Controllable photoelectron transfer in CdSe nanocrystal–carbon nanotube hybrid structures

Carbon nanotubes (CNTs) coated with nanocrystals (NCs) or quantum dots (QDs) form a new class of hybrid nanomaterials that could potentially display both the unique properties of NCs and those of CNTs. The photo-induced charge transfer within the hybrid nanostructure may either increase or decrease the CNT electrical conductivity. The use of a chemical vapor deposition method realizes direct assembly of CdSe NCs onto the external surfaces of single-walled CNTs without applying any organic linkers. The NC loading on the nanotubes can be tuned simply through deposition duration. Upon visible light excitation, photo-generated electrons are injected into CNTs from the excited states of CdSe NCs, which is monitored by the measurement of the photocurrent and field effect transistor (FET) characteristics. The direction of the electron transfer could be controlled with the NC coverage on CNTs and the gate voltage.