Highly Distorted Chiral Two-Dimensional Tin Iodide Perovskites for Spin Polarized Charge Transport

Area of Science:

• Materials Science
• Solid-State Physics
• Organic Chemistry

Background:

• Chiral organic molecules can impart unique properties to hybrid materials.
• Organic/inorganic hybrid 2D metal-halide perovskites are a class of materials with tunable electronic and optical properties.
• Understanding the interplay between organic and inorganic components is crucial for designing novel functional materials.

Purpose of the Study:

• To synthesize and characterize new chiral hybrid tin iodide perovskites.
• To investigate the structural, chiroptical, and electronic properties of these materials.
• To explore the spin-dependent charge transport in these chiral perovskites.

Main Methods:

• Synthesis of layered tin iodide perovskites templated by chiral (R/S-)methylbenzylammonium (MBA) cations.
• Structural characterization to analyze octahedral bond distortion.
• Optical absorption spectroscopy to determine chiroptical activity.
• Electrical transport measurements on oriented thin films to assess spin polarization.

Main Results:

• Three new layered tin iodide perovskites, (R/S-MBA)2SnI4, were synthesized, exhibiting significant octahedral bond distortion.
• Chiral MBA cations induced circularly polarized absorption in the inorganic Sn-I sublattice (300-500 nm).
• Spin-dependent charge transport was observed in oriented (R/S-MBA)2SnI4 thin films, with spin polarization up to 94% due to the chiral-induced spin selectivity (CISS) effect.

Conclusions:

• Chiral hybrid semiconductors based on tin iodide perovskites offer a promising platform for spintronics.
• The structural and electronic properties can be tuned by alloying with lead.
• These materials demonstrate significant potential for controlling both spin and charge degrees of freedom.