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Electronic Supplementary Information
Room-Temperature and Gram-Scale Synthesis of
CsPbX3 (X=Cl, Br, I) Perovskite Nanocrystals with
50-85% Photoluminescence Quantum Yields
Song Wei,1,2 Yanchun Yang,1,2 Xiaojiao Kang,1 Lan Wang,1,2 Lijian Huang1* and
Daocheng Pan1*
1State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of
Applied Chemistry, Chinese Academy of Sciences, 5625 Renmin Street, Changchun,
Jilin, 130022, China; 2University of the Chinese Academy of Sciences, Beijing,
100049, China
Tel & Fax: +86-431-85262941; Email: [email protected] and [email protected]
Experimental Section
Chemcials
Cs2CO3 (99.9%), CsOH·H2O (99.9%), PbO (99.9%), tetraoctylammonium bromide
(98%), tetrabutylammonium bromide (99%), cetyltrimethylammonium bromide
(CTAB, 99%), dihexadecyldimethylammonium bromide (97%), tetrabutylammonium
chloride (97%), tetrabutylammonium iodide (99%), butyric acid (99%), hexanoic acid
(99%), octanoic acid (98%), decanoic acid (99%), myristic acid (99%), and
γ-butyrolactone (99%) were purchased by Aladdin Inc. Oleic acid (90%) was obtained
from Sigma-Aldrich Inc. Toluene, hexane, chloroform, xylene, and dichloromethane
Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 2016
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were bought from Beijing Chemical Works, and all solvents were of analytical grade
and were used as received without further purification.
Preparation of mixed Cs-oleate and Pb-oleate precursor solution
First, 1.0 mmol CsOH·H2O (or 0.5 mmol Cs2CO3), 1.0 mmol PbO, and 5.0 mL of
oleic acid were loaded into a 20 mL of glass vial, and the mixture was magnetically
stirred on a hot plate at 160 oC until a transparent solution was obtained. Then, the
glass vial was putted into a 120 oC oven for 30 min to remove the water. Next, Cs and
Pb precursor solution was diluted to be 0.1 M by adding 5 mL of toluene. Finally, the
mixed Cs and Pb precursor solution was sealed and stored in air for further use. Note
that all experimental procedures in this paper were conducted in the open air. To
investigate the impact of the solvent on the synthesis of CsPbBr3 quantum dots,
chloroform, dichloromethane, xylene, or hexane was used to replace toluene. In
addition, butyric acid, hexanoic acid, octanoic acid, decanoic acid, or myristic acid
was used to substitute oleic acid for the synthesis of CsPbBr3 quantum dots.
Small-scale synthesis of CsPbBr3 quantum dots
In a typical procedure, 1.0 mL of Cs and Pb precursor solution and 15.0 mL of
toluene were mixed in a 20 mL of glass vial with vigorously stirring at room
temperature (25~30oC). A Br precursor solution containing 0.1 mmol
tetraoctylammonium bromide, 0.5 mL oleic acid, and 2.0 mL of toluene was swiftly
added into the glass vial. A clear and green CsPbBr3 quantum dot solution was formed
immediately. After 10 s, the CsPbBr3 quantum dots were precipitated by adding
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γ-butyrolactone. Finally, the CsPbBr3 quantum dots were centrifigued and redispersed
in toluene for various characterizations. Note that the crude solution of quantum dots
was used for long-term storage.
Synthesis of alloyed CsPbX3 (X=Cl, Br, I) perovskite quantum dots
First, the oleic acid-capped CsPbBr3 quantum dots were prepared in chloroform.
Subsequently, the different volumes of chloroform solution of tetrabutylammonium
chloride (0.02 M) or tetrabutylammonium iodide (0.2 M) were dropped into the crude
solution of CsPbBr3 QDs until the desired emission peak position was achieved.
Large-Scale synthesis of CsPbBr3 quantum dots
First, 50 mL of oleic acid was used to dissolve 2.5 mmol Cs2CO3 and 5.0 mmol
PbO in a 1.0 L of beaker, followed by a drying process in a 120 oC oven for 30 min.
900 mL of toluene was added into Cs and Pb precursor solution. Under magnetic
stirring, a Br precursor solution which was prepared by dissolving 5.0 mmol
tetraoctylammonium bromide into 40 mL of toluene and 10 mL of oleic acid was
added into the Cs and Pb precursor solution. Finally, ~1.0 L of the quantum dot
solution was achieved. The yield was estimated by precipitating 2.0 mL of QD crude
solution in a pre-weighted centrifuge tube.
Characterizations
UV-vis absorption spectra were measured by Metash 5200 spectrophotometer.
Photoluminescence (PL) spectra were taken using Shimadzu RF 5301PC. The relative
photoluminescence quantum yields (PLQYs) of the quantum dots were determined by
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comparing the integrated emission of the QD samples with a standard fluorescence
dye (coumarin 6 in ethanol, QY=78% or 9, 10-diphenylanthracene in cyclohexane,
QY=90%). The luminescence decay curves were obtained from a Lecroy Wave Runner
6100 digital oscilloscope (1 GHz) using a tunable laser (pulse width=4 ns, gate=50 ns)
as the excitation source (Continuum Sunlite OPO). The temperature dependent PL
spectra were monitored by a Maya 2000 Pro CCD-based fiber optic spectrometer
(Ocean Optics Inc.) in air, and the temperature was programmed to increase from 20
oC to 100 oC. The XRD patterns were recorded using a Bruker D8 FOCUS X-ray
diffractometer. High-resolution transmission electron microscopy (HR-TEM) images
were taken on a FEI Tecnai G2 F20 with an accelerating voltage of 200 kV. Energy
disperse spectroscopy (EDS) spectrum was recorded by using a scanning electron
microscope (Hitachi S-4800) equipped with a Bruker AXS XFlash detector 4010.
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Figure S1. The PL quantum yields and stability tests of different fatty acids-capped
CsPbBr3 nanocrystal solution stored in ambient environment.
Figure S2. UV-vis absorption (solid) and PL (dash) spectra of CsPbBr3 nanocrystals
synthesized in different organic solvents.
300 400 500 600 700
Hexane
Choloroform
XyleneDicholoromethane
Abs
orba
nce/
PL In
tens
ity (a
.u.)
Wavelength (nm)
Toluene
0 2 4 6 8 10 12 140.0
0.2
0.4
0.6
0.8
1.0
PL q
uant
um y
ield
(%)
Time (days)
Butyric acid Hexanoic acid Decanoic acid Oleic acid
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Figure S3. PL quantum yields and PL stability of oleic acid-capped CsPbBr3 quantum
dots synthesized in different organic solvents.
Figure S4. UV-vis absorption and PL spectra of CsPbBr3 nanocrystals synthesized at
different temperatures.
400 500 600 7000.00
0.05
0.10
0.15
0 oC 30 oC 60 oC 90 oC
Abs
orba
nce
Wavelength (nm)
0
200
400
600
PL In
tens
ity
0 2 4 6 8 10 12 140.0
0.2
0.4
0.6
0.8
1.0
PL q
uant
um y
ield
(%)
Time (days)
Toluene Xylene Hexane Dichloromethane
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Figure S5. PL decay curves of different fatty acids-capped CsPbBr3 nanocrystals.
0 30 60 90 120 1500.0
0.2
0.4
0.6
0.8
1.0
Time (ns)
PL
inte
nsity
(a.u
.)
Butyric acid-capped CsPbBr3 QDs Single exponential fitting
13.3 ns
a
0 30 60 90 120 1500.0
0.2
0.4
0.6
0.8
1.0
Time (ns)
PL in
tens
ity (a
.u.)
Hexanoic acid-capped CsPbBr3 QDs Single exponential fitting
9.4 ns
b
0 30 60 90 120 1500.0
0.2
0.4
0.6
0.8
1.0
Time (ns)
PL in
tens
ity (a
.u.)
Octanoic acid-capped CsPbBr3 QDs Single exponential fitting
9.8 ns
c
0 30 60 90 120 1500.0
0.2
0.4
0.6
0.8
1.0
Time (ns)
PL in
tens
ity (a
.u.)
Tetradodecanoic acid-capped CsPbBr3 QDs Single exponential fitting
13.3 ns
e
0 30 60 90 120 1500.0
0.2
0.4
0.6
0.8
1.0
Time (ns)
PL in
tens
ity (a
.u.)
Dodecanoic acid-capped CsPbBr3 QDs Single exponential fitting
9.3 ns
d
0 30 60 90 120 1500.0
0.2
0.4
0.6
0.8
1.0
Time (ns)
PL in
tens
ity (a
.u.)
Oleic acid-capped CsPbBr3 QDs Single exponential fitting
20.4 ns
f
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Figure S6. (a) AFM image of oleic acid-capped CsPbBr3 QDs; (b) AFM 3D image of
CsPbBr3 QDs; (c) height distribution curve of CsPbBr3 QDs.
2 4 6 8 100.0
0.4
0.8
1.2
Occ
urre
nce
prob
abili
ty (%
)
Height (nm)
Average height=7.2 nm
c+6.6 nm
-2.7 nm
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Figure S7. Size distribution of large-scale prepared CsPbBr3 nanocrystals.
Figure S8. XRD patterns of alloyed CsPbX3 (X=Cl, Br, I) nanocrystals.
3 6 9 12 150
10
20
30
40
Perc
enta
ge (%
)
Size (nm)
Size=8.4 nm
10 20 30 40 50
5
4
3
2
I
Cl
Inte
nsity
(a.u
.)
2Theta (Degree)
Br
(200
)
(110
)
(100
)
1
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Table S1. EDS results (atomic percent) of alloyed CsPbX3 (X=Cl, Br, I) nanocrystals
in Figure S8.
Sample Cs% Pb% Cl% Br% I%
1 21.75 20.55 36.41 21.29 ------2 20.36 20.80 23.49 35.35 ------3 20.64 22.25 ------ 57.11 ------4 21.09 22.16 ------ 46.62 10.135 21.54 23.64 ------ 35.55 19.27
Figure S9. The photographs of the aggregated CsPbBr3 nanocrystals under normal
indoor light (a) and UV light (b) illumination after 30 days of air storage.
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Figure S10. Temperature-dependent PL spectra of CsPbBr3 nanocrystal thin film.
400 450 500 550 6000
20000
40000
60000
80000
100000
120000
100 oC
20 oC
PL In
tens
ity
Wavelength (nm)
2 oC/step
