Solution-Processable Electronic-Grade 2D WTe Enabled by Synergistic Dual Ammonium Intercalation.

Tungsten ditelluride (WTe) exhibits thickness-dependent properties, including magnetoresistance, ferroelectricity, and superconductivity, positioning it as an ideal candidate for nanoelectronics and spintronics. Therefore, the scalable synthesis of WTe with defined thicknesses down to the monolayer limit is crucial for unlocking these properties. Here, we introduce a universal electrolyte chemistry utilizing dual-ammonium compounds to exfoliate WTe, enabling precise control over the intercalation stages and flake thicknesses. This approach achieves an 86% exfoliation yield, producing high-quality flakes averaging 2.83 nm in thickness, in which approximately 10% are monolayers. A solution-processed, single-flake device (10 nm thick) exhibits a magnetoresistance (MR) of 50% at 2 K and 9 T, and piezo-response force microscopy (PFM) indicates ferroelectricity in WTe flakes. Additionally, large-area WTe thin films (15 × 15 mm), fabricated using Langmuir-Schaefer deposition, exhibit metallic behavior with a high conductivity of 2.9 × 10 S/m. Overall, the hybrid electrolyte approach facilitates the scalable synthesis of high-quality, solution-processable, two-dimensional (2D) WTe flakes with excellent properties. This versatility of the developed method has been further exemplified through the exfoliation of other transition metal dichalcogenides (e.g., MoS and MoSe), expanding the potential for the extensive application of exfoliated 2D materials in printable and flexible nanoelectronics.