Enhanced White-Light Emission from a Water-Based Coating Film via Photocycloaddition Crosslinking in a Clusteroluminescence Polymer

High Resolution Image Download MS PowerPoint Slide We obtained a water-soluble clusteroluminescence (CL) copolymer comprising a photo-responsive aromatic luminophore. The copolymer emits concentration- and excitation-dependent visible light luminescence. After photodimerization crosslinking of the photo-responsive units, a hierarchal clustered domain with densely confined space induces a fluorescence red shift via through-space interactions. In its film-forming solid state, the polymer emits high-quantum-yield fluorescence-enhanced white light. The emission is almost pure white (CIE coordinates x = 0.30, y = 0.33) and derives from the intense overlapped short- and long-wavelength CL resulting from changes in the photodimerization degree. This is the first white-light emission coating with external photo-responsiveness produced by an environmentally benign and water-based process. We present a method of efficiently increasing fluorescence by regulating the hierarchical structures of the CL polymer and restricting intermolecular motion. The polymer will be useful for thinner flexible light displays and information encryption.