Chiral Two-Dimensional Cu-Pb Bromides: Circularly Polarized Luminescence and Pressure-Enhanced Optical Properties

Area of Science:

• Materials Science
• Inorganic Chemistry
• Crystallography

Background:

• Limited synthetic accessibility of bimetallic halides hinders the development of high-performance double perovskite-related materials.
• Incorporating chiral organic moieties into metal halide frameworks is a strategy to engineer noncentrosymmetric structures for targeted properties.

Purpose of the Study:

• To synthesize and characterize novel chiral two-dimensional (2D) copper(I)-lead (Cu(I)-Pb) bimetallic bromides.
• To investigate the optical properties and responsiveness of these materials to external stimuli like pressure and temperature.
• To explore their potential for advanced optoelectronic applications.

Main Methods:

• Synthesis of chiral 2D Cu(I)-Pb bimetallic bromides ((R/S-PCA)4Cu2PbBr8·H2O) and Pb-based bromides ((R/S-PCA)3Pb2Br7·H2O).
• Crystallographic analysis to determine noncentrosymmetric structures.
• Optical spectroscopy (photoluminescence, circularly polarized luminescence) and DFT calculations.

Main Results:

• Synthesized two pairs of chiral 2D bimetallic bromides crystallizing in noncentrosymmetric space groups.
• Observed broadband yellow emission and circularly polarized luminescence at room temperature with significant luminescence dissymmetry factors (glum).
• R-CuPbBr showed remarkable optical property enhancements under high pressure, including increased photoluminescence and second-harmonic generation.

Conclusions:

• Chiral organic moiety incorporation enables the synthesis of novel 2D bimetallic halide structures with tunable optoelectronic properties.
• These materials exhibit promising luminescence characteristics and significant pressure-induced optical enhancements.
• The findings open new possibilities for designing advanced functional materials for optoelectronics and photonics.