Phase-engineered 1T/2H MoS2 via spray coating: role of precursor concentration in structural and electronic tuning

Abstract

Molybdenum disulfide (MoS₂) is particularly compelling due to its tunable electronic properties, which are intrinsically linked to its polymorphic phases. Controlling the synthesis of mixed-phase MoS₂, comprising the metastable metallic 1T-MoS₂ phase and the semiconducting 2H-MoS₂, is essential for tailoring its structural and electronic properties. Here, we demonstrate the fabrication of 1T/2H-MoS₂ mixed-phase structures via a spray coating method, emphasizing the impact of precursor concentration on phase composition and crystallinity. Comprehensive structural and spectroscopic analyses confirm the coexistence of both phases, revealing that increased precursor concentration promotes phase modulation. Optical properties investigations indicate a bandgap energy reduction from 1.48 to 1.19 eV as precursor concentration increases from 5 to 15 mmol·L⁻¹, underscoring the semiconducting nature of the mixed-phase. Electrical characterization further shows that the sample synthesized at 15 mmol·L⁻¹ exhibits the highest electrical conductivity of 2.23 × 10^–² mS·cm^–1 and the lowest resistivity of 44.78 kΩ·cm, attributed to an increased fraction of the 1T-MoS₂ phase. These results provide a viable approach for engineering 1T/2H-MoS₂ mixed-phase with tunable structural and electronic properties.