Methylphosphonium Tin Bromide: A 3D Perovskite Molecular Ferroelectric Semiconductor

Area of Science:

• Materials Science
• Solid-State Physics
• Crystallography

Background:

• 3D ABX₃ organic-inorganic halide perovskites (OIHPs) are promising semiconductors.
• Low-dimensional lead-based OIHP ferroelectrics are known, but 3D versions are challenging to synthesize.
• Developing novel 3D OIHP ferroelectric semiconductors is crucial for advanced electronic applications.

Purpose of the Study:

• To synthesize a novel lead-free 3D ABX₃ OIHP ferroelectric semiconductor.
• To investigate the ferroelectric properties and bandgap of the synthesized material.
• To explore the potential of A-site cation engineering in OIHP ferroelectrics.

Main Methods:

• Synthesis of MPSnBr₃ using methylphosphonium (MP) as the A-site cation.
• Characterization of ferroelectric properties, including above-room-temperature ferroelectricity.
• Determination of the material's direct bandgap using optical spectroscopy.

Main Results:

• Successful synthesis of MPSnBr₃, the first MP-based 3D ABX₃ OIHP ferroelectric semiconductor.
• Demonstration of clear above-room-temperature ferroelectricity in MPSnBr₃.
• Measurement of a direct bandgap of 2.62 eV for MPSnBr₃.
• Identification of MPSnBr₃ as a multiaxial molecular ferroelectric with 12 polar axes, exceeding known OIHP and inorganic perovskite ferroelectrics.

Conclusions:

• MPSnBr₃ represents a significant advancement in 3D OIHP ferroelectric semiconductor research.
• The multiaxial nature and high number of polar axes in MPSnBr₃ offer unique opportunities for device applications.
• This work provides a new platform for designing and discovering other high-performance 3D OIHP ferroelectric semiconductors.