Field emission device and its method of fabrication

1. A field emission device, comprising:

a light transmitting substrate;

a cathode unit arranged on the light transmitting substrate and adapted to emit electrons, the cathode unit including:

a first electrode layer of a transparent conductive material arranged on the substrate;

a first electron emission layer of a semiconductive polymer organic material arranged on the first electrode layer;

a second electron emission layer of a composite of a carbon-based inorganic material and a semiconductive polymer organic material arranged on the first electron emission layer; and

a second electrode layer of a conductive material arranged on the second electron emission layer; and

an anode arranged to face the cathode unit.

2. The field emission device of claim 1 , wherein the carbon-based inorganic material is selected from the group consisting of C 60 , C 70 , C 76 , C 78 , C 84 , and carbon nanotubes (CNTs).

3. The field emission device of claim 1 , wherein the semiconductive polymer organic material is selected from the group consisting of poly 3-hexylthiophene (P3HT), poly 3-octylthiophene (P3OT), poly 3-methylthiophene (P3MT), poly bithiophene (PBT), poly p-phenylenevinylene (PPV), and thiophene-isothianaphthene-based copolymer (PDTI).

4. The field emission device of claim 1 , wherein the second electron emission layer comprises 0.5 wt % of a carbon-based inorganic material and 99.5 wt % of a semiconductive polymer organic material.

5. The field emission device of claim 1 , further comprising an external light source arranged on a rear surface of the light transmitting substrate and adapted to emit light with a wavelength in a range of 400 nm to 900 nm onto the first and second emission layers.

6. A field emission display device, comprising:

a light transmitting rear substrate;

a light transmitting front substrate arranged to face the light transmitting rear substrate;

a cathode unit arranged on a surface of the rear substrate and adapted to emit electrons, the cathode unit including:

a first electrode layer of a transparent conductive material arranged on the substrate;

a first electron emission layer of a semiconductive polymer organic material arranged on the first electrode layer;

a second electron emission layer of a composite of a carbon-based inorganic material and a semiconductive polymer organic material arranged on the first electron emission layer; and

a second electrode layer of a conductive material arranged on the second electron emission layer; and

an anode arranged on a surface of the front substrate to face the cathode unit; and

a phosphor layer arranged on the anode.

7. The field emission display of claim 6 , wherein the carbon-based inorganic material is selected from the group consisting of C 60 , C 70 , C 76 , C 78 , C 84 , and carbon nanotubes (CNT).

8. The field emission display of claim 6 , wherein the semiconductive polymer organic material is selected from the group consisting of poly 3-hexylthiophene (P3HT), poly 3-octylthiophene (P3OT), poly 3-methylthiophene (P3MT), poly bithiophene (PBT), poly p-phenylenevinylene (PPV), and thiophene-isothianaphthene-based copolymer (PDTI).

9. The field emission display of claim 6 , wherein the second electron emission layer comprises 0.5 wt % of a carbon-based inorganic material and 99.5 wt % of a semiconductive polymer organic material.

10. The field emission display of claim 6 , further comprising an external light source arranged on a rear surface of the light transmitting rear substrate and adapted to emit light with a wavelength in a range of 400 nm to 900 nm onto the first and second emission layers.

11. A method of manufacturing a field emission device, comprising:

providing a light transmitting substrate;

forming a cathode unit on a surface of the substrate, the cathode unit adapted to emit electrons; and

forming an anode facing the cathode unit such that the electrons are incident on the anode;

wherein forming the cathode unit includes:

forming a first electrode layer of a transparent conductive material on the light transmitting substrate;

forming a first electron emission layer of a semiconductive polymer organic material on the first electrode layer;

forming a second electron emission layer of a semiconductive polymer material and a carbon-based inorganic material layer on the first electron emission layer; and

forming a second electrode layer of a conductive material on the second electron emission layer.

12. The method of claim 11 , wherein the carbon-based inorganic material is selected from the group consisting of C 60 , C 70 , C 76 , C 78 , C 84 , and carbon nanotubes (CNTs).

13. The method of claim 11 , wherein the semiconductive polymer organic material is selected from the group consisting of poly 3-hexylthiophene (P3HT), poly 3-octylthiophene (P3OT), poly 3-methylthiophene (P3MT), poly bithiophene (PBT), poly p-phenylenevinylene (PPV), and thiophene-isothianaphthene-based copolymer (PDTI).

14. The method of claim 11 , wherein the second electron emission layer comprises 0.5 wt % of a carbon-based inorganic material and 99.5 wt % of a semiconductive polymer organic material.

15. The method of claim 11 , further comprising providing an external light source arranged on a rear surface of the light transmitting substrate and adapted to emit light with a wavelength in a range of 400 nm to 900 nm onto the first and second emission layers.

16. The method of claim 11 , wherein forming the first electron emission layer comprises:

forming a semiconductive polymer organic liquid by dissolving a semiconductive polymer organic material in chloroform (CHCl 3 );

coating the semiconductive polymer organic liquid on the first electrode layer; and

baking the semiconductive polymer organic coating layer.

17. The method of claim 16 , wherein the semiconductive polymer organic liquid is coated using one of a spin coating method, a spray coating method, a dip coating method, or a screen printing method.

18. The method of claim 16 , wherein the baking process is conducted at a temperature of 120° C. for one hour.

19. The method of claim 11 , wherein forming the second electron emission layer comprises:

forming a semiconductive polymer organic liquid by dissolving a semiconductive polymer organic material in chloroform (CHCl 3 );

forming a mixed liquid by mixing the semiconductive polymer organic liquid with the carbon-based inorganic material;

coating the mixed liquid on the first electron emission layer; and

baking the mixed coating layer.

20. The method of claim 19 , wherein the mixed liquid is coated using one of a spin coating method, a spray coating method, a dip coating method, or a screen printing method.

21. The method of claim 19 , wherein the baking process is conducted at a temperature of 120° C. for one hour.