Toc

a Schematic showing the synthetic procedure of ultra-stable CsPbBr3 NCs. b Reaction yield comparison between this experiment and conventional methods, such as hot injection and precipitation. The inset shows 5.75 g of as-synthesized nanosheets generated in a 100 mL-beaker. c PL QY measurements of both fresh and aged (stored in a capped vial) colloidal samples, indicating a robust storage stability. The error bar was obtained by three parallel measurements. d TEM image of the nanosheets. Scale bar represents 100 nm. e PL spectra of fresh and aged samples, showing no significant difference. f XRD pattern of self-assembled nanosheets, showing a cubic phase. The peaks marked with asterisks indicate the inter-plane spacing of assembled nanosheets

Phase engineering of CsPbBr3 NCs through feeding varied molar ratios of Pb/Cs. a TEM images showing morphology transformation from bulk cubes to thin nanosheets. b High-resolution TEM image of nanosheets (Pb/Cs=5/1). c XRD patterns showing a phase evolution from orthorhombic to cubic. d The magnified XRD peaks show a clear difference in peak width, indicating a shrinkage of grain size

a Lifetime measurement at 520 nm and b PL QY of CsPbBr3 NCs, showing a phase dependence. A 410-nm pulsed laser was used as excitation source, and the PL bands from 450 to 600 nm was monitored as emission. c TGA of nanosheets shows ample surface coverage of ligands

a Absorption and photoluminescence spectra of CsPbBr3 NCs, showing the PL fine-tuning ability of our synthesis. The purple stripe highlights the excitonic peak of the 3-monolayer nanosheets. b 2D pseudo-color transient emission map from CsPbBr3 nanosheets colloid (Pb/Cs=5/1). Streak camera measurement was conducted under excitation at 410 nm, flux at 1 pJ cm-2. c PL decay traces extracted at 460-nm and 510-nm window (± 5 nm)

X-ray scintillation screen based on CsPbBr3 nanosheets. a Radioluminescence spectra of thin films with varied thickness. The inset shows a semi-transparent thin-film sample of a flat surface. Radioluminescent image of b a crack-free screen and c a cracked screen. d Photograph and e X-ray image of a SIM card