An All-Inorganic Perovskite-Phase Rubidium Lead Bromide Nanolaser

Article abstract of DOI:10.1002/anie.201910617

Rubidium lead halides (RbPbX₃), an important class of all-inorganic metal halide perovskites, are attracting increasing attention for photovoltaic applications. However, limited by its lower Goldschmidt tolerance factor t≈0.78, all-inorganic RbPbBr₃ has not been reported. Now, the crystal structure, X-ray diffraction (XRD) pattern, and band structure of perovskite-phase RbPbBr₃ has now been investigated. Perovskite-phase RbPbBr₃ is unstable at room temperature and transforms to photoluminescence (PL)-inactive non-perovskite. The structural evolution and mechanism of the perovskite–non-perovskite phase transition were clarified in RbPbBr₃. Experimentally, perovskite-phase RbPbBr₃ was realized through a dual-source chemical vapor deposition and annealing process. These perovskite-phase microspheres showed strong PL emission at about 464 nm. This new perovskite can serve as a gain medium and microcavity to achieve broadband (475–540 nm) single-mode lasing with a high Q of about 2100.

Full text of DOI:10.1002/anie.201910617

Angewandte
Communications
Chemie
International Edition: DOI: 10.1002/anie.201910617
German Edition: DOI: 10.1002/ange.201910617
Perovskites
An All-Inorganic Perovskite-Phase Rubidium Lead Bromide
Nanolaser
+
+
Bing Tang , Yingjie Hu , Hongxing Dong,* Liaoxin Sun, Binbin Zhao, Xiongwei Jiang, and
Long Zhang*
Abstract: Rubidium lead halides (RbPbX ), an important
and thermo-stability, higher resistance to the atmosphere, and
3
[11–18]
class of all-inorganic metal halide perovskites, are attracting
increasing attention for photovoltaic applications. However,
limited by its lower Goldschmidt tolerance factor t ꢀ 0.78, all-
enhanced exciton binding energies.
In fact, few potential
alternatives can realize all-inorganic ABX3 perovskites
+
except those containing Cs . This is because the ionic radius
inorganic RbPbBr has not been reported. Now, the crystal
of A must exceed the threshold value of the Goldschmidt
3
structure, X-ray diffraction (XRD) pattern, and band structure
of perovskite-phase RbPbBr3 has now been investigated.
tolerance factor t ꢀ 0.8. The Goldschmidt tolerance factor, t =
pffiffi
(r + r )/ 2(r + r ), describes the formability and stability of
A
X
B
X
Perovskite-phase RbPbBr is unstable at room temperature
the perovskite structure, where r , r , and r represent the
A B X
3
[19,20]
and transforms to photoluminescence (PL)-inactive non-
perovskite. The structural evolution and mechanism of the
perovskite–non-perovskite phase transition were clarified in
RbPbBr . Experimentally, perovskite-phase RbPbBr was
radii of the A, B, and X ions, respectively.
The ideal
tolerance factor t of a perovskite structure is 0.8–1, resulting in
few alternative choices for the A cation. In fact, many
perovskite compounds have a tolerance factor lower than 0.8;
this indicates that the perovskite structure is hard to realize
3
3
realized through a dual-source chemical vapor deposition
and annealing process. These perovskite-phase microspheres
showed strong PL emission at about 464 nm. This new
perovskite can serve as a gain medium and microcavity to
achieve broadband (475–540 nm) single-mode lasing with
a high Q of about 2100.
[
21–23]
and readily transforms to non-perovskite phase.
That is
why few A cations can fit into the network of MX octahedra
6
to realize all-inorganic perovskites.
Rubidium (Rb), the neighbor alkali element of cesium
(Cs), is another potential choice for the A cation to realize all-
inorganic perovskites of the form ABX . More importantly,
3
A
ll-inorganic metal halide perovskites of the form CsPbX3
X = Cl, Br, I), owing to their remarkable properties, are
the RbPbBr perovskite may exhibit novel optoelectronic
3
(
properties and help us understand the structure–property
relationship of the perovskite family. In fact, great efforts
have been devoted toward the exploration of Rb-based
perovskites. Up to now, Rb/Cs mixed perovskites have been
attracting increasing attention for use in optoelectronic
devices such as solar cells, light-emitting diodes (LEDs),
and semiconductor nanolasers.
[1–10]
Such all-inorganic perov-
[23–26]
skites exhibit superior properties, including improved photo-
reported to show better photovoltaic performance.
Rb Cs PbBr3 perovskite quantum dots were found to
x
1ꢁx
[
+]
[
*] B. Tang, Prof. H. Dong, Prof. X. Jiang, Prof. L. Zhang
Key Laboratory of Materials for High-Power Laser, Shanghai Institute
of Optics and Fine Mechanics, Chinese Academy of Sciences
Shanghai, 201800 (China)
exhibit high quantum yield (93%), narrower photolumines-
cence (PL) emission linewidth (18–27 nm), and excellent wide
[27–31]
color gamut coverage.
However, all-inorganic perovskite
RbPbBr structures have still not been realized. Theoretical
3
E-mail: hongxingd@siom.ac.cn
stability, as indicated by the tolerance factor t, should be
considered carefully for the realization of the all-inorganic
lzhang@siom.ac.cn
[
+]
B. Tang
RbPbBr3 perovskite. The tolerance factor of RbPbBr is
3
Center of Materials Science and Optoelectronics Engineering,
University of Chinese Academy of Sciences
Beijing, 100049 (China)
+
2+
ꢁ
about 0.78 (the effective ionic radii of Rb , Pb , and Br are
1.61, 1.19, and 1.96 ꢀ, respectively). This indicates that
[
+]
Y. Hu
RbPbBr perovskite structures are hard to realize and have
3
[
23,28,30,31]
+
Key Laboratory of Advanced Functional Materials of Nanjing,
Nanjing Xiaozhuang University
Nanjing, 211171 (China)
poor stability.
The incorporation of Cs into RbPbBr
3
will lead to a larger tolerance factor and stabilize the
perovskite phase. Woodward and Chen et al. thus obtained
Prof. L. Zhang
[30,31]
Rb Cs PbBr3 perovskite quantum dots.
So far, the
x
1ꢁx
IFSA Collaborative Innovation Center, Shanghai Jiao Tong University
Shanghai, 200240 (China)
realization of the all-inorganic perovskite RbPbBr is still
3
a great challenge. A new preparation strategy should be
developed for the realization of all-inorganic RbPbBr3
perovskite structures.
Dr. L. Sun, B. Zhao
National Lab for Infrared Physics, Shanghai Institute of Technical
Physics, Chinese Academy of Sciences
Shanghai, 200083 (China)
In this work, to realize all-inorganic perovskite-phase
+
[
RbPbBr , a new preparation strategy combining a dual-source
] These authors contributed equally to this work.
3
chemical vapor deposition and a high-temperature annealing
process is developed. The crystal structures, XRD patterns,
and band structures of the perovskite and non-perovskite
Supporting information and the ORCID identification number(s) for
the author(s) of this article can be found under:
https://doi.org/10.1002/anie.201910617.
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RbPbBr were theoretically analyzed. The simulation results
perovskite and non-perovskite crystal structures is the
+
3
4
showed that perovskite-phase RbPbBr is unstable at room
[PbBr6] octahedral unit, which is formed with one Pb and
six coordinated Br atoms. Additionally, Rb atoms sit at the
3
temperature and easily transforms to a PL-inactive non-
perovskite structure. Furthermore, we clarified the perov-
4
+
vacant position of the [PbBr6] octahedra in the network.
Theoretical calculation of the Gibbs free energy at different
temperatures is shown in the Supporting Information, Fig-
ure S1. The simulation results show that the perovskite phase
skite–non-perovskite
phase-transition
mechanism
in
RbPbBr . This explains why perovskite-phase RbPbBr has
3
3
not yet been obtained. Based on our strategy, we obtained
perovskite-phase RbPbBr microspheres with regular spher-
of RbPbBr is unstable at room temperature and can be
3
3
ical structures, smooth surfaces, and strong PL emission at
about 464 nm. Such microspheres can be used as a whispering
gallery mode (WGM) microcavity for nanolasing. Single-
obtained at temperatures above 1478C. The formation of the
perovskite phase of RbPbBr3 is realized through atomic
rearrangement from the non-perovskite phase with the
NH CdCl -type structure. Theoretical XRD patterns of
ꢁ
2
mode lasing with a lasing threshold of P ꢀ 17.8 mJcm and
4
3
a high-quality factor Q of about 2100 was achieved in these
perovskite- and non-perovskite-phase RbPbBr are shown
3
RbPbBr microspheres. Furthermore, single-mode lasing can
in Figures 1c and d; these patterns were calculated using the
Reflex module of Material Studio software. To analyze the
3
be tuned continually from 475–540 nm by adjusting the cavity
size and the substitution of monovalent cation Rb with Cs.
Three crystal structures including cubic, tetragonal, and
orthorhombic, are widely reported for lead-halide perov-
optoelectronic properties of RbPbBr , the electronic struc-
3
tures and partial density of states (PDOS) of perovskite- and
non-perovskite-phase RbPbBr were calculated using density
3
skites. The tolerance factor of RbPbBr is about 0.78; this
functional theory. In Figures 1e and f, it can be clearly seen
that perovskite-phase RbPbBr3 has a direct band gap of
2.63 eV, while the non-perovskite phase shows an indirect
band gap of 3.04 eV. According to the distribution of the
PDOS, the minimum of the conduction band (CBM) and the
maximum of the valence band (VBM) of perovskite-phase
RbPbBr3 are mainly dominated by the Pb 6p and Br 4p
3
indicates that RbPbBr may be obtained with either perov-
3
skite or non-perovskite structure of the orthorhombic phase.
We reconstructed the exact crystal structures of perovskite
[32,33]
and non-perovskite RbPbBr3 from their isostructures.
The exact crystal structural parameters of RbPbBr3 in
perovskite and non-perovskite phases, respectively, are
given in the Supporting Information, Tables S1 and S2. They
were calculated using density functional theory (DFT)
methods. Figure 1a,b depict the crystal structures of perov-
orbitals, just as in the non-perovskite-phase RbPbBr , while
3
the orbital of Rb has less influence on the band structure. So
far, the crystal structures, XRD patterns, and band structures
skite- and non-perovskite-phase RbPbBr . Both phases con-
of perovskite and non-perovskite RbPbBr have been theo-
3
3
sist of an orthorhombic phase with Pnma symmetry and
retically analyzed. Theoretical simulation results revealed
4
+
involve a distorted rotation of the [PbBr ] octahedral units
that perovskite-phase RbPbBr with good optical properties
6
3
[
21,22]
compared with the cubic structure.
The main part of the
can be realized at high temperatures.
Experimentally, perov-
skite-phase RbPbBr3 was
obtained through a dual-
source chemical vapor dep-
osition and a high-temper-
ature annealing process
at 2908C. Non-perovskite
RbPbBr3
were prepared first through
one-step dual-source
microspheres
a
chemical vapor process.
These samples were then
annealed at 2908C for 1 h
to obtain perovskite struc-
tures. Detailed information
regarding this process can be
found in the experimental
section. Low- and high-mag-
nification scanning electron
microscopy (SEM) images
of the as-synthesized perov-
skite
microspheres
are
shown
in Figure 2a.
RbPbBr microspheres with
3
a
1
diameter
.2 mm were uniformly dis-
D of about
Figure 1. Theoretical simulation of the crystal structures, XRD patterns, energy band structures, and partial
density of states (PDOS) of RbPbBr with perovskite (a,c,e) and non-perovskite (b,d,f) phases. In (a) and (b):
3
+
2+
ꢁ
The Rb pink, Pb gray, Br green.
tributed on the silicon sub-
2
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This is consistent with the theo-
retical simulation results in Fig-
ures 1e and f, which show direct
and indirect band gaps for the
perovskite and non-perovskite
phases of RbPbBr , respectively.
3
The absorption edge of perov-
skite-phase RbPbBr is located at
3
about 460 nm, and thus the band
gap is about 2.70 eV, which agrees
well with the PL peak and simu-
lated results. So far, these results
experimentally demonstrate the
phase transition of RbPbBr from
3
non-perovskite to perovskite.
These perovskite-phase samples
have regularly spherical geome-
try, smooth surfaces, and strong
PL emission. Such perovskite
microspheres will be good candi-
dates for WGM microcavities and
gain medium to achieve nanolas-
ing.
To gain insight into the phase-
transition mechanism, the struc-
tural evolution details were ana-
lyzed. Figure 3a depicts the
reversible phase change between
the perovskite and non-perov-
Figure 2. a) Typical SEM images of the perovskite-phase RbPbBr microspheres. Top inset: The
3
magnified image of an individual RbPbBr microsphere. Left inset: PL images of the perovskite
3
skite structures of RbPbBr . The
RbPbBr microspheres. b) Energy-dispersive X-ray spectroscopy of a RbPbBr microsphere. Right inset:
3
3
3
perovskite structure is formed by
TEM image of single RbPbBr microsphere. c) X-ray diffraction results of perovskite and non-perovskite
3
RbPbBr samples. d) Photoluminescence and absorption spectra of the RbPbBr microsphere with
perovskite phase.
annealing
a
non-perovskite
3
3
sample at 2908C for 1 h in a N2-
filled environment. Similar to all-
inorganic cesium lead halide per-
strate. It can be clearly seen that most microspheres show
regularly spherical structures and smooth surfaces; this makes
them ideal candidates for whispering gallery mode (WGM)
microcavities. In the left inset of Figure 2a, uniformly blue PL
emission can be observed from these perovskite-phase
RbPbBr3 microspheres. A typical transmission electron
ovskites, the perovskitephase of RbPbBr3 is kinetically
trapped and metastable in a N -filled environment when
2
[
34,35]
cooled to room temperature.
When exposed to a natural
environment, perovskite samples undergo a reconstructive
phase transition to a non-perovskite phase. During the
4
+
reconstructive process, [PbBr6] octahedra undergoes a tran-
sition from a corner-sharing structure to an edge-sharing
structure. The detailed structural evolution process can be
observed in the video provided in the Supporting Informa-
tion. The typical structural evolution on the existence of a Br
vacancy is shown in Figure 3b. It can be clearly seen that the
whole process consists of the tilting of the octahedral unit, the
breaking of a PbꢁBr bond, and the recombination of a PbꢁBr
microscopy (TEM) image of single RbPbBr microsphere is
3
shown in the inset of Figure 2b, confirming its regularly
spherical morphology from the clear contrast. The formation
of RbPbBr was confirmed by the energy-dispersive X-ray
3
(
EDX) spectroscopy results shown in Figure 2b, which
presents a molar ratio of Rb/Pb/Br of about 1:1.03:2.99. The
X-ray diffraction patterns of RbPbBr in Figure 2c confirm
3
the phase transition from non-perovskite to perovskite at
bond. Furthermore, the formation of the non-perovskite
structure is also accompanied by the reorientation of Rb (see
Figure 3c). As shown in Figure 3c, the Rb atom is surrounded
by three adjacent Pb Br chains in the non-perovskite
2
908C, which agrees well with theoretical simulations.
According to the XRD results in Figures 2c, Figures 1c and
d, the non-perovskite phase dominates in the directly
obtained samples; the main phase of the annealed samples
2
10
structure. We also found that no perovskite–non-perovskite
phase transition took place when annealing a perovskite
[
30,31]
was transformed to a perovskite structure.
Figure 2d
depicts the PL and absorption spectra of perovskite-phase
RbPbBr . Interestingly, the perovskite-phase RbPbBr micro-
sample in a N -filled environment at temperatures between
2
30–2908C for 1 h. A RbPbBr sample stored in a N -filled
3
3
3
2
spheres showed strong PL emission at about 464 nm with
a full width at half maximum (FWHM) of about 12.4 nm,
environment at room temperature can maintain the perov-
skite phase for about 1 month or even longer. The XRD data
is shown in the Supporting Information, Figure S2. However,
while the non-perovskite RbPbBr samples were PL-inactive.
3
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emission spectra near the
lasing threshold. When the
pump density P was about
ꢁ2
1
3.2 mJcm
(below the
lasing threshold), a broad
emission peak at about
4
66 nm with
a
FWHM
of about 15.8 nm was
observed; this can be attrib-
uted to spontaneous emis-
sion. When P reached the
lasing threshold of about
ꢁ2
1
7.8 mJcm , a sharp peak
with narrow linewidth
appeared above the back-
ground. As the pump den-
sity
was
continually
increased, the intensity of
the lasing peak at about
Figure 3. Mechanism of the phase transition. a) The reversible phase transition between the perovskite and
+
2+
ꢁ
475.6 nm
grew
rapidly
non-perovskite structures. The Rb pink, Pb gray, Br green. b) The structural evolution from Pb Br to
4
20
while the PL emission
remained almost constant.
This confirms the realization
of single-mode lasing. As P
reached the lasing thresh-
old, the FWHM of the emis-
sion spectrum quickly drop-
ped from 15.8 to about
couple Pb Br on the existence of Br vacancies (pink sphere). Rb is not shown for simplicity. c) The structure
2
10
transformation from the perovskite to non-perovskite observed from [010] crystal surface. d),e) The
comparation of a Br vacancy formation energy in moisture (DEvac =0.67 eV) and vacuum (DEvac =2.73 eV)
conditions. f),g) Representation of the orbital arrangements for perovskite- and non-perovskite-phase
RbPbBr , VBM and CBM orbitals are represented by green and blue, respectively, The isosurface value is set
3
ꢁ3
+
2+
ꢁ
to be 0.018 eꢀ . The Rb , Pb , and Br ions in (b)–(e) are represented by violet, gray, and reddish-brown
spheres.
freshly prepared perovskite samples will degrade in about
0 min when exposed to the natural environment. DFT
calculations were carried out to clarify these differences. As
shown in Figure 3d,e, the presence of water molecules
reduces the formation energy of a Br vacancy to DEvac
0.23 nm, which also supports the appearance of lasing
action. It was noticed that the peak position of single-mode
lasing was blue-shifted with increasing pump density. This
might have resulted from band filling, thermo-optics, or
2
[
38,39]
electron/hole many-body interactions.
Figure 4d shows
ꢀ
0.67 eV; this will further lower the free-energy barrier of
the integrated PL intensity as a function of pump density.
These log–log plots show the S-curve model of lasing
nucleation (Figure 3b) and accelerate the phase transition at
[
36,37]
ꢁ2
room temperature.
the VBM and CBM orbitals of RbPbBr are significantly
shifted during the phase-transition process, resulting in
distinct optical properties. These results clarified the phase-
transition mechanism and the direct–indirect band gap
transition of RbPbBr3.
In Figures 3 f and g, it can be seen that
oscillation with two kinks at 17.8 and 30.1 mJcm , respec-
[
40]
tively. As the pump density increases, the evolution from
spontaneous emission to simulated emission occurs at
3
ꢁ2
ꢁ2
17.8 mJcm , and gain saturation starts at 30.1 mJcm . Such
behavior clarifies the achievement of single-mode lasing,
ꢁ2
giving the lasing threshold at about 17.8 mJcm . Figure 4e
depicts single-mode lasing at about 475.6 nm, and a Lorent-
zian curve with dl ꢀ 0.23 nm is used to fit these plots.
According to the equation Q = l/dl, the quality factor of
single-mode lasing at 475.6 nm was calculated to be Q ꢀ 2100,
which is higher than most reported nanolasing systems,
including microdisks, nanowires, and nanorods. The spherical
The optically pumped lasing properties of perovskite-
phase RbPbBr microspheres were probed through a home-
built confocal microphotoluminescence system. As presented
in Figure 4a, a femtosecond laser with a wavelength of
3
4
00 nm was used as the pumping source to excite single
RbPbBr perovskite microsphere. The waist of the pulsed
3
laser beam was about 3 mm to pump the whole RbPbBr3
microsphere homogeneously. The perovskite-phase RbPbBr3
microsphere acts as both a gain medium and WGM micro-
cavity. At a high pump density, the gain just balances or
exceeds the optical losses and a single-mode lasing at
shape of the perovskite RbPbBr microsphere makes them
3
ideal WGM candidates for total internal reflection, and
[41–45]
ensures lower optical losses.
Therefore, the achievement
of single-mode lasing with a high Q factor is mainly attributed
to the excellent WGM cavity structure.
4
75.6 nm can be observed. Figure 4b presents a two-dimen-
The lasing behaviors of a series of RbPbBr microspheres
3
sional (2D) pseudo-color plot recorded from a single
RbPbBr3 microsphere with D ꢀ 1.2 mm as a function of
pump density. By increasing the pump density from 5 to
were investigated to clarify the influence of microcavity size
on optical confinement and lasing properties. Figure 5a
presents single-mode lasing spectra recorded from different
ꢁ
2
1
00 mJcm , the transition from broadband emission to
RbPbBr microspheres. As the diameter increased from 1156
3
a sharp peak could be clearly observed. This indicates the
occurrence of lasing action. Figure 4c depicts typical PL
to 1260 nm, single-mode lasing was red-shifted from 471.2 to
478.9 nm. Detailed information about single-mode lasing at
4
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as squares, hexagonals, or
[
41–47]
other shapes.
That is
why most spherical micro-
cavities have excellent
lasing performance. The
band gap of APbX perov-
3
skites is mainly dependent
4
+
on the [PbX6] octahedral
unit, while the A cation
influences the band struc-
ture by changing the bond-
ing properties between the
Pb and X atoms of the
[21,22]
octahedra.
Rb Cs PbBr3
micro-
x
1ꢁx
spheres also can be
obtained through a chemi-
cal vapor deposition pro-
cess. Figure 5c depicts the
PL images and spectra of
as-prepared samples. Uni-
formly bright PL emission
can be observed from these
PL images. The PL emis-
sion peak was red-shifted
from 464 to 529 nm as the
+
ratio of Cs was increased.
SEM and PL images of
CsPbBr3 microspheres are
Figure 4. a) An individual RbPbBr microsphere pumped by a 400 nmfs-laser (ca. 40 fs, 10 kHz). The light
path inside the spherical cavity is signaled by the blue circle. b) 2D pseudo-color plot of a RbPbBr3
3
microsphere under different pump density. c) The PL spectra recorded from single RbPbBr microsphere
3
around the lasing threshold. Inset: Photoluminescence image recorded around the lasing threshold. d) The
integrated PL intensity is plotted as a function of pump density, giving the lasing threshold at about
presented in the Supporting
Information, Figure S5. As
shown in Figure 5d, high-Q
single-mode lasing can be
ꢁ2
1
7.8 mJcm . e) Lorentz fitting of the single-mode lasing at about 475.6 nm, giving a FWHM (dl)ꢀ0.23 nm,
the corresponding Q factor is about 2100.
tuned from blue to green
4
71.2 nm can be found in the Supporting Information,
(475–540 nm) in these perovskite microspheres. In the insets
of Figure 5d, clear interference patterns can be observed from
the PL images under a high pump density; this indicates the
formation of WGM lasing.
Figure S3. The wavelength of lasing in a spherical resonator
has been theoretically and experimentally demonstrated
as:
[
9,42–47]
In conclusion, perovskite-phase RbPbBr3 was realized
through a chemical vapor deposition and a high-temperature
annealing process. The crystal phase, XRD pattern, and band
l ꢀ pD Nn
ð1Þ
where n and l describe the mode number and wavelength of
the lasing peak, respectively, while D and N are the diameter
and refractive index of the spherical microcavity, respectively.
Figure 5b plots the peak position of single-mode lasing as
a function of the diameter of the microsphere. The single-
mode lasing wavelength is continuously red-shifted with
increasing cavity size. A linear curve can be used to fit these
plots in Figure 5b, which agrees well with the theoretical
prediction from the above equation. To deeply decouple the
modulation effect of the microcavity, optical mode simula-
tions were carried out using the finite domain time difference
structure of perovskite RbPbBr were investigated theoret-
3
ically. Theoretical results showed that perovskite-phase
RbPbBr3 is difficult to obtain directly because of the
instability of its phase structure at room temperature. The
perovskite–non-perovskite structural evolution was system-
atically analyzed to reveal the mechanism of the phase
transition of RbPbBr3. We obtained perovskite-phase
RbPbBr with regular spherical structures, smooth surfaces,
3
and strong PL emission at about 464 nm through this new
strategy. We found that these new perovskite samples can act
both as a gain medium and microcavity to achieve single-
mode lasing with a high Q of about 2100. By modulating the
microcavity size and/or the ratio of monovalent cation, single-
mode lasing can be tuned continuously from blue to green
(475–540 nm). Our work provides a simple way to achieve
(
FDTD) solution. The inset of Figure 5b shows the simulation
results for single-mode lasing at about 475.6 nm; it can be
clearly seen that the electrical field is well-confined inside.
The simulated electrical field distributions of other perovskite
RbPbBr3 microspheres can be found in the Supporting
Information, Figure S4. A spherical microcavity shows per-
fect successive total internal reflection and ensures lower
optical losses compared with other types of microcavity, such
perovskite-phase RbPbBr with superior optical properties,
3
which may be used as a promising candidate for micro/
nanolasers.
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Figure 5. a) Single-mode lasing recorded from five typical RbPbBr microspheres. b) The relationship between the wavelength of single-mode
3
lasing and the diameter of RbPbBr microsphere. Top inset: Simulated electric field distribution of single-mode lasing at about 475.6 nm.
3
c) Photoluminescence images and spectra of RbPbBr , Rb Cs PbBr , CsPbBr , microsphere. d) Single-mode lasing recorded from single
3
x
1ꢁx
3
3
Rb Cs PbBr microsphere. Insets: Photoluminescence images of perovskite microspheres under a high pump density.
x
1ꢁx
3
[
6] H. Zhou, S. Yuan, X. Wang, T. Xu, X. Wang, H. Li, W. Zheng, P.
Fan, Y. Li, L. Sun, A. Pan, ACS Nano 2017, 11, 1189.
Acknowledgements
[
7] X. Wang, M. Shoaib, X. Wang, X. Zhang, M. He, Z. Luo, W.
Zheng, H. Li, T. Yang, X. Zhu, L. Ma, A. Pan, ACS Nano 2018,
This work was supported financially by the NSFC (61675219,
6
1875256, 11674343, 91750103). H.D. acknowledges the
1
2, 6170.
8] X. He, P. Liu, H. Zhang, Q. Liao, J. Yao, H. Fu, Adv. Mater. 2017,
9, 1604510.
Youth Top-notch Talent Support Program in Shanghai. We
thank Q. Si for helping design and draw the picture in
Figure 4a and TOC.
[
2
[9] B. Tang, H. Dong, L. Sun, W. Zheng, Q. Wang, F. Sun, X. Jiang,
A. Pan, L. Zhang, ACS Nano 2017, 11, 10681.
[
10] K. Wang, S. Wang, S. Xiao, Q. Song, Adv. Opt. Mater. 2018, 6,
1
800278.
Conflict of interest
[
11] Z. Wu, J. Chen, Y. Mi, X. Sui, S. Zhang, W. Du, R. Wang, J. Shi,
X. Wu, X. Qiu, Z. Qin, Q. Zhang, X. Liu, Adv. Opt. Mater. 2018,
The authors declare no conflict of interest.
6, 1800674.
[
12] S. W. Eaton, M. Lai, N. A. Gibson, A. B. Wong, L. Dou, J. Ma,
Keywords: all-inorganic perovskite phases · nanolasers ·
rubidium lead bromide
L. W. Wang, S. R. Leone, P. Yang, Proc. Natl. Acad. Sci. USA
2016, 113, 1993.
[
13] G. Xing, M. H. Kumar, W. K. Chong, X. Liu, Y. Cai, H. Ding, M.
Asta, M. Grꢁtzel, S. Mhaisalkar, N. Mathews, T. C. Sum, Adv.
Mater. 2016, 28, 8191.
[
[
14] L. Huang, Q. Gao, L. D. Sun, H. Dong, S. Shi, T. Cai, Q. Liao,
C. H. Yan, Adv. Mater. 2018, 30, 1800596.
15] Y. Wang, X. Sun, R. Shivanna, Y. Yang, Z. Chen, Y. Guo, G. C.
Wang, E. Wertz, F. Deschler, Z. Cai, H. Zhou, T. M. Lu, J. Shi,
Nano Lett. 2016, 16, 7974.
[
1] T. Zhang, M. I. Dar, G. Li, F. Xu, N. Guo, M. Grꢁtzel, Y. Zhao,
Sci. Adv. 2017, 3, e1700841.
2] W. J. Yin, T. Shi, Y. Yan, Adv. Mater. 2014, 26, 4653.
3] J. Song, J. Li, X. Li, L. Xu, Y. Dong, H. Zeng, Adv. Mater. 2015,
[
[
[
16] 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.
27, 7162.
[
[
4] Q. Zhang, R. Su, X. Liu, J. Xing, T. C. Sum, Q. Xiong, Adv.
Funct. Mater. 2016, 26, 6238.
5] Y. Fu, H. Zhu, C. C. Stoumpos, Q. Ding, J. Wang, M. G.
Kanatzidis, X. Zhu, S. Jin, ACS Nano 2016, 10, 7963.
[
17] Y. Wang, X. Li, J. Song, L. Xiao, H. Zeng, H. Sun, Adv. Mater.
2015, 27, 7101.
6
www.angewandte.org
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Angew. Chem. Int. Ed. 2019, 58, 1 – 8
These are not the final page numbers!

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Communications
Chemie
[
18] J. Chen, Y. Fu, L. Samad, L. Dang, Y. Zhao, S. Shen, L. Guo, S.
[35] M. Lai, Q. Kong, C. G. Bischak, Y. Yu, L. Dou, S. W. Eaton, N. S.
Jin, Nano Lett. 2017, 17, 460.
19] V. M. Goldschmidt, Naturwissenschaften 1926, 14, 447.
20] M. A. Green, A. H. Baillie, H. J. Snaith, Nat. Photonics 2014, 8,
Ginsberg, P. Yang, Nano Res. 2017, 10, 1107.
[36] S. Dastidar, D. A. Egger, L. Z. Tan, S. B. Cromer, A. D. Dillon, S.
Liu, L. Kronik, A. M. Rappe, A. T. Fafarman, Nano Lett. 2016,
16, 3563.
[
[
506.
[
[
21] B. R. Sutherland, E. H. Sargent, Nat. Photonics 2016, 10, 295.
22] Q. Zhang, S. Rui, W. Du, X. Liu, L. Zhao, S. T. Ha, Q. Xiong,
Small Methods 2017, 1, 1700163.
23] M. Saliba, T. Matsui, K. Domanski, J. Y. Seo, A. Ummadisingu,
S. M. Zakeeruddin, J. P. Correa-Baena, W. R. Tress, A. Abate, A.
Hagfeldt, M. Grꢁtzel, Science 2016, 354, 206.
24] Y. Hu, E. M. Hutter, P. Rieder, I. Grill, J. Hanisch, M. F. Aygꢂler,
A. G. Hufnagel, M. Handloser, T. Bein, A. Hartschuh, K.
Tvingstedt, V. Dyakonov, A. Baumann, T. J. Savenije, M. L.
Petrus, P. Docampo, Adv. Energy Mater. 2018, 8, 1703057.
25] P. Yadav, M. I. Dar M, N. Arora, E. A. Alharbi, F. Giordano,
S. M. Zakeeruddin, M. Grꢁtzel, Adv. Mater. 2017, 29, 1701077.
26] M. Zhang, J. S. Yun, Q. Ma, J. Zheng, C. F. J. Lau, X. Deng, J.
Kim, D. Kim, J. Seidel, M. A. Green, S. Huang, A. W. Y. Ho-
Baillie, ACS Energy Lett. 2017, 2, 438.
[37] A. Mattoni, A. Filippetti, C. Caddeo, J. Phys. Condens. Mater.
2016, 29, 043001.
[38] H. Zhu, Y. Fu, F. Meng, X. Wu, Z. Gong, Q. Ding, M. V.
Gustafsson, M. T. Trinh, S. Jin, X. Y. Zhu, Nat. Mater. 2015, 14,
636.
[39] G. Li, T. Che, X. Ji, S. Liu, Y. Hao, Y. Cui, S. Liu, Adv. Funct.
Mater. 2019, 29, 1805553.
[40] Q. Song, H. Cao, S. T. Ho, G. S. Solomon, Appl. Phys. Lett. 2009,
94, 061109.
[
[
[41] H. Zhang, Q. Liao, X. Wang, J. Yao, H. Fu, Adv. Opt. Mater.
2016, 4, 1718.
[
[
[42] B. Tang, L. Sun, W. Zheng, H. Dong, B. Zhao, Q. Si, X. Wang, X.
Jiang, A. Pan, L. Zhang, Adv. Opt. Mater. 2018, 6, 1800391.
[43] S. Yang, Y. Wang, H. Sun, Adv. Opt. Mater. 2015, 3, 1136.
[44] A. Chiasera, Y. Dumeige, P. Fꢅron, M. Ferrari, Y. Jestin, G.
Nunzi Conti, S. Pelli, S. Soria, G. C. Righini, Laser Photonics
Rev. 2010, 4, 457.
[45] X. Wang, Q. Liao, H. Li, S. Bai, Y. Wu, X. Lu, H. Hu, Q. Shi, H.
Fu, J. Am. Chem. Soc. 2015, 137, 9289.
[46] Y. Liu, C. Xu, Z. Zhu, D. You, R. Wang, F. Qin, X. Wang, Q. Cui,
Z. Shi, Cryst. Growth Des. 2018, 18, 5279.
[
[
[
[
[
27] H. Wu, Y. Yang, D. Zhou, K. Li, J. Yu, J. Han, Z. Li, Z. Long, J.
Ma, J. Qiu, Nanoscale 2018, 10, 3429.
28] D. Amgar, T. Binyamin, V. Uvarov, L. Etgar, Nanoscale 2018, 10,
6060.
29] S. Baek, S. Kim, J. Y. Noh, J. H. Heo, S. H. Im, K. H. Hong, S. W.
Kim, Adv. Opt. Mater. 2018, 6, 1800295.
30] J. W. Xiao, Y. Liang, S. Zhang, Y. Zhao, Y. Li, Q. Chen, Chem.
Eur. J. 2019, 25, 2597.
[47] W. Du, S. Zhang, Z. Wu, Q. Shang, Y. Mi, J. Chen, C. Qin, X. Qiu,
Q. Zhang, X. Liu, Nanoscale 2019, 11, 3145.
31] M. R. Linaburg, E. T. McClure, J. D. Majher, P. M. Woodward,
Chem. Mater. 2017, 29, 3507.
[
[
32] M. Rodovꢃ, J. Bro zˇ ek, K. Knꢄ zˇ ek, J. Therm. Anal. 2003, 71, 667.
33] D. M. Trotsa, S. V. Myagkota, J. Phys. Chem. Solids 2008, 69,
2520.
[
34] J. Lin, M. Lai, L. Dou, C. S. Kley, H. Chen, F. Peng, J. Sun, D. Lu,
S. A. Hawks, C. Xie, F. Cui, A. P. Alivisatos, D. T. Limmer, P.
Yang, Nat. Mater. 2018, 17, 261.
Manuscript received: August 19, 2019
Accepted manuscript online: September 10, 2019
Version of record online: && &&, &&&&
Angew. Chem. Int. Ed. 2019, 58, 1 – 8
ꢀ 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
7
These are not the final page numbers!

Angewandte
Communications
Chemie
Communications
Perovskites
All inorganic: The crystal structure, phase
transition, band gap and optical proper-
B. Tang, Y. Hu, H. Dong,* L. Sun, B. Zhao,
ties of perovskite-phase RbPbBr were
3
X. Jiang, L. Zhang*
&&&& — &&&&
analyzed theoretically and experimentally.
This new perovskite microsphere can
serve as a gain medium and microcavity
to achieve broadband (475–540 nm)
single-mode lasing with a high Q of about
An All-Inorganic Perovskite-Phase
Rubidium Lead Bromide Nanolaser
2
100.
8
www.angewandte.org
ꢀ 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2019, 58, 1 – 8
These are not the final page numbers!