Stable and Efficient Blue-Emitting CsPbBr₃ Nanoplatelets with Potassium Bromide Surface Passivation

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Colloidal all-inorganic perovskite nanocrystals (NCs) show promise for displays and lighting due to superior optical characteristics.
• Blue-emitting perovskite NCs often exhibit low photoluminescence quantum yields (PLQYs) and inadequate stability, hindering full-color applications.
• These limitations represent a significant bottleneck for the advancement of all-perovskite optoelectronic devices.

Purpose of the Study:

• To enhance the emission efficiency and stability of blue-emitting perovskite nanocrystals.
• To address the limitations of low PLQY and poor stability in blue perovskite NCs.
• To enable the development of high-performance, full-color perovskite-based optoelectronic devices.

Main Methods:

• A facile surface passivation strategy using potassium bromide (KBr) was employed.
• Potassium oleate and excess PbBr₂ were added to precursor solutions for synthesizing CsPbBr₃ nanoplatelets (NPLs).
• The optical properties and stability of the synthesized KBr-passivated NPLs were evaluated under various conditions.

Main Results:

• Successfully synthesized KBr-passivated blue-emitting (≈450 nm) CsPbBr₃ NPLs with a high PLQY of 87%.
• Demonstrated exceptional photo- and thermal-stabilities with no emission wavelength shift after prolonged exposure to intense irradiation and elevated temperatures.
• Attributed enhancements to K-Br bonding on the surface, suppressing ion migration and bromide vacancies.

Conclusions:

• The KBr-passivation method effectively enhances the photoluminescence quantum yield and stability of blue CsPbBr₃ NPLs.
• The improved CsPbBr₃ NPLs are suitable for constructing all-perovskite white light-emitting diodes (WLEDs).
• This passivation strategy is crucial for advancing perovskite materials in diverse optoelectronic applications.