Microstructural study of a conducting polymer doped with carbon nanotubes

Abstract

This work concerns the microsctructure of benzimidazobenzophenanthroline, BBL, films doped with carbon nanotubes, CNTs, to increase the electron mobility of the films. The CNT dopings were 1, 9 and 50 wt% respectively. The microsctructures were studied using electron microscopy including scanning electron microscopy and transmission electron microscopy. The morphology of the films gradually changed from a continuous BBL film with a relatively rough surface morphology in the 1 wt% films with randomly oriented CNTs to a structure with the BBL forming a smooth shell of BBL on the CNTs. The CNTs were multiwalled with a high density of defects. The thickness of the BBL shell was about 20-30 nm in the 1 and 9 wt% films and 3-4 nm in the 50 wt% films. The results show that the electron mobility can be even further increased by aligning the CNTs that have a considerably higher mobility along their long axis and also compared to the BBL. It should be noted that an alignment of the CNTs would also result in a high directional anisotropy of the mobility in the BBL:CNT films.