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Title: Strongly Enhanced Photovoltaic Performance and Defect Physics of Air-Stable Bismuth Oxyiodide (BiOI)

Bismuth-based compounds have recently gained increasing attention as potentially nontoxic and defect-tolerant solar absorbers. However, many of the new materials recently investigated show limited photovoltaic performance. Herein, one such compound is explored in detail through theory and experiment: bismuth oxyiodide (BiOI). BiOI thin films are grown by chemical vapor transport and found to maintain the same tetragonal phase in ambient air for at least 197 d. The computations suggest BiOI to be tolerant to antisite and vacancy defects. All-inorganic solar cells (ITO|NiO x|BiOI|ZnO|Al) with negligible hysteresis and up to 80% external quantum efficiency under select monochromatic excitation are demonstrated. The short-circuit current densities and power conversion efficiencies under AM 1.5G illumination are nearly double those of previously reported BiOI solar cells, as well as other bismuth halide and chalcohalide photovoltaics recently explored by many groups. Through a detailed loss analysis using optical characterization, photoemission spectroscopy, and device modeling, direction for future improvements in efficiency is provided. In conclusion, this work demonstrates that BiOI, previously considered to be a poor photocatalyst, is promising for photovoltaics.
Authors:
ORCiD logo [1] ;  [2] ;  [3] ;  [2] ;  [2] ;  [3] ;  [3] ;  [3] ;  [3] ;  [3] ;  [2] ;  [3] ;  [3] ;  [4] ;  [3] ;  [2]
  1. Univ. of Cambridge, Cambridge (United Kingdom); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Univ. of Cambridge, Cambridge (United Kingdom)
  3. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  4. Colorado School of Mines, Golden, CO (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
Publication Date:
Report Number(s):
NREL/JA-5K00-68975
Journal ID: ISSN 0935-9648
Grant/Contract Number:
AC36-08GO28308; SC0001088
Type:
Published Article
Journal Name:
Advanced Materials
Additional Journal Information:
Journal Volume: 29; Journal Issue: 36; Journal ID: ISSN 0935-9648
Publisher:
Wiley
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; air-stability; bismuth oxyiodide; defect-tolerance; ns2 compounds; photovoltaics
OSTI Identifier:
1373141
Alternate Identifier(s):
OSTI ID: 1373142; OSTI ID: 1394737