Content
BASIS
SYNTHESIE
APPLICATION
• Quantum dot basic concepts • Typical synthesis methods
• Wide application environment
• Quantum dot’s future
OUTLOOK
What are Quantum Dots?
Liberato Manna Istituto Italiano di Tecnologia
Synthesis Approaches
1. Top-Down Synthesis Processes
Electron beam lithography
Ion beam etching 2. Bottom-Up Approaches
/articroaches 1. Top-Down Synthesis
Ion beam etching
/articles/Lithography.html
Synthesis Approaches
1. Top-Down Synthesis Processes
Electron beam lithography
Ion beam etching 2. Bottom-Up Approach
Sol-Gel process Microemulsion Process Hot-Solution Decomposition Process Other Synthesis Processes
Fig. 2. HRTEM Micrograph of ZnO Qdots shows that the average particle size is ∼3.5 nm.
Synthesis Approaches 2. Bottom-Up Approach
Microemulsion Process
effective mass approximation
effective mass with Coulomb interaction
size-dependent capacitance.
Quantum Confinement
J. Chem. Edu. 2005, 82, 11.
Quantum Dot Celebrities
Materials. 2010, 3, 2260-2345.
1. 2.
Quantum Confinement effective massTheory approximation based on quantum confinement
classical physics based on the dielectric properties of spheres
Compatible
The quantum dots require the ligand exchange or encapsulation to make them compatible in biological solutions.
Stability
Due to the nanosize of quantum dots, the photostability of them are very low. The stability of surface ligand capped quantum dots can be improved by the way of other drawbacks.
2. Synthesis condition: Changing the conditions of reaction media in synthesis of QDs that cause to produce QDs with improved characteristics. 3. Safer solvent: Use of safe solvent and stabiliser in QDs synthesis methods. 4. Nontoxic raw materials: Development of novel type of QDs without heavy metals such as cadmium. 5. energy-efficient: improvement of synthesis methods with low-energy loss. 6. Scaling-up: better understanding the synthesis mechanism at the atom level to get scaling-up synthesis.
J. Am. Chem. Soc. 2012, 134, 11701-11708. J. Am. Chem. Soc. 2014, 136, 7708-7716.
Synthesis Approaches Hot-Solution Decomposition Process
Examles:
(a)
(b)
Sol-Gel process Microemulsion Process Hot-Solution Decomposition Process Other Synthesis Processes
Synthesis Approaches 1. Top-Down Synthesis
Electron beam lithography
Application Solar energy conversion
J. Am. Chem. Soc., 2008, 130, 4007–4015. ChemSusChem. 2014, 7, 1468-1475. Chem. Soc. Rev., 2013, 42, 2963--2985
Application
Application
Bioimaging and drug delivery.
Angew. Chem., Int. Ed., 2014, 53, 5573–5577
Appl. Spectrosc., 2013, 67, 215–252
Application
Biosensors
Sci. Rep., 2013, 3, 1537
Quantum Confinement
Size-dependent quantum confinement effects develop when the thickness of an electronic layer approaches the de Broglie wavelength of the electron in a quantum well structure, and when the radius of a semiconductor sphere is smaller than the bulk-exciton Bohr radius, in a nanocrystal
Wide Applications
1. Fluorescence Application Bioimaging and drug delivery Biosensor 2. Semiconductor Application Solar energy conversion Electroluminescence Devices
(C)
Intensity (a.u.)
CdSe CdSe/CdS dot-in-rod
Absorption Emission
10 nm
10 nm
400
Wavelength (nm)
500
600
700
Synthesis Approaches
Other Synthesis Processes
Hydrothermal synthesis
Louis E. Brus Columbia Unv. Dep. of Chemistry
Moungi G Bawendi MIT Dep. of Chemistry
Paul Alivisatos Lawrence Berkeley National Laboratory
Xiaogang Peng Zhejiang University Dep. of Chemistry
Sonic waves or microwaves
By changing pressure, temperature, reaction and aging time and reactants, different shapes and sizes of the Qdots can be achieved.
Electroluminescence Devices
Nat. Photonics, 2015, 9, 259–266.
Application
Electroluminescence Devices
CdSe/CdS/ZnS QD-embedded poly(9-vinylcarbazole) (PVK) fiber
Oil-in-water or water-in-oil reverse micelle process
Langmuir 2004, 20, 550-553
Synthesis Approaches 2. Bottom-Up Approach
Hot-Solution Decomposition Process
Quantum Dots Science and Applications
Jiameng Cui, Jie Zhang, Dejuan Sun, Liuyang Zhu, Manman Qian, Qiang Huang, Lei Zhang, Haifeng Zhang, Qiudi Yue.
12, 2015