Chiral Two-Dimensional Cu-Pb Bromides: Circularly Polarized Luminescence and Pressure-Enhanced Optical Properties.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41110170.
- Also identified by DOI 10.1021/acsnano.5c14764.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
The search for high-performance double perovskite-related materials remains constrained by the limited synthetic accessibility of bimetallic halides compared to their conventional halide double perovskite counterparts, leaving substantial unexplored territory in this domain. A promising structural modification strategy involves the incorporation of chiral organic moieties into the metal halide frameworks, enabling precise engineering of noncentrosymmetric structures toward targeted functional properties. Here, we report a pair of chiral two-dimensional (2D) Cu(I)-Pb bimetallic bromides (<i>R</i>/<i>S</i>-PCA)<sub>4</sub>Cu<sub>2</sub>PbBr<sub>8</sub>·H<sub>2</sub>O (<i>R</i>/<i>S</i>-CuPbBr, <i>R</i>/<i>S</i>-PCA = <i>R</i>/<i>S</i>-3-piperidinecarboxylic acid) and investigate their behavior under external stimuli including pressure and temperature. The <i>R</i>/<i>S</i>-CuPbBr compounds crystallize in a noncentrosymmetric monoclinic <i>C</i>2 space group, consisting of inorganic bimetal [Cu<sub>2</sub>PbBr<sub>8</sub>] layers and organic layers formed via hydrogen bonding interactions. For comparison, another pair of 2D Pb-based bromides (<i>R</i>/<i>S</i>-PCA)<sub>3</sub>Pb<sub>2</sub>Br<sub>7</sub>·H<sub>2</sub>O (<i>R</i>/<i>S</i>-PbBr) was synthesized, crystallizing in the noncentrosymmetric orthorhombic <i>P</i>2<sub>1</sub>2<sub>1</sub>2<sub>1</sub>. These materials exhibit broadband yellow emission and circularly polarized luminescence emission at room temperature. The <i>g</i><sub>lum</sub> values of <i>R</i>/<i>S</i>-CuPbBr and <i>R</i>/<i>S</i>-PbBr are 8.63 × 10<sup>-3</sup> and -7.99 × 10<sup>-3</sup>, 4.33 × 10<sup>-3</sup> and -3.52 × 10<sup>-3</sup>, respectively. Density functional theory (DFT) calculations reveal <i>R</i>/<i>S</i>-CuPbBr and <i>R</i>/<i>S</i>-PbBr are indirect and direct bandgap semiconductors, respectively. More importantly, <i>R</i>-CuPbBr exhibits dramatic enhancements in optical properties under high pressure, with an 8-fold increase in photoluminescence and 44-fold boost in second-harmonic generation at elevated pressure.