Low-carbon, low-hazard synthesis of FAPbBr3 perovskite nanocrystals with KBr post-treatment for ultra-stable pure-green heterostructured luminescent powder

• Prepared FAPbBr 3 perovskite nanocrystals (PNCs) via milder and low-toxicity design. • Utilized SBE-18 zwitterion ligand to maximize PNCs passivation and stabilization. • Powdered PNCs with KBr to enhance storage stability and applicability. • Achieved pure green emission, narrow FWHM, and excellent durability PNCs. This study introduces a low-carbon, low-hazard synthesis method by lowering the traditional hot injection temperature to 60 °C and avoiding high-toxicity solvents, thereby reducing energy use and organic waste for more sustainable production. Lead oxide, formamidine acetate, and benzoyl bromide were employed as precursors, followed by post-treatment with KBr salts to enhance environmental stability and enable powderization of the material. The resulting FAPbBr 3 @KBr heterostructure shows a sharp photoluminescent peak at 535 nm with a narrow full width at half maximum of ∼20 nm. Stability tests revealed no decrease in photoluminescence intensity for solution samples stored at room temperature or 60 °C after 14 days. Even after heating to 80 °C and cooling, the intensity retained 99 % of its initial value. In summary, this work presents a milder synthesis and post-treatment strategy that significantly improves stability, supporting the future commercialization of perovskite nanocrystals.