Liquid-Phase van der Waals Epitaxy of a Few-Layer and Unit-Cell Thick Ruddlesden-Popper Halide Perovskite

Area of Science:

• Materials Science
• Solid-State Physics
• Optoelectronics

Background:

• 2D Ruddlesden-Popper (RP) halide perovskites offer natural multiple quantum well structures.
• These structures are ideal for vertical heterostructures, potentially yielding unique optoelectronic properties.
• Integrating different 2D RP perovskites can lead to novel functionalities not found in bulk crystals.

Purpose of the Study:

• To demonstrate liquid-phase van der Waals epitaxy of 2D RP hybrid perovskites on mica.
• To fabricate perovskite-perovskite vertical heterostructures using epitaxially grown materials.
• To investigate the optoelectronic properties, specifically interlayer emission, of these heterostructures.

Main Methods:

• Liquid-phase van der Waals epitaxy was used to grow (4,4-DFPD)₂PbI₄ nanobelt arrays on muscovite mica.
• Vertical heterostructures were fabricated by integrating the grown (4,4-DFPD)₂PbI₄ with R-NPB perovskite sheets.
• Characterization included crystallographic alignment assessment and photoluminescence lifetime measurements.

Main Results:

• Crystallographically aligned (4,4-DFPD)₂PbI₄ nanobelt arrays, down to unit-cell thickness, were successfully grown on mica.
• A novel interlayer photoemission with a lifetime of approximately 25 ns at 120 K was observed in the R-NPB/(4,4-DFPD)₂PbI₄ heterostructure.
• The growth method provides an ordered platform for 2D RP perovskites for advanced heterostructure integration.

Conclusions:

• Liquid-phase van der Waals epitaxy is a viable method for preparing ordered 2D RP perovskite arrays.
• The fabricated R-NPB/(4,4-DFPD)₂PbI₄ heterostructures exhibit unique interlayer emission, enriching understanding of charge transitions.
• This work establishes a pathway for creating complex vertical perovskite heterostructures with tailored optoelectronic properties.