Direction and Temperature-Dependent Properties of an Antimony-Based Two-Dimensional Halide Double Perovskite

Area of Science:

• Materials Science
• Solid-State Physics
• Inorganic Chemistry

Background:

• Two-dimensional (2D) organic-inorganic halide double perovskites are recognized for their structural variety and tunable chemistry.
• These materials offer potential for advanced electronic and optoelectronic applications.

Purpose of the Study:

• To synthesize and characterize a novel 2D layered halide double perovskite, (BrPA)4AgSbBr8 (BPAS).
• To investigate and compare the structural, optical, and electrical properties of BPAS with related compounds like (BrPA)4AgInBr8 (BPAIn) and a noncentrosymmetric variant.

Main Methods:

• Crystallographic analysis to determine the crystal structure and space group (P2/c).
• Optical spectroscopy to measure the band gap and photoluminescence (PL) properties.
• Electrical transport measurements to assess charge transfer resistance and carrier mobility across varying temperatures.

Main Results:

• BPAS and BPAIn crystallize in a 2D layered structure with distorted inorganic octahedra, differing from 3D counterparts.
• Materials exhibit broadened optical gaps and PL emission influenced by band-to-band, excitonic, and self-trapped excitonic (STE) states.
• Anisotropic conduction properties were observed, with charge transfer resistance decreasing significantly with increasing temperature due to thermally activated mobility.

Conclusions:

• The distorted octahedral geometry in 2D double perovskites broadens optical gaps and influences PL characteristics.
• The 2D layered structure results in anisotropic charge transport, with conductivity modulated by temperature via a correlated barrier hopping mechanism.