White light-emitting diodes with enhanced luminous efficiency and high color rendering using separated quantum dots@silica/phosphor structure

White light-emitting diodes (WLEDs) composed of blue LED chip, yellow phosphor and red quantum dots (QDs) are considered as potential alternative for next generation artificial light source, with their high luminous efficiency (LE) and color rendering index (CRI). However, the poor compatibility of QDs/silicone and the optical reabsorption effect between the mixed QDs/phosphor particles severely hinder the wide utilization of QDs-WLEDs. Therefore, in this letter, a separated QDs/phosphor structure was proposed to eliminate the reabsorption energy losses, and a silica shell was coated onto the QDs surface to solve the compatibility problem between QDs and silicone. With CRI > 90 and R9 > 90, the newly proposed QDs@silica nanoparticles based WLEDs (QSNs-WLEDs) demonstrated a LE enhancement of 14.6 % over conventional mixed type WLEDs. Benefit from the silica shell coating, the QSNs-WLEDs also show high stability under different driving current.