Bidentate Ligand-Passivated CsPbI3 Perovskite Nanocrystals for Stable Near-Unity Photoluminescence Quantum Yield and Efficient Red Light-Emitting Diodes

Article abstract of DOI:10.1021/jacs.7b10647

Although halide perovskite nanocrystals (NCs) are promising materials for optoelectronic devices, they suffer severely from chemical and phase instabilities. Moreover, the common capping ligands like oleic acid and oleylamine that encapsulate the NCs will form an insulating layer, precluding their utility in optoelectronic devices. To overcome these limitations, we develop a postsynthesis passivation process for CsPbI₃ NCs by using a bidentate ligand, namely 2,2′-iminodibenzoic acid. Our passivated NCs exhibit narrow red photoluminescence with exceptional quantum yield (close to unity) and substantially improved stability. The passivated NCs enabled us to realize red light-emitting diodes (LEDs) with 5.02% external quantum efficiency and 748 cd/m² luminance, surpassing by far LEDs made from the nonpassivated NCs.

Full text of DOI:10.1021/jacs.7b10647

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Communication
Bidentate Ligand-passivated CsPbI3 Perovskite
Nanocrystals for Stable Near-unity Photoluminescence
Quantum Yield and Efficient Red Light-emitting Diodes
Jun Pan, Yuequn Shang, Jun Yin, Michele De Bastiani, Wei Peng, Ibrahim Dursun, Lutfan Sinatra, Ahmed M.
El-Zohry, Mohamed N. Hedhili, Abdul-Hamid Emwas, Omar F. Mohammed, Zhijun Ning, and Osman M. Bakr
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.7b10647 • Publication Date (Web): 17 Dec 2017
Downloaded from http://pubs.acs.org on December 17, 2017
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Bidentate Ligand-passivated CsPbI3 Perovskite Nanocrystals for
Stable Near-unity Photoluminescence Quantum Yield and Efficient
Red Light-emitting Diodes
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Jun Pan,†#• Yuequn Shang,‡• Jun Yin,† Michele De Bastiani,† Wei Peng,† Ibrahim Dursun,†# Lutfan Si-
natra,† Ahmed M. El-Zohry,# Mohamed N. Hedhili,§ Abdul-Hamid Emwas,§ Omar F. Mohammed,†
Zhijun Ning,*,‡ and Osman M. Bakr*,†#
† King Abdullah University of Science and Technology (KAUST), KAUST Catalysis Center (KCC), #KAUST Solar Center
(KSC), Division of Physical Science and Engineering (PSE), § Imaging and Characterization Laboratory, Thuwal 23955,
Saudi Arabia.
‡ School of Physical Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China
Supporting Information Placeholder
LEDs.8-10 Despite significant advancements in the de-
ABSTRACT: Although halide perovskite nanocrystals
(NCs) are promising materials for optoelectronic devices,
velopment of LEDs based on perovskite NCs,16-18 espe-
cially for green LEDs for which external quantum effi-
ciencies (EQE) have exceeded 10%,19 device perfor-
mances are still far from meeting application require-
ments, particularly when red LEDs are needed A com-
mon issue is the intrinsic chemical instability of CsPbX3
NCs due to the dynamic nature of the bonding between
they suffer severely from chemical and phase instabilities.
Moreover, the common capping ligands like oleic acid and
oleylamine that encapsulate the NCs will form an insulat-
ing layer, precluding their utility in optoelectronic devices.
To overcome these limitations, we develop a post-synthesis
passivation process for CsPbI3 NCs by using a bidentate
ligand, namely 2,2’-Iminodibenzoic acid. Our passivated
NCs exhibit narrow red photoluminescence with excep-
tional quantum yield (close to unity) and substantially im-
proved stability. The passivated NCs enabled us to realize
red light-emitting diodes (LEDs) with 5.02% external
quantum efficiency and 748 cd/m2 luminance, surpassing
by far LEDs made from the non-passivated NCs.
the inorganic surface and the long-chain capping lig-
23-26
ands.
Furthermore, common capping ligands like
oleylamine (OAm) and oleic acid (OA) act as electrical-
ly insulating layers on the NC’s surface which hinder
significantly charge carrier injection and transport at the
interface of the ensuing device. To add to this list of
challenges afflicting perovskites, CsPbI3 NCs in particu-
lar suffer from a non-perovskite phase transition at room
temperature.27 While recent efforts have led to consider-
able stabilization of iodide perovskite NCs,11, 28-29 there
is still a critical need for a NC passivation strategy that
combines stability and high PLQY with surface ligands
that are compatible with the charge transport require-
ments of LEDs and optoelectronic applications in gen-
eral.30
The development of solution-processed halide perov-
skites has disrupted the global roadmap of semiconduc-
tors.1-4 While research on halide perovskites was solely
motivated by solar cell technologies, it has quickly
grown to encompass the whole optoelectronic research
community.5 The use of all-inorganic cesium lead halide
perovskite (CsPbX3, X = Cl, Br, and I) nanocrystals
(NCs) exhibiting high photoluminescence quantum
yields (PLQY), narrow emission,6 and tunable absorp-
tion/emission wavelengths7 has accelerated the emer-
gence and development of perovskite-based nanomateri-
In this communication, we explore a bidentate ligand,
namely 2,2’-Iminodibenzoic acid (IDA, Figure 1a), to
passivate the NC surface. Theoretical calculations (vide
infra) show much stronger bonding between the
pervoskite surface and this ligand in comparison to OA.
The IDA-treated NCs display a PLQY of over 95%
(much higher than untreated NCs), significantly
enhanced stability in the desired cubic perovskite phase,
as well as enhanced electronic coupling between ligands
and NCs. As a result, we were able to fabricate red
LEDs with broadly superior characteristics (i.e., two-
als for applications such as light-emitting diodes
12
(LED),8-10 solar cells,11 lasers,
visible-light communication.14
photodetectors,13 and
Since the first reported synthesis of nearly monodis-
persed CsPbX3 NCs using a hot-injection approach,15
many efforts have been expended on optimizing NC
synthesis procedures to facilitate the fabrication of
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Figure 1. a) Molecular structure of OA (1), and IDA (2) ligands. b) Low- and high- c) magnification TEM images of untreated QDs. d)
Low- and high- e) magnification SEM images for IDA-treated NCs. (f) Powder XRD patterns of untreated (blue) and IDA-treated NCs
(red). (g) Absorption and PL spectra for untreated (blue) and IDA-treated NCs (red) from equimolar concentrated solutions, with the rela-
tive PL quantum yield in the inset.
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fold higher EQE and luminescence intensity) to those of
LEDs based on pristine NCs.
sivation.32,33
To investigate how IDA affects the NC surface, we
performed X-ray photoelectron spectroscopy (XPS),
CsPbI3 perovskite NCs were synthesized following a
1
solution H nuclear magnetic resonance (1H-NMR), and
well-established synthesis process with minor modificai-
tons11, 31 (see SI for details). The purified NCs (labelled
as “untreated” NCs) had a cubic shape with an average
dimension of 13.6±2.9 nm (Figure S1a) determined by
high-resolution transmission electron microscopy (HR-
TEM) (Figure 1b). Passivated NCs were obtained by
adding a small amount of IDA powder directly into a
solution of untreated NCs (see SI for details). After
treatment, the excess IDA was removed by centrifuga-
tion. The IDA-treated NCs were cubic shaped (Figure
1d) with an average size of 12±1.5 nm (Figure S1b). It
should be noted that the particles are easily aggregated if
IDA is used directly in the synthesis (Figure S2). Both
the untreated and treated NCs have a lattice distance of
0.31 nm, corresponding to the (200) crystal plane of the
cubic phase perovskite (Figure 1c and 1e), suggesting
that the crystal structure remained unchanged during
treatment process, which was further confirmed by X-
ray diffraction (XRD, Figure 1f).
infrared spectroscopy (IR) experiments on untreated and
treated NCs. The XPS analysis revealed no significant
changes in the Cs 3d, Pb 4f, I 3d core-level spectra of
both samples (Figure SI4); yet, the high-resolution spec-
tra of the N 1s core-level exhibited a noticeable variation
(Figure SI5). We fitted the N 1s core level for untreated
NCs to a single peak at 401.8 eV, corresponding to pro-
+
tonated amine groups (NH3 ) from oleyl ammonium. An
additional peak at 399.4 eV appeared in the IDA-treated
NC N 1s core-level spectrum, attributed to -NH- group
from IDA.34-35 Indeed, the ratio of the two different N 1s
+
core levels (NH3 and -NH-) by comparing the
integrated area of the two peaks suggests that the OAm
to IDA ratio in the passivated NCs was 3.3:1. The exist-
ence of the -NH- group after IDA treatment was further
verified by 1H-NMR with a signal at 10.9 ppm, while the
proton signal of the -COOH group from IDA at 13 ppm
disappeared. This suggests that the -COOH functional
groups in IDA were converted to carboxyls (Figure S6).
Quantitative NMR analysis also reveals a significant
reduction in OA after IDA treatment (Figure S7 and Ta-
ble S1). We also investigated the binding mode of IDA
on the NCs by IR spectroscopy. Four additional IR peaks
are recorded for IDA treated NCs. The peaks at 1602
cm-1and 1496 cm-1 are ascribed to aromatic C=C vibra-
tion, while 1575 cm-1 is ascribed to the conjugated aro-
matic ring and 750 cm-1is ascribed to aromatic C-H
bending, respectively36 (Figure S8). Thus, we conclude
However, significant changes in optical properties
were observed. With IDA treatment, PLQY increased to
near unity (95±2%) compared with that of the untreated
NCs (80±5%). Accompanying the rise in PLQY, PL
emission retained the same peak position at 680 nm,
while no significant change was observed in the absorp-
tion spectrum (Figure 1g). Moreover, the PL lifetime
exhibited a slight improvement from 10.5 ns to 12.8 ns
after IDA treatment (Figure S3), suggesting that a reduc-
tion in surface trap states occurred through IDA pas-
Figure 2. a), b) Surface charge redistributions of optimized PbI2-rich CsPbI3 surfaces with OA and IDA ligand modification. c) Normal-
ized PLQY intensities as a function of days for untreated (blue) and IDA-treated NCs (red). d) Photograph of untreated and treated QDs
as-synthesized and aged for 15 days.
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Figure 3. a) Schematic of the device structure of the light emitting diode. b) Electroluminescence (EL) spectra at various applied voltages.
The inset shows a photograph of a working PLED. c) Current density-voltage (J-V) and luminance-voltage (L-V). d) Luminous power
efficiency - current density and external quantum efficiency - current density (EQE-J) curves of original and IDA-treated CsPbI3 PLED.
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that IDA binds to the NC surface via coordination with
the carboxyl group.
note, the IDA ligand passivation process that we devised
works well with other halide (Br and Br/I mixtures) per-
ovskite NCs (Figure S12 and Table S2).
To further understand the binding nature of IDA on the
NC surface, we performed density functional theory
(DFT) calculations assuming a PbI2-rich (positive
charged) CsPbI3 surface with both OA and IDA pas-
sivation (see Figure 2a, b). In both cases, the carboxylic
groups can bind to surface Pb atoms with similar charge
redistributions after ligand attachment, where the nega-
tive charge (blue cloud) is localized on the carboxylic
group and the positive charge (red cloud) delocalizes
along surface Pb atoms. In the case of the IDA-treated
CsPbI3 surface, the double carboxylic groups can sepa-
rately bind to two surface-exposed Pb atoms, resulting in
a much larger binding energy (1.4 eV) as compared to
the single carboxylic-capped surface using an OA ligand
(1.14 eV). Moreover, the double carboxylic groups in
the IDA ligand could efficiently stabilize the NC surface
with fewer surface structural distortions, avoiding the
conversion to the undesirable yellow phase at room tem-
perature.
Finally, we explored the ability of IDA-treated CsPbI3
NCs to perform in light emitting devices (PLEDs). We
used poly (3,4- ethylenedioxythiophene): poly styrene
sulphonate (PEDOT: PSS) on an indium–tin oxide (ITO)
glass substrate as the hole-injection layer (HIL) and
Poly[bis(4-phenyl) (4-butylphenyl) amine] (Poly-TPD)
as a hole-transporting layer (HTL). The electron trans-
porting layer was 2,2’,2’’-(1,3,5-Benzinetriyl)-tris(1-
phenyl-1-H-benzimidazole) (TPBi). The PLED structure
is shown in Figure 3a. The PLEDs show sharp EL peaks
under various biases (Figure 3b) with peak wavelengths
of 688 nm and a narrow full width at half-maximum of
~33 nm. The peak position is slightly red shifted com-
pared with the PL peak, which we attribute to the inter-
dot interaction37 and Stark effect.38 A photograph of the
working PLED based on IDA-treated CsPbI3 shows uni-
form emission (inset to Figure 3b). Relative to the con-
trol NCs, the PLEDs based on IDA-treated CsPbI3 NCs
exhibit higher current density (Figure 3c). This can be
explained by the effective electronic coupling between
unoccupied molecular orbital (LUMO) of IDA and the
conduction band edge of CsPbI3 NCs (see the calculated
project density of states in Figure S13), but not ascribed
to the conductive nature of IDA (since IDA has a low
conductivity, Figure S14). The turn-on voltages (where
luminance is >1 cd·m-2) of the original and IDA-treated
CsPbI3 PLEDs are 4.1 V and 4.5 V, respectively. The
slightly reduced turn-on voltage indicates better carrier
injection into the IDA-treated NCs layer. The maximum
luminance of IDA-treated CsPbI3 PLED reaches 748
cd·m-2 under the applied voltage of 7 V, which is over
two times higher than the control device (314 cd·m-2
under the same applied voltage). The IDA-treated NC
PLED device has a maximum luminous power efficien-
cy of 0.47 lm·W-1, corresponding to a max EQE of
5.02% (8.70 mA·cm-2), which is a factor of two better
than 0.22 lm·W-1 power efficiency and 2.26% EQE ex-
hibited by the control device (Figure 3d).
To demonstrate the stability of IDA-treated NCs, we
tracked the PL emission over several days (Figure 2c).
The PL emission of untreated NCs was almost
completely quenched after five days. On the other hand,
IDA-treated NCs maintained a constant PL emission
with a record value of 90% even after 15 days. Moreo-
ver, according to XRD data, no phase change was ob-
served for IDA-treated NCs after 40 days, while untreat-
ed NCs essentially transformed into PbI2 (Figure S9).
Significant ligand loss was also confirmed by FTIR for
the untreated NCs (Figure S10). A photograph of as-
synthesized and 15-days-old NC and IDA-treated NC
solutions is presented in Figure 2d. The stability of IDA-
treated NCs is also apparent when purifying the samples
by anti-solvent wash (see SI). Ethyl acetate (EA) washed
untreated NCs exhibit a drop in PLQY down to 60%,
while the emission of treated NCs remains relatively
unchanged. We ascribe the obvious reduction in PLQY
in untreated NCs to the loss of surface ligands from the
washing step, due to the more labile nature of the OA
surface ligand.24The amount of OAm on the surface is
also reduced after washing (as ascertained from the sig-
In conclusion, we described bidentate ligand pas-
sivation of CsPbI3 NCs that effectively increases their
PLQY, leading to near-unity values with a good stability.
Our results also suggest that IDA ligands can bind firmly
to PbI2-rich surfaces through dual carboxyl groups,
+
nal of the two different N 1s core levels of NH3 to -NH-
) reaching a 1:1 ratio with IDA (Figure S11), further
confirming the highly stable binding of IDA. We also
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12. Yakunin, S.; Protesescu, L.; Krieg, F.; Bodnarchuk, M. I.; Nedelcu,
G.; Humer, M.; De Luca, G.; Fiebig, M.; Heiss, W.; Kovalenko, M. V.
Nat. Commun. 2015, 6, 8056.
13. Li, X. M.; Yu, D. J.; Chen, J.; Wang, Y.; Cao, F.; Wei, Y.; Wu, Y.;
Wang, L.; Zhu, Y.; Sun, Z. G.; Ji, J. P.; Shen, Y. L.; Sun, H. D.; Zeng, H.
B. Acs Nano 2017, 11, 2015-2023.
14. Dursun, I.; Shen, C.; Parida, M. R.; Pan, J.; Sarmah, S. P.; Priante,
D.; Alyami, N.; Liu, J.; Saidaminov, M. I.; Alias, M. S.; Abdelhady, A. L.;
Ng, T. K.; Mohammed, O. F.; Ooi, B. S.; Bakr, O. M. Acs Photonics
2016, 3, 1150-1156.
15. Protesescu, L.; Yakunin, S.; Bodnarchuk, M. I.; Krieg, F.; Caputo,
R.; Hendon, C. H.; Yang, R. X.; Walsh, A.; Kovalenko, M. V. Nano Lett.
2015, 15, 3692-3696.
16. Cho, H.; Jeong, S.-H.; Park, M.-H.; Kim, Y.-H.; Wolf, C.; Lee, C.-
L.; Heo, J. H.; Sadhanala, A.; Myoung, N.; Yoo, S.; Im, S. H.; Friend, R.
H.; Lee, T.-W. Science 2015, 350, 1222-1225.
17. Chiba, T.; Hoshi, K.; Pu, Y. J.; Takeda, Y.; Hayashi, Y.; Ohisa, S.;
Kawata, S.; Kido, J. Acs Appl. Mater. Interf. 2017, 9, 18054-18060.
18. Shi, Z.; Li, Y.; Zhang, Y.; Chen, Y.; Li, X.; Wu, D.; Xu, T.; Shan,
C.; Du, G. Nano Lett. 2017, 17, 313-321.
which can reduce the surface traps and inject extra elec-
trons into NCs. In addition, we achieved similar results
with the other halide perovskite NCs, clearly indicating
the positive role induced by the bidentate ligand. More-
over, fabricated LED devices based on the IDA-treated
CsPbI3 NCs are broadly superior to devices based on
untreated NCs. We believe that our work paves the way
for new strategies to increase the stability and charge
transport of lead halide perovskite nanostructures with
potential applications across optoelectronics devices.
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56
57
58
59
60
ASSOCIATED CONTENT
Supporting Information.
Materials, synthesis, XPS, NMR, FTIR, HUMO-LUMO calcula-
tion and film conductivity measurement.
19. Wang, N. N.; Cheng, L.; Ge, R.; Zhang, S. T.; Miao, Y. F.; Zou, W.;
Yi, C.; Sun, Y.; Cao, Y.; Yang, R.; Wei, Y. Q.; Guo, Q.; Ke, Y.; Yu, M.
T.; Jin, Y. Z.; Liu, Y.; Ding, Q. Q.; Di, D. W.; Yang, L.; Xing, G. C.;
Tian, H.; Jin, C. H.; Gao, F.; Friend, R. H.; Wang, J. P.; Huang, W. Nat.
Photonics 2016, 10, 699-704.
20. Tan, Z. K.; Moghaddam, R. S.; Lai, M. L.; Docampo, P.; Higler, R.;
Deschler, F.; Price, M.; Sadhanala, A.; Pazos, L. M.; Credgington, D.;
Hanusch, F.; Bein, T.; Snaith, H. J.; Friend, R. H. Nat. Nanotech. 2014, 9,
687-692.
21. Wang, J.; Wang, N.; Jin, Y.; Si, J.; Tan, Z.-K.; Du, H.; Cheng, L.;
Dai, X.; Bai, S.; He, H.; Ye, Z.; Lai, M. L.; Friend, R. H.; Huang, W. Adv.
Mater. 2015, 27, 2311-2316.
22. Zhang, S.; Yi, C.; Wang, N.; Sun, Y.; Zou, W.; Wei, Y.; Cao, Y.;
Miao, Y.; Li, R.; Yin, Y.; Zhao, N.; Wang, J.; Huang, W. Adv. Mater.
2017, 29, 1606600.
23. Pan, A. Z.; He, B.; Fan, X. Y.; Liu, Z. K.; Urban, J. J.; Alivisatos, A.
P.; He, L.; Liu, Y. Acs Nano 2016, 10, 7943-7954.
24. De Roo, J.; Ibáñez, M.; Geiregat, P.; Nedelcu, G.; Walravens, W.;
Maes, J.; Martins, J. C.; Van Driessche, I.; Kovalenko, M. V.; Hens, Z.
ACS Nano 2016, 10, 2071-2081.
25. Ahmed, G. H.; Liu, J. K.; Parida, M. R.; Murali, B.; Bose, R.;
AlYami, N. M.; Hedhili, M. N.; Peng, W.; Pan, J.; Besong, T. M. D.;
Bakr, O. M.; Mohammed, O. F. J. Phys. Chem. Lett. 2016, 7, 3913-3919.
26. Ahmed, G. H.; Yin, J.; Bose, R.; Sinatra, L.; Alarousu, E.; Yengel,
E.; AlYami, N. M.; Saidaminov, M. I.; Zhang, Y.; Hedhili, M. N.; Bakr,
O. M.; Brédas, J.-L.; Mohammed, O. F. Chem. Mater. 2017, 29, 4393-
4400.
27. Trots, D. M.; Myagkota, S. V. J. Phys. Chem. Solids 2008, 69, 2520-
2526.
28. Wang, C. J.; Chesman, A. S. R.; Jasieniak, J. J. Chem. Commun.
2017, 53, 232-235.
29. Liu, F.; Zhang, Y.; Ding, C.; Kobayashi, S.; Izuishi, T.; Nakazawa,
N.; Toyoda, T.; Ohta, T.; Hayase, S.; Minemoto, T.; Yoshino, K.; Dai, S.;
Shen, Q. ACS Nano 2017, 11, 10373-10383.
30. Li, G.; Rivarola, F. W. R.; Davis, N. J. L. K.; Bai, S.; Jellicoe, T. C.;
de la Peña, F.; Hou, S.; Ducati, C.; Gao, F.; Friend, R. H.; Greenham, N.
C.; Tan, Z.-K. Adv. Mater. 2016, 28, 3528-3534.
31. Pan, J.; Sarmah, S. P.; Murali, B.; Dursun, I.; Peng, W.; Parida, M.
R.; Liu, J.; Sinatra, L.; Alyami, N.; Zhao, C.; Alarousu, E.; Ng, T. K.; Ooi,
B. S.; Bakr, O. M.; Mohammed, O. F. J. Phys. Chem. Lett. 2015, 6, 5027-
5033.
32. Nag, A.; Kovalenko, M. V.; Lee, J.-S.; Liu, W.; Spokoyny, B.;
Talapin, D. V. J. Am. Chem. Soc. 2011, 133, 10612-10620.
33. Tang, J.; Kemp, K.; Hoogland, S.; Jeong, K.; Liu, H.; Levina, L.;
Furukawa, M.; Wang, X.; Debnath, R.; Cha, D.; Chou, K. W.; Fischer, A.;
Amassian, A.; B Asbury, J.; Sargent, E. Nat. Mater. 2011, 10, 765-771.
34. Liao, B.; Long, P.; He, B.; Yi, S.; Ou, B.; Shen, S.; Chen, J. J.
Mater. Chem. C 2013, 1, 3716-3721.
35. Yang, D. Q.; Meunier, M.; Sacher, E. Appl. Surf. Sci. 2005, 252,
1197-1201.
36. Mayo, D. W. In Course Notes on the Interpretation of Infrared and
Raman Spectra, Wiley, Inc.: Hoboken, NJ, 2004; pp 101-140.
37. Kagan, C. R.; Murray, C. B.; Bawendi, M. G. Phys Rev B Condens
Matter 1996, 54, 8633-8643.
AUTHOR INFORMATION
Corresponding Author
ningzhj@shanghaitech.edu.cn
osman.bakr@kaust.edu.sa
Author Contributions
•J.P. and Y.Q.S. contributed equally
Acknowledgement
The authors acknowledge funding support from KAUST. Ning, Z.
J. and Shang Y. Q. acknowledge financial support from the
Shanghai International Cooperation Project (16520720700), Na-
tional Key Research and Development Program of China (under
Grants No. 2016FYA0204000), and Shanghai key research pro-
gram (16JC1402100).
REFERENCES
1. Burschka, J.; Pellet, N.; Moon, S. J.; Humphry-Baker, R.; Gao, P.;
Nazeeruddin, M. K.; Gratzel, M. Nature 2013, 499, 316-319.
2. Xing, G. C.; Mathews, N.; Lim, S. S.; Yantara, N.; Liu, X. F.; Sabba,
D.; Gratzel, M.; Mhaisalkar, S.; Sum, T. C. Nat. Mater. 2014, 13, 476-
480.
3. Zhou, H. P.; Chen, Q.; Li, G.; Luo, S.; Song, T. B.; Duan, H. S.;
Hong, Z. R.; You, J. B.; Liu, Y. S.; Yang, Y. Science 2014, 345, 542-546.
4. Tsai, H.; Nie, W.; Blancon, J.-C.; Stoumpos, C. C.; Asadpour, R.;
Harutyunyan, B.; Neukirch, A. J.; Verduzco, R.; Crochet, J. J.; Tretiak, S.;
Pedesseau, L.; Even, J.; Alam, M. A.; Gupta, G.; Lou, J.; Ajayan, P. M.;
Bedzyk, M. J.; Kanatzidis, M. G.; Mohite, A. D. Nature 2016, 536, 312-
316.
5. Manser, J. S.; Christians, J. A.; Kamat, P. V. Chem. Rev. 2016, 116,
12956-13008.
6. Begum, R.; Parida, M. R.; Abdelhady, A. L.; Murali, B.; Alyami, N.
M.; Ahmed, G. H.; Hedhili, M. N.; Bakr, O. M.; Mohammed, O. F. J. Am.
Chem. Soc. 2017, 139, 731-737.
7. Akkerman, Q. A.; D’Innocenzo, V.; Accornero, S.; Scarpellini, A.;
Petrozza, A.; Prato, M.; Manna, L., J Am Chem Soc 2015, 137, 10276-
10281.
8. Song, J. Z.; Li, J. H.; Li, X. M.; Xu, L. M.; Dong, Y. H.; Zeng, H. B.
Adv. Mater. 2015, 27, 7162-7167.
9. Pan, J.; Quan, L. N.; Zhao, Y. B.; Peng, W.; Murali, B.; Sarmah, S.
P.; Yuan, M. J.; Sinatra, L.; Alyami, N. M.; Liu, J. K.; Yassitepe, E.;
Yang, Z. Y.; Voznyy, O.; Comin, R.; Hedhili, M. N.; Mohammed, O. F.;
Lu, Z. H.; Kim, D. H.; Sargent, E. H.; Bakr, O. M. Adv. Mater. 2016, 28,
8718-8725.
10. Yassitepe, E.; Yang, Z.; Voznyy, O.; Kim, Y.; Walters, G.;
Castañeda, J. A.; Kanjanaboos, P.; Yuan, M.; Gong, X.; Fan, F.; Pan, J.;
Hoogland, S.; Comin, R.; Bakr, O. M.; Padilha, L. A.; Nogueira, A. F.;
Sargent, E. H. Adv. Func. Mater. 2016, 26, 8757-8763.
11. Swarnkar, A.; Marshall, A. R.; Sanehira, E. M.; Chernomordik, B.
D.; Moore, D. T.; Christians, J. A.; Chakrabarti, T.; Luther, J. M. Science
2016, 354, 92-95.
38.
Caruge, J. M.; Halpert, J. E.; Bulovic, V.; Bawendi, M. G. Nano
Lett. 2006, 6 , 2991-2994.
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