Low-Dimensional Perovskite in Acrylic Monomers for Underwater White LED

White light-emitting low-dimensional organic-inorganic hybrid lead halide perovskite materials have been considered as candidates for next generation of light sources because of the potential in daily lighting acting as white light emitters or phosphors. However, due to the instability of perovskite materials in water, the underwater application scenario has not been well developed. In this work, we report a method employing an ultraviolet (UV)-polymerizable acrylic monomer to wrap a low dimensional white light emitting perovskite single crystal (DMEDAPbBr $_{\text{4}}$ ) powders in the polymer matrix. We investigate the exciton dynamics in this composite material by transient absorption spectra. More importantly, white light-emitting devices (WLEDs) are manufactured employing this composite material as phosphor excited by UV-LED. Thanks to the protection of the polymer matrix, the stability against the water of this WLED is very good allowing the devices to work underwater for many days. This strategy in this work illustrates a facile way for the application of white light emitting low dimensional perovskite single crystals in WLEDs.