Mechanochemical synthesis of a processable halide perovskite quantum dot-MOF composite by post-synthetic metalation

Article abstract of DOI:10.1039/c9ta05977f

Perovskite quantum dots (PQDs) are some of the most sought after materials for optoelectronic and photovoltaic applications. We report the mechanochemical, solvent-free synthesis of a PQD?MOF composite using a post-synthetically Pb^II metalated

Full text of DOI:10.1039/c9ta05977f

View Article Online
View Journal
Journal of
Materials Chemistry A
Materials for energy and sustainability
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: S. Bhattacharyya,
D. Rambabu and T. K. Maji, J. Mater. Chem. A, 2019, DOI: 10.1039/C9TA05977F.
Volume
Number 12
28 March 2018
Pages 4883-5230
6
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Journal of
Materials Chemistry A
Materials for energy and sustainability
rsc.li/materials-a
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 2050-7488
COMMUNICATION
Zhenhai Wen et al.
An electrochemically neutralized energy-assisted low-cost
acid-alkaline electrolyzer for energy-saving electrolysis
hydrogen generation
rsc.li/materials-a

Please do not adjust margins
Journal of Materials Chemistry A
Page 1 of 7
View Article Online
DOI: 10.1039/C9TA05977F
ARTICLE
Mechanochemical Synthesis of Processable Halide Perovskite
Quantum Dot-MOF Composite by Post-synthetic Metalation
Sohini Bhattacharyya, a Darsi Rambabu a and Tapas Kumar Maji *a
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Perovskite quantum dots (PQDs) are some of the most sought after materials for optoelectronic and photovoltaic
applications. We report the mechanochemical, solvent-free synthesis of PQD@MOF composite using a post-synthetically
PbII
metalated
anionic
MOF
AMOF-1
{[(NH2Me2)2][Zn3(L)2].9H2O}
(L=5,5′-(1,4-
phenylenebis(methylene))bis(oxy)diisophthalate) as template. CsPbX3 PQDs are formed on the surface of AMOF-1 just by
grinding PbII@AMOF-1 with CsX (X=Cl, Br and I). The PQD@AMOF composites are characterized using PXRD and TEM. The
size of the PQDs thus formed is restricted by AMOF-1 thereby manifesting quantum confinement effect. The composites
show narrow and intense emission bands typical of PQDs. The luminescent AMOF is exploited for Försters Resonance
Energy Transfer (FRET) to the stabilized CsPbBr3 PQDs. AMOF-1 also imparts superior stability and processibility to the
PQDs
which
is
manifested
by
fabricating
a
colour-tunable
ink
using
the
composite.
NCs by confining them within the nanospaces of a porous
Metal-organic framework (MOFs)22-24 is an intriguing technique
to tune their optical band gap while enhancing their
stability.20,25-30 MOFs, well known for their porosity, tunability
and high surface area, surpass contemporary porous materials
in their flexibility and easy functionalization.23 The regular
structure of MOFs is particularly advantageous in quantum
confinement of such NCs, thereby enhancing their
optoelectronic properties, and providing extra stability for
better performance in devices.25-30 There are only a handful of
reports of PQD@MOF composites and the synthetic methods
all involve harsh conditions concerning expensive and
precarious organic solvents, capping agents and
organometallic complexes. In a recent report, Zhang, et al.
have derived PQDs from a PbII-based MOF.25 However, the
MOF template cannot sustain the harsh synthetic procedure
Introduction
Over the past decade, colloidal nanocrystal halide perovskite
quantum dots (PQDs) have emerged as supremely important
materials for photovoltaic and optoelectronic applications.1-4
The miniscule sizes of PQDs endow them with a variety of
interesting features5-7 involving an intriguing surface
chemistry, which are otherwise not observed in their bulk
counterparts.8 Among these, cesium lead halide (CsPbX3)
perovskite nanocrystals (NCs) have gathered the attention of
scientists because of excellent photovoltaic efficiency.5,9 Their
high emission intensities and quantum yield, narrow emission
bands and tunable band gaps by composition, size or
morphology have made them perfect candidates for
optoelectronic devices, e.g., LEDs, lasers or specific
detection.10-11 However, the use of these materials in practical
applications is hindered by their poor stability when exposed
to variable atmospheric conditions e.g., humidity, temperature
or light.12 This instability can be majorly attributed to the ionic
character of CsPbX3 NCs along with their labile surfaces and
metastable structures.13-14 In order to address this issue,
besides the conventional method of synthesizing these NCs
like hot injection and various liquid phase methods,15-17
attempts have also been made to immobilise them in silica or
polymer matrices.18-21 The size and spatial control of such PQD
and is broken down in the process. In contrast,
a
mechanochemical method would be simple, fast, efficient and
environmentally benign for synthesizing such PQD@MOF
composites.31-34 However, attaining PQDs by such
mechanochemical methods is a highly challenging task owing
to the lack of control over crystal growth. Moreover, the
instability of the PQDs also demands synthesis in controlled
and inert atmosphere.5,31-34 A porous template like MOF can
alleviate this issue by restricting the size of the NCs and also by
providing extra stability.
This work demonstrates the synthesis and characterization of
unique
CsPbX3@MOF
composites
by
a
simple
post-
mechanochemical grinding method involving
a
a. Molecular Materials Laboratory, Chemistry and Physics of Materials Unit, School
of Advanced Materials (SAMat). Jawaharlal Nehru Centre for Advanced Scientific
Research (JNCASR), Jakkur, Bangalore- 560 064. India. Email: tmaji@jncasr.ac.in
#Dedicated to Prof. C. N. R. Rao on the occasion of his 86th birthday.
Electronic Supplementary Information (ESI) available: PDF containing synthetic and
characterization details, Movie showing mechanochemical synthesis. See
DOI: 10.1039/x0xx00000x
synthetically PbII metalated anionic MOF (AMOF). This process
ensures the stabilization of PQD on the MOF surface, thus
restricting their size and dictating their optical properties
based on quantum confinement effect. The CsPbX3@AMOF
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry A
Page 2 of 7
ARTICLE
Journal Name
sample was intermittently checked under UV lVaiemwpArtifcolerOntlhinee
DOI: 10.1039/C9TA05977F
appearance of characteristic perovskite emission.
Physical Measurements
The elemental analysis was carried out using a Thermo
Fischer Flash 2000 Elemental Analyzer. Thermogravimetric
analysis (TGA) was carried out using
a Mettler-Toledo
instrument in nitrogen atmosphere (flow rate = 50 ml min-1) in
the temperature range from 30 – 550 °C (heating rate: 3°C
min-1). Powder X-ray diffraction (PXRD) was recorded by using
Cu-Kα radiation (Bruker D8 Discover; 40 kV, 30 mA). IR spectra
of the compounds were recorded with a Bruker IFS 66v/S
spectrophotometer using the KBr pellets in the region
4000−400 cm−1. The scanning electron microscopy images
were obtained using a Nova Nanosem 600 FEI field emission
scanning electron microscope (FESEM). Transmission electron
microscopy (TEM) analysis has been performed using a JEOL
JEM-3010 with an accelerating voltage at 300 kV or a FEI
TECNAI G2 20 STWIN TEM operating at 200 kV. One drop of
the samples dispersed in ethanol solution was taken in a holey
carbon coated Cu grid for TEM imaging. Inductively Coupled
Scheme 1. Mechanochemical synthesis of PQD@MOF composites mediated by PbII
exchanged AMOF-1.
composites show intense luminescence, enhanced stability,
processibility and also manifests energy transfer from the
framework to the PQDs when X=Br. This is also the first report
of (Förster Resonance Energy Transfer) FRET from the host
luminescent framework to the stabilized CsPbBr3 PQDs.
Plasma-Optical
Emission
Spectroscopy
(ICP-OES)
measurements were recorded on a Perkin Elmer Optima
7000dv ICP-OES instrument. UV–Vis spectra were recorded on
a
Perkin Elmer Model Lambda 900 spectrophotometer.
Experimental Section
Materials
Fluorescence studies were accomplished using Perkin Elmer Ls
55 Luminescence spectrometer. Time-resolved decay
experiments were recorded on a Horiba Delta Flex time-
correlated single-photon-counting (TCSPC) instrument. A 442-
nm nano-LED with a pulse repetition rate of 1 MHz was used
as the light source. The instrument response function (IRF) was
collected by using a scatterer (Ludox AS40 colloidal silica,
Sigma-Aldrich). For the 442-nm LED light source, the
instrumental full width at half maximum including detector
response was 0.2 ns. The excited state decay of the sample
was collected by fixing the emission wavelength at a particular
wavelength. The decay was fitted using IBH software (DAS6).
Zn(NO3)2.6H2O,
dimethyl-5-hydroxy isophthalate, α,α'
dibromo paraxylene, dibenzo 18 crown-6 and K2CO3 were all
obtained from Sigma Aldrich Co. and were used as procured
without further purification. All the solvents were obtained
from Spectrochem Co.
Methods
Synthesis of {[(NH2Me2)2][ Zn3(L)2].9H2O} (AMOF-1)
AMOF-1 was synthesized according to a previous report.40
Zn(NO3)2.6H2O (0.2 mmol, 0.059 g) and L (0.1 mmol, 0.047 g)
were dissolved in DMF (6 ml), ethanol (3 ml) and distilled
water (5 ml) in a 23 mL Teflon-lined stainless steel autoclave
and was stirred for 30 minutes. The autoclave was sealed and
was kept in an oven at 80 °C for 96 h. After completion of the
reaction, the reactor was cooled at RT for 12 h. Colourless
crystalline product was collected by filtration.
Results and Discussions
Characterization of CsPbX3@AMOF-1
In this work, we have chosen {[(NH2Me2)2][Zn3(L)2].9H2O}
Synthesis of PbII@AMOF-1
(AMOF-1;
L=5,
5′-
(1,4-phenylenebis(methylene))bis--
(oxy)diisophthalate), which is an 3D flexible AMOF,35-40 with
dimethyl ammonium (DMA) guest cations maintaining its
AMOF-1 was degassed overnight at 120°C under vacuum. 150
mg of the degassed sample is then immersed in 5 ml 10-2
M
charge neutrality. In AMOF-1,
a trinuclear [Zn3(CO2)8]
solution of Pb(NO3)2 for a week and the solution is changed
every alternate day. After a week, the residue wad centrifuged
and washed several times with water to yield PbII@AMOF-1.
ICP-OES reveals that 18 wt% Pb is present in PbII@AMOF-1,
which is equivalent to 0.8 molecules of PbII per formula unit of
AMOF-1.
secondary building is connected by tetracarboxylate L linker to
form the 3D network. In a previous report by us, AMOF-1
manifested excellent water stability, along with high affinity
towards heavy metal cations like PbII by exchange with the
guest DMA cation.40 We seek to transform the PbII
encapsulated AMOF (PbII@AMOF-1) into
a value-added
Synthesis of CsPbX3@AMOF-1
3 equivalents of CsX are taken for 1 equivalent of PbII present
in PbII@AMOF-1. Accordingly, 40 mg of PbII@AMOF-1 was
taken and 0.104 mmol of CsX was taken and grinded with
PbII@AMOF-1 in a mortar and pestle for 15-20 mins. The
PQD@MOF composite by simple solvent-free means which will
be ideal for several optoelectronic applications. The as-
synthesized AMOF-1 is desolvated under vacuum at 150°C in
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry A
Page 3 of 7
View Article Online
DOI: 10.1039/C9TA05977F
ARTICLE
Figure 1 (a) PXRD pattern of CsPbCl3@AMOF-1 along with AMOF-1. (b) FESEM images of as-synthesized AMOF-1. (c) TEM, and (d) HRTEM of CsPbCl3@AMOF-1. (e)
PXRD pattern of CsPbBr3@AMOF-1 along with AMOF-1. (f) TEM, and (g) HRTEM of CsPbBr3@AMOF-1. (h) TEM of CsPbBr3_mc synthesized without template.
order to remove water and DMF guests, after which it is the MOF surface and corresponding blocking of the pore
immersed in a 0.1 M Pb(NO3)2 solution in water for a week. channels is also evidenced by the adsorption isotherm for CO2
The solution is changed every day, in order to ensure at 195 K, where CsPbBr3@AMOF-1 shows a marked decrease
maximum PbII loading. The sample thus obtained is washed in the total adsorption amount from AMOF-1.44 Under FESEM,
with water several times to yield PbII@AMOF-1, which AMOF-1 shows cuboidal microcrystallites which are 500-700
contains 18 wt% Pb, as determined by ICP-OES. Accordingly, 3 nm in length (Figure 1(c)). The PQDs stabilized on the MOF
molar equivalents of CsX (X= Cl, Br, I) are taken and grinded matrix were visualized using TEM, where well-defined
with PbII@AMOF-1 in a mortar and pestle without any solvent quantum dots, 2-9 nm in diameter were observed uniformly
for 15 mins in the open atmosphere. When observed under UV distributed on rectangular MOF microcrystallites for
lamp, the bright emission (blue when X=Cl, green when X=Br CsPbCl3@AMOF-1 (Figure 1(d)). HRTEM of a single PQD shows
and red when X=I) starts appearing immediately with the a lattice spacing of 0.301 nm, corresponding to (110) plane
grinding. The samples thus synthesized are characterized typical in orthorhombic CsPbCl3 (Figure 1(e)). In case of
initially using powder X-ray diffraction (PXRD) where we clearly CsPbBr3@AMOF-1, the size distribution is similar and the PQDs
see the presence of perovskite peaks in addition to the peaks show a lattice spacing of 0.298 nm, which corresponds to the
for AMOF-1 (Figure 1 (a,b)).44 In each case, the low angle peak (200) plane in orthorhombic CsPbBr3 (Figure 1(f,g)).41 Similar
of AMOF-1 is present at 2θ = 5°. Since AMOF-1 is a flexible morphology is also observed in case of CsPbI3@AMOF-1,
MOF, the mechanical grinding may bring about orientational where a uniform distribution of PQDs of 5-8 nm dimensions is
changes which are reflected by the appearances of some new seen over the AMOF matrix.44 In the absence of any template,
peaks and change in intensities of the peaks in PXRD. These CsPbBr3_mc grows to large cuboidal nanocrystals, 100-200 nm
perovskite peaks have been matched with orthorhombic Pbnm in dimension without any uniformity in size (Figure 1(h)).31,44
phase in all three cases, which indicates that during However, in case of CsPbX3@AMOF-1, confinement effect by
mechanical synthesis, all of the CsPbX3 PQDs crystallize in the the MOF surface supported by the post-synthetic cation
orthorhombic
phase.
For
comparison,
we
have exchange in AMOF-1 restricts the size of the PQDs to lower
mechanochemically synthesized CsPbBr3 (CsPbBr3_mc) ranges of the nanoscale. Elemental colour mapping of
without a template by grinding PbBr2 and CsBr in the open CsPbX3@AMOF-1 shows the presence of Pb, Cs and Cl/Br/I in
atmosphere which also crystallized in the orthorhombic the respective samples.44 NC growth is restricted by AMOF,
phase.44 A previous report on the mechanochemical synthesis thereby controlling its size and it could be a prominent method
of CsPbX3 has also recorded the formation of the perovskites in to produce a library of CsPbX3 PQDs. In order to demonstrate
the orthorhombic phase.31 Thermogravimetric analysis (TGA) that homogeneous CsPbX3 PQDs are not formed merely due to
of CsPbX3@AMOF-1 composites show high thermal stability by
remaining unharmed till 280°C.44 The growing of the PQDs on
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry A
Page 4 of 7
ARTICLE
Journal Name
broad due to the heterogeneity in size. Owing to size
View Article Online
restriction of the PQDs by the AMOF, qDuOanI:t1u0m.103c9o/Cn9fiTnAe0m59e7n7Ft
effect is at play in the composites.42-43 This is established by
the blue-shift in the emission maximum of CsPbBr3@AMOF-1
from that in CsPbBr3_mc and the uniformity in size also
ensures a sharp narrow peak.31 According to a calculation by
Protesescu, et al., the exciton Bohr diameter of the CsPbCl3,
CsPbBr3 and CsPbI3 are 5, 7 and 12 nm, respectively.8 In order
to behave like a PQD, the semiconductor NCs should have
diameters lower than their exciton Bohr diameter.8 Hence
clearly, in case of CsPbX3@AMOF-1, the nanocrystals which
are 2-9 nm in diameter are indeed highly luminescent PQDs
formed by the confinement effect of the AMOF.
Energy Transfer in CsPbBr3@AMOF-1
The emission peak of AMOF-1 is a broad band with a
maximum at 420 nm whose tail extends till 580 nm (Figure
2(e)). Hence it finds an overlap with the absorbance of
CsPbBr3, giving rise to the possibility of energy transfer from
donor AMOF-1 host to PQD. True to our conjecture, upon
exciting CsPbBr3@AMOF-1 at 320 nm (absorbance MOF), the
emission of the pristine AMOF-1 at 420 nm is almost quenched
(Figure 2(e)), however it yields very high intensity emission
peak with a maximum at 515 nm corresponding to CsPbBr3. In
addition, the direct excitation at 400 nm shows less intensity
of the 515 nm peak compared to indirect excitation at 320 nm,
clearly indicating a light harvesting phenomenon through FRET
mechanism (Figure 2(e)). This is further supported by the
excitation spectrum of the 515 nm peak of CsPbBr3@AMOF-1
which shows a maximum at ~320 nm, clearly suggesting the
contribution of MOF to the observed PQD emission.44 The
transfer of energy from the framework to encapsulated
CsPbBr3 is also evident from the time-resolved
photoluminescence decays of CsPbBr3@AMOF-1. The original
AMOF-1 emission at 420 nm shows a lifetime of 4.25 ns, which
is reduced to 0.01 ns in CsPbBr3@AMOF-1. Moreover, the 515
nm peak corresponding to acceptor CsPbBr3 shows a lifetime
of 7.97 ns when excited at 295 nm (Figure 2(f)). However,
when excited directly at 370 nm, a shortening emission
lifetime (3.3 ns) is observed, as compared to indirect excitation
(Figure 2(e)).44 The fluorescence lifetimes of the other samples
were also measured and have been tabulated in Table S2.44
When excited at wavelength 295 nm, the 417 nm peak of
CsPbCl3@AMOF-1 shows an average lifetime of 6.11 ns and
the 695 nm emission peak of CsPbI3@AMOF-1 show a lifetime
of 30.3 ns, when excited at 370 nm. CsPbCl3@AMOF-1 records
a quantum yield of 1.71%, whereas CsPbBr3@AMOF-1 and
CsPbI3@AMOF-1 show quantum yields of 14% and 4.62%
respectively.
Figure 2 (a) UV-Vis spectra of CsPbX3@AMOF-1 and AMOF-1. (b) Photographs of
solid samples of CsPbX3@AMOF-1 (I: CsPbCl3@AMOF-1; II: CsPbClxBr3-x@AMOF-
1; III: CsPbBr3@AMOF-1; IV: CsPbBrxI3-x@AMOF-1; V: CsPbI3@AMOF-1) under
ambient and UV light. (c) Emission spectra of I-V. (d) Dispersions of
CsPbX3@AMOF-1 in acetonitrile under ambient light and UV light. (e) Energy
transfer in CsPbBr3@AMOF-1 nanocomposite. Green: Absorbance spectrum of
CsPbBr3@AMOF-1, Blue: Emission spectrum of AMOF-1; Pink and orange:
Emission spectra of CsPbBr3@AMOF-1 excited at 320 and 400 nm, respectively.
(f) Fluorescence decay profiles for CsPbBr3@AMOF-1 at different excitation
wavelengths.
capping by the MOF ligand, we have prepared another batch
of sample by grinding PbBr2 and CsBr with the ligand L
(CsPbBr3_L). Under TEM, for CsPbBr3_L, we observe large
rectangular chunks of bulk perovskite along with a few dots
which have a non-uniform size distribution. This is a clear
indication that the intact AMOF template restricts the size of
CsPbX3 and provided extra stability and the PQDs are not
formed due to capping by the ligand leached from the
framework.44
Optical Properties of CsPbX3@AMOF-1
The optical properties of the CsPbX3@AMOF-1 have been
studied extensively. The solid-state UV spectrum of AMOF-1
shows absorption maximum at 316 nm and a blue emission
with a broad emission peak centred at 420 nm. The optical
properties of PbII@AMOF-1 are identical to that of AMOF-1.
However, in case of all the CsPbX3@AMOF-1 samples, the
individual absorption bands of the respective PQDs also
appear with maxima at 401 nm when X = Cl, at 508 nm when X
= Br and at 670 nm when X = I, in addition to the 316 nm band
for AMOF-1 (Figure 2(a)). CsPbCl3@AMOF-1 shows intense
blue emission with emission maxima at 412 nm (λex=320 nm)
whereas CsPbBr3@AMOF-1 shows a bright green emission
with emission maxima at 515 nm when excited at 365 nm. The
CsPbI3@AMOF-1 shows red emission with emission maxima at
695 nm, when excited at 500 nm (Figure 2(b,c)). The emission
bands are extremely narrow which indicates towards the
narrow size distribution owing to quantum confinement.8 All
the samples show typical intense luminescence under UV lamp
in both solid states as well as when dispersed in ethanol
(Figure 2(b,d)). When excited at 365 nm, CsPbBr3_mc shows
an emission peak with a maximum at 530 nm, which is very
In addition to CsPbX3@AMOF-1, we have been also able to
synthesize two intermediates CsPbClxBr3-x@AMOF-1 and
CsPbBrxI3-x@AMOF-1 which show emission maxima at 458 nm
and 548 nm, respectively. CsPbClxBr3-x@AMOF-1 is
synthesized
CsPbBr3@AMOF-1 together, whereas CsPbBrxI3-x@AMOF-1 is
synthesized by grinding CsPbBr3@AMOF-1 and
by
grinding
CsPbCl3@AMOF-1
and
CsPbI3@AMOF-1 together. Since these are intermediate
compounds that have been
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 7
Journal of Materials Chemistry A
Please do not adjust margins
Journal Name
ARTICLE
dispersed PbII@AMOF-1 in toluene and inserted iVtieiwntAortictlhe eOnilninke
DOI: 10.1039/C9TA05977F
chamber of a roller ball pen (Figure 3(c)) and wrote with it on a
piece of paper. This writing shows a pale blue emission under
UV lamp. As soon as the writing is sprayed with a CsBr
solution, the writing turns green emissive and conspicuous
owing to the formation of CsPbBr3. Hence this is a highly
processable material which can be used for easy colour
tunability and can find applications in security ink. The
emission of the CsPbX3@AMOF-1 samples and the
intermediates when plotted on CIE chromaticity covers a wide
colour gamut.5,8,44
Conclusions
In conclusion, in this work, we have demonstrated a simplistic
green approach for the sustainable solvent-free synthesis of
PQDs on an AMOF template with high stability and exciting
optoelectronic properties. The PbII stabilized AMOF restricts
the size of the QDs and determine their luminescent
properties. Energy transfer is also observed from the
framework to the stabilized CsPbBr3 QDs. The AMOF template
also renders supreme stability to the PQDs, making stable
dispersion in a variety of solvents, thereby enhancing their
processibility. This work is remarkable since it does not involve
the several environmentally hazardous organic reagents
traditionally used for the synthesis of halide perovskite
quantum dots. Thus this method can be further used for the
synthesis of a library of such composites for various specific
applications owing to their intense luminescence and solvent
stability.
Figure 3(a) Photograph of dispersion of CsPbBr3@AMOF-1 in different solvents
under a UV light over several days. (b) Stability of emission of CsPbBr3@AMOF-1
dispersed in different solvent over 14 days. (c) Colour tunability and easy
containing PbII@AMOF-1 and then spraying it with CsBr.
processiblity in this composite material displayed by writing with
a pen
prepared by grinding two different perovskites together, we
have little control over the size and composition of the
resultant PQDs. Hence owing to the heterogeneity in size and
composition, they show very broad emission bands. We
observed an interesting anion exchange feature as well, where
CsPbBr3@AMOF-1 upon grinding with CsI completely converts
to CsPbI3@AMOF-1, as evident from the complete conversion
of the emission colour from green to red.44 This indicates
towards a facile anion exchange in case of the perovskite
nanocrystals, assisting in easy inter-conversion and hence,
colour-tuning.
Stability and Processibility of CsPbX3@AMOF-1
Conflicts of interest
There are no conflicts to declare.
One of the most important features of the CsPbX3@AMOF-1
composites is their exceptional robustness owing to caging by
the framework which makes them lucrative for several
applications. The solvent stability of the composite material
was tested by immersing the solid CsPbBr3@AMOF-1 in
different solvents over long periods of time while checking the
emission intermittently. The emission intensity is found to be
same in acetonitrile, toluene and dimethylformamide even
after two weeks (Figure 3(a,b)).44 However, CsPbBr3_mc loses
its emission even when exposed to air for more than 24 hrs
and its stability in the different solvents is only for a few
hours.44 This clearly elucidates that the strong binding of the
PQDs on the AMOF surface provides them with superior
stability in different media and thus they can be easily
processable for a variety of applications. Although the
emission is quenched immediately when CsPbBr3@AMOF-1 is
immersed in water, the framework remains intact and can be
reused, as is evident from the PXRD pattern obtained after
exposure to water. This is also an evidence that the formation
of the PQDs do not disrupt the structural integrity of the
framework.44
Acknowledgements
SB and DR are grateful to Mr. Rudradip Pattanayak, Mr. Aritra
Sarkar and Prof. Subi J. George for TCSPC lifetime
measurements and to Mr. Anaranya Ghorai for quantum yield
measurement. SB is grateful to INSPIRE Fellowship, DST, Govt.
of India. DR is grateful to National Post-doctoctoral Fellowship
(PDF/2017/002041), DST, SERB. TKM acknowledges
Department of Science and Technology (DST, project no. MR-
2015/001019 for financial support.
Note
This article is dedicated to Prof. C. N. R. Rao on the occasion of
his 86th birthday.
References
In order to illustrate the processibility and application of
CsPbBr3@AMOF-1, we attempted the development of a colour
changing security ink exploiting the simple synthetic technique
of the PQD@MOF composite and its supreme stability. We
1
A. Kojima, K. Teshima, Y. Shirai, T. Miyasaka, J. Am. Chem.
Soc. 2009, 131, 6050.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Journal of Materials Chemistry A
Page 6 of 7
ARTICLE
Journal Name
2
3
4
5
6
Y. Dong, T. Qiao, D. Kim, D. Parobek, D. Rossi and D. H. Son, 33 D. Prochowicz, M. Franckevičius, A. M. Cieślak, S. M.
Nano Lett., 2018, 18, 3716−3722.
Zakeeruddin, M. Grätzel and J. LewińsDkOi,I:J.10M.10aV3ti9ee/wrC.A9CrTthicAel0em5O9n.7liA7nFe,
2015, 3, 20772.
M. Leng, Z. Chen, Y. Yang, Z. Li, K. Zeng, K. Li, G. Niu, Y. He, Q.
Zhou and J. Tang, Angew. Chem. Int. Ed. 2016, 55, 15012.
V. K. Ravi, N. Singhal and A. Nag, J. Mater. Chem. A 2018, 6,
21666.
M. V. Kovalenko, L. Protesescu and M. I. Bodnarchuk, Science
2017, 358, 745.
T. Chiba, K. Hoshi, Y.-J. Pu, Y. Takeda, Y. Hayashi, S. Ohisa, S.
34 A. D. Jodlowski, A. Ypez, R. Luque, L. Camacho and G. de
Miguel, Angew. Chem. Int. Ed. 2016, 55, 14972.
35 L. Liu, X.-N. Zhang, Z.-B. Han, M.-L. Gao, X.-M. Cao and S.-M.
Wang, J. Mater. Chem. A 2015, 3, 14157.
36 X.-X. Jia, R.-X. Yao, F.-Q. Zhang and X.-M. Zhang, Inorg. Chem.
2017, 56, 2690.
Kawata and J. Kido, ACS Appl. Mater. Interfaces 2017, 9, 37 J. Li, H.-R. Fu, J. Zhang, L.-S. Zheng and J. Tao, Inorg. Chem.
18054.
2015, 54, 3093.
7
8
9
F. Locardi, M. Cirignano, D. Baranov, Z. Dang, M. Prato, F. 38 J. Yu, Y. Cui, C. Wu, Y. Yang, Z. Wang, M. OKeeffe, B. Chen
Drago, M. Ferretti, V. Pinchetti, M. Fanciulli, S. Brovelli, L. De
Trizio and L. Manna, J. Am. Chem. Soc. 2018, 140, 12989.
L. Protesescu, S. Yakunin, M. I. Bodnarchuk, F. Krieg, R.
and G. Qian, Angew. Chem. Int. Ed. 2012, 51, 10542.
39 S. Bhattacharyya, A. Chakraborty, K. Jayaramulu, A. Hazra
and T. K. Maji, Chem. Commun. 2014, 50, 13567.
Caputo, C. H. Hendon, R. X. Yang, A. Walsh and M. V. 40 Chakraborty, A.; Bhattacharyya, S.; Hazra, A.; Ghosh, A.C.;
Kovalenko, Nano Lett. 2015, 15, 3692.
X. Sheng, Y. Liu, Y. Wang, Y. Li, X. Wang, X. Wang, Z. Dai, J.
Bao and X. Xu, Adv. Mater. 2017, 29, 1700150.
Maji, T. K. Post-synthetic metalation in an anionic MOF for
efficient catalytic activity and removal of heavy metal ions
from aqueous solution. Chem. Commun. 2016, 52, 2831.
10 J. Y. Woo, Y. Kim, J. Bae, T. G. Kim, J. W. Kim, D. C. Lee and S. 41 S. Wei, Y. Yang, X. Kang, L. Wang, L. Huang and D. Pan, Chem.
Jeong, Chem. Mater. 2017, 29, 7088. Commun. 2016, 52, 7265.
11 P. Gui, Z. Chen, B. Li, F. Yao, X. Zheng, Q. Lin and G. Fang, ACS 42 J. A. Sichert, Y. Tong, N. Mutz, M. Vollmer, S. Fischer, K. Z.
Photonics 2018, 5, 2113.
12 Y. Dong, Y. Zhao, S. Zhang, Y. Dai, L. Liu, Y. Li and Q. Chen, J.
Mater. Chem. A, 2018, 6, 21729.
Milowska, R. G. Cortadella, B. Nickel, C. Cardenas-Daw, J. K.
Stolarczyk, A. S. Urban and J. Feldmann, Nano Lett. 2015, 15,
6521.
13 H. Huang, M. I. Bodnarchuk, S. V. Kershaw, M. V. Kovalenko, 43 L. Polavarapu, B. Nickel, J. Feldmann and A. S. Urban, Adv.
and A. L. Rogach, ACS Energy Lett. 2017, 2, 2071. Energy Mater. 2017, 7, 1700267.
14 F. Krieg, S. T. Ochsenbein, S. Yakunin, S. t. Brinck, P. Aellen, 44 See supporting information.
A. Süess, B. Clerc, D. Guggisberg, O. Nazarenko, Y.
Shynkarenko, S. Kumar, C-J. Shih, I. Infante and M.
Kovalenko, ACS Energy Lett. 2018, 3, 641.
15 S. Bai, Z. Yuan and F. Gao, J. Mater. Chem. C, 2016, 4, 3898.
16 M. Yarema, O. Yarema, W. M. M. Lin, S. Volk, N. Yazdani, D.
Bozyigit and V. Wood, Chem. Mater. 2017, 29, 796.
17 V. K. Ravi, R. A. Scheidt, J. DuBose and P. V. Kamat, J. Am.
Chem. Soc. 2018, 140, 8887.
18 H. Parala, H. Winkler, M. Kolbe, A. Wohlfart, R. A. Fischer, R.
Schmechel, H. von Seggern, Adv. Mater. 2000, 12, 1050.
19 V. Malgras, S. Tominaka, J. W. Ryan, J. Henzie, T. Takei, K.
Ohara and Y. Yamauchi, J. Am. Chem. Soc. 2016, 138, 13874.
20 J. Aguilera-Sigalat and D. Bradshaw, Coord. Chem. Rev. 2016,
307, 267.
21 S. Huang, Z. Li, L. Kong, N. Zhu, A. Shan and L. Li, J. Am.
Chem. Soc. 2016, 138, 5749.
22 S. Roy, A. Chakraborty and T. K. Maji, Coord. Chem. Rev.
2014, 273-274, 139.
23 S. Kitagawa, R. Kitaura and S.-i. Noro, Angew. Chem. Int. Ed.
2014, 43, 2334.
24 S. Bhattacharyya, C. Das and T. K. Maji, RSC Adv. 2018, 8,
26728.
25 C. Zhang, B. Wang, W. Li, S. Huang, L. Kong, Z. Li and L. Li,
Nat. Commun. 2017, 8, 1138.
26 S. Jin, H-J. Son, O. K. Farha, G. P. Wiederrecht and J. T. Hupp,
J. Am. Chem. Soc. 2013, 135, 955.
27 Z. Chen, Z-G. Gu, W-Q. Fu, F. Wang and J. A. Zhang, ACS Appl.
Mater. Interfaces, 2016, 8, 28737.
28 H. He, Y. Cui, B. Li, B. Wang, C. Jin, J. Yu, L. Yao, Y. Yang, B.
Chen and G. Qian, Adv. Mater. 2018, 1806897.
29 D. Zhang, Y. Xu, Q. Liu and Z. Xia, Inorg. Chem. 2018, 57,
4613.
30 K. Mandel, T. Granath, T. Wehner, M. Rey, W. Stracke, N.
Vogel, G. Sextl and K. Muller-Buschbaum, ACS Nano, 2017,
11, 779.
31 P. Pal, S. Saha, A. Banik, A. Sarkar and K. Biswas, Chem. Eur. J.
2018, 24, 1811.
32 C. C. Stoumpos, C. D. Malliakas and M. G. Kanatzidis, Inorg.
Chem. 2013, 52, 9019.
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 7 of 7
Journal of Materials Chemistry A
Please do not adjust margins
Journal Name
Table of Contents Graphic
ARTICLE
View Article Online
DOI: 10.1039/C9TA05977F
CsPbX3 perovskite quantum dots mechanochemically
synthesized within an anionic MOF show intense luminescence
and high solvent stability.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
Please do not adjust margins