Efficient and Air-Stable Doping of Folded MoS₂ Nanosheets for Use in Field-Effect Transistors

In recent years, doping technology has been widely used to modulate the electronic structure and transfer characteristics of two-dimensional (2D) materials. The addition of metal ions to 2D materials induces changes in the carrier type, which has promoted the development of 2D material-based optoelectronics. However, normal doping methods only modulate the top surface of a 2D material at the atomic level, which severely limits the doping efficiency and stability. Here, we report a method for highly efficient and air-stable doping of molybdenum disulfide (MoS2) using a folded structure. Chloroauric acid (HAuCl4) is used as the dopant to control the band gap of folded MoS2 and gradually modify MoS2 from an n-type to a p-type semiconductor. The intercavity of the folded structure creates a relatively closed environment, whereby the doped nanoparticles in the MoS2 interlayer are protected. Therefore, three-face doping of the folded bilayer is achieved, that is, double-face doping of the top layer and single-face doping of the bottom layer; doping is thus unequivocally more efficient and stable, which leads to a change in the electronic band gap of MoS2. This study provides an effective method for highly efficient and stable doping of 2D materials.