Multifunctional Polar 2D Lead Iodide Perovskites Exhibiting Persistent Spin Texture

Area of Science:

• Materials Science
• Solid-State Physics
• Chemistry

Background:

• Ferroelectric Rashba semiconductors offer switchable spin textures for spin-orbitronics.
• Hybrid organic-inorganic perovskites are tunable but their interactions are poorly understood.

Purpose of the Study:

• To synthesize new polar 2D lead iodide perovskites with enhanced properties.
• To understand the role of asymmetric spacer cations in achieving noncentrosymmetry.

Main Methods:

• Synthesis of novel 2D perovskites using 2-fluorobenzylammonium (2FBZ) spacer cations.
• Single-crystal structure analysis and Density Functional Theory (DFT) calculations.
• Characterization of symmetry-dependent properties like second harmonic generation and ferroelectric polarization.

Main Results:

• Three new polar 2D perovskites with C_2v symmetry and n > 1 quantum well thickness were synthesized.
• Structural distortions enabling Rashba and Dresselhaus band splitting and persistent spin texture were confirmed.
• Switchable ferroelectric semiconducting properties were demonstrated.

Conclusions:

• A general chemical design strategy for polar symmetry in quasi-2D halide perovskites was introduced.
• The interplay between asymmetric spacer cations and A-site cations is key for multifunctional materials.
• These materials hold promise for future spin-orbitronic applications.