Metal Halide Perovskite Heterostructures: Blocking Anion Diffusion with Single-Layer Graphene

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• Metal halide perovskite/perovskite heterostructures are crucial for optoelectronics.
• Interfacial halide diffusion degrades heterostructure sharpness and performance.
• Developing methods to maintain sharp interfaces is essential for device stability.

Purpose of the Study:

• To develop an effective ion-blocking layer for metal halide perovskite heterostructures.
• To investigate the impact of single-layer graphene (SLG) on interfacial halide diffusion.
• To explore the potential of SLG-intercalated perovskite heterostructures in optoelectronic devices.

Main Methods:

• Fabrication of CsPbBr3/SLG/CsPbI3 heterostructures.
• Spatially resolved elemental analysis and spectroscopic measurements (e.g., UPS, TAS).
• Density Functional Theory (DFT) calculations.
• Fabrication and testing of light-emitting diodes (LEDs).

Main Results:

• SLG effectively blocked anion diffusion between CsPbBr3 and CsPbI3 layers.
• Control samples without SLG showed rapid halide homogenization and interface loss.
• SLG exhibited minimal electronic impact on the individual perovskite semiconductors.
• A type I band alignment was observed, facilitating photogenerated carrier transfer.
• LEDs demonstrated electroluminescence from both perovskite layers without ion diffusion during operation.

Conclusions:

• Single-layer graphene serves as an effective ion-blocking layer in perovskite heterostructures.
• This approach enables the creation of stable, sharp all-perovskite interfaces.
• The developed heterostructures show promise for advanced optoelectronic applications requiring controlled charge and light management.