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 Ce 3+ -based zero-dimensional (0D) chiral hybrid metal halides (HMHs), R/S-(C 14 H 24 N 2 ) 2 CeBr 7 , 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-(C 14 H 24 N 2 ) 2 CeBr 7 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-(C 14 H 24 N 2 ) 2 CeBr 7 . 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.