Flexible quantum dot–PVA composites for white LEDs

Abstract

Integration of blue light-emitting diode (LED) chips with yellow phosphors has been the most practical way to achieve white lighting, but finding a low-cost alternative for Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce) phosphors, which are expensive and lack red emission, is still a great challenge. The present report documents a strategy of combining quantum dot–polyvinyl alcohol (PVA) composites and blue chips for white LEDs. Cadmium-free and water-soluble ZnSe:Mn/ZnS quantum dots (QDs) were synthesized through a nucleation doping strategy, and then embedded in PVA. The flexible composite contains well-dispersed QDs and exhibits highly efficient photoluminescence at 590–635 nm, and hence is available for resin-free white LEDs. Besides excellent stability, the assembled white LEDs possess promising color characteristics, including a color rendering index (CRI) value of 93.5, a correlated color temperature (CCT) of 2913 K at Commission Internationale de l'Eclairage (CIE) color coordinates of (0.41,0.37), and a luminous efficacy (LE) of 18.9 lm W⁻¹ under 300 mA current excitation. This work demonstrates that such a silica-coated QD–PVA composite plate, as a reliable color converter, would be promising for the next-generation QD-based LEDs.