A hierarchical shell locks and stabilizes perovskite nanocrystals with near-unity quantum yield

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Solid-state emitters, particularly perovskite nanocrystals (PeNCs), face challenges with low external quantum yields (EQYs) and poor operational stability due to soft ionic lattices and labile surfaces.
• Existing systems rarely achieve both unity photoluminescence quantum yield (PLQY) and commercial viability.
• These limitations hinder the widespread application of PeNCs in displays and optoelectronics.

Purpose of the Study:

• To introduce a novel hierarchical shell (HS) structure for stabilizing perovskite nanocrystals (PeNCs).
• To improve the photoluminescence quantum yield (PLQY) and external quantum yield (EQY) of PeNC-based solid-state emitters.
• To enhance the operational stability of PeNCs under accelerated aging conditions.

Main Methods:

• Development of a hierarchical shell (HS) structure using interbonded PbSO₄-SiO₂-polymer multilayers.
• Application of the HS structure to various perovskite nanocrystal compositions, including CsPbBr₃ and MAPbBr₃.
• Testing of HS-PeNC films under accelerated 60°C, 90% relative humidity (RH) and continuous blue-light exposure to evaluate stability (T₉₀).

Main Results:

• HS-CsPbBr₃ PeNC films demonstrated remarkable stability with T₉₀ = 3211 hours (60°C, 90% RH) and T₉₀ = 12,000 hours (blue light).
• The HS strategy generalized across multiple PeNC compositions, with HS-MAPbBr₃ achieving T₉₀ = 3900 hours (60°C, 90% RH) and T₉₀ = 27,234 hours (blue light).
• HS-MAPbBr₃ films achieved 100.0% PLQY and an EQY of 91.4%, nearing the theoretical limit, while also preventing lead leakage.

Conclusions:

• The hierarchical shell (HS) structure effectively locks and stabilizes soft perovskite nanocrystal lattices and interfaces, overcoming critical limitations in PeNC stability.
• This approach enables highly efficient solid-state emitters with near-unity PLQY and significantly improved operational lifetimes, suitable for commercial applications.
• The HS barrier ensures safety by preventing lead leakage, paving the way for large-area, high-resolution displays and bio-optoelectronic devices.