of 5
1
Supporting Information
Stabilization
of
Hybrid
Perovskite
CH
3
NH
3
PbI
3
Thin
Films
by
Graphene Passivation
Wei-Shiuan
Tseng,
a,b
Meng-Huan
Jao,
a,c
Chen-Chih
Hsu,
a
Jing-Shun
Huang,
d
Chih-
I
Wu,
b
and N.-C. Yeh
*,a
a
Department
of
Physics,
California
Institute
of
Technology,
Pasadena,
CA
91125,
USA
b
Graduate
Institute
of Photonics
and
Optoelectronics
and
Department
of
Electrical
Engineering,
National Taiwan University, Taipei 106, Taiwan
c
Department
of
Materials
Science
and
Engineering,
National
Taiwan
University,
Taipei
106, Taiwan
d
Tomas J. Watson Laboratories of Applied Physics, CA 91125, USA
*
E-mail: Nai-Chang Yeh (ncyeh@caltech.edu)
Electronic
Supplementary
Material
(ESI)
for
Nanoscale.
This
journal
is
©
The
Royal
Society
of
Chemistry
2017
2
Supporting figures:
Figure
S1.
Raman
spectra
of
the
same
graphene
samples
as
shown
in Figure
1 before
the
removal
of
their
Cu
substrate:
(a)
As-grown
graphene
on
Cu
before
the
water-free
transfer;
and
(b)
as-grown
graphene
on
Cu
before
the
water-assisted
polymer-free
transferring.
Figure
S2.
Optical
micrographs
of
graphene
sheets
on
(a)
ITO
and
(b)
glass
surfaces
3
transferred by
the water-free transferring
method.
Figure
S3.
The
work
functions
of as-transferred
graphene
measured
via
UPS.
(a)
UPS
data
of
graphene
transferred
with
the
water-free
method
before
and
after
rinse.
(b)
UPS
data of
graphene transferred with the water-assisted method before
and after rinse.
Figure
S4.
Evolution
of XPS
N-1s
peaks
as
a function
of
ambient
storage
time.
(a)
Perovskite surface
without any protection. (b)
Perovskite with
graphene covered.
4
Figure
S5.
Evolution
of
perovskite
degradation
monitored
via
high-resolution
UPS
without
graphene
protection.
(a)
The
evolution
of
secondary
electron
cutoff
as
a
function
of aging
time.
(b)
The
evolution
of
high-resolution
valence
band
UPS
spectra.
5
Figure
S6.
Statistics
of
the
sheet
resistance
of graphene
transferred
onto
a
-SiO
2
by
both
(a)
water-free
and
(b)
water-assisted
methods,
showing
values
very
close
to the
typical
sheet
resistance
of
graphene
that
was
transferred
by
other
polymer-free
methods
but
much
lower
than
those
of
the
PMMA-transferred
graphene
samples
indicated
in
the
shaded
band.
Here
the
sheet
resistance
measurements
were
carried
out
on
20
different
areas of each
sample.