Robust Heterostructures in Two-Dimensional Perovskites by Threshold-Dominating Anion Exchange.

Area of Science:

• Materials Science
• Solid-State Chemistry
• Optoelectronics

Background:

• Heterostructures are crucial for high-performance optoelectronic devices.
• Preparing robust perovskite heterostructures is difficult due to halogen anion interdiffusion.

Purpose of the Study:

• To develop a universal vapor-phase anion exchange method for robust 2D Ruddlesden-Popper perovskite (RPP) heterostructures.
• To investigate anion diffusion mechanisms and stability in 2D perovskites.

Main Methods:

• Fabrication of 2D RPP heterostructures using exfoliated RPP microplates via vapor-phase anion exchange.
• Experimental studies on anion diffusion behavior (lateral vs. vertical) influenced by organic cations.
• Quantitative investigation of halogen anion diffusion coefficients.

Main Results:

• A new vapor-phase anion exchange method successfully created robust 2D RPP heterostructures.
• Anion diffusion in 2D RPPs exhibits threshold-dominating lateral transport and suppressed vertical transport, dependent on organic cations.
• Lateral diffusion coefficients are 6-7 orders of magnitude larger than vertical coefficients, indicating highly anisotropic diffusion.
• Anion exchange thresholds enhance thermodynamic stability at elevated temperatures.

Conclusions:

• The developed method provides a general route to fabricate robust lateral RPP heterostructures.
• The study offers critical insights into the unique anisotropic anion diffusion behavior in low-dimensional perovskites.
• This work paves the way for improved stability and performance in perovskite-based optoelectronic devices.