Preparation of a photo-degradation- resistant quantum dot-polymer composite plate for use in the fabrication of a high-stability white-light-emitting diode.

We report on the synthesis of highly fluorescent double-ZnS-shell-capped, yellow-emitting Cu-In-S quantum dots (QDs) with a surprisingly high quantum yield of 92%, the preparation of a free-standing QD-polymethylmethacrylate composite plate, and the application of the QD plate in the fabrication of QD-based white-light-emitting diodes (WLEDs). A free-standing QD plate with QDs embedded uniformly inside a polymeric matrix is used to fabricate a remote-type, resin-free WLED. The QD plate-based WLED displays a high luminous efficiency; however, it suffers from a significantly unstable device performance due to QD degradation upon prolonged photo-excitation. An exceptional operational stability of the QD plate-based WLED is realized by generating hybrid double layers of an organic adhesion layer and a gas barrier layer of sol-gel-derived silica, rendering the QD plate impermeable to oxygen. Our success in achieving a color converter robust against photo-degradation and applying it in the fabrication of a reliable QD-based LED is greatly encouraging as regards the development of next-generation QD-based LED lighting sources.