The First Chiral Cerium Halide towards Circularly-polarized Luminescence in the UV Region

Chiral organic-inorganic hybrid metal halides (OIHMHs) have attracted broader scientific community recently in circularly polarized photodetectors, spin light-emitting diodes and circularly polarized light-emitting diodes. However, the emission peaks of the reported chiral OIHMHs mainly locate in the visible region, and chiral OIHMH with ultraviolet (UV) circularly polarized luminescence (CPL) has been rarely reported. To fill this gap, cerium, a unique rare-earth (RE) element with tunable luminescence from UV to the visible region owing to the 4f-related electronic transition, was introduced to construct the first RE-based chiral OIHMHs, R/S-MCC. The chirality is successfully transferred from the chiral organic cations to the inorganic cerium chloride framework in R/S-MCC, as confirmed by the single crystal structures, circular dichroism and circularly polarized luminescence. The emission spectra of R/S-MCC are in the UV region, originating from the characteristic d-f transition of Ce3+, which making the Ce-based metal halides are ideal candidates towards CPL light sources in the UV region. Notably, R/S-MCC are the first RE-based OIHMHs, also the first chiral metal-halides with UV CPL. Our work opens a new avenue for the development of the chiral OIHMH family towards RE-based chiral OIHMH. The RE-based chiral metal halides couple the unique and superior optical, electrical, magnetic and spintronic properties of RE elements with chirality could accelerate the development of chiral optoelectronics and spintronics toward real applications.