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Download fileSpatially Heterogeneous Chlorine Incorporation in Organic–Inorganic Perovskite Solar Cells
journal contribution
posted on 2016-08-30, 00:00 authored by Yanqi Luo, Shany Gamliel, Sally Nijem, Sigalit Aharon, Martin Holt, Benjamin Stripe, Volker Rose, Mariana I. Bertoni, Lioz Etgar, David P. FenningSpatial heterogeneities
in the chemical makeup of thin film photovoltaic
devices are pivotal in determining device efficiency. We report the
in-plane spatial distribution and degree of chlorine incorporation
in organic–inorganic lead halide perovskite absorbers by means
of nondestructive synchrotron-based nanoprobe X-ray fluorescence.
The presence of chlorine is positively identified in CH3NH3PbI3 films synthesized with Cl-containing
precursors and as an impurity in some films synthesized with nominally
Cl-free precursors. The impurity may be introduced from precursors
or as contaminants during film synthesis. The films formed from Cl-containing
precursors contain roughly an order of magnitude higher amount of
chlorine, with Cl:I values greater than 0.02 found whether Cl is present
in either the organic or the inorganic precursor for both one- and
two-step fabrication processes. A spatial variation in the Cl incorporation
is observed within single particles and as well as between particles
within a given film, and the standard deviation of the Cl:I ratio
across the films is up to 30% of the average value. Understanding
and controlling the heterogeneous distribution of chlorine in hybrid
perovskite layers may offer a path to improve their photovoltaic performance.