Field emission enhancement of PbS colloidal quantum dot-decorated single-walled carbon nanotubes

Herein, a simple and effective PbS colloidal quantum dot (CQD) decoration method for single-walled carbon nanotube (SWNT) is demonstrated. By dipping the SWNT film into a CQD dispersion followed by a solid-state ligand exchange, CQDs were successfully decorated onto the wall of SWNT without compromising a narrow size distribution. Spectroscopic studies suggested that (1) the CQD decoration and subsequent ligand exchange process did not alter the chemical nature of the SWNT framework and (2) there was a charge (electron) transfer process from the PbS CQD to the SWNT. Field emission (FE) characteristics of the CQD-decorated SWNT films revealed that FE enhancement was indeed established from SWNTs with a moderate degree of CQD decoration, while those with excessive decoration (coating) exhibited notable FE suppression. Horizontal current-voltage measurements with perpendicular-directional external electric field modulation suggested that electron supplement of SWNT from PbS CQD was pronounced as the amount of decorated CQDs increased. Based on the experimental results, we proposed a new mechanism demonstrating FE enhancement of a CQD/SWNT heterostructure.