Display devices comprising green-emitting quantum dots and red KSF phosphor

Abstract

LED devices emitting white light comprise a blue-emitting LED, green-emitting quantum dots (QDs) and red-emitting K₂SiF₆:Mn⁴⁺ (KSF) phosphor. A backlight unit (BLU) for a liquid crystal display (LCD) comprises one or more blue-emitting LEDs and a polymer film containing green-emitting QDs and KSF phosphor. The QDs and/or KSF phosphor may be encapsulated in beads that provide protection from oxygen and/or moisture.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS:[0001]This application claims the benefit of U.S. Provisional Application No. 62 / 249,595 filed on Nov. 2, 2015, the contents of which are hereby incorporated by reference in their entirety.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]Not ApplicableBACKGROUND OF THE INVENTION[0003]1. Field of the Invention.[0004]The present invention relates to materials and processes for the production of display devices. More specifically, the invention relates to backlight units for display devices comprising quantum dots and K2SiF6:Mn4+ (KSF) phosphor.[0005]2. Description of the Related Art including information disclosed under 37 CFR 1.97 and 1.98.[0006]Quantum dots (QDs) have been used in the backlight unit (BLU) of liquid crystal displays (LCDs) to improve the color gamut compared to conventional LCD backlight units comprising a blue LED and a conventional rare earth phosphor. The color gamut is compared to standards in the Commis...

AI Technical Summary

Benefits of technology

[0013]Herein, a method is disclosed for combining a blue-emitting LED, green-emitting QDs, and red-emitting KSF phosphor to produce white light with a wide color gamut, in such a way that the optical properties of the QDs are not deteriorated by exposure to heat. LED devices comprising a blue-emitting LED chip, green-emitting QDs and red-emitting KSF phosphor are also disclosed.

Problems solved by technology

However, achieving good overlap with Rec. 2020 is a challenge, in part owing to the full-width at half-maximum (FWHM) of the spectral emission peaks of the QDs.

However, in the EU, the Restriction of the Use of Certain Hazardous Substances (RoHS) Directive limits the amount of cadmium (and other heavy-metals) that may be used in electrical and electronic equipment.

Though the study demonstrates that a large color gamut may be achieved by combining green QDs with a red KSF phosphor, the CH3NH3PbX3 QDs are not currently commercially available and contain lead, another heavy-metal subject to RoHS regulations.

Further, the on-chip configuration may create thermal stability issues due to the close proximity of the QDs to the LED chip, resulting in short device lifetimes.

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