Pseudohalide-Induced Moisture Tolerance in Perovskite CH3NH3Pb(SCN)2I Thin Films

Article abstract of DOI:10.1002/anie.201503038

Two pseudohalide thiocyanate ions (SCN^-) have been used to replace two iodides in CH₃NH₃PbI₃, and the resulting perovskite material was used as the active material in solar cells. In accelerated stability tests, the CH₃NH₃Pb(SCN)₂I perovskite films were shown to be superior to the conventional CH₃NH₃PbI₃ films as no significant degradation was observed after the film had been exposed to air with a relative humidity of 95% for over four hours, whereas CH₃NH₃PbI₃ films degraded in less than 1.5 hours. Solar cells based on CH₃NH₃Pb(SCN)₂I thin films exhibited an efficiency of 8.3%, which is comparable to that of CH₃NH₃PbI₃ based cells fabricated in the same way.

Full text of DOI:10.1002/anie.201503038

Angewandte
Chemie
International Edition: DOI: 10.1002/anie.201503038
German Edition: DOI: 10.1002/ange.201503038
Solar Cells Very Important Paper
Pseudohalide-Induced Moisture Tolerance in Perovskite
CH NH Pb(SCN) I Thin Films**
3
3
2
Qinglong Jiang, Dominic Rebollar, Jue Gong, Elettra L. Piacentino, Chong Zheng, and Tao Xu*
ꢀ
[10b]
Abstract: Two pseudohalide thiocyanate ions (SCN ) have
HTMs,
and the noble metal Au with cheaper metals, such
In particular, perovskite materials decompose in
[
12]
been used to replace two iodides in CH NH PbI , and the
resulting perovskite material was used as the active material in
solar cells. In accelerated stability tests, the CH NH Pb(SCN) I
perovskite films were shown to be superior to the conventional
CH NH PbI films as no significant degradation was observed
as Ni.
moist air,
3
3
3
[
8b,13]
which is the main barrier for their future
commercialization. Only a handful of studies have been
conducted to improve the stability of perovskite materials, for
example
3
3
2
by
using
NH CH=NH PbI
and by changing the morphology of the
instead
of
3
3
3
2
2
3
[
14]
after the film had been exposed to air with a relative humidity
of 95% for over four hours, whereas CH NH PbI films
CH NH PbI
3
3
3
[15]
perovskite material. Herein, however, we describe a meth-
ods for the design of new perovskite materials that involves
the replacement of the halide ions with pseudohalide ions.
Pseudohalides have similar chemical behaviors and prop-
erties to true halides. In this study, we developed a new
perovskite material, CH NH Pb(SCN) I, for perovskite solar
3
3
3
degraded in less than 1.5 hours. Solar cells based on
CH NH Pb(SCN) I thin films exhibited an efficiency of
.3%, which is comparable to that of CH NH PbI based
3 3 3
3
3
2
8
[
16]
cells fabricated in the same way.
3
3
2
P
erovskite-type CH NH PbX solid-state solar cells with
cells by replacing two iodides in CH NH PbI with two
3 3 3
3
3
3
[
1]
ꢀ
over 19% efficiency have recently been reported. They
represent promising candidates for next-generation photo-
voltaic devices owing to their astoundingly high efficiency, the
low costs associated with their solution-based fabrication, and
thiocyanate ions. As illustrated in Figure 1, two thirds of the I
ions in traditional CH NH PbI have been replaced by
3
3
3
ꢀ
pseudohalide SCN ions.
[2]
tunable optical properties.
performs very well in terms of both charge transport
electron/hole diffusion lengths of ca. 1 mm and 1.2 um,
Furthermore, this material
(
[3]
respectively, for CH NH PbI Cl ), and light absorption
3
3
[4]
3ꢀx
x
4
ꢀ1
(
1.5 ꢀ 10 cm at 550 nm). In general, perovskite solar cells
are configured as a sandwich structure, and the photoanode
[5]
morphologies affect the performance of the overall device.
Typically, a layer of three-dimensional (3D) TiO is used as
2
[
6]
the photoanode with perovskite materials. These 3D
structures, acting as an electron-buffer, structure-supporting,
and reflection layer, are filled up with a CH NH PbX
3
3
3
perovskite as the photovoltaically active layer, followed by
capping with a layer of hole transport material (HTM) and
a metal counter electrode, such as Au or Ag.
Figure 1. Perovskite structures of CH NH Pb(SCN) I (left) and
3 3 2
CH NH PbI (right) for comparison. Carbon gray, iodine red, lead pink,
3 3 3
nitrogen blue, sulfur yellow.
[6e]
[7]
Despite success in boosting their efficiency, perovskite
solar cells are still facing several critical challenges, including
According to the crystal structure of CH NH PbX
3
3
3
[
8]
[9]
stability issues, the use of environmentally hazardous lead,
the expensive complex organic compounds in the HTM
perovskites, the lead and halide ions form the frame of the
[
17]
perovskite structure.
moisture involves the formation of a hydrated intermediate
The first step of degradation in
[10]
layer, and the use of precious metals as the back cath-
[
1,6e]
4ꢀ
[13b]
ode.
Great efforts have been made to replace the lead with
containing isolated PbX6 octahedra.
The formation
[
9,11]
non-toxic tin,
the organic HTMs with cheaper inorganic
constant of the lead halide complex is essentially its equilib-
rium constant, which reflects the binding tightness between
2
+
the halides and the central Pb ion. The formation constant
[*] Q. Jiang, D. Rebollar, J. Gong, E. L. Piacentino, Prof. C. Zheng,
K (cumulative formation constant b = K ꢀ K ꢀ …K ) has
4
n
1
2
n
Prof. T. Xu
2ꢀ [18]
been calculated to be only 3.5 for PbI4
range of the weak interactions between I and Pb . In the
case of CH NH Pb(SCN) I, the interaction between Pb and
SCN is much stronger, and the formation constant K is up to
Comparing the spherical shape of I ions
with the linear shape of SCN ions as indicated by their Lewis
structures, the lone pairs of electrons from the S and N atoms
,
which is in the
Department of Chemistry and Biochemistry
Northern Illinois University
DeKalb, IL 60115 (USA)
ꢀ
2+
2
+
3
3
2
ꢀ
E-mail: txu@niu.edu
4
for Pb(SCN)42
ꢀ [19]
ꢀ
7
.
[**] Financial support from the U.S. NSF (CBET-1150617) is gratefully
ꢀ
acknowledged.
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/anie.201503038.
ꢀ
in SCN can interact strongly with the Pb ion, which in turn
Angew. Chem. Int. Ed. 2015, 54, 1 – 5
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
These are not the final page numbers!

.
Angewandte
Communications
stabilizes the frame structure of CH NH Pb(SCN) I. We show
3
3
2
that a direct improvement of moisture tolerance has been
observed for CH NH Pb(SCN) I in accelerated stability tests
3
3
2
compared with the traditional CH NH PbI perovskite mate-
3
3
3
rial.
Figure 2 shows the X-ray diffraction (XRD) patterns of
perovskite-type CH NH Pb(SCN) I in comparison to with
3
3
2
those of CH NH PbI , Pb(SCN) , and CH NH I (MAI). The
3
3
3
2
3
3
XRD peaks (2q) characteristic for the conventional perov-
[20]
skite CH NH PbI are located at 148, 208, 298, 328, and 418,
3
3
3
which are all present as expected. These peaks are also found
for CH NH Pb(SCN) I, which strongly indicates that the
3
3
2
Figure 2. XRD patterns of the CH NH PbI and CH NH Pb(SCN) I
3
3
3
3
3
2
perovskite materials.
Figure 3. Accelerated stability tests with a) CH NH PbI and
3 3 3
b) CH NH Pb(SCN) I in air with 95% relative humidity.
3
3
2
CH NH Pb(SCN) I material also has a perovskite structure.
3
3
2
The calculated XRD pattern for CH NH Pb(SCN) I matches
the black color of the CH NH Pb(SCN) I film could last for
3 3 2
3
3
2
well with the major experimentally determined XRD peaks.
XRD patterns for Pb(SCN)2 and MAI are also given in
Figure 2 as references. The changes in the XRD patterns of
both the CH NH Pb(SCN) I and CH NH PbI films resulting
months when the film was kept in air with a relative humidity
of ꢁ 40%. The bottom insets in Figure 3a and 3b show the
CH NH PbI and CH NH Pb(SCN) I films, respectively, after
3
3
3
3
3
2
30 days in air with a relative humidity of 20–40%.
3
3
2
3
3
3
from exposure to air with 95% relative humidity are listed in
the Supporting Information, Figure S2. No obvious changes
could be observed for CH NH Pb(SCN) I after four hours,
To gain further insights into the stability of the perovskite
CH NH Pb(SCN) I during the accelerated moisture-toler-
3
3
2
ance tests, the changes in the band gaps were also determined
by plotting the square of the Kubelka–Munk function
3
3
2
whereas the XRD pattern of the CH NH PbI film had
3
3
3
[21]
severely deteriorated already after exposure to air with 95%
relative humidity for 1.5 hours, as confirmed by the appear-
ance of the peaks characteristic for PbI2.
[F(R ) ꢀ photon energy(hn)] versus hn. The band gap of
1
CH NH PbI was determined to be 1.504 eV, which is in
3
3
3
[
20c,22]
accordance with previously reported values (Figure 4a).
The accelerated moisture-tolerance tests for perovskite
materials were performed by monitoring the reflection of the
corresponding perovskite films in air with 95% relative
humidity at room temperature. The increase in reflection for
CH NH PbI is due to the decomposition of the perovskite
The band gap decreased to 1.470 eV after 2.5 hours, which
indicates the decomposition of the CH NH PbI perovskite
3
3
3
structure in moisture, resulting in the formation of a mixture
of MAI·H O, MAIPbI , PbI ·H O, and other iodide complex-
2
x
x
2
[8b,13]
es.
In contrast, CH NH Pb(SCN) I exhibited a slightly
3 3 2
3
3
3
[
8b]
structure when subjected to moisture (Figure 3a). Perov-
skite-type CH NH PbI started to decompose immediately
wider band gap of 1.532 eV, which remained nearly the same
after four hours of exposure to air with 95% relative
humidity, suggesting that CH NH Pb(SCN) I is a more
3
3
3
after being exposed to moisture. After 1.5 hours, most of the
black film had decomposed and turned yellow, which is due to
3
3
2
stable perovskite structure (Figure 4b).
the formation of PbI , and the corresponding reflection
The presence of SCN groups in the material was further
confirmed by total internal reflection Fourier transform
infrared (TIR-FTIR) spectroscopy. Indeed, we observed the
2
increased from approximately 10 to 20%. In the case of
CH NH Pb(SCN) I (Figure 3b), no obvious increase in
3
3
2
[
23]
reflection was observed even after exposure to moisture for
four hours. The corresponding reflection increased by only
characteristic thiocyanate FTIR peak
at approximately
ꢀ
1
2050 cm for both a pure CH NH Pb(SCN) I film on glass
3
3
2
2
% after four hours of exposure to moisture, from approx-
and spin-coated CH NH Pb(SCN) I on a TiO nanoparticle
3 3 2 2
imately 6 to 8%. Some very small white patches emerged at
photoanode (Figure S1). Furthermore, energy-dispersive X-
ray spectroscopy (EDXS) measurements suggest that the
the corners, which are likely due to Pb(SCN) . Furthermore,
2
2
www.angewandte.org
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2015, 54, 1 – 5
These are not the final page numbers!

Angewandte
Chemie
Figure 5. SEM images of perovskite solar cells. a,b) Cross-sections of
CH NH PbI (a) and CH NH Pb(SCN) I (b) based solar cells. c,d) Top
3
3
3
3
3
2
views of CH NH PbI (c) and CH NH Pb(SCN) I (d) based solar cells.
3
3
3
3
3
2
Figure 4. Tauc plots from accelerated stability tests with
a) CH NH PbI and b) CH NH Pb(SCN) I in air with 95% relative
3
3
3
3
3
2
humidity.
CH NH Pb(SCN) I based device contains pronouncedly
3
3
2
more sulfur than the CH NH PbI based device. (Tables S1–
3
3
3
S3). The sulfur in the CH NH PbI based device originates
3
3
3
from the HTM layer, which contains lithium bis(trifluorome-
thane)sulfonamide.
Scanning electron microscopy (SEM) images of the cross-
sections of solar cells with CH NH PbI and CH NH Pb-
3
3
3
3
3
(
5
5
SCN) I as the active materials are shown in Figure 5a and
2
b, respectively. Both solar cells used an approximately
Figure 6. J–V curves of perovskite solar cells with CH NH Pb(SCN) I
3
3
2
or CH NH PbI as the active layer.
3
3
3
00 nm thick TiO nanoparticle as the photoanode, a 200 nm
2
thick HTM layer, and a 80 nm thick Au layer. No obvious
morphological differences can be observed for these two solar
cells.
critical parameters highlighting the photovoltaic performance
of the devices are given in Table 1. The J–V curves of the cell
made with CH NH Pb(SCN) I that were recorded on the first
3
3
2
The J–V curves of solar cells that are based on either
CH NH Pb(SCN) I or CH NH PbI but use the same types of
day and on the 14th day after fabrication, and the corre-
sponding curves of the cell made with CH NH PbI on the
3
3
2
3
3
3
3
3
3
photoanodes, HTM layers, and Au counter electrodes and
were prepared in our laboratory are compared in Figure 6.
Apparently, CH NH Pb(SCN) I exhibits a lower current
first and seventh day are shown in Figure S3. The efficiency of
the CH NH PbI cell dropped from 8.8% on the first day to
3
3
3
6.9% on the seventh day; in contrast, the efficiency of the
CH NH Pb(SCN) I cell only dropped from 8.3% on the first
3
3
ꢀ
2
2
ꢀ2
density (15.1 mAcm ) than CH NH PbI (21.1 mAcm ).
3
3
3
3
3
2
However, the CH NH Pb(SCN) I based cell displays better
day to 7.4% on the 14th day (Table S4), which thus exhibits
a much better stability than the CH NH PbI cell.
3
3
2
Voc and FF values (V = 0.87 V, FF = 0.63) than the
oc
3
3
3
CH NH PbI based solar cell (V = 0.80 V, FF = 0.52). The
3
3
3
oc
Table 1: Photovoltaic performance of solar cells with CH NH Pb(SCN) I
3
3
2
efficiencies of the two cells were relatively similar, namely
.3% for the CH NH Pb(SCN) I based cell and 8.8% for the
or CH NH PbI as the active layer.
3
3
3
8
3
3
2
ꢀ
2
Cell
Jsc [mAcm
]
Voc [V] FF
h [%] Rsh [W] Rs [W]
CH NH PbI based cell. Compared to the best reported
3
3
3
efficiency for CH NH PbI cells, the lower efficiency of our
CH
3
NH
3
PbI
3
21.1
0.80
0.87
0.52 8.8
0.63 8.3
555.0 19.1
981.7 31.4
3
3
3
CH NH Pb(SCN) I 15.1
cells is mainly due to the low V value, which is largely due to
3
3
2
oc
the crystallinity of the perovskite film, the quality of the
interfaces, and the film engineering procedure. All of the
FF=fill factor, J =short-circuit current density, V = open-circuit
sc
oc
voltage, R =series resistance, R =shunt resistance.
s
sh
Angew. Chem. Int. Ed. 2015, 54, 1 – 5
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3
These are not the final page numbers!

.
Angewandte
Communications
In summary, we have developed a new type of perovskite
material, CH NH Pb(SCN) I. The replacement of two iodides
[3] S. D. Stranks, G. E. Eperon, G. Grancini, C. Menelaou, M. J.
Alcocer, T. Leijtens, L. M. Herz, A. Petrozza, H. J. Snaith,
Science 2013, 342, 341 – 344.
3
3
2
by two thiocyanate ions in a conventional CH NH PbI
3
3
3
[
4] S. Kazim, M. K. Nazeeruddin, M. Grꢁtzel, S. Ahmad, Angew.
Chem. Int. Ed. 2014, 53, 2812 – 2824; Angew. Chem. 2014, 126,
material drastically improved the moisture tolerance of the
resulting perovskite material.
2854 – 2867.
[
5] a) X. Feng, K. Zhu, A. J. Frank, C. A. Grimes, T. E. Mallouk,
Angew. Chem. Int. Ed. 2012, 51, 2727 – 2730; Angew. Chem.
2012, 124, 2781 – 2784; b) Q. Jiang, F. Liu, T. Li, T. Xu, J. Mater.
Chem. C 2014, 2, 618 – 621.
Experimental Section
Synthesis of Pb(SCN) : An aqueous solution of Pb(BF ) (10 mL,
2
4
[
6] a) Q. Jiang, X. Sheng, Y. Li, X. Feng, T. Xu, Chem. Commun.
Aldrich) and NaSCN (3.5 g, Aldrich) were mixed under stirring in
deionized (DI) water (10 mL). The precipitate was filtered off and
washed 6 times with DI water to obtain Pb(SCN) . CH NH I was
2014, 50, 14720 – 14723; b) H. S. Kim, J. W. Lee, N. Yantara, P. P.
Boix, S. A. Kulkarni, S. Mhaisalkar, M. Grꢁtzel, N. G. Park,
Nano Lett. 2013, 13, 2412 – 2417; c) A. Yella, L. P. Heiniger, P.
Gao, M. K. Nazeeruddin, M. Grꢁtzel, Nano Lett. 2014, 14, 2591 –
2
3
3
[
6a]
synthesized as described previously. The CH NH PbI precursor
3
3
3
solution was prepared as follows: PbI2 (0.289 g, Aldrich) and
2596; d) M. M. Lee, J. Teuscher, T. Miyasaka, T. N. Murakami,
CH NH I (0.1 g) were dissolved in g-butyrolactone (0.52 mL,
3
3
[
6a]
H. J. Snaith, Science 2012, 338, 643 – 647; e) J. Burschka, N.
Pellet, S. J. Moon, R. Humphry-Baker, P. Gao, M. K. Nazeer-
uddin, M. Grꢁtzel, Nature 2013, 499, 316 – 320.
Aldrich) at 608C under stirring for 3 h. The CH NH Pb(SCN) I
3
3
2
precursor solution was prepared as follows: Pb(SCN) (0.203 g) and
2
CH NH I (0.15 g) were dissolved in dimethylformamide (DMF,
3
3
[
[
7] M. Liu, M. B. Johnston, H. J. Snaith, Nature 2013, 501, 395 – 398.
8] a) T. Leijtens, G. E. Eperon, S. Pathak, A. Abate, M. M. Lee,
H. J. Snaith, Nat. Commun. 2013, 4, 2885; b) G. D. Niu, W. Z. Li,
F. Q. Meng, L. D. Wang, H. P. Dong, Y. Qiu, J. Mater. Chem. A
0
.6 mL) under stirring at 608C for 3 h. The HTM layer was prepared
by dissolving 2,2’,7,7’-tetrakis(N,N-di-para-methoxyphenylamine)-
,9’-spiro-bifluorene (spiro-MeOTAD, 92 mg), lithium bis(trifluoro-
methane)sulfonamide (7.2 mg), and 4-tert-butylpyridine (12 mg), in
9
[
6a]
2014, 2, 705 – 710.
chlorobenzene (1 mL).
[
9] F. Hao, C. C. Stoumpos, D. H. Cao, R. P. H. Chang, M. G.
The photoanodes were prepared as follows: Titanium(IV)
bis(ethyl acetoacetato) diisopropoxide in 1-butanol (0.2m) was
sprayed on pre-cleaned FTO glass substrates at 4008C, followed by
sintering at 4508C for 1 h to form a blocking layer. The electrodes
were then soaked in TiCl (0.2m) in a sealed vial at 708C for 2 h,
followed by sintering at 5008C for 0.5 h. The resulting TiO /FTO
electrodes were dipped into a solution of H O /NH ·H O (9:1, v/v) for
2
Finally, the electrodes were soaked in TiCl (0.04m) in a sealed vial at
7
Kanatzidis, Nat. Photonics 2014, 8, 489 – 494.
[
10] a) P. Qin, S. Tanaka, S. Ito, N. Tetreault, K. Manabe, H. Nishino,
M. K. Nazeeruddin, M. Grꢁtzel, Nat. Commun. 2014, 5, 3834;
b) J. A. Christians, R. C. Fung, P. V. Kamat, J. Am. Chem. Soc.
[
6c]
4
2014, 136, 758 – 764.
2
[
11] M. H. Kumar, S. Dharani, W. L. Leong, P. P. Boix, R. R.
Prabhakar, T. Baikie, C. Shi, H. Ding, R. Ramesh, M. Asta, M.
Grꢁtzel, S. G. Mhaisalkar, N. Mathews, Adv. Mater. 2014, 26,
122 – 7127.
12] Q. Jiang, X. Sheng, B. Shi, X. Feng, T. Xu, J. Phys. Chem. C 2014,
18, 25878 – 25883.
13] a) A. Abate, M. Saliba, D. J. Hollman, S. D. Stranks, K.
Wojciechowski, R. Avolio, G. Grancini, A. Petrozza, H. J.
Snaith, Nano Lett. 2014, 14, 3247 – 3254; b) J. Yang, B. D.
Siempelkamp, D. Liu, T. L. Kelly, ACS Nano 2015, 9, 1955 – 1963.
14] a) N. J. Jeon, J. H. Noh, W. S. Yang, Y. C. Kim, S. Ryu, J. Seo, S. I.
Seok, Nature 2015, 517, 476 – 480; b) J. W. Lee, D. J. Seol, A. N.
Cho, N. G. Park, Adv. Mater. 2014, 26, 4991 – 4998.
15] J. H. Kim, S. T. Williams, N. Cho, C.-C. Chueh, A. K. Y. Jen, Adv.
Energy Mater. 2014, 1401229.
16] F. Bella, A. Sacco, G. P. Salvador, S. Bianco, E. Tresso, C. F. Pirri,
R. Bongiovanni, J. Phys. Chem. C 2013, 117, 20421 – 20430.
17] F. De Angelis, Acc. Chem. Res. 2014, 47, 3349 – 3360.
18] H. L. Clever, F. J. Johnston, J. Phys. Chem. Ref. Data 1980, 9,
51 – 784.
19] G. W. Leonard, M. E. Smith, D. N. Hume, J. Phys. Chem. 1956,
0, 1493 – 1495.
2
2
3
2
0 s, and the substrates were then washed with DI water and ethanol.
4
7
08C for 1 h, and then heated to 5008C for 0.5 h.
[
[
Fabrication of the corresponding perovskite solar cells: The
1
perovskite precursor solution was spin-coated onto the photoanodes
at 2000 rmp for 1 min in dry air, followed by annealing at 1058C in air
for 30 min. The HTM layer was spin-coated at 2500 rpm. An 80 nm
thick Au film was thermally coated atop the HTM layer using an
Edward 306 A thermal evaporator.
Characterization: A potentiostat (Gamry Reference 600) and
a solar simulator (Photo Emission Inc. CA, model SS50B) were used
to acquire the current density–voltage (J–V) curves. SEM images
were taken on a Tescan scanning electron microscope (Vega II SBH).
Diffusive reflectance measurements were conducted with a Filmetrics
F20-EXR thin-film analyzer with an integrating sphere for measuring
the reflectance. XRD spectra were collected on a Miniflex X-ray
diffractometer. EDX spectra were recorded with a scanning electron
microscope equipped with an INCAX-act Analytical Standard EDX
Detector (Oxford Instruments). FTIR spectra were recorded with
a reflective infrared spectrometer (ATI Mattson). Band-gap energies
[
[
[
[
[
7
[
[
[
21]
6
were calculated according to literature. The calculation of the XRD
patterns for CH NH Pb(SCN) I was carried out using Accelrys MS
modelling software (version 3.0.1).
20] a) Q. Chen, H. P. Zhou, T. B. Song, S. Luo, Z. R. Hong, H. S.
3
3
2
Duan, L. T. Dou, Y. S. Liu, Y. Yang, Nano Lett. 2014, 14, 4158 –
4
163; b) B.-w. Park, B. Philippe, T. Gustafsson, K. Sveinbjçrns-
son, A. Hagfeldt, E. M. J. Johansson, G. Boschloo, Chem. Mater.
014, 26, 4466 – 4471; c) T. Baikie, Y. N. Fang, J. M. Kadro, M.
Keywords: moisture tolerance · perovskite phases ·
pseudohalides · solar cells · thiocyanates
2
Schreyer, F. X. Wei, S. G. Mhaisalkar, M. Grꢁtzel, T. J. White, J.
Mater. Chem. A 2013, 1, 5628 – 5641.
[
[
[
21] X. T. Lu, Z. B. Zhuang, Q. Peng, Y. D. Li, Chem. Commun. 2011,
47, 3141 – 3143.
22] J. H. Noh, S. H. Im, J. H. Heo, T. N. Mandal, S. I. Seok, Nano
Lett. 2013, 13, 1764 – 1769.
23] K. Ganesan, L. Ratke, Soft Matter 2014, 10, 3218 – 3224.
[
1] Q. C. H. Zhou, G. Li, S. Luo, T.-b. Song, H.-S. Duan, Z. Hong, J.
You, Y. Liu, Y. Yang, Science 2014, 345, 542 – 546.
[
2] a) P. Gao, M. Grꢁtzel, M. K. Nazeeruddin, Energy Environ. Sci.
2014, 7, 2448; b) H. J. Snaith, J. Phys. Chem. Lett. 2013, 4, 3623 –
Received: April 1, 2015
3630; c) N. G. Park, J. Phys. Chem. Lett. 2013, 4, 2423 – 2429.
Published online: && &&, &&&&
4
www.angewandte.org
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2015, 54, 1 – 5
These are not the final page numbers!

Angewandte
Chemie
Communications
Solar Cells
The replacement of two iodides by two
pseudohalide thiocyanate ions in
CH NH PbI results in a perovskite
Q. Jiang, D. Rebollar, J. Gong,
E. L. Piacentino, C. Zheng,
T. Xu*
3
3
3
material with superior tolerance to mois-
ture when used as the active material of
a solar cell. For the CH NH Pb(SCN) I
&&&& — &&&&
3
3
2
Pseudohalide-Induced Moisture
Tolerance in Perovskite
perovskite films, no significant degrada-
tion was observed after the film had been
exposed to air with a relative humidity of
CH NH Pb(SCN) I Thin Films
3
3
2
9
5% for over four hours, whereas the
CH NH PbI films degraded in less than
3
3
3
1
.5 hours.
Angew. Chem. Int. Ed. 2015, 54, 1 – 5
ꢀ 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!