Nonlinear optical enhancement and origin of BP/Ag nanohybrids

Abstract

Black phosphorene (BP) nanosheet, a new type of two-dimensional material with the characteristics of ultra-thin structure and ultra-fast conductivity, has achieved wide attention of researchers in basic research and technical application fields. However, the nonlinear optical (NLO) absorption of black phosphorene is not strong enough to meet the application requirements of NLO devices. Interconnecting black phosphorene with nano-materials is an effective method to improve its NLO effect. In this work, Ag nanoparticles were anchored on the surface of BP nanosheets by thermochemical method and the BP/Ag nanohybrids (NHs) were successfully formed, which is certified by TEM, XRD, Raman and XPS measurements. The covalent functionalization with Ag nanoparticles can tune the bandgap of BP nanosheets and improve their NLO response. Compared with the NLO simple addition of BP and Ag, the additional synergistic effect between them plays a major role in enhancing the NLO absorption of BP/Ag nanohybrids, and this synergistic nonlinear enhancement is closely related to the Ag concentration and the non-radiation defect density in the nanocomposites. The NLO enhancement mechanisms of extra charger transfer and local field are confirmed by femtosecond-ultrafast dynamics analysis and FDTD calculation. This work provides the new BP/Ag NH material with good optical nonlinearity and NLO mechanism discussion for potential opto-electronical applications.