KR101712037B1 - Reversible halide exchange reactions in Cesium Lead Halide NanoCrystals - Google Patents
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Abstract
Description
The present invention relates to a reversible halide exchange method of cesium lead halide nanocrystals.
Colloidal semiconductor nanocrystals having dimensions in the range of 2-10 nm regime have been intensively studied and used in a variety of optoelectronic devices such as photovoltaics, light emitting diodes, photodectors, , And field-effect transistors (FETs). Most of their unique properties are related to the band gap energy of nanocrystals, which can be easily controlled by manipulating the size, shape and composition of these nanocrystals (Talapin, DV; Lee, J.-S .; Kovalenko, MV, Shevchenko, EV Chem Rev. 2010, 110, 389 .; Regulacio, MD; Han, M.-Y. Acc.Chem.Res. 2010, 43, 621. Kershaw, SV; Susha, AS; Rogach, AL Chem. Soc. Rev. 2013, 42, 3033.). In addition, the colloidal nanoclusters can be well dispersed in a variety of solvents to produce nanocrystalline inks, which can be produced by simple manufacturing techniques such as drop casting, spin coating and ink-jet printing Thereby making it possible to manufacture a low-cost, large-area optoelectronic device.
Recently, a hybrid organic-inorganic lead halide perovskite (CH 3 NH 3 PbX 3, X = Cl, Br, I) is due to the rapid rise to their surprisingly large as the light absorbent (light absorbers) in the solar cells (photovoltaics) I am interested.
In addition to solar cells, these perovskites have also been studied for their potential in other applications such as water splitting and light emitting diodes.
Other potentially interesting but less studied perovskites are all inorganic cesium lead / tin halides (CsPb (Sn) X 3 , X = Cl, Br, I). CsSnI 3 has been reported to have excellent hole transport properties in solid state dye-sensitized solar cells (Chung, I .; Lee, B .; He, J., Chang, RPH; Kanatzidis, MG Nature, 486). More recently, a solar cell manufactured using CsPbBr 3 as a light absorbing material has shown comparable performance to an organic material (CH 3 NH 3 PbBr 3 ). In particular, a high open circuit voltage characteristic of a perovskite solar cell (Kulbak, M .; Cahen, D .; Hodes, GJ Phys. Chem. Lett., 2015, 6, 2452.).
Most CsPb (Sn) X 3 perovskite studies use bulk crystals or thin films of these materials. On the other hand, the reduction in area on the nanoscale leads to more exciting properties in these perovskites. Recently, Protesescu et al. Reported a new method of synthesis of colloidal CsPbX 3 nanocrystals. All nanocrystals exhibited bright luminescence with quantum yields of up to 90% and narrow emission wavelengths were adjusted to the entire visible region depending on the size of the nanocrystals and the halide ion composition (Protescu, L., Yakinin, S., Bodnarchuk, MI, Krieg, F. Caputo, R. Hendon, CH, Yang, RX; Walsh, A .; Kovalenko, MV Nano Lett., 2015, 15, 3692.). Post-synthesis conversion reactors in nanocrystals, such as cation and anion exchange reactions, have been used as powerful tools for fine control of the crystal composition. While cation exchange reactions have been widely reported in nanocrystals, anion-related reactions have been reported recently. Park et al. Reported the synthesis of ZnS hollow nanoparticles through anion exchange reactions involving ZnO nanoparticles (Park, J .; Zheng, H .; Jun, Y.-w .; Alivisatos, APJ Am. Chem Soc., 2009, 131, 13943.). In addition, a recent study of the Gratzel group reported halide ion exchange in CH 3 NH 3 PbX 3 perovskite films using CH 3 NH 3 X (X = Cl, Br, I) (Pellet, , J., Maier, J .; Gratzel, M. Chem.Materials 2015, 27, 2181.).
However, there is no report on the halide exchange reaction in colloidal nanocrystals for the production of materials with high luminescence properties in the literature so far known.
It is an object of the present invention to provide a reversible halide exchange method of cesium lead halide colloidal nanocrystals.
Another object of the present invention is to provide a method for reversible halide exchange of cesium lead halide colloidal nanocrystals at room temperature in a short time.
In order to accomplish the above object, the present invention provides a reversible halide exchange method of cesium lead halide nanocrystals, which comprises reacting, at room temperature, lithium halide (LiY, LiCl) with a first cesium lead halide (CsPbX 3 , And Y = a second halide) to convert the halide into an exchanged second cesium lead halide (CsPbY 3, Y = second halide).
X and Y are any one selected from the group consisting of Br, I, and Cl, and X and Y are different halides.
The conversion step is a step of adding the ethanol solution of lithium halide to the hexane solution of the first cesium lead halide.
Wherein the first halide is Br and the second halide is I or Cl.
The first cesium lead halide is converted into a second cesium lead halide having a progressive change in wavelength length in the wavelength range from 508 nm to 654 nm depending on the addition concentration of lithium iodide (LiI).
The first cesium lead halide is converted to a second cesium lead halide having a progressive wavelength length change in the wavelength range from 508 nm to 425 nm depending on the concentration of lithium chloride (LiCl) added.
The second cesium lead halide is preferably selected from the group consisting of a transition of a progressive wavelength length in the wavelength range from 654 nm to 508 nm or a progressive change in the wavelength length in the wavelength range from 425 nm to 508 nm depending on the concentration of lithium bromide (LiBr) Lead halide.
According to the present invention, there is provided a reversible halide exchange method of cesium lead halide colloidal nano-crystals.
Also provided is a method for reversible halide exchange of cesium lead halide colloidal nanocrystals within a short time at room temperature.
FIG. 1 (a) shows the concept of a halide exchange reaction in CsPbX 3 (X = Cl, Br, I) nanocrystals, (b) shows the synthesis of CsPbBr 3 nanocrystals and halide exchanged CsPbI 3 and CsPbCl 3 XRD pattern, (c) TEM image of CsPbI 3 nanocrystal, and
Figure 2 shows the XRD analysis results of the cesium lead halide colloidal nano crystals of the present invention,
Figure 3 (a) shows the ultraviolet visible absorption spectra and the photoemission spectroscopy of the CsPbBr 3 nanocrystals exchanged according to different concentrations of LiI and LiCl, and Figure 4 (b) shows the photoabsorption spectra of the CsPbBr 3 nanocrystals exchanged according to different concentrations of LiI and LiCl in a hexane solution (C) shows all samples according to the concentration, and (d, e) shows the time-resolved PL decay and radiative lifetime of all the samples shown in (c) and,
4 shows TEM analysis results of the cesium-lead halide colloidal nano-crystals of the present invention,
Figure 5 shows the theoretical fit of an experimental absorption spectrum of (a) CsPbCl 3 nanocrystals, (b) CsPbBr 3 nanocrystals, and (c) CsPbI 3 nanocrystals, A plot of the excitation energy as a function is shown,
Figure 6 shows the results of PL spectral analysis of the cesium lead halide colloidal nano-crystals of the present invention,
7 (a) and 7 (b) show CsPbI 3 -CsPbBr 3 , (c, d) show absorption and PL spectra of the reversible halide exchange reaction of CsPbCl 3 -CsPbBr 3 ,
Figure 8 shows the results of PL spectral analysis of the complete exchange cycle of the reversible conversion of the cesium lead halide colloidal nano crystals of the present invention,
FIG. 9 shows various color changes of nanocrystals produced by the halide exchange reaction of the present invention.
The present invention provides a reversible halide exchange method of cesium lead halide nanocrystals wherein the exchange method comprises reacting lithium halide (LiY, Y) at a room temperature with a first cesium lead halide (CsPbX3 , X = first halide) = Second halide) to convert the halide to an exchanged second cesium lead halide (CsPbY 3, Y = second halide).
X and Y are any one selected from the group consisting of Br, I, and Cl, and X and Y are different halides.
The conversion step is a step of adding the ethanol solution of lithium halide to the hexane solution of the first cesium lead halide.
Wherein the first halide is Br and the second halide is I or Cl.
The first cesium lead halide is converted into a second cesium lead halide having a progressive change in wavelength length in the wavelength range from 508 nm to 654 nm depending on the addition concentration of lithium iodide (LiI).
The first cesium lead halide is converted to a second cesium lead halide having a progressive wavelength length change in the wavelength range from 508 nm to 425 nm depending on the concentration of lithium chloride (LiCl) added.
The second cesium lead halide is preferably selected from the group consisting of a transition of a progressive wavelength length in the wavelength range from 654 nm to 508 nm or a progressive change in the wavelength length in the wavelength range from 425 nm to 508 nm depending on the concentration of lithium bromide (LiBr) Lead halide.
As described above, when the halide exchange reaction of CsPbBr 3 perovskite colloidal nanocrystals is performed using a lithium salt (LiX, X = I, Cl, Br) at room temperature as described above, the CsPbBr 3 perovolume Green emission (508 nm) from the skewed colloidal nanocrystals can be converted to the entire visible light region (425-654 nm) using the lithium salt (LiI or LiCl). The halide exchange reaction can be accomplished very quickly and can be completed in a few seconds, and the halide exchange reaction is also reversible and up to five complete exchange cycles can be performed.
We have studied the halide exchange reaction by selecting a CsPbBr 3 perovskite colloidal nanocrystal that has a visible green emission near 508 nm and converts Br into Cl or I to convert it to blue or red in the visible light spectrum It can be.
A CsPbBr 3 perovskite colloidal nanocrystal of about 8 nm in size was synthesized using the procedure reported by Protesescu et al. The exchange reaction is to add a calculated amount of ethanol solution of LiCl or LiI to the CsPbBr 3 perovskite colloidal nanocrystals in hexane was carried out at room temperature. The mixture was then agitated vigorously to change color from green to red for LiI and colorless for LiCl. The total exchange reaction was completed in less than 5 seconds. The solution was filtered through a 0.2 [mu] m filter and used for analysis. FIG. 1 (a) shows the concept of a halide exchange reaction in CsPbX 3 (X = Cl, Br, I) nanocrystals, (b) shows the synthesis of CsPbBr 3 nanocrystals and halide exchanged CsPbI 3 and CsPbCl 3 XRD pattern, and (c) TEM image of CsPbI 3 nanocrystals. As shown in FIG. 1 (b), the synthesized CsPbBr 3 perovskite colloidal nano-crystal does not change even after being exchanged with I or Cl with a cubic structure (JCPDS No. 54-0752) Is maintained. However, the reflection at 30.68 ° (200) was changed to a lesser angle at the time of exchange of Br with I, due to the lattice expansion due to the replacement of the smaller Br ion with the larger I ion. In a similar manner, the
The present inventors also observed changes in the intensity of the XRD peak. In the case of the iodine-exchanged sample, the intensity of the
The CsPbI 3 nanocrystals are thicker than the original CsPbBr 3 nanocrystals while the CsPbCl 3 nanocrystals are thinner than the original CsPbBr 3 nanocrystals. This is in agreement with the above XRD observation, and growth along the plane of the plane of scarring can increase the thickness of the crystal (see Fig. 2 (b)).
The elemental composition of the exchanged sample was obtained using energy dispersive X-ray spectroscopy (EDS). The EDS data obtained from these three different positions suggest a complete conversion of Br into I, as shown in Table 1 below.
2
3
22.4
15.5
22.9
20.4
54.7
64.1
21.4
21.6
19.0
20.7
59.6
57.7
The halide exchange reaction to CsPbBr CsPbI 3 of 3 at a concentration of mutually different LiI was monitored using XRD, absorption (absorbance), and an optical emission spectroscopy (photoluminescence spectroscopy). The synthesized CsPbBr 3 had an absorption peak near 485 nm but reacted with 10 μL of 0.16 M LiI and converted to 510 nm red (see FIG. 2 (a)). By increasing the concentration of LiI, the absorption peak is progressively red-shifted to reach a final value of 634 nm for 1.28 M LiI.
The color conversion correlates with the XRD measurement, which shows a gradual shift of the
As shown in FIG. 3 (c), the PL peak can be converted from 508 to 654 nm with different concentrations of LiI. All of the above exchanged samples showed the same bright luminescence as the original CsPbBr 3 . When instead of LiCl was used LiI, and a luminance peak of the absorption CsPbBr 3 was converted to the less blue wavelength. This is due to the gradual conversion of CsPbBr 3 CsPbCl 3. CsPbCl 3 nanoclusters showed strong absorption and narrow emission peak (FWHM = 15 nm). Table 2 shows the positions of CsPbBr 3 nanocrystal absorption and emission peak at different concentrations of lithium halide.
The emission characteristics of all the halide exchanged nanocrystals are almost the same as those of chemically synthesized nanocrystals by Protesescu et al., Which shows high quality of the exchanged nanocrystals (Protesescu, L .; Yakunin, S .; Bodnarchuk, MI ; Krieg, F .; Caputo, R .; Hendon, CH, Yang, RX; Walsh, A .; Kovalenko, MV Nano Lett., 2015, 15, 3692.).
In addition, the present invention shows that it is possible to make clear control over the emission peak position by simply changing the lithium halide concentration, which is not possible in the halide exchange reaction reported in the CH 3 NH 3 PbX 3 film reported by the Gratzel group (Pellet, N., Teuscher, J .; Maier, J .; Gratzel, M. Chem., 2015, 27, 2181.).
To obtain information about the carrier consumption process, a time-resolved PL (TRPL) spectrum was measured and the results are as shown in Figure 3 (d). Surprisingly, while the PL decay curve can be fitted well by the biexponential decay function (1) in the blue emitting regime, single exponential decay is observed in the red emission regime .
The short (long) -speed lifetime for each wavelength is summarized in Figure 3 (e). At longer wavelengths, the fast collapse process is weakened and the slow collapse process becomes dominant. Since all observations are performed under low pumping power (~ 3 nJ / cm2), consideration of the two molecules and Auger recombination can be ignored.
Two decay process, an organic metal halide perovskite (CH 3 NH 3 PbX 3, X = Br, I, Cl) and has been observed in CdSe QDs (Zhang, F .; Zhong , H .; Chen, C .; Wu, X.-g .; Hu, X .; Huang, H.; Han, J .; Zou, B .; Dong, Y. ACS Nano 2015, 9, 4533 .; Wang, X .; Zhang, J .; Peng, X., Xiao, M. Nano Lett., 2003, 3, 1103.). The fast collapse process may be associated with a glass carrier or a radiative recombination of the excitations, while the longer lifetime component corresponds to the recombination of the carrier-related surfaces. In CdSe QDs, the larger QD has many surface trap states, which leads to a slower collapse process. It is reasonable to assume that the red-emitting CsPbI 3 nanocrystals are more thicker than the blue-emitting CsPbCl 3 nanocrystals (TEM image in FIG. 4), thus having more surface trapped states, which in turn can enhance the slower decay process .
To investigate the rapid decay process in the blue regime, the present inventors studied the stability of excitons at room temperature. Band gap energy and Wannier exciton binding energy can be extracted using the absorption coefficients of Eliot's theory, including Coulombic interaction (Elliott, RJ Phys. Rev. 1957, 108 , S .; Sartu, N .; Figus, C .; Aresti, M .; Piras, R .; Geddo Lehmann, A., Cannas, C .; Musinu, A .; Quochi, F., Mura, A., Bongiovanni, G. Nat. Commun., 2014, 5, 5049.).
Figure 5 shows the theoretical pit for the experimental absorption spectrum of each sample. FIG. 5 shows the theoretical fit of an experimental absorption spectrum of (a) CsPbCl 3 nanocrystals, (b) CsPbBr 3 nanocrystals, and (c) CsPbI 3 nanocrystals, Is a plot of the excitation energy and the blue line represents the thermal energy at room temperature. The exciton binding energy increases as the bandgap increases, which is similar to that observed in a variety of direct gap semiconductors (Klingshirn, C. Semiconductor Optics, 2nd ed. Springer-Verlag, Berlin / Heidelberg / New York) 2005.).
Taking into account the room temperature thermal energy (~ 25 meV), the exciton separation is activated in samples with a band gap energy of less than 2.34 eV (530 nm). As can be seen in Figure 3 (a), a clear exciton absorption in the blue regime can be observed due to the more stable excitons. However, in the green emission regime where the band gap energy is lower than 2.34 eV, the absorption can not be completely separated due to band gap and exciton. At this point, the fast collapse component disappears due to exciton recombination in the TRPL and the slow collapse process dominates. This also supports the fact that the fast decay process corresponding to the recombination of the excitons is dominant in the blue luminescent sample.
The present invention is also characterized in that the halide (anion) exchange reaction is reversible. If the exchange CsPbBr 3 to CsPbI 3, due to the CsPbI 3 nano crystals in the reenactment of the LiBr may go back again CsPbBr 3.
7 (a) and 7 (b) show CsPbI 3 -CsPbBr 3 , and (c, d) show absorption and PL spectra of the reversible halide exchange reaction of CsPbCl 3 -CsPbBr 3 . Figure 7 (a) shows the absorption spectra of reversible anion-exchange spectra of CsPbI 3 nanocrystals at different concentrations of LiBr. The absorption peaks of the CsPbI 3 nanocrystals were progressively blue converted to lower wavelengths and reached a final value of 501 nm, which corresponded to the CsPbBr 3 -xIx NCs (510 nm), which was slightly iodinated with pure CsPbBr 3 nanocrystals (485 nm) ). This shows that complete reversibility of CsPbBr 3 is not possible.
We also found a maximum of five complete halide exchange cycles possible (e.g., green to red and red to green) in the same nanocrystal solution (FIG. 8). After this, due to the increased concentration of ethanol in hexane, the nanocrystals were precipitated in hexane solution. In a similar manner, CsPbCl 3 nanocrystals can also be converted back to CsPbBr 3 using LiBr (see (c) and (d) in FIG. 7).
As described above, the present invention relates to an effective method of halide exchange reaction of CsPbX 3 nanocrystals (X = Br, I, Cl). The exchange reaction proceeds very rapidly and is completed within a few seconds at room temperature. The emission wavelength of any CsPbX 3 nanocrystal can be converted into the entire visible light spectral range. The halide exchange reaction is largely reversible, and the nanocrystals are stable for up to five complete exchange cycles. It can be easily extended to organometallic halide perovskide (CH3NH3PbX3) in a very simple and economical way to adjust the bandgap.
In addition to sensors, the application of the Nato crystals according to the invention is possible in optoelectronic devices such as photovoltaics and light emitting diodes.
Details of the materials and the experimental tools in the above-described experimental procedure are as follows.
Materials : Cesium carbonate (Cs2Co3, 99.9%), lead (II) bromide, PbBr2, 99.999% and lithium iodide (LiI, 99%) were all available from Sigma Aldrich ). Lithium bromide (LiBr, 99.998%) and lithium chloride (LiCl, 99.995%) were purchased from AlphaEd. 1-octadecene (ODE, 90%), hexane (95%, anhydrous grade) and ethanol (anhydrous grade, 99.5%) were purchased from Sigma-Aldrich and used without further purification.
Oleic acid (OA, 90%) and oleylamine (Oleylamine, OAm, 70%) were purchased from Sigma-Aldrich and dried under vacuum.
Preparation of Cs-oleate : In a three-necked flask, 0.207 g of Cs 2 CO 3 was mixed with 10 mL of ODE and 625 μL of OA. The mixture was dried under vacuum at 120 < 0 > C for 1 hour. And the mixture was heated until all of the Cs 2 CO 3 are reacted with the OA is maintained at 100 ℃ to 150 ℃ under N 2.
Synthesis of CsPbBr 3 nano-crystals : 0.069 g of PbBr 2 and 5 mL of ODE were loaded into a 25 mL three-necked flask and dried under vacuum at 120 ° C for 1 hour. The dry OAm (0.5 mL) and dried OA (0.5 mL) was injected at 120 ℃ under N 2. After complete dissolution of the PbBr2 salt, the temperature was raised to 160 < 0 > C. After 0.4 s of the above-mentioned Cs-oloate solution was injected rapidly and after 5 s, the reaction mixture was cooled in an ice-water bath. The nanocrystals were precipitated with ethanol, re-dispersed in 30 mL of hexane and filtered through a 0.2 μm PTFE filter.
PbBr 2 salt After complete solubilization, the temperature was raised to 160 ℃. 0.4 mL of the above-mentioned Cs-oloate solution was injected quickly, and after 5 s, the reaction mixture was cooled in an ice bath. The nanocrystals were precipitated with ethanol, redispersed in 30 mL of hexane and filtered through a 0.2 μm PTFE filter.
Anion exchange reaction : All exchange reactions were carried out at room temperature. Typically, 10 μL of an ethanol solution of LiI or LiCl was added to 1 mL of the CsPbBr 3 nanocrystals in the prepared hexane solution. Thereafter, the mixture was vigorously stirred, resulting in a color conversion from green to red for LiI and colorless for LiCl. The total exchange reaction was completed in less than 5 seconds. The mixture was filtered through a 0.2 μm PTFE filter and used for analysis.
Reversible Anion Exchange Reaction : For the reversible anion exchange reaction, the CsPbBr 3 nanocrystals were first exchanged with CsPbI 3 or CsPbCl 3 nanocrystals using LiI or LiCl. At this time, 10 μL of a LiBr ethanol solution was added to 1 mL of the prepared CsPbI 3 or CsPbCl 3 nanocrystals. At this time, the mixture is drawn in the case of nanocrystalline CsPbI 3 are vigorously stirred red, a color change took place in the case of nanocrystalline CsPbCl 3 drawn from colorless. The mixture was then filtered through a 0.2 μm PTFE filter and used for analysis.
The absorption due to the lithium halide at different concentrations and the positions of the luminescent peaks are shown in Table 2 above.
characteristic:
X-Ray Diffraction (XRD)
XRD was obtained using a
The XRD measurement results are shown in FIG. FIG. 2A shows the XRD pattern of the halide exchange reaction in CsPbBr 3 nanocrystals with LiI and LiCl, and FIG. 2b shows the structure of CsPbBr 3 nanocrystals having plane (100) and plane (110) .
TEM (Transmission Electron Microscopy)
TEM, HRTEM (High-resolution TEM) image and STEM energy dispersive X-ray spectroscopy (EDS) spectra were performed on a JEOL-2100F microscope operating at 200 KeV. Samples were prepared by dropping a diluted nanocrystalline colloidal suspension onto a carbon-coated 200 mesh copper grid.
The TEM results are shown in FIG. 4 (a) is a TEM image of a CsPbCl 3 nanocrystal, (b) is a TEM image of a CsPbBr 3 nanocrystal, and (c) is an image of a CsPbI 3 nanocrystal.
The EDS data of CsPbBr 3 and CsPbI 3 nanocrystals are shown in Table 1 above.
In the case of CsPbCl 3 nanocrystals, no quantitative data were obtained due to their very thin nature.
UV-vis Absorption Spectroscopy
The absorption spectrum of the nanocrystals dissolved in hexane was measured in a 1 cm path length quartz quartz using a Cary 5000 UV-vis-NIR (Agilent Technologies) spectrometer.
The equation used to fit the experimental absorption curve is: < RTI ID = 0.0 >
The Wannier exciton's three-dimensional Eliot formula was modeled as the absorption coefficient near the band boundary. μ cv is the transition dipole moments;
Photoluminescence Spectroscopy
The PL spectra of the nanocrystals dissolved in hexane were measured using a Cary Eclipse fluorescence spectrophotometer. (λ exc = 400 nm for all samples, or 350 nm for blue-emitting CsPbCl 3 samples)
Time resolved PL spectrum (PL spectrum)
The time-resolved PL spectra were measured using a time-correlated single photon counting system (Picoquant, Fluotime 200). The PL radiation from the sample was collected with a concave holographic grating at 1200 g / mm by a pair of lenses and measured by a PMT (photomultiplier tube). Time resolution and repetition rate are 80 ps and 10 MHz, respectively. The samples were excited at room temperature by a 375 nm pulse (LDH-P-C-375, 3 kV).
The results of the time-resolved PL spectrum are shown in FIG. Figure 6 shows the time-resolved PL decay and radiative lifetimes of the reversible halide exchanged samples listed in Table 3;
Also Fig. 8 as showing the PL spectrum of a full exchange cycle, (a) of FIG. 8 (b) for showing a PL spectrum, and Figure 8 the fully exchange cycle to CsPbBr 3 in CsPbI 3 is CsPbBr in CsPbCl 3 3 shows the PL spectrum of the complete exchange cycle. According to Figure 8, in CsPbI 3 to CsPbBr 3, it was confirmed a complete exchange cycle yirueojim over a total of 5 times from 3 to CsPbBr CsPbCl 3.
FIG. 9 shows various color changes of nanocrystals produced by the halide exchange reaction of the present invention. FIG. 9 (a) shows emission from specific CsPbX 3 nanocrystals (black spots) and blue LED (λ = (White point) on the CEI chromaticity coordinates. Figure 9 (b) also shows the emission spectrum of CsPbX 3 nanocrystals shining with a blue LED chip (λ = 460 nm, V f = 3 V, I f = 60 mA) and a high radioactivity CsPbX 3 nanocrystal (? = 365 nm).
Claims (7)
At room temperature, the first cesium lead halide (CsPbX 3, X = a first halide) second cesium lead halide by adding a lithium halide (LiY, Y = a second halide) to the nanocrystal the halide exchange (CsPbY 3, Y = A second halide)
X and Y are any one selected from the group consisting of Br, I, and Cl,
X and Y are different halides,
In the conversion step,
Wherein an ethanol solution of the lithium halide is added to a hexane solution of the first cesium chloride halide.
Wherein the first halide is Br,
Wherein the second halide is I or Cl. ≪ RTI ID = 0.0 > 11. < / RTI >
The first cesium lead halide is converted into a second cesium lead halide having a progressive change in wavelength length in a wavelength range from 508 nm to 654 nm depending on the concentration of lithium iodide (LiI), wherein the reversible halide of the cesium lead halide nano- Exchange method.
The first cesium lead halide is converted to a second cesium lead halide having a change in the progressive wavelength length in the wavelength range from 508 nm to 425 nm according to the concentration of lithium chloride (LiCl) added, wherein the reversible halide of the cesium lead halide nanocrystal Exchange method.
The second cesium lead halide is preferably selected from the group consisting of a transition of a progressive wavelength length in the wavelength range from 654 nm to 508 nm or a progressive change in the wavelength length in the wavelength range from 425 nm to 508 nm depending on the concentration of lithium bromide (LiBr) Lt; / RTI > is converted to a lead halide.
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| CN111517657A (en) * | 2020-04-30 | 2020-08-11 | 武汉理工大学 | Sr2+Doped CsPbBr3Quantum dot germanium borosilicate glass, preparation method and application |
| CN111517657B (en) * | 2020-04-30 | 2021-05-18 | 武汉理工大学 | Sr2+Doped CsPbBr3Quantum dot germanium borosilicate glass, preparation method and application |
| CN114213003A (en) * | 2021-09-02 | 2022-03-22 | 闽都创新实验室 | Perovskite quantum dot glass with composite structure and preparation method and application thereof |
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| WO2024080664A1 (en) * | 2022-10-11 | 2024-04-18 | 주식회사 지티아이바이오사이언스 | Method for producing iron oxide based nanoparticles, and iron oxide based nanoparticles formed therefrom |
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