硒化镉CdSe量子点的制备和应用

1、1,Synthesis and Applications of CdSe Quantum Dots,Speaker: 林天全 Other Members： 刘海涛 冷 雪 李 菲 李 魁,2,A quantum dot is a nano-particulate semiconductor, whose excitons are confined in all three spatial dimensions.,What are Quantum Dots ?,3,Structure of CdSe Quantum Dots,Zinc blende,Wurtzite,Rock salt,戴全钦.

2、 吉林大学博士学位论文，2007,4,Cd(CH3)2 + TOPSe + TOPO CdSe/TOPO,Nucleation,Cooling,Solvent: TOPO (300),Combining,Injecting,Solution B: Se + TOP,Solution A: Cd(CH3)2 + TOP,MIT M.G. Bawendi, et al. J. Am. Chem. Soc. 1993, 115 (19): 8706-8715.,Prevent further nucleation,5,Room temperature optical absorption spect

3、ra of CdSe nanocrystallites dispersed in hexane and ranging in size from 1.2 nm to 11.5 nm.,M.G. Bawendi, et al. J. Am. Chem. Soc. 1993, 115 (19): 8706-8715.,6,CdO + TOPSe + TOPO + TDPA CdSe,Solution (270),TDPA+TOPO (300-320),CdO,Se + TOP,Nucleation,Dissolving,Cooling,Injecting,Cooling,X.G. Peng, et

4、 al. J. Am. Chem. Soc, 2001. 123(1): 183-184.,7,CdO + Se/ODE + ODE = CdSe,X.G. Peng, et al. Angewandte Chemie-International Edition, 2002, 41(13): 2368-2371.,Mixture (300),OA+ODE,CdO,Se+ODE,Nucleation,Dissolving,Heating,Injecting,Cooling,8,L.J. An, et al. Journal of Physical Chemistry C. 2007, 111:

5、5661-5666.,Versatile two-phase approach to synthesize highly luminescent CdE (E=S, Se, Te) QDs.,9,CdAc2 + Na2SeSO3 CdSe,Y.D. Li. Inorganic Chemistry. 2008, 47(11): 5022-5028.,NaOH,OA,C2H5OH+H2O,CdAc2H2O,Na2SeSO3,Dissolving,By stiring,By stiring,Autoclave (40-150),Nucleation,Green Methods,10,Fluoresc

6、ence of the CdSe with different emission (ex ) 365nm,Y.D. Li, et al. Inorganic Chemistry. 2008, 47(11): 5022-5028.,11,Q. J. Sun, et al. Nature Photonics. 2007,1, 717.,TEM,Coreshell structures,Photo-luminescence,12,Applications of Quantum Dots,LED,Solar cell,Biological probe,Medical Imaging,Biochip,L

7、aser devices,Biological Labeling,Drug Screening,13,Martin Green,“The emergence of semiconductor nanocrystals as the building blocks of nanotechnology has opened up new ways to utilize them in next generation solar cells.”,14, Photoelectrodes comprising quantum dots arrays,Semiconductor nano- structu

8、re polymer solar cell,Quantum Dot Solar Cell,Metal-semiconductor photovoltaic cell,Quantum dot sensitized solar cell,A. J. Nozik. Physica E, 2002 (14): 115-200.,Four major ways to utilize semi- conductor dots in solar cell,Prashant V. Kamat,A. J. Nozik,15,Schematic diagram showing the strategies to

9、develop quantum dot (semiconductor nanocrystal) based solar cells: (a) metal-semiconductor junction (b) polymer-semiconductor (c) semiconductor-semiconductor systems,Prashant V. Kamat. J. Phys. Chem. C, 2008, 112 (48): 18737-18753.,16,Quantum dot sensitized solar cellQDSSC,Principle of operation of

10、quantum dot sensitized solar cell Charge injection from excited CdSe quantum dots into TiO2 nanoparticles is followed by collection of charges at the electrode surface. The redox electrolyte (e.g. sulfide/polysulfide) scavenges the holes and thus ensures regeneration of the CdSe.,Lopez-Luke, T. J. P

11、hys. Chem. C. 2008, 112:12821292.,Nitrogen doped,17,Charge injection of excited CdSe quantum dot into TiO2 nanoparticle. The scheme on the right shows the modulation of energy levels (and hence the charge injection) by size control.,Prashant V. Kamat. J. Phys. Chem. C, 2008, 112 (48): 18737-18753.,Q

12、uantum dot sensitized solar cellQDSSC,18,Left: The dependence of electron transfer rate constant on the energy difference between the conduction bands. Right: Scheme illustrating the principle of electron transfer from two different size CdSe quantum dots into TiO2 nanoparticle.,Prashant V. Kamat, J

13、. Am. Chem. Soc. 2007, 129: 41364137.,Quantum dot sensitized solar cellQDSSC,19,Linking CdSe QDs to TiO2 Surface with a Bifunctional Surface Modifier,Prashant V. Kamat. J. Phys. Chem. C, 2008, 112 (48): 18737-18753.,Prashant V. Kamat. J. AM. CHEM. SOC. 2006, 128: 2385-2393.,20,I-V characteristics of

14、 (a) OTE/TiO2 and (b) OTE/TiO2/MPA/CdSe films. Electrolyte 0.1 M Na2S.,Bifunctional organic molecule,a,b,Prashant V. Kamat. J. AM. CHEM. SOC. 2006, 128: 2385-2393.,Fast capture of electrons at the quantum dot interface remains a major challenge for efficient harvesting of light energy.,Photocurrent

15、generation using CdSe-nC60 composite clusters,Prashant V. Kamat. J. Phys. Chem. C, 2008, 112 (48): 18737-18753.,Emerging Strategies to Capture and Transport Photogenerated Electrons,IPCE：Incident Photon to Current-generation Efficiency,Prashant V. Kamat. J. Phys. Chem. C, 2008, 112 (48): 18737-18753.,Left: Photocurrent response as a function of the amount of TiO2 deposited on carbon fiber electrode (CFE)； Right: Scheme showing the electron transport through SWCNT and SEM image of the SWCN