Diiodine-Induced Dimensionality Evolution in Two Antimony(III) Halides for Optimal-Bandgap Photovoltaics

Area of Science:

• Materials Science
• Solid-State Chemistry
• Optoelectronics

Background:

• Developing stable, lead-free hybrid metal halides for optoelectronics is challenging.
• Precisely controlling crystalline phases and electronic structures is crucial for material performance.

Purpose of the Study:

• To report a novel lead-free hybrid material with enhanced optoelectronic properties.
• To investigate the structural and electronic consequences of iodine-induced phase transitions.

Main Methods:

• Controlled solution-cooling crystallization to synthesize single crystals.
• X-ray diffraction (XRD), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) for characterization.
• Theoretical calculations to elucidate electronic structures and optical properties.

Main Results:

• A structural transition from 1D (C6H11NH3)2SbI5 to a 0D supramolecular host-guest complex (C6H11NH3)3[Sb2I9]·I2 was achieved.
• N-H···I hydrogen bonding and halogen bonding stabilized the structure and anchored iodine guests.
• The material exhibited high phase purity, thermal stability, and a direct optical bandgap of 1.46 eV.

Conclusions:

• Supramolecular host-guest interactions effectively modulate lattice evolution in lead-free antimony-based materials.
• Halogen guest engineering is a viable strategy for designing advanced optoelectronic materials.
• The developed material shows significant potential for visible-light harvesting applications.