Composition controlled metallic Sn-doped MoS2 nanosheets for a flexible and wearable temperature sensor

Abstract

Two-dimensional (2D) MoS₂ demonstrates significant potential for applications in flexible electronic sensing devices due to its unique physical and chemical properties and ultrathin layered structure. Metallic 1T phase MoS₂ is inherently metastable and tends to transform into the thermodynamically stable semiconducting 2H phase. Atomic doping can regulate the crystal phase of the MoS₂ and carrier concentration, and enhance the material stability. In this study, 2D metallic Sn-doped MoS₂ (Sn_xMo_1−xS₂) nanosheets were successfully synthesized via a hydrothermal method. The film resistance of Sn_xMo_1−xS₂ can be precisely controlled to change by two orders of magnitude through the precise regulation of the Sn doping concentration. The Sn_0.4Mo_0.6S₂-based temperature sensor displayed a negative temperature coefficient of resistance of −0.020 °C⁻¹, exhibiting an 82% improvement compared with 1T MoS₂. Meanwhile, the temperature-sensing performance of Sn_0.4Mo_0.6S₂ nanosheets is superior to that of reported doped and un-doped TMDs and their composites. In addition, the TCR remained stable under different bending conditions owing to the special nanosheet structure. Therefore, the Sn_0.4Mo_0.6S₂ sensor showed promising applicability for flexible and wearable human body temperature monitoring and activity tracking devices.