TY - JOUR
T1 - Elucidating the Role of a Tetrafluoroborate-Based Ionic Liquid at the n-Type Oxide/Perovskite Interface
AU - Noel, Nakita K.
AU - Habisreutinger, Severin N.
AU - Wenger, Bernard
AU - Lin, Yen Hung
AU - Zhang, Fengyu
AU - Patel, Jay B.
AU - Kahn, Antoine
AU - Johnston, Michael B.
AU - Snaith, Henry J.
N1 - Funding Information:
This work was partly funded by the Engineering and Physical Sciences Research Council, UK. N.K.N. acknowledges funding via a fellowship from the Princeton Center for Complex Materials (PCCM). B.W. acknowledges funding from the European Commission via a Marie Skłodowska-Curie individual fellowship (REA Grant No. 706552-APPEL). A.K. and F.Z. gratefully acknowledge funding from the US Department of Energy. S.N.H. was supported by the Director's Fellowship program of the National Renewable Energy Laboratory under Contract No. DE-AC36-08GO28308. This work was authored in part by Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The authors acknowledge the use of Princeton's Imaging and Analysis Center (IAC), which was partially supported by the Princeton Center for Complex Materials, a National Science Foundation (NSF) Materials Research Science and Engineering Center (MRSEC; DMR-1420541).
Publisher Copyright:
© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2020/1/1
Y1 - 2020/1/1
N2 - Halide perovskites are currently one of the most heavily researched emerging photovoltaic materials. Despite achieving remarkable power conversion efficiencies, perovskite solar cells have not yet achieved their full potential, with the interfaces between the perovskite and the charge-selective layers being where most recombination losses occur. In this study, a fluorinated ionic liquid (IL) is employed to modify the perovskite/SnO2 interface. Using Kelvin probe and photoelectron spectroscopy measurements, it is shown that depositing the perovskite onto an IL-treated substrate results in the crystallization of a perovskite film which has a more n-type character, evidenced by a decrease of the work function and a shift of the Fermi level toward the conduction band. Photoluminescence spectroscopy and time-resolved microwave conductivity are used to investigate the optoelectronic properties of the perovskite grown on neat and IL-modified surfaces and it is found that the modified substrate yields a perovskite film which exhibits an order of magnitude lower trap density than the control. When incorporated into solar cells, this interface modification results in a reduction in the current–voltage hysteresis and an improvement in device performance, with the best performing devices achieving steady-state PCEs exceeding 20%.
AB - Halide perovskites are currently one of the most heavily researched emerging photovoltaic materials. Despite achieving remarkable power conversion efficiencies, perovskite solar cells have not yet achieved their full potential, with the interfaces between the perovskite and the charge-selective layers being where most recombination losses occur. In this study, a fluorinated ionic liquid (IL) is employed to modify the perovskite/SnO2 interface. Using Kelvin probe and photoelectron spectroscopy measurements, it is shown that depositing the perovskite onto an IL-treated substrate results in the crystallization of a perovskite film which has a more n-type character, evidenced by a decrease of the work function and a shift of the Fermi level toward the conduction band. Photoluminescence spectroscopy and time-resolved microwave conductivity are used to investigate the optoelectronic properties of the perovskite grown on neat and IL-modified surfaces and it is found that the modified substrate yields a perovskite film which exhibits an order of magnitude lower trap density than the control. When incorporated into solar cells, this interface modification results in a reduction in the current–voltage hysteresis and an improvement in device performance, with the best performing devices achieving steady-state PCEs exceeding 20%.
KW - fermi level
KW - ionic liquids
KW - perovskite solar cell
KW - reduced defect density
KW - time-resolved microwave conductivity
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U2 - 10.1002/aenm.201903231
DO - 10.1002/aenm.201903231
M3 - Article
AN - SCOPUS:85076372551
SN - 1614-6832
VL - 10
JO - Advanced Energy Materials
JF - Advanced Energy Materials
IS - 4
M1 - 1903231
ER -