A facile method to intimately contacted nanocomposites as thermoelectric materials: Noncovalent heterojunctions

Abstract We develop a facile method to intimately contacted hybrid organic-inorganic nanocomposites as thermoelectric materials. By utilizing branched alkyl naphthalimide molecules as the organic component, monodispersed single walled carbon nanotubes are tethered via strong Van der Waals' forces between the two components (i.e., forming heterojunctions). Comparing with using the linear alkyl naphthalimide molecules as the organic component, this leads to much more intimate contact between the two components, which is identified by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy. Consequently, the carrier transport is promoted much more at the interface of the branched composites and the thermoelectric properties are enhanced much more compared with those of the linear composites who possess the weaker interactions. The maximum value of the power factor reaches 158.8 μWm −1 K −2 while only 85.0 μWm −1 K −2 for the linear ones. Because naphthalimide molecules are noncovalently connected to single walled carbon nanotubes, a complex chemical synthesis is avoided, enhancing the use of hybrid nanocomposites in the new energy-related applications, especially the environmentally-friendly applications. We envision that this general, robust and unconventional strategy could be used to create other nanocomposites for use in a variety of applications.