Chalcogenidometallate Clusters as Surface Ligands for PbSe Nanocrystal Field-Effect Transistors

We introduce a method to process colloidal PbSe nanocrystals (NCs) into inorganic NC thin films using chalcogenidometallate (ChaM) clusters as surface ligands, resulting in electrically coupled NC solids. NCs are first immobilized on a substrate via a self-assembled monolayer followed by chemical treatment to exchange the insulating oleate ligands with ChaM clusters. Quantum confinement in the PbSe NCs is preserved as evidenced by persistent excitonic features in the absorption spectrum. PbSe NC–ChaM composites exhibit rectification (“off” states), saturation, n-type electrical behavior, and high electron mobilities of 1.28 and 0.475 cm 2 V –1 s –1 for different composite compositions.