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New Journal of Chemistry
Page 6 of 8
ARTICLE
NJC
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the electrolyte solution. It should be noted that the anodic ECL
intensity of CsPbBr3 NCs and RbxCs1-xPbBr3 is related to their
previous surface charge. With the potential scanned initially
from 0 to -2.0 V and then from -2.0 to 2.0 V (Figure 7C), the
anodic ECL intensity at potential around 1.15V is much weaker
than those with potential scanned directly from 0 to 2.0 V
(Figure 7D). The reason may be that the initial negative
potential scanning results in the inactivation of CsPbBr3 NCs
and Rb0.2Cs0.8PbBr3 NCs as well as the accumulation of
negative charges on the surface of the electrode. Up injecting
hole in the following positive potential scanning, the holes
were neutralized firstly with the accumulated negative charges,
indicating by the higher anodic currents in Figure 7A. As a
result, the amount of holes to excite the anodic ECL of CsPbBr3
and Rb0.2Cs0.8PbBr3 NCs were reduced. When the potential was
scanned directly from 0 to 2.0 V, more of the holes were
participated in the anodic ECL process. Hence, the anodic ECL
intensity in Figure 7D is much higher than that in Figure 7C.
As discussed above, the surface of RbxCs1-xPbBr3 NCs is be
electron-rich states. Generally, NCs in electron-rich states do
not produce strong cathodic ECL without co-reactant. Hence,
only weak cathodic ECL emissions were observed in Figures
7C&7D, which is possible due to some impurities in perovskite
NCs or supporting electrolyte solutions. As the cathodic ECL
signals are very weak, they were not investigated further in
this work. As compared in Figure S6, the Rb0.2Cs0.8PbBr3 NCs
has more superior annihilation ECL performance than that of
CsPbBr3 NCs. When the Rb+ content increased from x=0.2 to
x=0.8, the ECL emission became weaker and the peak potential
was shifted from 1.2 V to 1.8 V. The lower stability and larger
surface defect in RbxCs1-xPbBr3 NCs at higher Rb+ content may
be the reason of the subdued ECL emission.
DOI: 10.1039/C9NJ05665C
Acknowledgements
This project was supported by the National Natural Science
Foundation of China (Grant Nos. 21874083, 21427808), and
the Fundamental Research Funds of Shandong University
(2018JC017).
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Conclusions
In this work, we have demonstrated the tunable ECL
performance of RbxCs1-xPbBr3 NCs with by adjusting the
Rb+/Cs+ ratio. The RbxCs1-xPbBr3 NCs could be electrochemically
injected with holes to produce radicals of different charged
states, and then both annihilation and co-reactant ECL were
generated. With the increase of Rb+ concentration, the ECL
spectra were gradually moved towards the blue light region.
The ECL intensity has an up-and-down tendency with the
strongest ECL signal was obtained in Rb0.2Cs0.8PbBr3 NCs. The
potential position of emission peak is turned from 1.60 V to
1.80 V. The Rb0.2Cs0.8PbBr3 NCs could have superior ECL
properties than that from CsPbBr3 NCs. The tunable ECL of
RbxCs1-xPbBr3 NCs might open up new possibilities to design
novel ECL emitters in multiple color ECL analysis and other
optoelectronic device applications.
Conflicts of interest
22 L. Z. Hu and G. B. Xu, Chem. Soc. Rev., 2010, 39, 3275-3304.
23 W. Miao, Chem. Rev., 2008, 108, 2506-2553.
There are no conflicts to declare.
6 | New J. Chem., 2019, 00, 1-3
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