One-Step Preparation of High-Stability CsPbX₃/CsPb₂X₅ Composite Microplates with Tunable Emission

Area of Science:

• Materials Science
• Nanotechnology
• Solid State Physics

Background:

• Cesium lead halide (CsPbX₃) perovskite quantum dots (QDs) show promise for optoelectronic applications but suffer from stability issues.
• Existing core-shell strategies for CsPbX₃ QDs are limited by ionic radius differences across the system.
• Improving the stability and optoelectronic properties of CsPbX₃ QDs is crucial for their practical implementation.

Purpose of the Study:

• To develop a universal core-shell packaging strategy for the entire CsPbX₃ system.
• To enhance the stability and optoelectronic performance of CsPbX₃ QDs.
• To explore the potential of CsPbX₃/CsPb₂X₅ heterostructures in optoelectronic devices.

Main Methods:

• Optimized hot-injection method for epitaxial growth of CsPb₂X₅ on CsPbX₃.
• Precise control of reaction time and lead halide precursor ratios.
• Crystallographic analysis and density functional theory (DFT) calculations.

Main Results:

• Synthesized CsPbX₃/CsPb₂X₅ composite microplates covering the entire visible spectrum.
• Identified minimal lattice mismatch facilitating type-I heterojunctions.
• Observed morphological evolution and enhanced optical properties and stability due to CsPb₂X₅ passivation.

Conclusions:

• The CsPbX₃/CsPb₂X₅ core-shell structure offers a viable strategy for enhancing QD performance.
• The composite microplates demonstrate excellent luminescence efficiency (136.76 lm/W) and stability in white light-emitting diodes.
• This work provides a pathway for developing robust and efficient perovskite-based optoelectronic devices.