Quantum dot-based color-converted light emitting device and method for manufacturing the same

1. A light-emitting device comprising:

a flip-chip light-emitting diode (LED) semiconductor chip configured to provide a primary light;

a photoluminescent structure comprising a first photoluminescent layer, an optically transparent isolation layer, a second photoluminescent layer, and an optically transparent moisture barrier layer, wherein:

the first photoluminescent layer, comprising a first polymer matrix material and a lower-excitation-energy-level phosphor material dispersed within the first polymer matrix material, is disposed on a chip-upper surface of the flip-chip LED semiconductor chip; the optically transparent isolation layer is disposed on the first photoluminescent layer; the second photoluminescent layer, comprising a second polymer matrix material and a higher-excitation-energy-level quantum dot material dispersed within the second polymer matrix material, is disposed on the optically transparent isolation layer; and the optically transparent moisture barrier layer is disposed on the second photoluminescence layer; and

a moisture-barrier reflective structure covering a photoluminescent-side surface of the photoluminescent structure and a chip-edge surface of the flip-chip LED semiconductor chip, but not covering a lower electrode surface of the flip-chip LED semiconductor chip;

wherein,

the lower-excitation-energy-level phosphor material of the first photoluminescent layer is configured to convert a portion of the primary light into a lower-energy-level visible light, and

wherein the moisture-barrier reflective structure comprises a third polymer matrix material and light scattering particles dispersed within the third polymer matrix material, and wherein the third polymer matrix material has a water vapor transmission rate of not more than 20 g/(m 2 ⋅day) at a thickness of 1 mm, and

wherein an intensity of an unconverted portion of the primary light is not greater than a light intensity that the higher-excitation-energy-level quantum dot material can sustain; the primary light is a blue light, a deep blue light, a violet light or an ultraviolet light the lower-excitation-energy-level phosphor material comprises a red phosphor material; and the higher-excitation-energy-level quantum dot material comprises a green quantum dot material.

2. The light-emitting device of claim 1 , wherein the green quantum dot material is capable of sustaining a light intensity of the primary light of no more than 10 W/cm 2 .

3. The light-emitting device of claim 1 , wherein the photoluminescent structure further comprises an optically transparent heat-spreading layer disposed adjacent to the second photoluminescent layer; and a thermal conductivity of the optically transparent heat-spreading layer is greater than a thermal conductivity of the optically transparent moisture barrier layer or the optically transparent isolation layer.

4. The light-emitting device of claim 3 , wherein the optically transparent heat-spreading layer comprises a metallic thin film, a metallic mesh grid, a transparent conductive oxide or graphene.

5. The light-emitting device of any one of claims 1 and 2 to 4 , wherein the photoluminescent structure further comprises an optically transparent spacer layer, and the first photoluminescent layer is disposed on the optically transparent spacer layer.

6. The light-emitting device of any one of claims 1 and 2 to 4 , further comprising a chip-edge-surface spacer structure covering the chip-edge surface of the flip-chip LED semiconductor chip, wherein the chip-edge-surface spacer structure comprises an inclined side-spacer surface slanted with respect to the chip-edge surface of the flip-chip LED semiconductor chip, and is covered by the moisture-barrier reflective structure.

7. The light-emitting device of any one of claims 1 and 2 to 4 , wherein the first polymer matrix material is solidified by thermal curing, and the second polymer matrix material is solidified by ultraviolet light curing.

8. The light-emitting device of any one of claims 1 and 2 to 4 , wherein at least one of the optically transparent isolation layer or the optically transparent moisture barrier layer comprises an optically transparent inorganic material.

9. The light-emitting device of any one of claims 1 and 2 to 4 , wherein at least one of the optically transparent isolation layer or the optically transparent moisture barrier layer comprises a polymer matrix material having a water vapor transmission rate of not more than 20 g/(m 2 ⋅day) at a thickness of 1 mm.

10. The light-emitting device of any one of claims 1 and 2 to 4 , wherein the moisture-barrier reflective structure has a thermal conductivity that is not less than a thermal conductivity of the optically transparent isolation layer or a thermal conductivity of the optically transparent moisture barrier layer.

11. The light-emitting device of any one of claims 1 and 2 to 4 , wherein the second photoluminescent layer further comprises light scattering particles, and the light scattering particles are dispersed in the second polymer matrix material.

12. The light-emitting device of any one of claims 1 and 2 to 4 , wherein the red phosphor material comprises a fluoride phosphor material or a nitride phosphor material.

13. The light-emitting device of claim 12 , wherein the fluoride phosphor material comprises at least one of: (A) A 2 [MF 6 ]: Mn 4+ , wherein A is selected from the group consisting of Li, Na, K, Rb, Cs, NH 4 , and combinations thereof, and M is selected from the group consisting of Ge, Si, Sn, Ti, Zr, and combinations thereof; (B) E 2 [MF 6 ]: Mn 4+ , wherein E is selected from the group consisting of Mg, Ca, Sr, Ba, Zn, and combinations thereof, and M is selected from the group consisting of Ge, Si, Sn, Ti, Zr, and combinations thereof; (C) Ba 0.65 Zr 0.35 F 2.70 : Mn 4+ ; or (D) A 3 [ZrF 7 ]: Mn 4+ , wherein A is selected from the group consisting of Li, Na, K, Rb, Cs, NH 4 , and combinations thereof.

14. The light-emitting device of claim 12 , wherein the fluoride phosphor material comprises:

(x-a) MgO⋅(a/2)⋅Sc 2 O 3 ⋅yMgF 2 ⋅cCaF 2 ⋅(1-b) GeO 2 ⋅(b/2) Mt 2 O 3 : zMn 4+ ; wherein, 2.0≤x≤4.0, 0<y<1.5, 0<z<0.05, 0≤a<0.5, 0<b<0.5, 0≤c<1.5, y+c<1.5, and Mt is selected from the group consisting of Al, Ga, and In.

15. The light-emitting device of any one of claims 1 and 2 to 4 , wherein the second photoluminescent layer further comprises a blue quantum dot material.

16. A method of manufacturing a light-emitting device, comprising:

laminating a flip-chip LED semiconductor chip to a photoluminescent structure; and

forming a moisture-barrier reflective structure to cover a photoluminescent-side surface of the photoluminescent structure and a chip-edge surface of the flip-chip LED semiconductor chip;

wherein:

the photoluminescent structure includes a first photoluminescent layer, an optically transparent isolation layer, a second photoluminescent layer, and an optically transparent moisture barrier layer, wherein:

the first photoluminescent layer, comprising a first polymer matrix material and a lower-excitation-energy-level phosphor material dispersed within the first polymer matrix material, is disposed to cover a chip-upper surface of the flip-chip LED semiconductor chip; the optically transparent isolation layer is disposed on the first photoluminescent layer; the second photoluminescent layer, comprising a second polymer matrix material and a higher-excitation-energy-level quantum dot material dispersed within the second polymer matrix material, is disposed on the optically transparent isolation layer; and the optically transparent moisture barrier layer is disposed on the second photoluminescent layer;

the moisture-barrier reflective structure covers the photoluminescent-side surface of the photoluminescent structure and the chip-edge surface of the flip-chip LED semiconductor chip, but does not cover a lower electrode surface of the flip-chip LED semiconductor chip; and

the flip-chip LED semiconductor chip is configured to provide a primary light, the primary light being a blue light, a deep blue light, a violet light, or an ultraviolet light, and the lower-excitation-energy-level phosphor material of the first photoluminescent layer is configured to convert a portion of the primary light into a lower-energy-level visible light such that an intensity of an unconverted portion of the primary light is not greater than a light intensity that the higher-excitation-energy-level quantum dot material can sustain.

17. The method of claim 16 , further comprising:

forming the photoluminescent structure, comprising:

providing the optically transparent moisture barrier layer;

forming the second photoluminescent layer on the optically transparent moisture barrier layer;

forming the optically transparent isolation layer on the second photoluminescent layer; and

forming the first photoluminescent layer on the optically transparent isolation layer.

18. The method of claim 16 , further comprising:

forming the photoluminescent structure, comprising:

providing the optically transparent moisture barrier layer and forming the second photoluminescent layer on the optically transparent moisture barrier layer;

providing the optically transparent isolation layer and forming the first photoluminescent layer on the optically transparent isolation layer; and

laminating the second photoluminescent layer to the optically transparent isolation layer.

19. The method of claim 16 ,

wherein:

the photoluminescent structure further comprises an optically transparent heat-spreading layer adjacent to the second photoluminescent layer;

and

the optically transparent heat-spreading layer has a thermal conductivity greater than a thermal conductivity of the optically transparent isolation layer or a thermal conductivity of the optically transparent moisture barrier layer.

20. The method of any one of claims 16 to 19 , wherein the photoluminescent structure further comprises an optically transparent spacer layer formed on the first photoluminescent layer, wherein the optically transparent spacer layer faces and covers the chip-upper surface of the flip-chip LED semiconductor chip.

21. The method of any one of claims 16 to 19 , further comprising:

forming a chip-edge-surface spacer structure on the first photoluminescent layer and covering the chip-edge surface of the flip-chip LED semiconductor chip, wherein the chip-edge-surface spacer structure comprises an inclined side-spacer surface slanted with respect to the chip-edge surface of the flip-chip LED semiconductor chip;

wherein, when forming the moisture-barrier reflective structure, the moisture-barrier reflective structure covers the inclined side-spacer surface of the chip-edge-surface spacer structure.