Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Formation of asymmetric one-sided metal-tipped semiconductor nanocrystal dots and rods


Multicomponent nanoparticles represent a new approach for creating smart materials, requiring the development of the growth of different material types on one particle. Here, we report the synthesis of asymmetric metal–semiconductor heterostructures where gold is grown on one side of CdSe nanocrystal quantum rods and dots, creating nanostructures offering intrinsic asymmetry for diverse device functionalities such as diode elements, along with one-sided chemical accessibility through the gold tips. Surprisingly, one-sided growth is preceded by two-sided growth and is generally observed in different particle shapes. Theoretical modelling in a lattice-gas model and experimental analysis show that a ripening process drives gold from one end to the other, transforming two-sided growth to one-sided growth. Ripening is therefore occurring on the nanostructure itself, leading to a phase-segregated structure. This thereby extends the realm of ripening phenomena and their significance in nanostructure synthesis, in particular for nanocrystals composed of different materials.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: One-sided gold tips grown on CdSe nanocrystals of different shapes and sizes.
Figure 2: Effect of increasing Au/rod molar ratio on the growth.
Figure 3: Behaviour of growth onto dots and long rods as a function of gold concentration.
Figure 4: Simulation of the growth dynamics of the gold on the nanocrystal.
Figure 5: Gold growth kinetics.
Figure 6: Gold growth experiment on tetrapods, experiment versus simulation and on rods with a defect.


  1. 1

    Ostwald, W. F. Studien über die Bildung und Umwandlung fester Körper. Z. Phys. Chem. 22, 289–302 (1897).

    Google Scholar 

  2. 2

    Voorhees, P. W. The theory of Ostwald ripening. J. Stat. Phys. 38, 231–252 (1985).

    Article  Google Scholar 

  3. 3

    Boistelle, R. & Astier, J. P. Crystallization mechanisms in solution. J. Cryst. Growth 90, 14–30 (1988).

    Article  Google Scholar 

  4. 4

    Zinke-Allmang, M., Feldman, L. C. & Grabow, M. H. Clustering on surfaces. Surf. Sci. Rep. 16, 377 (1992).

    Article  Google Scholar 

  5. 5

    Redmond, P. L., Hallock, A. J. & Brus, L. E. Electrochemical Ostwald ripening of colloidal Ag particles on conductive substrates. Nano Lett. 5, 131–135 (2005).

    Article  Google Scholar 

  6. 6

    Talapin, D. V., Rogach, A. L., Haase, M. & Weller, H. Evolution of ensemble of nanoparticles in colloidal solution: Theoretical study. J. Phys. Chem. B 105, 12278–12285 (2001).

    Article  Google Scholar 

  7. 7

    Peng, X., Wickham, J. & Alivisatos, A. P. Kinetics of II-VI and III-V colloidal semiconductor nanocrystal growth: “Focusing” of size distributions. J. Am. Chem. Soc. 120, 5343–5344 (1998).

    Article  Google Scholar 

  8. 8

    Mokari, T., Rothenberg, E., Popov, I., Costi, R. & Banin, U. Selective growth of metal tips onto semiconductor quantum rods and tetrapods. Science 304, 1787–1790 (2004).

    Article  Google Scholar 

  9. 9

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

    Article  Google Scholar 

  10. 10

    Kudera, S. et al. Selective growth of PbSe on one or both tips of colloidal semiconductor nanorods. Nano Lett. 5, 445–449 (2005).

    Article  Google Scholar 

  11. 11

    Talapin, D. V. et al. Highly emissive colloidal CdSe/CdS heterostructures of mixed dimensionality. Nano Lett. 3, 1677–1681 (2003).

    Article  Google Scholar 

  12. 12

    Teranishi, T., Inoue, Y., Nakaya, M., Oumi, Y. & Sano, T. Nanoacorns: anisotropically phase-segregated CoPd sulfide nanoparticles. J. Am. Chem. Soc. 126, 9914–9915 (2004).

    Article  Google Scholar 

  13. 13

    Gu, H., Zheng, R., Zhang, X. & Xu, B. Facile one-pot synthesis of bifunctional heterodimers of nanoparticles: A conjugate of quantum dot and magnetic nanoparticles. J. Am. Chem. Soc. 126, 5664–5665 (2004).

    Article  Google Scholar 

  14. 14

    Yu, H. et al. Dumbbell-like bifunctional Au-Fe3O4 nanoparticles. Nano Lett. 5, 379–382 (2005).

    Article  Google Scholar 

  15. 15

    Pacholski, C., Kornowski, A. & Weller, H. Site-specific photodeposition of silver on ZnO nanorods. Angew. Chem. Int. Edn Engl. 43, 4774–4777 (2004).

    Article  Google Scholar 

  16. 16

    Trentler, T. J. et al. Solution-liquid-solid growth of crystalline III-V semiconductors — an analogy to vapor-liquid-solid growth. Science 270, 1791–1794 (1995).

    Article  Google Scholar 

  17. 17

    Kan, S., Mokari, T., Rothenberg, E. & Banin, U. Synthesis and size-dependent properties of zinc-blende semiconductor quantum rods. Nature Mater. 2, 155–158 (2003).

    Article  Google Scholar 

  18. 18

    Yu, H., Li, J. B., Loomis, R. A., Wang, L. -W. & Buhro, W. E. Two- versus three-dimensional quantum confinement in indium phosphide wires and dots. Nature Mater. 2, 517–520 (2003).

    Article  Google Scholar 

  19. 19

    Barrelet, C. J., Wu, Y., Bell, D. C. & Lieber, C. M. Synthesis of CdS and ZnS nanowires using single-source molecular precursors. J. Am. Chem. Soc. 125, 11498–11499 (2003).

    Article  Google Scholar 

  20. 20

    Persson, A. I. et al. Solid-phase diffusion mechanism for GaAs nanowire growth. Nature Mater. 3, 677–681 (2004).

    Article  Google Scholar 

  21. 21

    Liu, H. & Alivisatos, A. P. Preparation of asymmetric nanostructures through site selective modification of tetrapods. Nano Lett. 4, 2397–2401 (2004).

    Article  Google Scholar 

  22. 22

    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).

    Article  Google Scholar 

  23. 23

    Xia, Y. et al. One-dimensional nanostructures: synthesis, characterization, and applications. Adv. Mater. 15, 353–389 (2003).

    Article  Google Scholar 

  24. 24

    Kovtyukhova, N. I., Kelley, B. K. & Mallouk, T. E. Coaxially gated in-wire thin-film transistors made by template assembly. J. Am. Chem. Soc. 126, 12738–12739 (2004).

    Article  Google Scholar 

  25. 25

    Netzer, L. & Sagiv, J. A new approach to construction of artificial monolayer assemblies. J. Am. Chem. Soc. 105, 674–676 (1983).

    Article  Google Scholar 

  26. 26

    Loweth, C. J., Caldwell, W. B., Peng, X. G., Alivisatos, A. P. & Schultz, P. G. DNA-based assembly of gold nanocrystals. Angew. Chem. Int. Edn Engl. 83, 1808–1812 (1999).

    Article  Google Scholar 

  27. 27

    Mitchell, G. P., Mirkin, C. A. & Letsinger, R. L. Programmed assembly of DNA functionalized quantum dots. J. Am. Chem. Soc. 121, 8122–8123 (1999).

    Article  Google Scholar 

  28. 28

    Orendorff, C. J., Hankins, P. L. & Murphy, C. J. pH-triggered assembly of gold nanorods. Langmuir 21, 2022–2026 (2005).

    Article  Google Scholar 

  29. 29

    Murray, C. B., Norris, D. J. & Bawendi, M. G. Synthesis and characterization of nearly monodisperse CdE (E=sulfur,selenium,tellurium) semiconductor nanocrystallites. J. Am. Chem. Soc. 115, 8706–8715 (1993).

    Article  Google Scholar 

  30. 30

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

    Article  Google Scholar 

  31. 31

    Rabani, E., Reichman, D. R., Geissler, P. L. & Brus, L. E. Drying-mediated self-assembly of nanoparticles. Nature 426, 271–274 (2003).

    Article  Google Scholar 

  32. 32

    Sztrum, C. G., Hod, O. & Rabani, E. Self-assembly of nanoparticles in three-dimensions: Formation of stalagmites. J. Phys. Chem. B 109, 6741–6747 (2005).

    Article  Google Scholar 

  33. 33

    Plieth, W. J. Correlations between the equilibrium potential and the potential of zero charge of metals in different modifications. J. Electroanal. Chem. 204, 343–349 (1986).

    Article  Google Scholar 

  34. 34

    Empedocles, S. A. & Bawendi, M. G. Quantum-confined stark effect in single CdSe nanocrystallite quantum dots. Science 278, 2114–2117 (1997).

    Article  Google Scholar 

  35. 35

    Muller, J. et al. Monitoring surface charge movement in single elongated semiconductor nanocrystals. Phys. Rev. Lett. 93, 167402 (2004).

    Article  Google Scholar 

  36. 36

    Rothenberg, E., Kazes, M., Shaviv, E. & Banin, U. Electric field induced switching of the fluorescence of single semiconductor quantum rods. Nano Lett. 5, 1581–1586 (2005).

    Article  Google Scholar 

  37. 37

    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).

    Article  Google Scholar 

  38. 38

    Cui, Y., Banin, U., Bjork, M. T. & Alivisatos, A. P. Electrical transport through a single nanoscale semiconductor branch point. Nano Lett. 5, 1519–1523 (2005).

    Article  Google Scholar 

  39. 39

    Rabani, E., Hetenyi, B., Berne, B. J. & Brus, L. E. Electronic properties of CdSe nanocrystals in the absence and presence of a dielectric medium. J. Chem. Phys. 110, 5355–5369 (1999).

    Article  Google Scholar 

  40. 40

    Rabani, E. Structure and electrostatic properties of passivated CdSe nanocrystals. J. Chem. Phys. 115, 1493–1497 (2001).

    Article  Google Scholar 

  41. 41

    Cleveland, C. L., Luedtke, W. D. & Landman, U. Melting of gold clusters: Icosahedral precursors. Phys. Rev. Lett. 81, 2036–2039 (1998).

    Article  Google Scholar 

  42. 42

    Wang, Y., Teitel, S. & Dellago, C. Melting and equilibrium shape of icosahedral gold nanoparticles. Chem. Phys. Lett. 394, 257–261 (2004).

    Article  Google Scholar 

  43. 43

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

    Article  Google Scholar 

  44. 44

    Peng, Z. A. & Peng, X. G. Mechanisms of the shape evolution of CdSe nanocrystals. J. Am. Chem. Soc. 123, 1389–1395 (2001).

    Article  Google Scholar 

Download references


We thank I. Popov from the Center for Nanoscience and Nanotechnology for the HRTEM measurement. We thank A. Willenz from the Electron Microscopy Lab, the Life Sciences Institute, for assistance in TEM measurements. This work was supported in part by the EU under the program SA-NANO and by the US–Israel Binational Science Foundation. T.M. acknowledges support of the Ministry of Science, Israel.

Author information



Corresponding authors

Correspondence to Eran Rabani or Uri Banin.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary figure S1-6 (PDF 228 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Mokari, T., Sztrum, C., Salant, A. et al. Formation of asymmetric one-sided metal-tipped semiconductor nanocrystal dots and rods. Nature Mater 4, 855–863 (2005).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing