Extended Data Fig. 4: Halide segregation in diluted neat nanocrystals.
From: Ligand-engineered bandgap stability in mixed-halide perovskite LEDs
a, b, Normalized photoluminescence spectra of spin-cast films of neat nanocrystals and polymethyl methacrylate (PMMA), in a nanocrystal:PMMA mass ratio of 1.03 (a) and 0.006 (b). A 405-nm continuous-wave laser was used as an excitation source and caused halide segregation, with the duration of irradiation indicated in the legend. The redshifted shoulder that developed during irradiation is ascribed to the recombination from within an iodide-enriched minority phase with a smaller bandgap. This shoulder showed no dependence on the nanocrystal concentration in the film, indicating that segregation can occur in isolated nanocrystals. c, d, Confocal photoluminescence images (c) and normalized photoluminescence spectra (d) of spin-cast films of neat nanocrystals over time under constant excitation with a 405-nm continuous-wave laser. The photoluminescence spectra were obtained from the highlighted region of c. e, f, Confocal photoluminescence images (e) and normalized photoluminescence spectra (f) of spin-cast films of neat nanocrystals and PMMA, in a nanocrystal:PMMA mass ratio of 0.001 over time under constant excitation with a 405-nm diode laser. The photoluminescence spectrum was obtained from the highlighted region of e.
