PbSe Quantum Dot Field-Effect Transistors with Air-Stable Electron Mobilities above 7 cm2 V-1 s-1

PbSe quantum dot (QD) field effect transistors (FETs) with air-stable electron mobilities above 7 cm² V^-1 s^-1 are made by infilling sulfide-capped QD films with amorphous alumina using low-temperature atomic layer deposition (ALD). This high mobility is achieved by combining strong electronic coupling (from the ultrasmall sulfide ligands) with passivation of surface states by the ALD coating. A series of control experiments rule out alternative explanations. Partial infilling tunes the electrical characteristics of the FETs.