There is an increasing number of potential applications for materials with dimensions in the nanometer range. For this purpose, carbon nanotubes (CNTs) and nanoparticles (NPs) are intensively investigated. Such systems show improved or even new properties emerging as a result of electronic confinement. In particular, CNTs find applications as transistors, conductive layers, field emitters, and mechanical components. At the same time, the knowledge acquired from well-established synthetic procedures has facilitated the tailoring and optimization of semiconductor nanoparticles with efficient, photostable luminescence properties. However, there is still a need for improvement in many systems such as the III-V semiconductor NPs. Furthermore, there is a strong interest to attach NPs to one-dimensional systems like CNTs. For example, metallic particles can serve as catalysts to create branches on CNTs, while semiconducting NPs can act as light absorbing sites to increase the photoconductivity of CNTs. In previous studies, semiconductor NPs have been grown on CNTs by generation of defects in the CNT lattice structure by means of covalent functionalization or ozonolysis. The drawback of such covalent functionalizations is that they modify the response of the CNTs in terms of conductivity, optical behaviour, and mechanical stability, a disadvantage for further applications.
In the presented work we study the influence of unfunctionalized CNTs on the synthesis of CdSe and PbS NPs by means of organic colloidal routes. This new synthesis methodology does not only provide an highly effective path to attach NPs non-covalently to CNTs (multiwalled and singlewalled ones) but represents also a new way to control nanoparticles’ shape. This opens up intriguing possibilities especially for photoelectric applications. We will discuss the synthesis of such CNT-NP composites, microscopical and spectroscopical characterizations, photoconductivity measurements, and an outline for the synthesis mechanism. |