more difficult for the charge to hop between
molecules (the more bent structure of Spiro-oF
core relative to that of Spiro-mF is shown in
the DFT study results).
We also evaluated the charge dynamics
occurring at the perovskite-HTM interface
using steady-state photoluminescence (PL) and
time-resolved PL (TRPL) decay measurements.
Figure S19A shows that upon depositing HTM
ontheperovskitefilm,theintensityofthesteady-
state PL spectrum was largely reduced, and
the quenching efficacy followed Spiro-mF>Spiro-oF > Spiro-OMeTAD, which is consistent
with the hole mobility trend. Figure S19B
shows the TRPL spectra of the devices based
on the each HTM as recorded with the peak
emission at 800 nm. The TRPL decay data
were modeled by a bi-exponential formula1618 25 SEPTEMBER 2020•VOL 369 ISSUE 6511 sciencemag.org SCIENCE
Fig. 3. Long-term stability
and hydrophobicity.
(A) Long-term stability of
Spiro-OMeTAD–, Spiro-mF–,
and Spiro-oF–based devices
in air (~50% RH) without
encapsulation. (B) Evolution
ofJ-Vcurves for the
unencapsulated PSC
devices, based on Spiro-
OMeTAD, Spiro-mF,
and Spiro-oF over a period
of 500 hours. (C) Time
evolution of XRD patterns
of perovskite films with
Spiro-OMeTAD, Spiro-mF,
and Spiro-oF. (D) Contact-
angle measurements
of pristine and doped
HTM films.
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