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. (© 2024 Wiley-VCH GmbH)