@article{b06b0c1cb2884afa88952e0a47297e57,
title = "Organic Hole Transport Material Ionization Potential Dictates Diffusion Kinetics of Iodine Species in Halide Perovskite Devices",
abstract = "Iodine-containing volatiles are major degradation products of halide perovskite materials under irradiation, yet iodine diffusion kinetics into and throughout organic hole transport materials (HTMs) and consequent reactions are largely unexplored. Here, we modify the Ca:O2 corrosion test to Ag:I2 to quantify I2 transmission rates through common organic HTMs. We observe I2 permeability to inversely correlate with HTM ionization energy, or the highest occupied molecular orbital (HOMO) energy. Tracking electronic conductance during exposure to I2 confirms shallow HOMO HTMs are strongly oxidized (i.e., doped), leading to substantial I2 uptake and increased transmission rates. Finally, relationships between HOMO level, doping, and transmission rate are maintained when methylammonium lead triiodide (MAPbI3) photolysis products are the only source of iodine. While HTM energetics influence the initial performance of halide perovskite devices by selective charge extraction, our results further suggest they will affect device stability; deeper HOMO energy HTMs will suppress iodine migration and associated degradation mechanisms.",
author = "Kerner, {Ross A.} and Sungyeon Heo and Kwangdong Roh and Kyle MacMillan and Larson, {Bryon W.} and Rand, {Barry P.}",
note = "Funding Information: This work received partial support from ExxonMobil through its membership in the Princeton E-filliates Partnership of the Andlinger Center for Energy and the Environment. K.R. acknowledges support from DARPA Award no. N66001-20-1-4052. The authors acknowledge the use and aid of Princeton{\textquoteright}s Imaging and Analysis Center, which is partially supported by the Princeton Center for Complex Materials, a National Science Foundation (NSF)-MRSEC program (DMR-1420541). We thank Andrew Shapiro for initial experiments, and Prof. Andrew Bocarsly and Dr. Steven Tignor for helpful discussions. S.H. thanks Saeed-Uz-Zaman Khan and Lianfeng Zhao for help with the conductivity measurement setup. This work was authored in part by the National Renewable Energy Laboratory (NREL), operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. The Derisking Halide Perovskite Solar Cells program of the National Center for Photovoltaics, funded by the U.S. DOE, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies Office, is acknowledged by B.W.L. for project support. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. Publisher Copyright: {\textcopyright} 2021 American Chemical Society.",
year = "2021",
month = feb,
day = "12",
doi = "10.1021/acsenergylett.0c02495",
language = "English",
volume = "6",
pages = "501--508",
journal = "ACS Energy Letters",
issn = "2380-8195",
publisher = "American Chemical Society",
number = "2",
}
