Defect modification engineering on a laminar MoS2 film for optimizing thermoelectric properties

Abstract

Two-dimensional (2D) transition-metal dichalcogenide (TMD) films have emerged as promising semiconducting materials for electronic and optoelectronic applications. However, a defect region, such as gap or void areas between the edges of the nanosheets originating from the layer-by-layer assembly of 2D nanosheets, is often inevitably present in laminar TMD films and strongly affects the semiconductor properties. In this work, we developed a defect modification strategy to patch the gap regions in molybdenum disulfide (MoS₂) film for optimizing its thermoelectric performance. The defect regions can be bridged through the nanoconfinement electrostatic force between the surface anisotropic MoS₂ nanosheets and inserted copper, leading to a MoS₂–Cu lateral heterostructure. Compared with the MoS₂ film, the carrier mobility of the modified MoS₂ film increased 15 times, resulting in a high Seebeck coefficient of 159.4 μV K⁻¹ at room temperature. In addition, the thermoelectric stability of MoS₂ films can be improved simultaneously. Our results provide a new concept of microstructure regulation on laminar TMD films to improve thermoelectric performances and will promote 2D laminar films with potential applications in other semiconductor fields.