Electronic transport behaviours of lead chalcogenide (PbE)n (E = S and Se) nanocluster junctions by ab initio simulation
Abstract
Lead chalcogenide nanoclusters possess relatively narrow band gaps and large Bohr exciton radii, making them indispensable in many modern applications. All the potential applications require the integration of their nanoclusters into scalable and robust device structures. In this paper, the geometric structural behaviour of the nanoscale lead chalcogenides (PbS)n and (PbSe)n (n = 2, 3 and 4) clusters as well as their electronic transport properties are comparatively investigated by employing ab initio simulation of non-equilibrium Green's function (NEGF) combined with density functional theory (DFT). Results indicate that all the investigated (PbS)n and (PbSe)n nanocluster-based molecular junctions show metallic behavior at low biases (−2 V, 2 V) while negative differential resistance (NDR) appears at a certain high bias range. Our calculations show that the current of (PbE)4 nanocluster-based molecular junctions is almost the largest at any bias. The mechanisms of the current–voltage characteristics of all the (PbE)n (E = S and Se) nanocluster junctions are proposed.