Colloidal nanocrystals

FIGURE 14.5 Multiprotein electrical detection protocol based on different inorganic colloid nanocrystal tracers, (a) Introduction of antibody-modified magnetic beads (b) binding of the antigens to the antibodies on the magnetic beads (c) capture of the nanocrystal-labeled secondary antibodies (d) dissolution of nanocrystals and electrochemical stripping detection (reproduced from [29] with permission). 

Colloidal semiconductor nanocrystals are attracting growing attention as the building blocks for inexpensive, large-area, solution-processed solar cells. The advantages here are the scalable and controlled synthesis, an ability to be processed in solution, the broadband absorption, and the superior transport properties of traditional photovoltaic semiconductors. Solar cells that rely exclusively on colloidal nanocrystals have been anticipated theoretically58 and... 

Yin, Y. Alivisatos, A. P. 2005. Colloidal nanocrystal synthesis and the organic-inorganic interface. Nature 437 664-670. 

Fig. 1 Schematic drawing to show the concept of system dimensionality (a) bulk semiconductors, 3D (b) thin film, layer structure, quantum well, 2D (c) linear chain structure, quantum wire, ID (d) cluster, colloid, nanocrystal, quantum dot, OD. In the bottom, it is shown the corresponding density of states [A( )] versus energy (E) diagram (for ideal cases).

Puntes, V.F., Krishnan, K.M., and Ahvisatos, A.P., Colloidal nanocrystal shape and size control the case of cobalt Science, 291, 2115,2001. 

Ji X, Copenhaver D, Sichmeller C, Peng X (2008) Ligand bonding and dynamics on colloidal nanocrystals at room temperature the case of alkylamines on CdSe nanocrystals. J Am Chem Soc 130 5726-5735... 

V. F. Puntes, K. M. Krishnan, and A. P. Alivisatos, Colloidal nanocrystal shape and size control The case of cobalt. Science 291, 2115-2117 (2001). 

Cui Y, Bjork MT, Liddle JA, Sonnichsen C, Boussert B, Alivisatos AP (2004) Integration of colloidal nanocrystals into lithographically patterned devices. Nano Lett 4 1093-1098... 

Many approaches have been taken to prepare colloidal doped semiconductor nanocrystals. For example, hot-injection methods have been used to synthesize colloidal Mn2+-doped CdSe (47, 48), ZnSe (49), and PbSe (50) colloidal nanocrystals. Colloidal ZnO DMS-QDs doped with Co2+, Ni2+, and Mn2+ have been prepared by low-temperature hydrolysis and condensation (51-54). Sol-gel methods have been used to prepare colloidal doped TiC>2 (55-57) and Sn02 (58-62) nanocrystals. Inverted micelle methods have been used for preparation of a range of doped II-VI sulfide DMS-QDs at low temperatures (63-68). A high-temperature lyothermal single-source method was used to synthesize Co2+- and Eu3+-doped CdSe nanocrystals (69, 70). Autoclaving has occasionally been used to induce crystallization at lower temperatures than reached under atmospheric pressures while retaining colloidal properties, for... 

Although this chapter focuses on colloidal nanocrystals, one of the motivations for preparing materials in this form is the flexibility they offer for further processing and application. In this section, we introduce a few examples in which colloidal nanocrystals were used as building blocks to construct more complex architectures having interesting and potentially useful physical properties. 

Rogach AL Eychmuller A Hickey SG Kershaw SV, Infrared-emitting colloidal nanocrystals Synthesis, assembly, spectroscopy, and applications, Small, 2007, 3, 536—557. 

Pompa, P. P., Martiradonna, L., Della Torre, A., Della Sala, F., Manna, L., De Vittorio, M., Calabi, F., Cingolani, R. and Rinaldi, R. (2006). Metal-enhanced fluorescence of colloidal nanocrystals with nanoscale control. Nat. Nanotech. 1 126-130. 

Further simulations showed also that the optimal thickness of the gold nanostructures was in the 30-35 nm range, while lower thicknesses (< 20 nm) were characterized by a significant red-shift of the SPs resonance band, thus lowering the spectral overlap with the colloidal nanocrystals. 

A major problem in using QDs for STED super-resolution imaging is significant overlapping between the absorption and emission spectra of conventional semiconductor nanocrystals. To address this problem, we have recently developed strain-tunable colloidal nanocrystals by using lattice-mismatched heterostructures that are grown by epitaxial deposition of a compressive shell... 

Figure 1. TEM image of the CdTe gel fragment (left). Absorption (middle) and PL (right) spectra of initial colloidal nanocrystals and aerogel.

L. Huang, Z. Wang, H. Wang, J. Sun, Q. Li, D. Zhao, and Y. Yan, Hierarchical Zeolite Structures with Designed Shape by Gel-casting of Colloidal Nanocrystal Suspensions. Chem. Commun., 2001, 1364—1365. 

Wang, H. Huang, L. Wang, Z. Mitra, A. Yan, Y. Hierarchical zeolite structures with designed shapes by gelcasting of colloidal nanocrystal suspensions. Chem. Comm. 2001, 1364-1365. 

Kher S S and Wells R L 1996 Synthesis and characterization of colloidal nanocrystals of capped gallium arsenide Nanostruct. Mater 7 591... 

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