Enhanced thermoelectric properties of copper phthalocyanine/single-walled carbon nanotubes hybrids

Abstract

Copper phthalocyanine (CuPc)/single-walled carbon nanotube (SWCNT) hybrids were prepared by high energy ball milling combined with cold pressing method. The electrical conductivity of the hybrids increased with the increasing SWCNT content, whereas the Seebeck coefficient decreased. Moreover, the electrical conductivity of CuPc/SWCNT hybrids were much higher than the values calculated based on the general parallel and series connected two-component mixture model. SEM, TEM, XPS, Raman and XRD analyses indicated that there existed a large number of CuPc-SWCNT nano-interfaces in the hybrids. The strong donor-acceptor and π-π conjugation interactions between CuPc molecules and SWCNTs can induce CuPc to highly ordered face-on packing on the surface of SWCNTs, which contributed to the efficient interface charge transport between CuPc and the surface of SWCNTs, and therefore both the carrier concentration and carrier mobility of CuPc/SWCNT hybrids were significantly increased. Finally, the maximum thermoelectric (TE) power factor at room temperature reached 70.1 μW m−1 K−2. The optimal TE property of the CuPc/SWCNT hybrids is remarkably higher than those of either individual component of the hybrid, and is among the highest values of metal-organic small molecules based TE materials. This study may provide a new route to enhance the TE properties of metal-organic small molecules materials.