Quantum dot films, lighting devices, and lighting methods

1. A display backlighting unit (BLU), comprising:

(a) at least one primary light source that emits primary light;

(b) a light guide panel (LGP) optically coupled to the at least one primary light source, whereby the primary light is transmitted through the LGP;

(c) a remote phosphor film comprising at least two populations of light emitting quantum dots (QDs), wherein the remote phosphor film is disposed over the LGP, wherein the primary light transmits through the LGP and into the remote phosphor film;

(d) a first barrier film and a second barrier film, wherein the first and second barrier films are each disposed adjacent the remote phosphor film and on opposite sides thereof, and wherein the remote phosphor film is not directly physically coupled to the LGP;

(e) a first reflector film disposed beneath the LGP, wherein the first reflector film reflects primary light toward the QDs in the remote phosphor film; and

(f) a second reflector film disposed on top of the remote phosphor film, wherein the second reflector film reflects and recycles a portion of the primary light, such that the portion of the primary light has an increased optical path length within the remote phosphor film to cause increased primary light absorption by the QDs and thereby increase emission of secondary light.

2. The BLU of claim 1 , wherein the second reflector film comprises a brightness enhancing film (BEF).

3. The BLU of claim 1 , wherein the at least two populations of light emitting QDs comprises a first population of QDs configured to emit first secondary light and a second population of QDs configured to emit second secondary light at a different wavelength than the first secondary light, whereby at least a portion of the primary light is absorbed by the two populations of QDs and reemitted by the QDs as the first and second secondary light.

4. The display BLU of claim 2 , wherein:

each of the first and second barrier films includes a polymer sublayer and an oxide sublayer; and

one of the first and second barrier films is directly physically coupled to the LGP.

5. The display BLU of claim 2 , wherein the second reflector film further comprises:

a first BEF configured to reflect and recycle a first portion of the primary light; and

a second BEF configured to reflect and recycle a second portion of the primary light;

wherein the first portion of the primary light and the second portion of the primary light have different incident angle ranges towards the second reflector film.

6. The display BLU of claim 5 , wherein the second reflector film further comprises:

a third BEF configured to reflect and recycle a third portion of the primary;

wherein the third portion of the primary light has a different incident angle range towards the second reflector film compared to the first portion and the second portion of the primary light.

7. The display BLU of claim 5 , wherein the at least one of the BEF and the second BEF is a reflective polarizer BEF.

8. The BLU of claim 1 , wherein the first reflector film is a white film.

9. The BLU of claim 1 , wherein the first reflector film comprises a reflective mirror.

10. The BLU of claim 1 , wherein the first reflector film comprises scattering features.

11. The display BLU of claim 1 , wherein the remote phosphor film comprises a plurality of layers.

12. The display BLU of claim 1 , wherein the remote phosphor film comprises a plurality of individual films cut from one or more larger phosphor films.

13. The display BLU of claim 1 , wherein a thickness of the polymer sublayer and a thickness of the oxide sublayer are less than a quarter of a thickness of the remote phosphor film.

14. A display backlighting unit (BLU), comprising:

(a) at least one primary light source that emits primary light;

(b) a light guide panel (LGP) optically coupled to the at least one primary light source, whereby the primary light is transmitted through the LGP;

(c) a remote phosphor film comprising at least two populations of light emitting quantum dots (QDs), wherein the remote phosphor film is disposed beneath the LGP, wherein the primary light transmits through the LGP and into the remote phosphor film;

(d) a barrier film disposed adjacent a top surface of the remote phosphor film and a first reflector film disposed on an opposite side thereof, and wherein the remote phosphor film is not directly physically coupled to the LGP; and

(e) a second reflector film disposed on top of the LGP, wherein the second reflector film reflects and recycles a portion of the primary light, such that the portion of the primary light has an increased optical path length within the remote phosphor film to cause increased primary light absorption by the QDs and thereby increase emission of secondary light.

15. The BLU of claim 14 , wherein the second reflector film comprises a BEF.

16. The BLU of claim 14 , wherein the first reflector film comprises one or more plastic or polymer barrier film layers and one or more reflective material layers.

17. The BLU of claim 14 , wherein the first reflector film includes at least a first plastic or polymer barrier layer disposed directly adjacent to and in direct physical contact with the QD remote phosphor film, and a reflective film layer comprising a metal layer beneath the barrier layer.

18. The BLU of claim 17 , wherein the metal layer comprises aluminum.

19. The display BLU of claim 14 , wherein a thickness of the polymer sublayer and a thickness of the oxide sublayer are less than a quarter of a thickness of the remote phosphor film.

20. The display BLU of claim 14 , wherein the barrier film is directly physically coupled to the LGP and includes a polymer sublayer and an oxide sublayer.