Carbon Nanotubes and Semiconducting Polymer Nanocomposites

Abstract

The increasing demand for efficient machines has driven a trend towards the miniaturation of devices and instruments with smaller volume, lesser power consumption but greater performance. The progression relies upon the searching out new desirable materials and the ability of making tiny structures with high precission. However, the development is not so smooth and easy. For instance, current electronic industry based on silicon is very mature and reliable, but it is reaching an unsurmountable barrier of quantum effects as nanoscale approaching. Search for new suitable materials and fabrication methods therefore are being urgent tasks for the near coming development. Carbon nanotubes (CNTs) and conducting polymers (CPs), newfound materials have shown exceptional characteristics. The coupling of CPs and CNTs furthermore reveals synergistic effects which offer an attractive route to create new multifunctional materials with greater potential in application. Envisioned applications from CPs/CNTs systems involve mechanical, thermal, electrical, electrochemical features such as supercapacitors, sensors, organic light emitting diodes (OLEDs), solar cells, electromagnetic absorbers, and, last but not the least, advanced electronic devices. Conducting polymers commonly are classified as conjugated polymers which consist of alternating single and double bonds along its linear chains (sp2 hybridized structure). The conductivity of the CPs relies on these double bonds which are sensitive to physical or chemical interactions [1-3]. Similarly, CNTs also have sp2 hybridized bonds over the structure. CNTs possess unique structures and exhibit extraordinary electrical, optical, chemical, and mechanical properties, which are somewhat complementary to those of CPs [4-6]. For instance, CNTs have a very long mean free path, ultrahigh carrier mobility, and can be either very good conductors or narrow bandgap semiconductors depending on the chirality and diameter. Mixing up together, both materials show a strong interfacial coupling via dono-acceptor binding and pi-pi interaction [7, 8]. The coupling of CNTs and CPs in a composite has been found to affect their chemical and electronic structure. Beyond a simple combination of their properties, some synergistic effects and new features appear and can develop into applications [9-14]. From a chemical viewpoint of consideration, two possible impacts may take place in a CPs/CNTs system: either the CNTs are functionalized by the CPs or the CPs are modified (doped) with the CNTs. Therefore, either the morphological modifications, electronic interactions, charge transfers or a combination of these effects may occur between the two constituents in the system [15-18]. Due to the