Lead-free Rb₂SnCl₆:Bi Perovskite Nanocrystals for Luminescence Emission

The development of lead-free nanomaterials, compared to the conventional (CsPbX3, X = Cl, Br, and I) perovskites, for potential optoelectronic devices has gained much scientific attention due to the increasing lead toxicity and photostability issues. Herein, the development of undoped (Rb2SnCl6) and bismuth-doped (Rb2SnCl6:X%Bi) perovskite nanocrystals was carried out via the facile hot-injection method using available non-toxic precursors. Different production parameters such as tin precursors (SnCl2 and SnCl4), ligands (OA/OLAM), and dopant (Bi3+) concentrations were optimized using XRD measurements to improve the photoluminescence quantum yield (PLQY) and photostability of Rb2SnCl6:Bi perovskite nanocrystals. Comprehensive structural/functional characterization was performed which exhibited the passivated attachment of ligands on the surface of nanostructures. Moreover, a positive influence of dopant addition on the fluorescence intensity and stability properties of nanocrystals was observed, with highest improvement at 4% concentration (Rb2SnCl6:4% Bi). The slight blue luminescence emission, peaking at 426 nm, was observed at 4% Bi, with a stokes shift of 70 nm and full width at half-maximum (FWHM) of 65 nm. In conclusion, the present study provides a consistent pathway toward the design optimization of lead-free perovskite nanostructures for the induction of improved photoluminescence properties for light-emitting, solar cells and in vivo imaging applications.