by Researchers from the Fujian Institute of Research on the Structure of Matter of the Chinese Academy of Sciences have successfully designed a series of enantiomeric lead-free halide double perovskites using an innovative achiral-chiral cation intercalation strategy. The study, published in the journal Chem, presents a new approach to exploring chiral lead-free halide double perovskites, which hold great potential in various fields such as remote sensing, three-dimensional display, and optical information storage.
Chiral optical materials have gained significant attention across multiple disciplines due to their versatile applications in various industries. However, the scarcity of chiral lead-free double perovskites has been a challenge in harnessing their unique properties. The main hurdle lies in the limited availability of organic cations in the interlayer of double perovskites, restricting the selective domain of chiral cations.
To overcome this challenge, the researchers utilized an achiral-chiral cation intercalation strategy. By intercalating diverse cations, including achiral cations, the researchers achieved charge conservation and overall steric hindrance balance. This modification led to the arrangement of original intercalated cations changing from a single cation A to diverse cations A+A’, where A’ represents abundant achiral cations.
The team successfully synthesized six new enantiomeric lead-free halide double perovskites using this achiral-chiral cation intercalation strategy. These perovskites, namely (R/S-PPA)2(BA)2AgBiBr8, (R/S-PPA)2(BrPA)2AgBiBr8, and (R/S-PPA)2(Br-EA)2AgBiBr8, demonstrated the feasibility of this novel synthesis approach.
Single crystal X-ray diffraction analysis revealed that the achiral and chiral cations arranged alternately and formed various non-covalent intermolecular interactions, such as CH···π, π···π, and CH···Br. These interactions allowed the stable coexistence of chiral organic cations and achiral organic cations in the chiral halide double perovskites.
Furthermore, the researchers discovered that chiral compounds tend to possess a more distorted structure due to their inherent asymmetric features. Larger structural distortions result in lower crystal symmetries, causing asymmetry breaking and enabling the generation of circular dichroism (CD) and second harmonic generation (SHG) signals.
The (R/S-PPA)2(Br-EA)2AgBiBr8 compounds, for instance, exhibited a strong nonlinear optical response up to two times that of the state-of-the-art KH2PO4 nonlinear crystals. Additionally, they demonstrated robust circular dichroism signals in the visible region.
This study not only provides a new avenue for exploring chiral lead-free halide double perovskites but also showcases the potential of these materials in chiroptical and optoelectronic applications. With their stable and environmentally-friendly properties, these two-dimensional chiral perovskites could revolutionize various industries, including remote sensing, three-dimensional display technology, and optical information storage.
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Source: Coherent Market Insights, Public sources, Desk research
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