CdSe Quantum dots presentation for Intro to Inorganic and Materials module

1. Cell Glow
By Phoebe Bray, Lucy Hague, Jvaireya Akbar,
Steven Cline and Matt Franklin

2. Cell Glow
By Phoebe Bray, Lucy Hague, Jvaireya Akbar,
Steven Cline and Matt Franklin

3. Introduction
● Nanocell is currently looking into the development of cellglow.
● Cellglow involves the use of quantum dots which are made up of Cadmium Selenide (CdSe)
nanocrystals
Semiconductor
resistant to photo and
chemical degradation
excellent choice for
use in biomedical
imaging
Cadmium Selenide
Quantum Dots
2-10 nm
diameter

4. Manufacturing
● Quantum dots were discovered by Alexey Ekimov in 1981
● The term “Quantum dot” was coined by Mark Reed
How are Cadmium Selenide Quantum
Dots manufactured?
● can be synthesised using
precursors and organic surfactants
● mixture is heated at a high
temperature
● Temperature is an important
factor as it determines the growth
of nanorcystals
● the monomer concentration is also
under strict control during
nanocrystal growth
● Alternative method is High
TEM of quantum dots and their
corresponding colours at the
wavelength of emission

5. Applications -
White Light-Emitting Diodes
● Quantum dots have replaced phosphor-based
materials in WLEDs
● Quantum dots have unique optical properties that are
more useful than the phosphor-based materials
● The emission wavelength of the quantum dots can be
tuned by controlling the size of the nanocrystal size
of CdSe
● The fluorescence of the WLEDs can then be tuned
● Quantum dots have fewer scattering effects because
of their narrow size distribution

6. Applications -
Hybrid Solar Cells
● Colloidal nanocrystals (NC) combine
with polymers to make a photoactive
layer
● Cadmium selenide is a colloidal
semiconductor nanocrystal
● Can be used as an electron acceptor
● Efficient energy conversions
● Large scale synthesis is very
expensive
● Some solvents that coat the CdSe are
hazardous, unstable and not
environmentally friendly

7. ● One of the earliest commercial applications of
quantum dots
● The quantum dots are tagged to nanoscale
agents - DNA
● The quantum dots glow when exposed to UV
light
● Can target a particular cell - cancer cells
● Useful in surgery - the surgeon can see the
glowing tumour and use it as a guide for more
accurate tumour removal
● Allows medical researchers to understand
molecular interactions better
Applications -
Biological Markers

8. Future Applications
● Medical uses - medical imaging/screening
● Qubit- unit of quantum information
● Quantum Computers- theoretical computation systems that use quantum-
mechanical phenomena such as superposition and entanglement.

9. Advantages and Disadvantages of CdSe
Quantum Dots
Advantages:
● They are better than fluorophore dyes - 20
times brighter
● They make solar cells more efficient
● It is easy to alter the wavelength of light
emitted in the 400-4000 nm range -
different colours
Disadvantages:
● CdSe is highly toxic - needs a stable
polymer shell
● The shells can alter the optical
properties and it is also hard to control
the size of the particles.
● In aqueous and UV conditions
degradation increases - mechanism
needs to be studied

10. X-Ray Diffractometers
Diagram of what happens inside the machine
(Molecular Expressions, 2013)
XRay Diffractometer
(Molecular Expressions, 2013)

11. Braggs' Law
D-Spacing (interplanar spacing), explained using
Braggs' Law
(Henry et. al, 2012)
An example results graph (Henry et. al, 2012)

12. Benefits
•Non-destructive, fast, easy
sample prep
•High-accuracy for d-spacing
calculations
•Single crystal, poly, and
amorphous materials
•Standards are available for
thousands of material systems
Sources of Error
•Specimen displacement
•Instrument misalignment
•Peak distortion due to
certain wavelengths

13. Transmission Electron Microscope (TEM)
•Transmission electron microscopy (TEM) is a technique
in which a beam of electrons is transmitted through an
ultra-thin specimen, interacting with the specimen as it
passes through.
•TEMs work in the range 1 micron to 1 nanometre.
• It is a electron microscope which produces an image of
a cross-sectional slice of a specimen.
•The TEM uses electromagnetic lenses to focus the
electrons into a very thin beam. The electron beam
then travels through the specimen you want to study. •TEMs produce high-resolution, two-dimensional images,
allowing for a wide range of scientific and industry
applications.
•The limitations for TEM are mainly due to cost but also the
preparation of cells for TEM requires fixation with chemicals
that can introduce artificial damage.

14. Ultraviolet - Visible Spectrometer
• Ultraviolet–visible spectroscopy refers to the
absorption spectroscopy in the ultraviolet-visible
spectral region.
• The range is roughly 10 nm to 800 nm due to the
inclusion of ultra violet.
• A beam of light from a visible or UV light source is
separated into its wavelengths by a prism. Each single
wavelength beam is split into two.
• One beam, the sample beam, passes through a
cuvette containing a solution of the compound being
studied in a transparent solvent.
• The intensities of these light beams are then measured by
electronic detectors and compared.
• UV/Vis spectroscopy is used in analytical chemistry for the
determination of different analytes, such as transition metal
ions.
• UV-Visible spectroscopy works well on liquids and solutions,
but if the sample is solid particles in liquid, the sample will
scatter the light.
• Also to obtain reliable data, the peak of absorbance needs to
be at least three times higher in intensity than the background
noise of the instrument.
A diagram of a
UV-Visible
Spectrometer
UV-Visible
Spectrum of
Rose Bengal

15. References
● ANDERSON, H. (2010). Transmission Electron Microscope. [online] Available:
http://www.microscopemaster.com/transmission-electron-microscope.html.
● BOTTRILLl, M., and GREEN, M.; Chem. Commun., 2011, 47, 7039 - 7050
● DAVIDSON, M. W. (2013) Latest Gallery Additions, Molecular Expressions. [online] Available at:
www.micro.magnet.fsu.edu/primer/java/interference/index.html (Accessed: 8 December 2014).
● EFROS, Al. L.; ROSEN, M. (2000). The electronic structure of semiconductor nanocrystals. Annual Review of Materials
Science 30: 475–521.
● HENRY, D., EBY, N., GOODGE, J. and MOGK, D. (2012) X-ray reflection in accordance with Bragg’s Law, Geochemical
Instrumentation and Analysis. X-ray reflection in accordance with Bragg’s Law. [online] Available at:
http://serc.carleton.edu/research_education/geochemsheets/BraggsLaw.html (Accessed: 7 February 2015).
● ‘Quantum dot’ (2015) Wikipedia. Wikipedia. Available at: http://en.wikipedia.org/wiki/Quantum_dot (Accessed: 10
February 2015).
● MURRAY, C. B, et al. (2000). Synthesis and characterisation of mono disperse nanocrystals and close-packed nanocrystal
assemblies. [online] Annual review of Materials, 30 (1), p545.
● NANN, T. et.al., (2008) Nature Publishing Group, Quantum dots versus organic dyes as fluorescent labels. [online]
Available at: http://nathan.instras.com/ResearchProposalDB/doc-168.pdf
● no date). Technologies >> Preparation of Quantum Dots. Available at: http://www.oceannanotech.com/nav.php?qid=5
(Accessed: 10 February 2015).
● HAN, Lili, QIN, Donghuan, et al. (2006). Synthesis of High Quality Zinc-Blende CdSe Nanocrystals and Their Application
in Hybrid Solar Cells. [online]. Nanotechnology, 17 (18).
● XU Xianmei, WANG Yilin, GULE Teri, et al. (2013). Synthesis and Optical Properties of Cadmium Selenide Quantum Dots
for White Light-Emitting Diode Application, [online]. Materials Research Bulletin, 48 (3), 983-987.

16. Introduction
● Nanocell is currently looking into the development of cellglow.
● Cellglow involves the use of quantum dots which are made up of Cadmium Selenide (CdSe)
nanocrystals
Semiconductor
resistant to photo and
chemical degradation
excellent choice for
use in biomedical
imaging
Cadmium Selenide
Quantum Dots
2-10 nm
diameter

17. Manufacturing
● Quantum dots were discovered by Alexey Ekimov in 1981
● The term “Quantum dot” was coined by Mark Reed
How are Cadmium Selenide Quantum
Dots manufactured?
● can be synthesised using
precursors and organic surfactants
● mixture is heated at a high
temperature
● Temperature is an important
factor as it determines the growth
of nanorcystals
● the monomer concentration is also
under strict control during
nanocrystal growth
● Alternative method is High
TEM of quantum dots and their
corresponding colours at the
wavelength of emission

18. Applications -
White Light-Emitting Diodes
● Quantum dots have replaced phosphor-based
materials in WLEDs
● Quantum dots have unique optical properties that are
more useful than the phosphor-based materials
● The emission wavelength of the quantum dots can be
tuned by controlling the size of the nanocrystal size
of CdSe
● The fluorescence of the WLEDs can then be tuned
● Quantum dots have fewer scattering effects because
of their narrow size distribution

19. Applications -
Hybrid Solar Cells
● Colloidal nanocrystals (NC) combine
with polymers to make a photoactive
layer
● Cadmium selenide is a colloidal
semiconductor nanocrystal
● Can be used as an electron acceptor
● Efficient energy conversions
● Large scale synthesis is very
expensive
● Some solvents that coat the CdSe are
hazardous, unstable and not
environmentally friendly

20. ● One of the earliest commercial applications of
quantum dots
● The quantum dots are tagged to nanoscale
agents - DNA
● The quantum dots glow when exposed to UV
light
● Can target a particular cell - cancer cells
● Useful in surgery - the surgeon can see the
glowing tumour and use it as a guide for more
accurate tumour removal
● Allows medical researchers to understand
molecular interactions better
Applications -
Biological Markers

21. Future Applications
● Medical uses - medical imaging/screening
● Qubit- unit of quantum information
● Quantum Computers- theoretical computation systems that use quantum-
mechanical phenomena such as superposition and entanglement.

22. Advantages and Disadvantages of CdSe
Quantum Dots
Advantages:
● They are better than fluorophore dyes - 20
times brighter
● They make solar cells more efficient
● It is easy to alter the wavelength of light
emitted in the 400-4000 nm range -
different colours
Disadvantages:
● CdSe is highly toxic - needs a stable
polymer shell
● The shells can alter the optical
properties and it is also hard to control
the size of the particles.
● In aqueous and UV conditions
degradation increases - mechanism
needs to be studied

23. X-Ray Diffractometers
Diagram of what happens inside the machine
(Molecular Expressions, 2013)
XRay Diffractometer
(Molecular Expressions, 2013)

24. Braggs' Law
D-Spacing (interplanar spacing), explained using
Braggs' Law
(Henry et. al, 2012)
An example results graph (Henry et. al, 2012)

25. Benefits
•Non-destructive, fast, easy
sample prep
•High-accuracy for d-spacing
calculations
•Single crystal, poly, and
amorphous materials
•Standards are available for
thousands of material systems
Sources of Error
•Specimen displacement
•Instrument misalignment
•Peak distortion due to
certain wavelengths

26. Transmission Electron Microscope (TEM)
•Transmission electron microscopy (TEM) is a technique
in which a beam of electrons is transmitted through an
ultra-thin specimen, interacting with the specimen as it
passes through.
•TEMs work in the range 1 micron to 1 nanometre.
• It is a electron microscope which produces an image of
a cross-sectional slice of a specimen.
•The TEM uses electromagnetic lenses to focus the
electrons into a very thin beam. The electron beam
then travels through the specimen you want to study. •TEMs produce high-resolution, two-dimensional images,
allowing for a wide range of scientific and industry
applications.
•The limitations for TEM are mainly due to cost but also the
preparation of cells for TEM requires fixation with chemicals
that can introduce artificial damage.

27. Ultraviolet - Visible Spectrometer
• Ultraviolet–visible spectroscopy refers to the
absorption spectroscopy in the ultraviolet-visible
spectral region.
• The range is roughly 10 nm to 800 nm due to the
inclusion of ultra violet.
• A beam of light from a visible or UV light source is
separated into its wavelengths by a prism. Each single
wavelength beam is split into two.
• One beam, the sample beam, passes through a
cuvette containing a solution of the compound being
studied in a transparent solvent.
• The intensities of these light beams are then measured by
electronic detectors and compared.
• UV/Vis spectroscopy is used in analytical chemistry for the
determination of different analytes, such as transition metal
ions.
• UV-Visible spectroscopy works well on liquids and solutions,
but if the sample is solid particles in liquid, the sample will
scatter the light.
• Also to obtain reliable data, the peak of absorbance needs to
be at least three times higher in intensity than the background
noise of the instrument.
A diagram of a
UV-Visible
Spectrometer
UV-Visible
Spectrum of
Rose Bengal

28. References
● ANDERSON, H. (2010). Transmission Electron Microscope. [online] Available:
http://www.microscopemaster.com/transmission-electron-microscope.html.
● BOTTRILLl, M., and GREEN, M.; Chem. Commun., 2011, 47, 7039 - 7050
● DAVIDSON, M. W. (2013) Latest Gallery Additions, Molecular Expressions. [online] Available at:
www.micro.magnet.fsu.edu/primer/java/interference/index.html (Accessed: 8 December 2014).
● EFROS, Al. L.; ROSEN, M. (2000). The electronic structure of semiconductor nanocrystals. Annual Review of Materials
Science 30: 475–521.
● HENRY, D., EBY, N., GOODGE, J. and MOGK, D. (2012) X-ray reflection in accordance with Bragg’s Law, Geochemical
Instrumentation and Analysis. X-ray reflection in accordance with Bragg’s Law. [online] Available at:
http://serc.carleton.edu/research_education/geochemsheets/BraggsLaw.html (Accessed: 7 February 2015).
● ‘Quantum dot’ (2015) Wikipedia. Wikipedia. Available at: http://en.wikipedia.org/wiki/Quantum_dot (Accessed: 10
February 2015).
● MURRAY, C. B, et al. (2000). Synthesis and characterisation of mono disperse nanocrystals and close-packed nanocrystal
assemblies. [online] Annual review of Materials, 30 (1), p545.
● NANN, T. et.al., (2008) Nature Publishing Group, Quantum dots versus organic dyes as fluorescent labels. [online]
Available at: http://nathan.instras.com/ResearchProposalDB/doc-168.pdf
● no date). Technologies >> Preparation of Quantum Dots. Available at: http://www.oceannanotech.com/nav.php?qid=5
(Accessed: 10 February 2015).
● HAN, Lili, QIN, Donghuan, et al. (2006). Synthesis of High Quality Zinc-Blende CdSe Nanocrystals and Their Application
in Hybrid Solar Cells. [online]. Nanotechnology, 17 (18).
● XU Xianmei, WANG Yilin, GULE Teri, et al. (2013). Synthesis and Optical Properties of Cadmium Selenide Quantum Dots
for White Light-Emitting Diode Application, [online]. Materials Research Bulletin, 48 (3), 983-987.