Nanorods, CdSe/CdTe

Figure 13.1 (a) TEM images of different shaped semiconductor NCs. From left to the right CdSe quantum dots, CdSe nanorods, and CdTe tetrapods. (b) Schematic illustration of a colloidal semiconductor QD capped with surface ligands. 

In bulk (or dispersed) heterojunctions, nanocrystals are blended into the polymer to create a heterogeneous composite with a high interface surface area. In this hybrid solar cell concept, photo induced charge separation is favored between high electron affinity inorganic semiconductors and relatively low ionization potential polymer. The maximum power conversion efficiency has reached 2.8 % under AM 1.5 illumination condition by using the composite of tetrapods of CdSe nanocrystals and MDMO-PPV [4], while the PCE of the device based on the composite of CdTe nanorods and MEH-PPV is only 0.052 % in similar conditions [5]. 

Keywords Quantum confinement, quantum-confined nanomaterials (QCNs), quantum dots (QDs), tetrapods, nanocrystals, nanorods, carbon dots (C-dots), graphene quantum dots (GQDs), CdSe, CdS, CdTe, PbS, PbSe, blends, nanocomposites, in-situ polymerization, organic photovoltaics (OPVs), organic light-emitting diodes (OLEDs), dye-sensitized solar cells (DSSCs)... 

Nanomaterials in the form of a colloidal solution or quantum dots are attributed to have a tremendous impact in analytical chemistry for their unique physical and chemical properties (Alivisatos 2004 Katz and Willner 2004). A different methodology has been adopted to analyse vitamin Bi spectro-fluorimetrically by using cadmium selenide quantum dots (CdSe QDs), cadmium telluride (CdTe) nanorods, and silica and gold nanoparticles. A fluorescence resonance Rayleigh scattering (RRS) method was applied for determining vitamin Bi at sub-nanomolar level (Liu et al. 2006). In this technique, vitamin Bi was mixed with acidic buffer and prepared gold nanoparticles. After incubation, the solution mixture was excited in synchronous mode to obtain RRS spectra. The RRS spectral intensity correlated with the concentration of vitamin Bi. 

Fig. 1 Examples of morphologies of semiconductor nanostructures, (a) metal assisted Si etching and formation of Si-NWs. Electrochemical formation of (b) microporous silicon, (c) ZnO nanorods, (d) porous CdSe using porous alumina template, (e) CdTe nanowires using alumina template, (1) CdS nanowires using alumina template, (g) mesoporous Xi02 film using doctor blade method, (h) self-ordered anodic Xi02 nanotubes and (i) cross section image of the same Xi02 nanotubes (reproduced with permission from Ref. 8,27,28,45 8).

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