Perovskite Core-Shell Nanocrystals with Metal Oxide Shells
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Solution Overview
Problem
Current methods for manufacturing luminescent core-shell nanocrystals, such as colloidal atomic layer deposition (c-ALD), are not suitable for commercial production due to non-uniform shell thickness and instability in polar solvents, which compromises their optoelectronic properties and longevity in devices.
Innovation Solution
A method involving a dispersion of perovskite crystals in a non-polar solvent with a solution containing a metal halide and metal alkoxide, combined under oxygen-free conditions, results in a dense metal oxide shell that fully covers the core, providing stability and maintaining luminescent properties even in harsh conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If colloidal atomic layer deposition (c-ALD) is used to grow alumina shells, then shell thickness can be tuned, but the shells are non-uniform and production is not scalable
Solution Approach 1:
The invention changes the fundamental parameters of the deposition process by using a single-step solvothermal method instead of multi-step c-ALD. This involves changing from sequential Al-deposition and oxidation steps to a one-pot reaction using aluminum alkoxide precursors in high-boiling solvents at elevated temperatures, achieving uniform shells up to 10 nm thick with scalable production
Solution Approach 2:
The invention extracts and eliminates the intermediate steps of c-ALD (sequential deposition and oxidation cycles) by directly forming the oxide shell in a single solvothermal step, removing the complexity of multiple cycles while achieving the desired shell thickness and uniformity
2Reliability
If luminescent crystals are stabilized with shells, then stability improves, but manufacturing complexity increases
Solution Approach 1:
The invention merges the shell formation process with the crystal synthesis process by performing both steps in a single solvothermal reaction. The aluminum precursor is added to the crystal suspension, and both the crystal growth and shell formation occur simultaneously in one pot, eliminating separate stabilization steps
Solution Approach 2:
The solvothermal method enables self-assembled uniform shell formation where the aluminum alkoxide precursors automatically deposit evenly on the crystal surfaces through solvent-mediated processes, eliminating the need for complex controlled deposition equipment and procedures
3Length of stationary object
If multiple c-ALD cycles are used to increase shell thickness, then thickness increases, but production time and complexity increase
Solution Approach 1:
The invention uses pre-synthesized aluminum alkoxide complexes as starting materials that are designed to decompose and form oxide shells at solvothermal conditions. This preliminary preparation of reactive precursors allows direct shell formation in one step rather than requiring multiple sequential deposition cycles
Solution Approach 2:
The solvothermal process maintains continuous shell formation throughout the reaction period at elevated temperatures, with the aluminum precursors continuously decomposing and depositing on crystal surfaces. This continuous action achieves thick uniform shells (up to 10 nm) in a single prolonged reaction rather than intermittent cycling
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces highly luminescent and stable core-shell nanocrystals with a quantum yield of at least 50%, resistant to degradation by polar solvents and gases, enabling their use in optoelectronic devices with improved performance and longevity.
Implementation Method 1
combining suitable starting materials under oxygen-free conditions
Implementation Method 2
combining suitable starting materials under oxygen-free conditions
Implementation Method 3
Luminescent crystals are of key importance in many areas of technology, such as optoelectronic applications including photovoltaics and lighting devices
Data Source
AI summary
The present invention relates to the field of luminescent crystals (LCs) of the core-shell type, components and devices comprising the same. Particularly, the present invention relates to the manufacturing of luminescent core-shell nanocrystals, wherein said nanocrystal core comprises or consists of a perovskite crystal having a size of 3-100 nm, and said nanocrystal shell comprises a metal oxide having a thickness of 0.5-10 nm and wherein said method comprises combining suitable starting materials under oxygen-free conditions. The invention further provides for specific luminescent core-shell nanocrystals, to components and products containing such luminescent core-shell nanocrystals.