Photoluminescence from chemically exfoliated MoS 2

Abstract

A two-dimensional crystal of molybdenum disulfide (MoS 2) monolayer is a photoluminescent direct gap semiconductor in striking contrast to its bulk counterpart. Exfoliation of bulk MoS 2 via Li intercalation is an attractive route to large-scale synthesis of monolayer crystals. However, this method results in loss of pristine semiconducting properties of MoS 2 due to structural changes that occur during Li intercalation. Here, we report structural and electronic properties of chemically exfoliated MoS 2. The metastable metallic phase that emerges from Li intercalation was found to dominate the properties of as-exfoliated material, but mild annealing leads to gradual restoration of the semiconducting phase. Above an annealing temperature of 300 °C, chemically exfoliated MoS 2 exhibit prominent band gap photoluminescence, similar to mechanically exfoliated monolayers, indicating that their semiconducting properties are largely restored. © 2011 American Chemical Society.