Blue-Light-Emitting Photostable Hybrid Films for High-Efficiency Large-Area Light Converter and Photonic Applications

A blue fluorophore of Schiff base zinc complex is prepared by a hydrolysis free solution-based synthetic method. Under ultraviolet (UV) excitation, the complex produces blue emission with a quantum yield (Q) of 42.6% in methylene chloride and 24.0% in standalone powder form. Quantum mechanical calculations show that the blue emission is generated by the change in the chemical state of the ligand associated with the complexation with Zn cations. Thin films of Zn complexes incorporated in polymethylmethacrylate (PMMA) and cellulose acetate butyrate (CAB) polymers are also prepared by dispersing the complexes into the polymer matrices. These hybrid polymer films exhibit several notable features, particularly enhanced luminescence efficiency (with maximum Q of 85.8% for PMMA and 30.0% for CAB) and scalability for fabrication over a large area while retaining the original properties of the host polymers. Light-emitting diodes are also fabricated using the CAB hybrid thin films, and they show a Q of 43.2% with excellent photostability. The complex and its hybrid films demonstrate their great potential for such applications as UV-to-blue conversion devices in photoelectronics, solar-cell concentrators, solid-state lighting and display, and greenhouse agriculture.