Fig. 2: Fabrication and characterization of rainbow perovskite films.
From: Spectrum projection with a bandgap-gradient perovskite cell for colour perception
a Scheme of the halide-exchanging method via dipping. Fluorescence microscopy photo(s) of b Br/I GBG films with different LGBG (the dipping speeds from left to right are 1, 2, 3, and 5 mm/s, respectively, and the concentration of the CsI solution is 16 g/L) and c a Br/Cl GBG film (the dipping speed is 1 mm/s and the concentration of the CsCl solution is 16 g/L). d Cross-sectional SEM image of a Br/I GBG film. e Marked positions on the Br/I GBG film. f SEM images and g linear scan of the elemental distributions around the different marked positions on the Br/I GBG film.
