Colloidal nanocrystal heterostructures with linear and branched topology


The development of colloidal quantum dots has led to practical applications of quantum confinement, such as in solution-processed solar cells1, lasers2 and as biological labels3. Further scientific and technological advances should be achievable if these colloidal quantum systems could be electronically coupled in a general way. For example, this was the case when it became possible to couple solid-state embedded quantum dots into quantum dot molecules4,5. Similarly, the preparation of nanowires with linear alternating compositions—another form of coupled quantum dots—has led to the rapid development of single-nanowire light-emitting diodes6 and single-electron transistors7. Current strategies to connect colloidal quantum dots use organic coupling agents8,9, which suffer from limited control over coupling parameters and over the geometry and complexity of assemblies. Here we demonstrate a general approach for fabricating inorganically coupled colloidal quantum dots and rods, connected epitaxially at branched and linear junctions within single nanocrystals. We achieve control over branching and composition throughout the growth of nanocrystal heterostructures to independently tune the properties of each component and the nature of their interactions. Distinct dots and rods are coupled through potential barriers of tuneable height and width, and arranged in three-dimensional space at well-defined angles and distances. Such control allows investigation of potential applications ranging from quantum information processing to artificial photosynthesis.

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Figure 1: Survey of nanocrystal heterostructures.
Figure 2: A closer look at nanocrystal heterostructures.
Figure 3: Analytical electron microscopy of heterojunctions.
Figure 4: High-resolution electron microscopy of heterojunctions.
Figure 5: Optoelectronic properties of type I and type II heterostructures.


  1. 1

    Huynh, W. U., Dittmer, J. J. & Alivisatos, A. P. Hybrid nanorod-polymer solar cells. Science 295, 2425–2427 (2002)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Kazes, M., Lewis, D. Y., Ebenstein, Y., Mokari, T. & Banin, U. Lasing from semiconductor quantum rods in a cylindrical microcavity. Adv. Mater. 14, 317–321 (2002)

    CAS  Article  Google Scholar 

  3. 3

    Bruchez, M., Moronne, M., Gin, P., Weiss, S. & Alivisatos, A. P. Semiconductor nanocrystals as fluorescent biological labels. Science 281, 2013–2016 (1998)

    ADS  CAS  Article  Google Scholar 

  4. 4

    Schedelbeck, G., Wegscheider, W., Bichler, M. & Abstreiter, G. Coupled quantum dots fabricated by cleaved edge overgrowth: From artificial atoms to molecules. Science 278, 1792–1795 (1997)

    ADS  CAS  Article  Google Scholar 

  5. 5

    Bayer, M. et al. Coupling and entangling of quantum states in quantum dot molecules. Science 291, 451–453 (2001)

    ADS  CAS  Article  Google Scholar 

  6. 6

    Gudiksen, M. S., Lauhon, L. J., Wang, J., Smith, D. C. & Lieber, C. M. Growth of nanowire superlattice structures for nanoscale photonics and electronics. Nature 415, 617–620 (2002)

    ADS  CAS  Article  Google Scholar 

  7. 7

    Thelander, C. et al. Single-electron transistors in heterostructure nanowires. Appl. Phys. Lett. 83, 2052–2054 (2003)

    ADS  CAS  Article  Google Scholar 

  8. 8

    Collier, C. P., Vossmeyer, T. & Heath, J. R. Nanocrystal superlattices. Annu. Rev. Phys. Chem. 49, 371–404 (1998)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Ouyang, M. & Awschalom, D. D. Coherent spin transfer between molecularly bridged quantum dots. Science 301, 1074–1078 (2003)

    ADS  CAS  Article  Google Scholar 

  10. 10

    Hines, M. A. & Guyot-Sionnest, P. Synthesis and characterization of strongly luminescing ZnS-capped CdSe nanocrystals. J. Phys. Chem. 100, 468–471 (1996)

    CAS  Article  Google Scholar 

  11. 11

    Dabbousi, B. O. et al. (CdSe)ZnS core–shell quantum dots: Synthesis and characterization of a size series of highly luminescent nanocrystallites. J. Phys. Chem. B 101, 9462–9475 (1997)

    Article  Google Scholar 

  12. 12

    Peng, X., Schlamp, M. C., Kadavanich, A. V. & Alivisatos, A. P. Epitaxial growth of highly luminescent CdSe/CdS core/shell nanocrystals with photostability and electronic accessibility. J. Am. Chem. Soc. 199, 7019–7029 (1997)

    Article  Google Scholar 

  13. 13

    Cao, Y. & Banin, U. Growth and properties of semiconductor core/shell nanocrystals with InAs cores. J. Am. Chem. Soc. 122, 9692–9702 (2000)

    CAS  Article  Google Scholar 

  14. 14

    Kim, S., Fisher, B., Eisler, H.-J. & Bawendi, M. Type II quantum dots: CdTe/CdSe(core/shell) and CdSe/ZnTe(core/shell) heterostructures. J. Am. Chem. Soc. 125, 11466–11467 (2003)

    CAS  Article  Google Scholar 

  15. 15

    Eychmüller, A., Mews, A. & Weller, H. A quantum dot quantum well: CdS/HgS/CdS. Chem. Phys. Lett. 208, 59–62 (1993)

    ADS  Article  Google Scholar 

  16. 16

    Borchert, H. et al. Photoemission study of onion like quantum dot quantum well and double quantum well nanocrystals of CdS and HgS. J. Phys. Chem. B 107, 7486–7491 (2003)

    CAS  Article  Google Scholar 

  17. 17

    Manna, L., Scher, E. C. & Alivisatos, A. P. Synthesis of soluble and processable rod-, arrow-, teardrop-, and tetrapod-shaped CdSe nanocrystals. J. Am. Chem. Soc. 122, 12700–12706 (2000)

    CAS  Article  Google Scholar 

  18. 18

    Peng, Z. A. & Peng, X. Nearly monodisperse and shape-controlled CdSe nanocrystals via alternative routes: Nucleation and growth. J. Am. Chem. Soc. 124, 3343–3353 (2002)

    CAS  Article  Google Scholar 

  19. 19

    Manna, L., Milliron, D. J., Meisel, A., Scher, E. C. & Alivisatos, A. P. Controlled growth of tetrapod-branched inorganic nanocrystals. Nature Mater. 2, 382–385 (2003)

    ADS  CAS  Article  Google Scholar 

  20. 20

    Yeh, C. Y., Lu, Z. W., Froyen, S. & Zunger, A. Zincblende–wurtzite polytypism in semiconductors. Phys. Rev. B 46, 10086–10097 (1992)

    ADS  CAS  Article  Google Scholar 

  21. 21

    Peng, X. et al. Shape control of CdSe nanocrystals. Nature 404, 59–61 (2000)

    ADS  CAS  Article  Google Scholar 

  22. 22

    Manna, L., Scher, E. C., Li, L. S. & Alivisatos, A. P. Epitaxial growth and photochemical annealing of graded CdS/ZnS shells on colloidal CdSe nanorods. J. Am. Chem. Soc. 124, 7136–7145 (2002)

    CAS  Article  Google Scholar 

  23. 23

    Mokari, T. & Banin, U. Synthesis and properties of CdSe/ZnS core/shell nanorods. Chem. Mater. 15, 3955–3960 (2003)

    Article  Google Scholar 

  24. 24

    Gupta, J. A., Awschalom, D. D., Peng, X. & Alivisatos, A. P. Spin coherence in semiconductor quantum dots. Phys. Rev. B 59, 10421–10424 (1999)

    ADS  Article  Google Scholar 

  25. 25

    Li, J. & Wang, L. W. Shape effects of electronic states of nanocrystals. Nano Lett. 3, 1357–1363 (2003)

    ADS  CAS  Article  Google Scholar 

  26. 26

    Capistosti, G. J., Cramer, S. J., Rajesh, C. S. & Modarelli, D. A. Photoinduced electron transfer within porphyrin-containing poly(amide) dendrimers. Org. Lett. 3, 1645–1648 (2001)

    Article  Google Scholar 

  27. 27

    Wang, L. W. Charge-density patching method for unconventional semiconductor binary systems. Phys. Rev. Lett. 88, 256402 (2002)

    ADS  Article  Google Scholar 

  28. 28

    Wang, L. W. & Zunger, A. Solving Schrödinger's equation around a desired energy: Application to silicon quantum dots. J. Chem. Phys. 100, 2394–2397 (1994)

    ADS  CAS  Article  Google Scholar 

  29. 29

    Canning, A., Wang, L. W., Williamson, A. & Zunger, A. Parallel empirical pseudopotential electronic structure calculations for million atom systems. J. Comp. Phys. 160, 29–41 (2000)

    ADS  MathSciNet  CAS  Article  Google Scholar 

  30. 30

    Li, L. S. & Alivisatos, A. P. Origin and scaling of the permanent dipole moment in CdSe nanorods. Phys. Rev. Lett. 90, 097402 (2003)

    ADS  Article  Google Scholar 

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This work was supported by the US Department of Energy. Some high-resolution and analytical electron microscopy was performed at the National Center for Electron Microscopy (NCEM) with the help of E. C. Nelson and some low-resolution electron microscopy was performed at the Electron Microscope Laboratory at UCB with the help of M. Casula. For the theoretical calculations we used the National Energy Research Scientific Computing Center.

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Correspondence to A. Paul Alivisatos.

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Supplementary information

Supplementary Figure 1

TEM images of core/shell tetrapod shaped nanocrystals. (PDF 1330 kb)

Supplementary Figure 2

Local EDS spectra of CdS/CdSe heterostructure. (PDF 25 kb)

Supplementary Figure 3

XRD patterns of CdSe/CdTe heterostructures. (PDF 36 kb)

Supplementary Figure 4

Length and diameter distributions of heterostructures. (PDF 27 kb)

Supplementary Figure 5

Optical absorption spectra of heterostructures. (PDF 18 kb)

Supplementary Figure 6

Additional high resolution TEM images of heterojunctions. (PDF 2618 kb)

Supplementary Figure Legends

(DOC 20 kb)

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Milliron, D., Hughes, S., Cui, Y. et al. Colloidal nanocrystal heterostructures with linear and branched topology. Nature 430, 190–195 (2004).

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