Nonlinear electronic and ultrafast optical signatures in chemical vapor-deposited ultrathin PtS2 ribbons.

The emerging two-dimensional (2D) platinum disulfide (PtS₂) has driven increasing attentions due to its high electron mobility, good air-stability, and strong interlayer interaction which leads to a widely tunable electronic structure. However, a detailed study on its covalent-like layer-dependent properties remains infant. Herein, we demonstrate the successful production of ultrathin 1T-PtS₂ ribbons with thickness centralized almost at monolayer 1L–4L and large domain size up to 210 µm on Au foils using chemical vapor deposition (CVD) technique, which enables macro- and microscopic study of its extraordinary layer-dependent features with precise control of the number of layers. Using electron energy loss spectroscopy (EELS) and optical pump-probe spectroscopy (OPPS), we reveal that both the electron and ultrafast optical absorption signals of the as-grown 2D PtS₂ show strong nonlinear layer-dependent responses which manifest discriminated transition in 1L–4L PtS₂ ribbons. The layer-dependent nonlinear response of 2D PtS₂ can be well interpreted in the frame of calculated electron and phonon structures. These achievements offer a platform for successfully fabricating large-sized ultrathin 2D PtS₂ and facilitating our knowledge about its electronic and optoelectronic properties. [ABSTRACT FROM AUTHOR]