3] ;  [4] ;  [2] ;  [1]
  1. National Inst. of Standards and Technology (NIST), Boulder, CO (United States). Material Measurement Lab., Applied Chemicals and Materials Division
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States). Chemistry and Nanoscience Center
  3. National Inst. of Standards and Technology (NIST), Boulder, CO (United States). Physical Measurement Lab., Applied Physics Division
  4. National Renewable Energy Lab. (NREL), Golden, CO (United States). National Center for Photovoltaics
Publication Date:
Report Number(s):
NREL/JA-5900-67690
Journal ID: ISSN 1754-5692; EESNBY
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
Energy & Environmental Science
Additional Journal Information:
Journal Volume: 9; Journal Issue: 12; Journal ID: ISSN 1754-5692
Publisher:
Royal Society of Chemistry
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 77 NANOSCIENCE AND NANOTECHNOLOGY; 36 MATERIALS SCIENCE; nanoscale; methylammonium lead iodide thin films
OSTI Identifier:
1339245