Ionic Conduction in Ultrathin Ligand-Free Lead Sulfide Colloidal Quantum Dots

Abstract

We fabricated an ultrathin ligand-free lead sulfide (PbS) colloidal quantum dot (CQD) field effect transistor (FET) and probed interfacial charge transport properties sensitized by the combination of gate electric field and ultrathin CQD layer thickness at low temperature. Large gate-modulated current hysteresis of the (NH4)2S-treated PbS CQD FET was significantly reduced at lower temperature. Interfacial charge transport after oleic acid ligand removal of PbS CQDs close to the gate dielectric is investigated through analysis of temperature dependent mobility and threshold voltage, hypothesizing that gate field screening by ionic conduction and thermally-activated electronic transport determine the interfacial charge transport properties.

Keywords

• ionic conduction
• pbs
• ligand treatment
• interfacial charge transport