Fig. 3: Mechanistic investigations on upconversion dynamics in dye-sensitized perovskite nanocrystals.

a IR783 density dependent upconversion luminescence spectra of IR783-CsPbBr₃:Yb³⁺ nanocrystals. b Power density dependent upconversion luminescence intensity of IR783-CsPbBr₃:Yb³⁺ nanocrystals; excited at 804 nm. c Upconversion (solid line) and Stokes (dashed line) luminescence spectra of CsPbBr₃: Yb³⁺ nanocrystals; inset shows the corresponding relation between power density and upconversion luminescence intensity; excited at 980 nm. d Absorption spectra of Yb³⁺ ions (orange solid line), contrasted with fluorescence (blue solid line) and phosphorescence (blue dashed line) spectra of IR783 dye. e Upconversion luminescence spectra of IR783-CsPbBr₃:Yb³⁺ in atmospheres with varied N₂/O₂ ratios; excited at 804 nm, power density= 8.4 Wcm⁻². All nanocrystals were dispersed in hexane in a cuvette during spectroscopic characterizations.