A fluorescein-centered polymer as a phosphor for fabricating pure white light-emitting diodes

Abstract

White light-emitting diodes (LEDs) are very important energy-saving lighting devices. It is still a big challenge to fabricate pure white LEDs using low-cost, easy-to-process and environment-friendly phosphors. Herein, we report a pure white LED fabricated by combining rationally designed fluorescein-centered polymers with a blue LED chip. Pure white LEDs with Commission International de L’Eclairage (CIE) coordinates of (0.33, 0.33), a satisfactory color rendering index (CRI) of 82 and a correlated color temperature (CCT) of 5230 K were achieved. Covalently embedding fluorescein into the center of the polymer chain realized molecular dispersion of fluorescein. Of significance, by varying the types of the side groups of the polymer, the fluorescence properties of the embedded fluorescein unit can be regulated. The performance parameters (i.e., emission spectra, CIE coordinates, CRI and CCT) of the as-fabricated LEDs could also be tailored by varying the working voltages, and the types and amounts of fluorescein-centered polymers.