Rashba Spin Splitting Limiting the Application of 2D Halide Perovskites for UV-Emitting Devices.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Optoelectronics

Background:

• Layered lead halide perovskites are promising for optoelectronic devices.
• Understanding their fundamental properties is crucial for application development.

Purpose of the Study:

• Investigate the properties of 2D-layered (BA)2PbX4 perovskites with varying halide anions (X = I, Br, Cl).
• Explore the relationship between structural distortions, Rashba spin splitting, and optical properties.

Main Methods:

• Experimental measurements (cell parameter evolution, optical measurements).
• Theoretical calculations (ab initio calculations).

Main Results:

• Strong lattice distortions in metal halide octahedra observed, breaking local inversion symmetry in (BA)2PbCl4.
• Pronounced Rashba spin-splitting effect correlated with structural distortions.
• Photoluminescence quenching and reduced quantum yield in larger band gap (BA)2PbCl4.
• Calculated electrical polarization of 0.13 μC/cm² and spin-splitting energy of ~40 meV for (BA)2PbCl4.

Conclusions:

• Local octahedra distortions in layered perovskites induce Rashba spin splitting.
• The presence of Rashba effect, linked to local electric dipoles, contributes to reduced photoluminescence quantum yield.
• This mechanism explains the difficulty in developing high-PLQY UV-emitting perovskite materials.