Fig. 2: Physical properties and nonlinear optical characteristics.
From: Hot-carrier tunable abnormal nonlinear absorption conversion in quasi-2D perovskite
a, b Scanning electron microscope (SEM) and atomic force microscope (AFM) images of bilayer quasi-2D (a) and 3D (b) perovskite thin films. c, d are the corresponding X-ray diffraction (XRD) patterns and film step profiles. e Linear ultraviolet-vis absorbance (Abs.) spectra of the 3D perovskite and quasi-2D perovskite film with a strong 1 S exciton absorption peak at 570 nm. f Z-scan profile (hollow circles) evolutions of bilayer quasi-2D perovskite film collected at the blue side (540 nm) of 1 S exciton peak demonstrating a conversion from RSA to SA with excitation intensity rising. The solid lines are fitting curves using the abnormal NLA conversion model (Eq. 2) we developed. g Corresponding Z-scan results (hollow circles) of 3D counterpart at 700 nm above band-edge with a pure SA response fitting well with the standard SA model (solid lines) according to Eq. 4 in supplementary information.
