GB/T 24370-2021 English PDF (GB/T24370-2021)

GB/T 24370-2021: Nanotechnologies - Characterization of cadmium chalcogenide colloidal quantum dot - UV-Vis absorption spectroscopy
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GB/T 24370-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.040.50
CCS G 30
Replacing GB/T 24370-2009
Nanotechnologies - Characterization of Cadmium
Chalcogenide Colloidal Quantum Dot - UV-Vis Absorption
Spectroscopy
(ISO/TS 17466.2015, Use of UV-Vis absorption spectroscopy in the characterization
of cadmium chalcogenide colloidal quantum dots, MOD)
ISSUED ON. DECEMBER 31, 2021
IMPLEMENTED ON. JULY 1, 2022
Issued by. State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword... 3
Introduction... 6
1 Scope... 7
2 Normative References... 7
3 Terms and Definitions... 7
4 Abbreviations and Symbols... 8
5 Principle... 9
6 Sample Preparation... 12
7 Test Procedures... 12
8 Data Analysis and Result Expression... 13
9 Measurement Uncertainty... 13
10 Test Report... 14
Appendix A (informative) Example of Determining the Diameter of CdSe Quantum
Dots using UV-Vis Absorption Spectrum... 15
Appendix B (informative) Example of Determining Particle Concentration of CdSe
Quantum Dots in Dispersion Liquid... 23
Bibliography... 27
Nanotechnologies - Characterization of Cadmium
Chalcogenide Colloidal Quantum Dot - UV-Vis Absorption
Spectroscopy
1 Scope
This Standard provides a method for evaluating the diameter and particle concentration of
monodisperse cadmium chalcogenide (CdTe, CdSe and CdS) colloidal quantum dots using UV-
Vis absorption spectroscopy.
This document is applicable to the analysis of monodisperse spheroidal quantum dots. CdTe
with a diameter of 3.5 nm ~ 9 nm, CdSe with a diameter of 1 nm ~ 8 nm and CdS with a
diameter of 1 nm ~ 5.5 nm.
2 Normative References
This document does not have normative references.
3 Terms and Definitions
The following terms and definitions are applicable to this Standard.
3.1 quantum dot; QD
Crystalline nanoparticles that exbibit size-dependent properties due to the quantum
confinement effect of electronic states.
[source. GB/T 32269-2015, 4.7]
3.2 quantum confinement
When the size of the system is equivalent to the de Broglie wavelength of the particle, the
movement of the particle in one, two or three dimensions is restricted.
NOTE 1.the main characteristic dimensions that lead to quantum confinement are the de Broglie
wavelength, Fermi wavelength, mean free path, (exciton) Bohr radius or (exciton)
coherence length of the particle.
NOTE 2.the main manifestation of quantum confinement is that the electronic energy level is split
from the continuous state into discrete energy levels.
[source. ISO/TS 80004-12.2016, 2.5, modified]
3.3 first excitonic absorption
Light absorption generated when electrons in quantum dots transition from the ground state to
the first excitonic excited state.
4 Abbreviations and Symbols
4.1 Abbreviations
The following abbreviations are applicable to this document.
HDA. hexadecylamine
HRTEM. high resolution transmission electron microscopy
HWHM. half width at half maximum
OPA. n-octylphosphonate
PPA. P-P-(di-n-octyl) pyrophosphonate
QD. quantum dot
TEM. transmission electron microscopy
TOPO. trioctylphosphine oxide
UV-Vis. ultraviolet-visible
4.2 Symbols
The following symbols are applicable to this document.
A absorbance
c particle concentration
d particle diameter
E1s first exciton transition energy
I transmitted light intensity
I0 incident light intensity
l optical path
 wavelength
E1s---the first exciton transition energy, expressed in (eV).
Formula (6) and Formula (8) come from Bibliography [5], and Formula (7) comes from
Bibliography [6]. The wavelength  (unit. nm) and transition energy E (unit. eV) can be
converted through  = 1,240/E.
6 Sample Preparation
The sample for the determination of the absorption spectrum shall be a uniform and stable
quantum dot dispersion liquid. Commercial quantum dots are usually synthesized through
organometallic chemical reaction solution method, and the surface of the quantum dots is coated
with organic molecules, such as. TOPO, OPA, PPA and HAD [7]. These organic molecules
prevent the quantum dots from agglomerating and maintain their dispersion. Typically, quantum
dots are small and can be well dispersed in a suitable solvent. It shall be ensured that the
prepared dispersion liquid is clear and transparent, and the solvent must be compatible with the
surface chemistry of the quantum dots and not interfere with the absorption spectrum of the
quantum dots. If the quantum dots are hydrophobic, then, non-polar solvents, such as. hexane
and chloroform shall be used. If the quantum dot surface becomes hydrophilic through ligand
exchange, then, polar solvents, for example, water, may be used.
In order to guarantee the applicability of the Beer-Lambert Law, a dilute dispersion liquid with
an absorbance (A) of the first excitonic absorption peak less than 1 shall be used for testing.
During the dilution process, quantum dot agglomeration caused by the shedding of ligand
molecules from the nanoparticle surface shall be avoided.
7 Test Procedures
7.1 UV-Vis Spectrophotometer
Use a calibrated spectrometer to cover UV-Vis wavelength. It is applicable to cadmium
chalcogenide colloidal quantum dots within the size range specified in this document, and the
spectrum range of the first excitonic absorption peak is 250 nm ~ 750 nm, depending on the
respective inorganic core material. Before the test, the UV-Vis spectrophotometer shall be
calibrated for wavelength and absorbance accuracy using standard substances (for example,
standard optical filters [8]).
7.2 Measurement Procedures of UV-Vis Absorption Spectrum
Refer to the instrument’s instruction manual and follow standard procedures for measuring
absorption spectra. Place the sample to be measured in a quartz cuvette, place the pure solvent
of dispersed quantum dots in another identical quartz cuvette as a reference for background
subtraction. At room temperature and normal pressure, carry out the test.
7.3 Recommended Test Parameters
The following test conditions should be used.
a) Wavelength range. 250 nm ~ 750 nm;
b) Step size. 0.5 nm or 1 nm;
c) Slit. 1 nm or 2 nm.
8 Data Analysis and Result Expression
8.1 Quantum Dot Size Estimation
Record the wavelength and absorbance at the maximum absorption point of the first excitonic
absorption peak. Within the applicable size range of the formula, utilize the Formula in 5.4 and
the recorded wavelength at the first excitonic absorption peak to calculate the average diameter
d.
NOTE. the Formula is applicable to quantum dots 3.5 nm ~ 9 nm CdTe, 1 nm ~ 8 nm CdSe and 1
nm ~ 5.5 nm CdS.
8.2 Estimation of Quantum Dot Particle Concentration
The procedures of calculating the particle concentration of quantum dot samples are as follows.
a) In accordance with the steps described in 8.1, measure the average particle diameter
d;
b) In accordance with Formula (6), Formula (7) and Formula (8), calculate the molar
extinction coefficient  of the quantum dot dispersion liquid;
c) If necessary, in accordance with Formula (5), normalize the peak absorbance;
d) In accordance with the Beer-Lambert Formula [Formula (4)], calculate the particle
concentration c of the quantum dot dispersion liquid.
9 Measurement Uncertainty
In accordance with the universal method described in Bibliography [9] or an equivalent
document, evaluate the obtained measurement uncertainty of quantum dot diameter and particle
concentration, which shall include the sources listed below.
a) Uncertainty introduced by non-normal size distribution of quantum dots in the sample;
b) Uncertainty introduced by the accuracy and precision of the formulas in 5.4 and 5.5.
These formulas are estimation formulas recommended by the literature, and there is
a certain degree of uncertainty. These formulas are the best fitting results of
experimental data, so the formula parameters A, B, C, D and E in 5.4 are dispersive.
Appendix A
(informative)
Example of Determining the Diameter of CdSe Quantum Dots using UV-Vis Absorption
Spectrum
A.1 General Rule
This Appendix provides an example of estimating the average diameter of a CdSe quantum dot
colloidal dispersion liquid using UV-Vis absorption spectroscopy, as well as the size determined
using high resolution transmission electron microscopy (HRTEM) for comparison.
A.2 CdSe Quantum Dot Sample
Analyze three different sizes of CdSe quantum dots (samples 1 ~ 3) with different first excitonic
absorption peak wavelengths. CdSe quantum dots are dispersed in analytically pure toluene for
UV-Vis absorption spectrum test.
A.3 Instrument
Utilize a Perkin Elmer Lambda 650 UV/Vis spectrometer and a quartz cuvette with a 1 cm
optical path to determine the UV-Vis absorption spectrum of the samples at room temperature.
Utilize FEI Tecnai G2 F20 S-TWIN TEM with a working voltage of 200 kV to obtain the
HRTEM image of CdSe quantum dots.
A.4 Test Conditions of UV-Vis Spectrum
Utilize standard filters to calibrate the UV-Vis absorption spectrum. The test conditions are as
follows;
a) Wavelength range. 250 nm ~ 750 nm;
b) Step size. 0.5 nm;
c) Slit. 2 nm;
d) Background subtraction. subtract the absorption spectrum of the solvent (analytically
pure toluene) used for the CdSe quantum dot dispersion liquid as the background.
A.5 Test Procedures of UV-Vis Spectrum
In accordance with the following procedures, conduct UV-Vis spectrum test on the samples.
a) Add an appropriate amount of CdSe quantum dot sample into a quartz cuvette with
an optical path of 1 cm;
b) Place the cuvette in the sample cell and set the test conditions of the UV-Vis
Appendix B
(informative)
Example of Determining Particle Concentration of CdSe Quantum Dots in Dispersion
Liquid
B.1 General Rule
This Appendix provides an example of estimating the particle concentration of a monodisperse
CdSe quantum dot colloidal dispersion liquid using UV-Vis absorption spectrum, and compares
the analysis results with those analyzed using ICP-MS.
B.2 CdSe Quantum Dot Samples
Analyze two CdSe quantum dots (Sample 4 and Sample 5) with different sizes and
concentrations, that is, different first excitonic absorption peak wavelengths and absorbances.
CdSe quantum dot are dispersed in analytically pure toluene for UV-Vis absorption spectrum
test.
B.3 Instrument
Utilize Perkin Elmer Lambda 650 UV/Vis spectrometer and quartz cuvette to test the UV-Vis
absorption spectrum of the samples at room temperature. Utilize Perkin Elmer NexIONTM
300X inductively coupled plasma mass spectrometer (ICP-MS) to conduct the analysis.
B.4 Test Conditions of UV-Vis Spectrum
Utilize standard filters to calibrate UV-Vis absorption spectrum. The test conditions are as
follows.
a) Wavelength range. 250 nm ~ 750 nm;
b) Step size. 0.5 nm;
c) Slit. 2 nm;
d) The solvent (analytically pure toluene) used for CdSe quantum dot dispersion liquid
is used as a reference.
B.5 Test Procedures of UV-Vis Spectrum
In accordance with the following procedures, conduct UV-Vis spectrum test on the samples.
a) Add an appropriate amount of CdSe quantum dot sample into a quartz cuvette with
an optical path of 1 cm;
b) Place the cuvette in the sample cell and set the test conditions of the UV-Vis
d) Transfer the obtained concentrated solution to a volumetric flask and use dilute HNO3
to reach a constant volume;
e) Prepare five Cd standard solutions.
B.9 ICP-MS Analysis
Before testing the sample, test 5 standard solutions to obtain a standard curve (multi-point linear
fitting). Subtract the background of the 2% HNO3 solution to correct the data. Utilize the
intensity of the elemental signal peaks obtained by ICP-MS for online quantitative analysis.
Repeatedly measure each sample for 3 times.
Assuming that the density of the nanoparticles is the same as that of the bulk material (CdSe.
5.81 g/cm3), divide the determined number of Cd atoms by the number of Cd atoms contained
in each nanoparticle to obtain the particle concentration of CdSe quantum dots. In accordance
with the steps in A.7, utilize the UV-Vis spectrum to calculate the size of CdSe quantum dots,
which is respectively 2.80 nm and 3.07 nm. Assuming that the CdSe quantum dots are spherical
and calculate their volume. Thus, it can be calculated that the number of Cd atoms contained in
each nanoparticle in Sample 4 and Sample 5 is respectively 210 and 280.
B.10 Comparison of Results Obtained through UV-Vis Spectroscopy and ICP-MS
Analysis
The particle concentration of CdSe quantum dot samples obtained through the UV-Vis
spectroscopy described in this document is compared with the results obtained through ICP-
MS analysis in Table B.1.It shows that the results obtained by the two methods are consistent.
the difference between the measurement values is within the corresponding uncertainty range
evaluated in Chapter 9.The analysis results are expressed as the average value of three
measurement results plus or minus the standard deviation.
GB/T 24370-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.040.50
CCS G 30
Replacing GB/T 24370-2009
Nanotechnologies - Characterization of Cadmium
Chalcogenide Colloidal Quantum Dot - UV-Vis Absorption
Spectroscopy
(ISO/TS 17466.2015, Use of UV-Vis absorption spectroscopy in the characterization
of cadmium chalcogenide colloidal quantum dots, MOD)
ISSUED ON. DECEMBER 31, 2021
IMPLEMENTED ON. JULY 1, 2022
Issued by. State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword... 3
Introduction... 6
1 Scope... 7
2...