title: Color-converting bilayered composite plate of quantum-dot-polymer for high-color rendering white light-emitting diode.
abstract: Highly bright CuInS₂ quantum dots (QDs), whose emission is easily tuned in orange and greenish-yellow colors through manipulating the ZnS shelling procedure, are integrated with polymethyl methacrylate (PMMA) to obtain a free-standing composite plate of QD-polymer. The composite plate embedded with orange or greenish-yellow QDs is combined in a remote type with a blue light-emitting diode (LED). No color rendering index (CRI) value results when orange QDs are applied, whereas use of greenish-yellow QDs leads to a limited CRI of 72. A higher-color rendering QD-LED is demonstrated through a spectral extension by devising a unique bilayer-structured QD plate, where two types of QD are separately incorporated into each PMMA matrix, with a buffer layer of polymer blend inserted between them. The bilayered QD plate LED exhibits an improved CRI of 81, a high luminous efficacy of 71.2 lm/W at an input current of 20 mA, and exceptional high-stability luminescent characteristics against the variation of applied current.
authors.affiliation: Department of Materials Science and Engineering, Hongik University, Seoul, South Korea.
authors.forename: Jong-Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Woo-Seuk
authors.initials: WS
authors.lastname: Song
authors.forename: Heesun
authors.initials: H
authors.lastname: Yang