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Special Properties of Nanomaterials High surface/bulk ratio Catalysis Nanoparticle reagents Heat dissipation Laminar flow Finite size effects Quantum confinement.

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Presentation on theme: "Special Properties of Nanomaterials High surface/bulk ratio Catalysis Nanoparticle reagents Heat dissipation Laminar flow Finite size effects Quantum confinement."— Presentation transcript:

1 Special Properties of Nanomaterials High surface/bulk ratio Catalysis Nanoparticle reagents Heat dissipation Laminar flow Finite size effects Quantum confinement Interparticle tunneling Proximity effects High probability of defect- free crystals

2 Emission spectra of several sizes of (CdSe)ZnS core-shell quantum dots M. Bawendi, et al., J. Phys. Chem. B 1999, 101, 9463. Semiconductor Core-Shell Quantum Dots Perfect quantum well structure leads to bright luminescence Nanocrystal size determines band gap

3 CdSe/CdS core-shell particles Excitons confined to core Defect-free nanocrystals high fluorescence quantum yield A. P. Alivisatos et al., Science 1998, 281, 2013. Dual fluorescence labeling of actin filaments and fibroblasts 2.1 - 4.6 nm

4 Cd Se Shape Control of Semiconductor Nanocrystals L. Manna, E. C. Scher, A. P. Alivisatos, JACS 122, 12700 (2000) Nanocrystal habit controlled by surfactant composition Multiple injection/growth cycles develop specific crystal faces

5 CdSe Tetrapods L. Manna, E. C. Scher, A. P. Alivisatos, JACS 122, 12700 (2000)

6 Conducting Polymer - Nanocrystal Solar Cells Two-color system - can utilize solar spectrum efficiently High aspect ratio nanocrystals, organized superstructure should minimize carrier recombination W. U. Huynh, J. J. Dittme, A. P. Alivisatos, Science 295, 2425 (2002)

7 Y. Wu, P. Yang, J. Am. Chem. Soc., 123, 3165, 2001 Vapor-liquid-solid (VLS) growth of semiconductor nanocrystals Single crystal nanowires Catalyst nanoparticle controls diameter Length determined by reaction time

8 Compositionally Modulated Semiconductor Nanocrystals Totem pole and core-shell structures Multiple bandgaps and p-n junctions Lieber, et al., Nature 415, 617 (2002); Nature 420, 57 (2002). Yang, et al., NanoLett 2, 83 (2002); Buhro et al., J. Am. Chem. Soc. 123, 4502 (2001).


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