Preparation Of Ultrathin Two-dimensional Black Phosphorus With Unique Optical Properties

Ultrathin two-dimensional black phosphorus(BP), with simultaneous high carrier mobility and on/off ratio, has emerged as a novel material bridging the gap of graphene and transition metal dichalcogenides(TMDs). However, as a completely new material, the preparation of BP faces huge challenges. Their applications in optoelectronic have just begun, and the study of their nonlinear optics is still in the infant stage. In this thesis, a small-molecule–assisted liquid phase exfoliation method was applied to prepare the thin two-dimensional materials with controllable size and morphology, and study their nonlinear optical properties with time resolved spectroscopy. The work of this paper is divided into the following parts:1. Research background and literature review.2. In this paper, a small molecule–assisted liquid phase exfoliation method was adopted for the first time and ultrathin two-dimensional black phosphorus materials were obtained. The size, morphology, surface structure and optical properties of the as-prepared samples were thoroughly characterized.3.The excited-state and electron-transport properties of ultrathin two-dimensional black phosphorus were investigated by transient time-resolved spectroscopy and steady-state spectroscopic techniques. Results indicated that electron transfer between black phosphorus and organic dyes occurred, and may eventually enable promising applications of BP in a wide range of fields such as photovoltaics and photocatalysis.4. Third order nonlinear optical properties of two-dimensional black phosphorus in solution are studied by Z- scan technique, which exhibited broadband nonlinear saturable absorption from visible at 532 nm to the near-infrared region at 1064 nm.5. Conclusions and discussion of the prospect of the application of BP nonlinear optics.