Light-emitting diode with UV-blocking nano-particles
A light-emitting device has an encapsulated light-emitter. Nano-particles substantially transparent to visible light block UV light.
1 . A light-emitting device having:
encapsulant;
a light-emitter within the encapsulant; and
UV-blocking nano-particles substantially transparent to visible light.
2 . The light-emitting device of claim 1 wherein the UV-blocking nano-particles comprise nano-alumina.
3 . The light-emitting device of claim 1 wherein the UV-blocking nano-particles are incorporated in a layer disposed on the encapsulant.
4 . The light-emitting device of claim 3 wherein the layer comprises nano-alumina comprises between about 8 weight percent and about 17 weight percent in an epoxy resin.
5 . The light-emitting device of claim 4 wherein the encapsulant comprises the epoxy resin.
6 . The light-emitting device of claim 5 wherein the encapsulant further comprises between about 5 weight percent and about 10 weight percent nano-alumina.
7 . The light emitting device of claim 5 wherein the encapsulant further comprises nano-silica.
8 . The light-emitting device of claim 1 wherein the UV-blocking nano-particles are disposed in the encapsulant.
9 . The light-emitting device of claim 8 wherein the UV-blocking nano-particles comprise between about 8 weight percent and about 17 weight percent nano-alumina in a liquid encapsulant precursor material to provide an encapsulant formulation.
10 . The light-emitting device of claim 9 wherein the liquid encapsulant precursor is an elastomeric resin.
11 . The light-emitting device of claim 9 wherein the liquid encapsulant precursor is an epoxy resin.
12 . The light-emitting device of claim 11 wherein the encapsulant formulation further comprises between about 3.5 weight percent and about 5 weight percent nano-titania.
13 . The light-emitting device of claim 11 wherein the encapsulant formulation further comprises between about 12.5 weight percent and about 20 weight percent nano-silica.
14 . The light-emitting device of claim 11 wherein the epoxy resin has an initial viscosity less than about 800 centipoise.
15 . The light-emitting device of claim 1 wherein the light emitter is an LED.
16 . The light-emitting device of claim 15 wherein the LED has an operating current of at least 20 mA.
17 . The light-emitting device of claim 15 wherein the LED emits UV light.