Highly Stable Amine-Free CsPbBr3 Perovskite Nanocrystals for Perovskite-Based Display Applications

X = Cl, Br, and I) perovskite nanocrystals (PNCs) often suffer from poor ambient and environmental stability conditions, limiting their practical applications. The commonly used surfactant oleylamine is converted to the oleylammonium cation, which pulls out the halide anion from the PNC surface, thus disrupting the structural integrity and stability of the nanocrystal. We developed a simple, completely amine-free colloidal synthesis with a hot injection method under open-atmospheric conditions and introduced bromooctane as a bromine precursor to overcome the above issues. These assynthesized amine-free PNCs show a photoluminescence quantum yield (PLQY) of around 60%, and the size of PNCs is similar to 25 nm. Moreover, these amine-free PNCs were highly stable in colloidal solutions and thin films for more than 5 months under ambient conditions, with 66% of their initial PLQY. In addition, these PNCs show exceptional stability under different environmental conditions, with 44% of the initial PL even after water treatment under 6 h and 28% of the initial PL under ethanol treatment of 120 min. Furthermore, they exhibit excellent photostability for 96 h and retain 36% of their initial PL under ceaseless UV light irradiation at 365 nm (8 W/cm2). In addition, these PNCs have good stability upon heat treatment and maintain 34% of the initial PL upon heating up to 90 degrees C. Finally, we fabricated a green-emitting downconversion light-emitting diode (LED) using these amine-free PNCs. Therefore, we envision that these amine-free CsPbBr3 PNCs are perhaps ideal candidates for perovskite-based display applications.

Automated summary

In this study, a simple amine-free synthesis method was developed to prepare stable CsPbBr3 nanocrystals with excellent photoluminescence properties. These nanocrystals exhibited long-term stability at room temperature and in different environmental conditions.