title: Carbon quantum dot-based field-effect transistors and their ligand length-dependent carrier mobility.
abstract: We report electrical measurements of films of carbon quantum dots (CQDs) that serve as the channels of field-effects transistors (FETs). To investigate the dependence of the field-effect mobility on ligand length, colloidal CQDs are synthesized and ligand-exchanged with several primary amines of different ligand lengths. We measure current as a function of gate voltage and find that the devices show ambipolar conductivity, with electron and hole mobilities as high as 8.49 × 10(-5) and 3.88 × 10(-5) cm(2) V(-1) s(-1), respectively. The electron mobilities are consistently 2-4 times larger than the hole mobilities. Furthermore, the mobilities decrease exponentially with the increase of the ligand length, which is well-described by the Miller-Abrahams model for nearest-neighbor hopping. Our results provide a theoretical basis to examine charge transport in CQD films and offer new prospects for the fabrication of high-mobility CQD-based optoelectronic devices, including solar cells, light-emitting devices, and optical sensors.
authors: System on Chip Chemical Process Research Center, Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 790-784, South Korea.
authors: Woosung
authors: W
authors: Kwon
authors: Sungan
authors: S
authors: Do
authors: Dong Chan
authors: DC
authors: Won
authors: Shi-Woo
authors: SW
authors: Rhee