High flex cycle testing of CVD monolayer WS₂ TFTs on thin flexible polyimide

Two-dimensional transition metal dichalcogenides are potential candidates for high-performance flexible electronics. In this paper, we report thin film transistors (TFTs) fabricated on ∼5 μm thick solution-cast polyimide substrates using chemical vapor deposition (CVD) synthesized single layer WS₂as the active layer. The linear region field effect mobility ranges from2to10 cm²V^-1s^-1, with current on-off ratio exceeding 10⁶. By using a thin polyimide substrate, the bending induced tensile stress on our TFTs is relatively small when compared to devices fabricated on thicker flexible substrates. Static bending and upto 50 000 bending/flattening cycles were employedto investigate the reliability of these TFTs for potential flexible electronic applications. Our results demonstrate that CVD grown WS₂TFTs fabricatedon thin polyimide have good performance stability for upto 2 mm radius bending and 50 000 bending cycles. It is therefore clear that thin polymeric substrates provide a simple approach for reliable, scalable, and high-performance 2D-TMD-basedflexible electronics.