Phase engineering of Cs-Pb-Br nanoparticles for tunable optical behavior

Area of Science:

• Materials Science
• Solid-State Chemistry
• Nanotechnology

Background:

• Cesium-lead-bromide (Cs-Pb-Br) nanomaterials exhibit diverse structural phases with distinct optical properties.
• Understanding the relationship between structure and luminescence is crucial for developing advanced optoelectronic devices.

Purpose of the Study:

• To investigate the tunable structural and optical properties of Cs-Pb-Br nanomaterials, including CsPbBr3, CsPb2Br5, and Cs4PbBr6.
• To explore the influence of precursor composition, reaction conditions, and external stimuli on phase formation and optical behavior.
• To elucidate the role of octahedral connectivity in governing absorption and emission characteristics.

Main Methods:

• Systematic variation of precursor composition and reaction conditions.
• Application of external stimuli (moisture, solvents) to induce controlled formation and phase transitions.
• Optical spectroscopy (absorption and emission) and density functional theory (DFT) calculations.

Main Results:

• Achieved controlled formation and reversible phase transitions among CsPbBr3, CsPb2Br5, and Cs4PbBr6 structures.
• Correlated octahedral connectivity with optical properties: CsPbBr3 (green emission, direct transitions), CsPb2Br5 (orange-red emission, indirect/forbidden transitions), Cs4PbBr6 (non-emissive).
• Demonstrated external stimuli-induced structural reorganization into emissive CsPbBr3 phase, enabling dynamic luminescence modulation.

Conclusions:

• The structural phases and emission properties of Cs-Pb-Br perovskite-inspired systems are highly tunable.
• Octahedral connectivity is a key factor determining photoluminescence behavior.
• These findings open avenues for switchable optoelectronic devices and stimuli-responsive luminescent materials.