Long live(d) CsPbBr₃ superlattices: colloidal atomic layer deposition for structural stability.

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Superlattices formed by metal halide perovskite nanocrystals exhibit high structural order.
• This order is significantly influenced by the surface chemistry and morphology of the nanocrystal building blocks.

Purpose of the Study:

• To investigate the formation of superlattices using aluminum oxide shelled cesium lead bromide (CsPbBr3) perovskite nanocrystals.
• To evaluate the impact of colloidal atomic layer deposition (c-ALD) for shell growth on superlattice properties.

Main Methods:

• Growth of aluminum oxide shells on CsPbBr3 perovskite nanocrystals via colloidal atomic layer deposition (c-ALD).
• Assembly of shelled nanocrystals into superlattices.
• Assessment of superlattice structural stability over time (25 days in inert atmosphere).
• Comparison of c-ALD shelled superlattices with those treated by gas phase ALD or excess capping agents.
• Analysis of nanocrystal size, supercrystal uniformity, photoluminescence quantum yield (PLQY), and radiative lifetimes.

Main Results:

• Superlattices formed from aluminum oxide shelled CsPbBr3 nanocrystals demonstrated preserved structural stability for over 25 days.
• c-ALD resulted in smaller nanocrystals, leading to uniform supercrystal formation.
• c-ALD provided structural protection, enhancing photoluminescence quantum yields and radiative lifetimes compared to other methods.
• Oleic acid capping on the aluminum oxide shell contributed to static capping group chemistry.

Conclusions:

• Colloidal atomic layer deposition is an effective method for creating stable, luminescent perovskite nanocrystal superlattices.
• The shelling process improves structural integrity and optoelectronic properties of the superlattices.
• These findings offer insights for designing future superlattice assembly strategies.