Large-Scale Synthesis of Highly Luminescent Perovskite-Related CsPb2Br5Nanoplatelets and Their Fast Anion Exchange

Article abstract of DOI:10.1002/anie.201602787

All-inorganic cesium lead-halide perovskite nanocrystals have emerged as attractive optoelectronic nanomaterials owing to their stabilities and highly efficient photoluminescence. Herein we report a new type of highly luminescent perovskite-related CsPb₂Br₅nanoplatelets synthesized by a facile precipitation reaction. The layered crystal structure of CsPb₂Br₅promoted an anisotropic two-dimensional (2D) crystal growth during the precipitation process, thus enabling the large-scale synthesis of CsPb₂Br₅nanoplatelets. Fast anion exchange has also been demonstrated in as-synthesized CsPb₂Br₅nanoplatelets to extend their photoluminescence spectra to the entire visible spectral region. The large-scale synthesis and optical tunability of CsPb₂Br₅nanoplatelets will be advantageous in future applications of optoelectronic devices.

Full text of DOI:10.1002/anie.201602787

Angewandte
Communications
Chemie
International Edition: DOI: 10.1002/anie.201602787
German Edition: DOI: 10.1002/ange.201602787
Luminescent Nanoparticles
Large-Scale Synthesis of Highly Luminescent Perovskite-Related
CsPb Br Nanoplatelets and Their Fast Anion Exchange
2
5
Kun-Hua Wang, Liang Wu, Lei Li, Hong-Bin Yao,* Hai-Sheng Qian, and Shu-Hong Yu*
Abstract: All-inorganic cesium lead-halide perovskite nano-
crystals have emerged as attractive optoelectronic nanomate-
rials owing to their stabilities and highly efficient photolumi-
nescence. Herein we report a new type of highly luminescent
platelets have been explored based on the thickness tuning by
[
3c]
surfactant concentration. Extremely, the atomically thin 2D
organic–inorganic hybrid perovskites have been produced via
[
3d]
a delicate ternary co-solvent controlled precipitation.
perovskite-related CsPb Br5 nanoplatelets synthesized by
a facile precipitation reaction. The layered crystal structure of
However, the material stability of organometal halide per-
ovskites is becoming a limiting factor for its study and
2
[
4]
CsPb Br5 promoted an anisotropic two-dimensional (2D)
application. All-inorganic perovskite nanocrystals, in which
cesium ions replace organic cations, are considered as
alternatives to hybrid perovskites owing to their higher
2
crystal growth during the precipitation process, thus enabling
the large-scale synthesis of CsPb Br nanoplatelets. Fast anion
2
5
[5]
exchange has also been demonstrated in as-synthesized
stability and extended application range. Very recently,
colloidal cesium lead-halide perovskites nanoplatelets have
CsPb Br5 nanoplatelets to extend their photoluminescence
2
spectra to the entire visible spectral region. The large-scale
synthesis and optical tunability of CsPb Br nanoplatelets will
be advantageous in future applications of optoelectronic
devices.
been prepared by the reaction of PbBr with metal–organic
2
complex (cesium oleate) in octadecene at relatively high
2
5
[
6]
temperature, which is similar to the synthesis of traditional
[
7]
metal chalcogenide nanoparticles. To further explore these
new 2D semiconductor materials, other phases of cesium
lead-halide nanoplatelets and their large-scale synthesis are in
demand, also as an alternative to the limited-scale synthesis of
the traditional metal–organic complex decomposition
C
olloidal quasi-2D semiconductor nanoplatelets are an
interesting class of nanocrystals owing to their unique
photo-physical properties, such as increased exciton binding
energy, reduced florescence decay times, and notable optical
[6,8]
method.
[
1]
nonlinearities. Recently, metal halides with perovskite or
perovskite-related crystal structures have emerged as attrac-
tive semiconducting materials owing to their optoelectronic
properties enabling high conversion efficiency in photovol-
Herein, we report a facile fast precipitation synthesis of
highly luminescent perovskite-related CsPb Br nanoplatelets
2
5
and their fast anion-exchange capabilities to tune optical
properties. The colloidal synthesis of CsPb Br nanoplatelets
2
5
[2]
taics and light-emitting diode devices. Colloidal nanoplate-
lets of perovskite metal halides are an important class of
nanomaterials because they not only enrich the diversity of
semiconducting nanomaterials but also potentially provide
a platform for exploring new photo-physical properties of 2D
semiconducting materials.
was carried out by modifying the synthesis of organometal
[3c]
halide perovskite nanoplatelets reported by Sichert et al.,
in which they used a high concentration of octylammonium in
the precipitation process to stabilize the quasi-2D methyl-
ammonium (MA) lead bromide nanoplatelets. In our study,
+
we found that by using inorganic cations Cs to replace
Arisen from the high performance of organometal halides
recently demonstrated in solar cells, the synthesis and
properties of colloidal nanoplatelets of organometal halide
hybrid perovskite attracted much attention. The quantum
size effect in colloidal organometal halide perovskite nano-
organic MA, a comparatively smaller amount of surfactant
hexylammonium (HA) with a shorter carbon chain can
introduce the formation of CsPb Br nanoplatelets. This is
2
5
[
3]
because the anisotropic 2D growth of CsPb Br during the
2 5
precipitation reaction is determined by the intrinsic symmetry
of its crystal structure. As shown in Figure 1a, the tetragonal
phase of CsPb Br exhibits a sandwich structure consisting of
2
5
[
*] K.-H. Wang, L. Wu, L. Li, Prof. Dr. H. B. Yao, Prof. Dr. S. H. Yu
Division of Nanomaterials & Chemistry, Hefei National Laboratory
for Physical Sciences at Microscale, Collaborative Innovation Center
of Suzhou Nano Science and Technology, Department of Chemistry
University of Science and Technology of China
Hefei, Anhui 230026 (P.R. China)
À
+
À
[
(
Pb Br ] layers and intercalated Cs . In the [Pb Br ] layer
2 5 2
+
Figure S1a, in the Supporting Information), one Pb
coordinates with four Br forming the elongated pentahe-
dron. All the Pb ions are confined in the center of the layer
5
2
À
2
+
À
and both bottom and top surface of the layer are Br ions
E-mail: yhb@ustc.edu.cn
shyu@ustc.edu.cn
Homepage: http://staff.ustc.edu.cn/~yulab/
Prof. Dr. H. S. Qian
School of Medical Engineering, Hefei University of Technology
Hefei, 230009 (China)
(
Figure S1b). The features of the CsPb Br crystal structure
2 5
are similar to that of layered double hydroxides, the nano-
platelets of which have been easily prepared by the facile
[
9]
precipitation process. In contrast, the monoclinic or cubic
phase of CsPbBr presents a three-dimensional connected
3
2
+
structure, in which the octahedral coordination of Pb with
six Br extends to three dimensions via sharing the vertex and
Cs ions localize in the octahedral voids (Figure 1b). The
Supporting information and the ORCID identification number(s) for
the author(s) of this article can be found under http://dx.doi.org/10.
À
+
1002/anie.201602787.
Angew. Chem. Int. Ed. 2016, 55, 1 – 6
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1
These are not the final page numbers!

Angewandte
Communications
Chemie
Figure 1. a) Perovskite-related crystal structure of CsPb Br . b) Perovskite crystal structure of CsPbBr . c) PXRD patterns of the products prepared
2
5
3
by the different ratio of reaction precursors. Stick patterns: Standard PXRD of CsPb Br (PDF#25-0211, orange lines) and CsPbBr (PDF#18-0364,
2
5
3
violet lines). d)–f) TEM images of the products of different ratio of reaction precursors of PbBr :HABr:CsBr=3:2:1, 2:2:1, and 1:2:1, respectively.
2
difference in the intrinsic symmetry of the crystal structures of
as-synthesized CsPb Br5 nanoplatelets was measured by
2
CsPb Br5 and CsPbBr3 determined their different crystal
growth behavior in precipitation reactions.
atomic force microscope (AFM) as approximately 3 nm and
nanoplatelets are likely to stack with each other forming the
aggregation (Figure S3). In contrast, with decreasing the
2
In a typical synthesis, 10 mL of a dimethylformamide
(
(
DMF) solution containing PbBr2 (0.05m) and HABr
0.033m) were added dropwise into 100 mL of toluene
molar ratio of PbBr :CsBr to 2:1 in the solution, the
2
morphologies of generated CsPb Br nanoplatelets were not
2
5
forming a mixture, and then 5 mL of CsBr/DMF suspension
0.033m) was added dropwise into the as-prepared toluene
well-defined square or rectangular and many irregular nano-
particles appeared due to the precipitation of CsPbBr3
(
mixture under vigorous stirring. The final molar ratio of
(Figure 1e). When the ratio of PbBr :CsBr is 1:1 in the
2
PbBr :HABr:CsBr in the toluene is 3:2:1. The powder X-ray
solution, the nanoplatelets of CsPb Br totally disappeared
2
2
5
diffraction (PXRD) patterns (Figure 1c, black curve) dem-
onstrated that high crystalline and pure phase of tetragonal
CsPb Br (PDF#25-0211) was synthesized in this fast precip-
and random sizes of nanoparticles were yielded (Figure 1 f)
indicating that the crystal growth of CsPbBr is uncontrollable
3
in this solution with relatively low concentration of surfactant
(HA).
2
5
itation reaction. When decreasing the molar ratio of
PbBr :CsBr to 2:1 or 1:1, we found that the monoclinic
The synthesis of CsPb Br5 nanoplatelets by this facile
2
2
CsPbBr (PDF#18-0364) gradually dominates the precipita-
tion product (Figure 1c blue curve and pink curve), which is
consistent with the elemental ratio in the reaction precursor.
precipitation process is easy to be scaled up (see Experimen-
tal Section, Supporting Information). All the precipitation
process can be completed in several minutes (Movie S1)
indicating the feasibility of the generation of CsPb Br
5
3
But the peak intensity of the PXRD pattern of CsPbBr is
3
2
much lower than that of CsPb Br which indicates that the
nanoplatelets. The obtained colloidal CsPb Br nanoplatelets
2 5
2
5
crystallinity of CsPbBr is much lower than that of CsPb Br .
suspension was shown in Figure 2a and it emitted green light
under the UV light (365 nm) irradiation (Figure 2b). The
finally obtained yellow CsPb Br nanoplatelets powder pro-
3
2
5
This also means that the quasi-2D anisotropic growth of
CsPb Br is much more favorable than that of CsPbBr in the
2
5
3
2
5
precipitation reaction system at room temperature. Trans-
mission electron microscope (TEM) images further con-
firmed the hypothesis of quasi-2D anisotropic crystal growth
derived from the comparison of PXRD patterns. As shown in
duced by a one-pot reaction was weighted as approximately
0.5 g (Figure S4a) and still maintained highly photolumines-
cence with emitting green light under the UV light (365 nm)
irradiation (Figure S4b). The phase of the product synthe-
sized in large scale is the pure tetragonal CsPb Br (Fig-
Figure 1d, the particles in the reaction of PbBr :HABr:CsBr
2
2
5
ratio of 3:2:1 are most square or rectangular nanoplatelets.
The statistic size distribution (in ab plane) of as-synthesized
CsPb Br nanoplatelets based on the TEM image is summar-
ure 2c). UV/Vis adsorption and photoluminescence emission
spectra of as-obtained colloidal CsPb Br nanoplatelets are
2
5
presented in Figure 2d. The absorption spectrum is domi-
nated by sharp exciton peaks which is similar to the optical
2
5
ized in Figure S2 showing that the size of most nanoplatelets
70%) is in the range of around 10–100 nm. The thickness of
[
6]
[1a]
(
features of previously reported CsPbBr3 and CdSe nano-
2
www.angewandte.org
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2016, 55, 1 – 6
These are not the final page numbers!

Angewandte
Communications
Chemie
CsPb Br are well-defined rectan-
2
5
gular platelets. High resolution
TEM (HRTEM) clearly shows the
two dimensional lattice fringe (Fig-
ure 2 f). The measured d-spacing
values of these two perpendicular
lattice fringes were 0.418 nm and
0
.417 nm (Figure 2g) correspond-
ing to that of (020) and (200) planes
of tetragonal CsPb Br , respec-
2
5
tively. This result further illustrated
that the lateral 2D anisotropic
growth directions of CsPb Br
2
5
nanoplatelets is along the ab plane.
We adopted different reaction
precursors to explore the influence
of ions on the precipitation of
CsPb X5 (X = Cl, Br or I) nano-
2
platelets. The reaction details are
summarized in Table S1–5. When
the MABr was used to replace
Figure 2. a),b) Photographs of as-obtained colloidal CsPb Br nanoplatelets suspension under ambi-
2
5
ent conditions and the UV light (365 nm) irradiation, respectively. c) PXRD of the product synthesized CsBr, the dominate phase in the
in a relatively large scale reaction. Orange lines: standard PXRD of CsPb Br (PDF#25-0211).
products is monoclinic MAPbBr3
with a tiny amount of tetragonal
MAPb Br (Figure 3a, pink curve).
2
5
d) Absorption (left) and PL (right) spectrum of colloidal CsPb Br nanoplatelets toluene solution.
2
5
e)–g) TEM and HRTEM images of CsPb Br nanoplatelets, respectively.
2
5
2
5
Using CsCl to replace CsBr
resulted in the formation of the
platelets. The PL emission spectrum of the CsPb Br exhib-
pure phase of CsPb Br Cl (Figure 3a, black curve) but the
2
5
2 5Àx x
ited a highly symmetric band centered at 512 nm with narrow
2 nm full-width-at-half-maximum (FWHM). The absolute
CsI resulted in the formation of the impurity of CsPbBr3 Ix
(Figure 3a red curve). The replacement of HABr by HACl or
Àx
1
PL quantum yield (PLQY) of CsPb Br5 nanoplatelets in
HAI exhibited the similar phenomenon that the pure
2
toluene solution is about 87%. TEM image in Figure 2e
further displayed that the nanostructures of as-synthesized
tetragonal phase of CsPb Br Cl was obtained (Figure 3a
2 5Àx x
blue curve) but the impure phase of CsPbBr3 Ix appeared in
Àx
Figure 3. a)–c) PXRD patterns of reaction products by using different reaction precursors (listed) in precipitation systems. Stick patterns:
Standard PXRD of CsPb Br (PDF#25-0211, orange lines), CsPbBr (PDF#18-0364, violet lines), CsBr (PDF#52-1144, cyan lines), and CsPbI
3
2
5
3
(
PDF#18-0376, red lines). d)–g) TEM images showing the representative nanostructures of CsPb Br Cl , CsPb Br Ix, CsBr Cl , and CsPbBr I ,
2 5Àx x 2 5Àx 1Àx x 3Àx x
respectively.
Angew. Chem. Int. Ed. 2016, 55, 1 – 6
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
3
These are not the final page numbers!

Angewandte
Communications
Chemie
the reaction (Figure 3a green curve). When the HABr and
CsBr were both replaced by the HACl and CsCl the resulted
halide sources added into the solution. To show the tunable
optical properties realized by anion exchange, the anion-
exchanged samples were characterized by the UV/Vis
adsorption and photoluminescence spectroscopy. As shown
in Figure 4a, the anion exchange reactions led to a blue shift
product is pure tetragonal CsPb Br Cl (Figure 3a violet
2
5Àx
x
curve). In contrast, using HAI and CsI leaded to the
formation of pure monoclinic CsPbBr3 Ix (Figure 3a dark
Àx
blue curve). The above
À
results indicate that
I
with relatively big ionic
radius limited the 2D
growth of CsPb Br Ix but
2
5Àx
À
Cl shows little influence
on the formation of tetrag-
onal
phase
of
CsPb Br Clx.
The
2
5Àx
replacement of lead salt
resulted in remarkable var-
iation of the precipitated
products without the for-
mation of pure tetragonal
phase of CsPb Br Cl or
2
5Àx
x
CsPb Br I . When the
2
5Àx
x
PbCl was used as the reac-
2
tion precursor the obtained
products contains both the
Figure 4. a) Evolution of the optical absorption (left) and PL (right) spectra of CsPb Br nanoplatelets with
CsPb Br Clx
and
2
5
2
5Àx
À
À
increasing quantities of anion-exchange of I and Cl , respectively. b) Photograph of CsPb Br nanoplatelets
2
5
CsBr1 Clx
(Figure 3b).
Àx
under the irradiation of a 365 nm UV lamp. c) PXRD patterns of the parent CsPb Br nanoplatelet and anion-
2
5
The PbI reaction precur-
2
exchanged samples.
sor resulted in the forma-
tion
of
orthorhombic
CsPbI3 (Figure 3c). TEM
images (Figure 3d–g) further show the different nanostruc-
tures of obtained products. As shown in Figure 3d,e,
(for Br-to-Cl) or a red shift (for Br-to-I) of the optical
features, correlating with the incorporation of the new anions.
photoluminescence of the obtained nanoplatelets can cover
all visible spectra and exhibited the bright and narrow
emission from blue to red. The photograph of the entire
visible spectrum emission of anion-exchanged samples under
UV light (365 nm) irradiation is shown in Figure 4b. The
PLQY of the obtained nanoplatelets are in the range of
approximately 20–90% (Figure S8), which is comparable to
CsPb Br Cl or CsPb Br Ix present typical 2D platelet-
2
5Àx
x
2
5Àx
like structures. In contrast, the morphologies of CsBr1 Clx
Àx
and CsPbI are random microparticles and brick-like nano-
3
particles, respectively (Figure 3 f,g), which indicate the uncon-
trolled crystal growth of CsBr Cl and CsPbI in the reaction
1
-x
x
3
system.
Ion exchange is a versatile tool for nanomaterial synthesis,
which has been used to prepare various nanostructured
[8b]
that of previously synthesized CsPbX cubic nanocrystals.
3
[10]
materials. In our case, as-prepared highly photolumines-
cent CsPb Br nanoplatelets exhibited fast anion exchange
Notably, with further processing the anion exchange the
PLQY of nanoplatelets decreased to a lower value with
respect to original CsPb Br , which is ascribed to intrinsic
2
5
behavior similar to very recently reported CsPbBr cubic
3
2
5
[
11]
[12]
nanocrystals.
The anion-exchange reactions in our case
properties of halide perovskites.
were conducted in toluene as a solvent by mixing a specific
ration of the desired halide source (HACl or HAI) and
The phases of anion-exchanged samples were analyzed by
PXRD (Figure 4c) indicating that the anion exchange process
did not deteriorate the layered crystal structure feature and
remarkably alter the crystal lattice. The details of PXRD
peaks at low angle (Figure S9) further showed that upon
CsPb Br5 nanoplatelets (see Experimental Section and
2
Table S6, Supporting Information). This anion exchange
process can be achieved in tens of seconds (Movie S2) at
room temperature indicating the fast diffusion capability of
À
À
5
incorporation of Cl , the distance between Pb X layers
2
À
halide ions in these CsPb X5 nanoplatelets. As shown in
shrunk, while the incorporation of I , the distance expanded.
This also means that upon halides anion exchange the
2
Figure S5, through the gradual anion exchange from Br-to-Cl,
the color of the CsPb Br nanoplatelets suspension changed
homogenous CsPb Br Cl or CsPb Br Ix solid solutions
2
5
2 5Àx x 2 5Àx
from yellow to light green and then to green-white. In the case
of anion exchange from Br-to-I, the color of the suspension
changed from yellow to orange and then to red. The energy
dispersive spectroscopy (EDS) analysis (Figure S6–7 and
Table S7) also indicates that the exchanged anions in final
nanoplatelets increased with the increase of the amount of
were formed in the layered structures. In addition, the
nanostructures of anion exchanged samples were still main-
tained as nanoplatelets (Figure S10) and the thickness of the
ion exchanged nanoplatelets is approximately 3 nm as well
(Figure S11,12) further indicating the stability of the layered
structures of CsPb Br during anion exchange processes.
2
5
4
www.angewandte.org
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2016, 55, 1 – 6
These are not the final page numbers!

Angewandte
Communications
Chemie
In summary, we report a facile and scalable route for the
Liu, G. E. Eperon, C. Ducati, K. Wojciechowski, J. T. Griffiths,
A. A. Haghighirad, A. Pellaroque, R. H. Friend, H. J. Snaith,
Chem. Mater. 2015, 27, 8066 – 8075; c) J. A. Sichert, Y. Tong, N.
Mutz, M. Vollmer, S. Fischer, K. Z. Milowska, R. G. Cortadella,
B. Nickel, C. Cardenas-Daw, J. K. Stolarczyk, A. S. Urban, J.
Feldmann, Nano Lett. 2015, 15, 6521 – 6527; d) L. Dou, A. B.
Wong, Y. Yu, M. Lai, N. Kornienko, S. W. Eaton, A. Fu, C. G.
Bischak, J. Ma, T. Ding, N. S. Ginsberg, L.-W. Wang, A. P.
Alivisatos, P. Yang, Science 2015, 349, 1518 – 1521; e) Y. Fu, F.
Meng, M. B. Rowley, B. J. Thompson, M. J. Shearer, D. Ma, R. J.
Hamers, J. C. Wright, S. Jin, J. Am. Chem. Soc. 2015, 137, 5810 –
synthesis of highly luminescent perovskites-related CsPb Br5
2
nanoplatelets. The fast anion-exchange performance of the
as-obtained CsPb Br nanoplatelets has been demonstrated to
2
5
extend their photoluminescence to the entire visible spec-
trum. These novel perovskites-related nanoplatelets have
potential for application in optoelectronic devices.
Acknowledgements
5
818; f) S. Zhuo, J. Zhang, Y. Shi, Y. Huang, B. Zhang, Angew.
Chem. Int. Ed. 2015, 54, 5693 – 5696; Angew. Chem. 2015, 127,
785 – 5788.
This work is supported by the National Natural Science
Foundation of China (Grant 51571184, 21431006), the Foun-
dation for Innovative Research Groups of the National
Natural Science Foundation of China (Grant 21521001), the
National Basic Research Program of China (Grants
5
[4] M. Kulbak, D. Cahen, G. Hodes, J. Phys. Chem. Lett. 2015, 6,
2452 – 2456.
[
[
[
5] J. Song, J. Li, X. Li, L. Xu, Y. Dong, H. Zeng, Adv. Mater. 2015,
27, 7162 – 7167.
6] Y. Bekenstein, B. A. Koscher, S. W. Eaton, P. Yang, A. P.
Alivisatos, J. Am. Chem. Soc. 2015, 137, 16008 – 16011.
7] a) L. Wu, B. Quan, Y. Liu, R. Song, Z. Tang, ACS Nano 2011, 5,
2
014CB931800, 2013CB931800), the Users with Excellence
and Scientific Research Grant of Hefei Science Center of
CAS (2015HSC-UE007, 2015SRG-HSC038), and the Chinese
Academy of Sciences (Grant KJZD-EW-M01-1).
2224 – 2230; b) W. Han, L. Yi, N. Zhao, A. Tang, M. Gao, Z.
Tang, J. Am. Chem. Soc. 2008, 130, 13152 – 13161.
[
8] a) D. Zhang, S. W. Eaton, Y. Yu, L. Dou, P. Yang, J. Am. Chem.
Soc. 2015, 137, 9230 – 9233; b) L. Protesescu, S. Yakunin, M. I.
Bodnarchuk, F. Krieg, R. Caputo, C. H. Hendon, R. X. Yang, A.
Walsh, M. V. Kovalenko, Nano Lett. 2015, 15, 3692 – 3696.
9] a) R. Ma, Z. Liu, K. Takada, N. Iyi, Y. Bando, T. Sasaki, J. Am.
Chem. Soc. 2007, 129, 5257 – 5263; b) G. G. C. Arizaga, K. G.
Satyanarayana, F. Wypych, Solid State Ionics 2007, 178, 1143 –
Keywords: anion exchange · cesium lead halides ·
nanoplatelets · perovskites · photoluminescence
[
1
162.
[
1] a) S. Ithurria, M. D. Tessier, B. Mahler, R. P. S. M. Lobo, B.
Dubertret, A. L. Efros, Nat. Mater. 2011, 10, 936 – 941; b) C. E.
Rowland, I. Fedin, H. Zhang, S. K. Gray, A. O. Govorov, D. V.
Talapin, R. D. Schaller, Nat. Mater. 2015, 14, 484 – 489; c) C.
Schliehe, B. H. Juarez, M. Pelletier, S. Jander, D. Greshnykh, M.
Nagel, A. Meyer, S. Foerster, A. Kornowski, C. Klinke, H.
Weller, Science 2010, 329, 550 – 553; d) Z. Tang, Z. Zhang, Y.
Wang, S. C. Glotzer, N. A. Kotov, Science 2006, 314, 274 – 278.
2] a) Z.-K. Tan, R. S. Moghaddam, M. L. Lai, P. Docampo, R.
Higler, F. Deschler, M. Price, A. Sadhanala, L. M. Pazos, D.
Credgington, F. Hanusch, T. Bein, H. J. Snaith, R. H. Friend,
Nat. Nanotechnol. 2014, 9, 687 – 692; b) N. J. Jeon, J. H. Noh,
W. S. Yang, Y. C. Kim, S. Ryu, J. Seo, S. I. Seok, Nature 2015, 517,
[
10] a) X. Wu, Y. Yu, Y. Liu, Y. Xu, C. Liu, B. Zhang, Angew. Chem.
Int. Ed. 2012, 51, 3211 – 3215; Angew. Chem. 2012, 124, 3265 –
3
269; b) Y. Yu, J. Zhang, X. Wu, W. Zhao, B. Zhang, Angew.
Chem. Int. Ed. 2012, 51, 897 – 900; Angew. Chem. 2012, 124, 921 –
24; c) B. J. Beberwyck, Y. Surendranath, A. P. Alivisatos, J.
9
Phys. Chem. C 2013, 117, 19759 – 19770; d) D. H. Son, S. M.
Hughes, Y. Yin, A. P. Alivisatos, Science 2004, 306, 1009 – 1012.
11] a) Q. A. Akkerman, V. D’Innocenzo, S. Accornero, A. Scarpel-
lini, A. Petrozza, M. Prato, L. Manna, J. Am. Chem. Soc. 2015,
[
[
1
37, 10276 – 10281; b) G. Nedelcu, L. Protesescu, S. Yakunin,
M. I. Bodnarchuk, M. J. Grotevent, M. V. Kovalenko, Nano Lett.
015, 15, 5635 – 5640.
12] a) N. Pellet, J. Teuscher, J. Maier, M. Grꢀtzel, Chem. Mater. 2015,
7, 2181 – 2188; b) G. Xing, N. Mathews, S. S. Lim, N. Yantara, X.
Liu, D. Sabba, M. Grꢀtzel, S. Mhaisalkar, T. C. Sum, Nat. Mater.
014, 13, 476 – 480.
2
[
476 – 480; c) M. M. Lee, J. Teuscher, T. Miyasaka, T. N. Mur-
2
akami, H. J. Snaith, Science 2012, 338, 643 – 647; d) A. Mei, X. Li,
L. Liu, Z. Ku, T. Liu, Y. Rong, M. Xu, M. Hu, J. Chen, Y. Yang,
M. Grꢀtzel, H. Han, Science 2014, 345, 295 – 298.
2
[
3] a) Y. Ling, Z. Yuan, Y. Tian, X. Wang, J. C. Wang, Y. Xin, K.
Hanson, B. Ma, H. Gao, Adv. Mater. 2016, 28, 305 – 311; b) S.
Pathak, N. Sakai, F. Wisnivesky Rocca Rivarola, S. D. Stranks, J.
Received: March 22, 2016
Published online: && &&, &&&&
Angew. Chem. Int. Ed. 2016, 55, 1 – 6
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
5
These are not the final page numbers!

Angewandte
Communications
Chemie
Communications
Luminescent Nanoparticles
The fast and the luminous: A new type of
highly luminescent cesium lead halide
nanoplatelets show fast anion exchange.
Fast anion exchange in the as-synthesized
CsPb Br nanoplatelets has also been
K.-H. Wang, L. Wu, L. Li, H. B. Yao,*
H. S. Qian, S. H. Yu*
&&&& — &&&&
2
5
Large-Scale Synthesis of Highly
Luminescent Perovskite-Related CsPb Br5
Nanoplatelets and Their Fast Anion
Exchange
demonstrated to extend their photolumi-
nescence spectra to the entire visible
spectral region of 410 nm–670 nm.
2
6
www.angewandte.org
ꢀ 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2016, 55, 1 – 6
These are not the final page numbers!