Quantum rod light emitting diode device

Abstract

The present invention discloses a quantum rod light emitting diode device, including a substrate, and a cathode, an electron functional layer, a light emitting layer, a hole functional layer and an anode sequentially stacked on the substrate. The light emitting layer includes quantum rods disposed therein. The quantum rods are oriented along a same direction. The light emitting layer of the quantum rod light emitting diode device of the present invention include the oriented quantum rods to change incident light into polarized light, which enhances transmittance of polarized light.

Claims

1. A quantum rod light emitting diode device, comprising: a substrate, and a cathode, an electron functional layer, a light emitting layer, a hole functional layer, and an anode sequentially stacked on the substrate; wherein the light emitting layer comprises a plurality of quantum rods disposed therein, and the quantum rods are arranged in an orientation; wherein long axes of the quantum rods are oriented along a same direction and parallel one another; wherein the long axes of the quantum rods are parallel to a perpendicular axis of the light emitting layer, and the perpendicular axis of the light emitting layer is arranged along a direction from the substrate to the hole functional layer; wherein each of the quantum rods comprises a shell and a core disposed in the shell, the shell is elongated-rod-shaped, and a ratio between a length of the shell and a diameter of the shell is greater than 2.

2. The quantum rod light emitting diode device as claimed in claim 1, wherein the electron functional layer comprises at least one of an electron injection layer, an electron transport layer, and a hole barrier layer.

3. The quantum rod light emitting diode device as claimed in claim 1, wherein the electron functional layer comprises an organic material or an inorganic material.

4. The quantum rod light emitting diode device as claimed in claim 1, wherein the hole functional layer comprises at least one of a hole injection layer, a hole transport layer, and an electron barrier layer.

5. The quantum rod light emitting diode device as claimed in claim 1, wherein the shell comprises zinc sulfide, cadmium sulfide, or zinc selenide, and the core comprises cadmium selenide, cadmium sulfide, zinc selenide, sulphur zinc selenide, indium phosphide, lead sulfide, or sulphur zinc indium copper.

6. The quantum rod light emitting diode device as claimed in claim 1, wherein each of the quantum rods comprises a transition region, the transition region is disposed between the core and the shell, and the transition region comprises cadmium selenide, zinc selenide, zinc sulfide, cadmium selenide, cadmium sulfide, or zinc sulfide.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic side view of a quantum rod light emitting diode device of the present invention.

(2) FIG. 2 is a schematic side view of a light emitting layer of the present invention.

(3) FIG. 3 is a schematic perspective view of a quantum rod of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(4) With reference to FIG. 1, a quantum rod light emitting diode (QLED) device of the present invention is an electroluminescent device, comprises a substrate 1, and a cathode 2, an electron functional layer 3, a light emitting layer 4, a hole functional layer 5, and an anode 6 that are sequentially stacked on the substrate 1.

(5) In a preferred embodiment of the present invention, the electron functional layer 3 comprises at least one of an electron injection layer, an electron transport layer, and a hole barrier layer. Furthermore, the electron functional layer 3 can be an organic material, and can be an inorganic material.

(6) With reference to FIG. 2, the light emitting layer 4 employs quantum rods (QD Rods) 10 as luminescent material. The light emitting layer 4 comprises a plurality of quantum rods 10 disposed therein, the quantum rods 10 oriented along a same direction. In other words, long axes A of the quantum rods 10 are along the same direction, and the long axes A of the quantum rods 10 parallel one another. Furthermore, the long axes A of the quantum rods 10 parallel a perpendicular axis V of the light emitting layer 4.

(7) In a preferred embodiment of the present invention, the hole functional layer 5 comprises at least one of a hole injection layer, a hole transport layer, and an electron barrier layer.

(8) With respect to the quantum rods 10, when the quantum rods 10 are stimulated and radiate, light with extremely high polarization degree and a very narrow width at half maximum is stimulated and radiates along the long axes of the quantum rods 10. The present invention, by manufacturing a quantum rod film with quantum rods arranged orderly, enhances transmittance of a backlight of the liquid crystal display (LCD) through a photoluminescent characteristic of the film. Because a polarizer is generally disposed on a light entering side of the LCD, under normal circumstances over 50% of the incident light will be absorbed. Therefore, employing orderly arranged quantum rods 10 facilitates changing the incident light into polarized light with extremely polarization degree. Therefore, when the polarized light passes through a polarizer having the same direction of polarization, transmittance of emitted light is improved.

(9) With reference to FIG. 3, the quantum rod 10 is developed from quantum dots and has obvious shape difference when compared to the quantum dots, which is elongated-rod-shaped compared to the spherical shape of the quantum rods. The quantum rod 10 comprises a shell 11 and a core 12 disposed in the shell 11. The shell 11 is elongated-rod-shaped, and a ratio of a length L of the shell 11 to a diameter R of the shell 11 is L/R>2. The length L of the shell 11 is greater than 5 nm, the core 12 can be spherical or rod-like. Material of the shell 11 comprises zinc sulfide (ZnS), cadmium sulfide (CdS), or zinc selenide (ZnSe). The core 12 is generally a combination of materials of group II-VI semiconductor or I group II-VI semiconductor, for example, cadmium selenide (CdSe), cadmium sulfide (CdS), zinc selenide (ZnSe), sulphur zinc selenide (ZnSeS), indium phosphide (InP), lead sulfide (PbS), or multi-component composite such as sulphur zinc indium copper (CuInZnS). The quantum rod 10 comprises a transition region, the transition region is disposed between the core 12 and the shell 11, and the transition region can comprise cadmium selenide (CdSe), zinc selenide (ZnSe), zinc sulfide (ZnS), cadmium selenide (CdSe), cadmium sulfide (CdS), or zinc sulfide (ZnS).

(10) In an embodiment of the present invention, the light emitting layer 4 is a quantum rod thin film. In the present embodiment, by an adequate compounding method, quantum rods 10 are purified and distributed in a solvent such as chlorobenzene to form a quantum rod solution, and then the quantum rod solution is coated on the electron functional layer 3. After the quantum rod solution is completely coated, the solvent in the quantum rod thin film is dried to form the quantum rod thin film.

(11) In another embodiment of the present invention, the light emitting layer 4 is a quantum rod thin film. In the present embodiment, the quantum rod 10 are distributed in a curable photoresist glue or solution, and then the photoresist glue or solution is coated on the electron functional layer 3. Under ultraviolet or heat such that the photoresist glue or solution is cured to form the light emitting layer 4. Furthermore, in an embodiment of the present invention, the above light emitting layer 4 can be doped with a certain amount of semiconductor nano-particles or conductive nano-particles to improve electrical conductivity of the light emitting layer 4.

(12) Compared to the prior art, the light emitting layer 4 of the present invention QLED device comprises quantum rods 10 oriented along the same direction (arranged orderly) to convert incident light into polarized light, such that the oriented (arranged orderly) quantum rods 10 facilitate changing the incident light to polarized light with extreme high polarization. Therefore, when the polarized light passes through a polarizer having the same direction of polarization, transmittance of emitted light is improved.