posted on 2022-10-20, 16:04authored byMichel De Keersmaecker, Neal R. Armstrong, Erin L. Ratcliff
Reactive defects in hybrid organic–inorganic metal
halide
perovskites that limit material functionality and durability, factors
which ultimately dictate (opto)electronic device performance, are
difficult to probe. Herein, we expand an electrochemical methodology
for near-valence defect quantification, using a solid-state electrolyte
“top contact,” to increase energy resolution and sensitivity
via a differential pulse protocol. A new low level of detection of
ca. 2 × 1015 cm–3 is reported for
reactive defects in a triple-cation system. We confirmed that these
defects are associated with mobile iodide ions in grain boundaries
and at interfaces by using iodide and bromide spiked electrolytes.
The detection limit for this electrochemical method is estimated to
be ca. 1014 cm–3, well below that of
many electrical or spectroscopic approaches. We predict this methodology
lends itself to operando defect characterization during and after
processing, at scale, of extremely low defect density perovskites
and related optoelectronic platforms, ultimately providing an in-line
approach to real-time performance and stability optimization.