The effect of the dopant’s reactivity for high-performance 2D MoS₂ thin-film transistor

There are many studies on the solution-processed thin-film transistor (TFT) using transition metal dichalcogenide (TMD) materials. However, it is hard to control the electrical property of chemically exfoliated TMD materials compared to the chemical vapor deposition TMD. An investigation into the electrical modulation behavior of exfoliated two-dimensional (2D) material is important to fabricate well-modulated electronic devices via solution processing. Here, we report the effects of reactivity of organic dopants on MoS₂ and investigate how the chemical doping behavior influences the electrical properties of MoS_2. The band state of dopants, which is related to the electron-withdrawing and donating behavior of chemical dopant, provides a proportional shift in the threshold voltages (V_th) of their field-effect transistors (FETs). However, on/off current ratio (I_on/I_off) and mobility (µ) are strongly influenced by the defect density depending on the reactivity of doping reaction, rather than the band state of organic dopants. Through the in-depth study on the doping reaction, we fabricate a FET and a TFT, having high mobility and a relatively high on/off ratio (10⁴) using a solution process.