Two-Dimensional Layered Germanium Iodide Perovskite Ferroelectric Semiconductors.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Two-dimensional (2D) semiconductors are crucial for next-generation electronics and spintronics.
• Ferroelectricity in 2D materials offers unique functionalities due to spontaneous polarization.
• Layered halide perovskites present a promising platform for low-dimensional ferroelectricity.

Purpose of the Study:

• To develop novel 2D layered germanium iodide perovskite ferroelectric semiconductors.
• To investigate their semiconducting properties and ferroelectric polarization.
• To explore their potential in photoelectronic applications.

Main Methods:

• Synthesis of a series of 2D layered germanium iodide perovskites (A2CsGe2I7, where A=PA, BA, AA).
• Characterization of their structural, electrical, and ferroelectric properties.
• Measurement of their bulk photovoltaic effect.

Main Results:

• The synthesized materials exhibit narrow direct band gaps (~1.8 eV) and high conductivity (>32.23 nS/cm).
• They demonstrate large in-plane ferroelectric polarization (>10.0 μC/cm²), attributed to Ge2+ off-centering.
• The 2D BA2CsGe2I7 shows a superior polarization-sensitive bulk photovoltaic effect (ratio 1.68, Jsc up to 81.25 μA/cm²).

Conclusions:

• A new class of 2D layered germanium iodide perovskite ferroelectric semiconductors has been successfully developed.
• These materials possess excellent semiconducting and ferroelectric properties.
• They offer a promising pathway for advanced photoelectronic devices and spintronics.