Efficient Ultraviolet Circularly Polarized Luminescence in Zero-Dimensional Hybrid Cerium Bromides

Ultraviolet circularly polarized luminescence (UV-CPL) with high photon energy shows great potential in polarized light sources and stereoselective photopolymerization. However, developing luminescent materials with high UV-CPL performance remains challenging. Here, we report a pair of rare earth Ce³⁺-based zero-dimensional (0D) chiral hybrid metal halides (HMHs), R/S-(C₁₄H₂₄N₂)₂CeBr₇, which exhibits characteristic UV emissions derived from the Ce 5d-4f transition. The compounds show simultaneously high photoluminescent quantum yields of (32-39)% and large luminescent dissymmetry factor (|g_lum|) values of (1.3-1.5)×10^-2. Thus, the figures of merits of R/S-(C₁₄H₂₄N₂)₂CeBr₇ are calculated to be (4.5-5.8)×10^-3, which are superior to the reported UV-CPL emissive materials. Additionally, nearly 91 % of their PL intensities at 300 K can be well preserved at 380 K (LED operating temperature) without phase transition or decomposition, demonstrating the excellent structural and optical thermal stabilities of R/S-(C₁₄H₂₄N₂)₂CeBr₇. Based on these enantiomers, the fabricated UV-emitting CP-LEDs exhibit high polarization degrees of ±1.0 %. Notably, the UV-CPL generated from the devices can significantly trigger the enantioselective photopolymerization of diacetylene with remarkable stereoselectivity, and consequently yield polymerized products with the anisotropy factors of circular dichroism (g_CD) up to ±3.9×10^-2, outperforming other UV-CPL materials and demonstrating their great potential as UV-polarized light sources.