LAUSR

Abstract The relation between surface chemistry and (Opto)electrical properties of lead sulfide quantum dots (PbS QDs) is of importance for the development of cost-effective field-effect transistor (FETs) and quantum dot solar cells. Herein, simple chloride surface treatment has been demonstrated by adding tetramethylammonium chloride (TMACl) into a QD washing step. Absorption, photoluminescence (PL) and X-ray photoelectron spectroscopic studies revealed that Cl− ions bound strongly to PbS QDs surfaces resulting in enhanced PL of colloidal QDs. Furthermore, FET studies on PbS QD thin films fabricated by an identical solid-state ligand exchanging with 1,2-ethanedithiol (EDT) showed that TMACl treatment enhanced hole mobility by ten times and at the same time switched the EDT-treated QD thin film from p-type to ambipolar semiconductor with electron mobility of 2.8 × 10−2 cm2V−1s−1. The results demonstrated herein offer a simple treatment for the fabrication of multiple QD junctions with minor change in processing.