Fabrication of wafer-scale free-standing quantum dot/polymer nanohybrid films for white-light-emitting diodes using an electrospray method†
Wafer-scale free-standing quantum dot (QD)/polymer nanohybrid (NHB) based down-conversion (DC) phosphor films for remote-type white-light-emitting diodes (W-LEDs) are developed. Organic-soluble and nontoxic dodecanethiol-capped AgIn5S8/ZnS QDs and a thermoplastic polymer, poly(methyl methacrylate) (PMMA), are used as a DC material and a matrix respectively. The NHB based DC films are successfully fabricated by an electrospray (e-spray) method and the extraordinarily high concentration of QDs are able to be loaded in the resulting e-sprayed NHB films. The wafer-scale free-standing NHB films are also achieved by using a delamination method with which the e-sprayed films on a thin interlayer of a water-soluble polymer are detached from the substrates. Finally, the free-standing e-sprayed QD/polymer NHB films are successfully applied on top of conventional blue LEDs for remote-type W-LEDs. The W-LED shows the luminous efficacy of 49 lm W−1 and color rendering index (CRI) of 64 with an applied current of 60 mA.