ORGANIC EL ELEMENT, DISPLAY DEVICE, AND LIGHT-EMITTING DEVICE

• US 20130119366A1
• Filed: 01/08/2013
• Published: 05/16/2013
• Est. Priority Date: 08/06/2010
• Status: Active Grant

• Current Assignee: JDI Design and Development GK
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: NISHIYAMA, Seiji, OHUCHI, Satoru, FUJIMURA, Shinya, FUJITA, Hirofumi
• Granted Patent: US 9,130,187 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• CPC Class Codes: H10K 50/17 Carrier injection layers
• CPC Class Codes: H10K 50/818 Reflective anodes, e.g. ITO combined with thick metallic layers
• CPC Class Codes: H10K 50/856 comprising reflective means
• CPC Class Codes: H10K 59/122 Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass

Abstract

The present invention aims to provide organic EL elements operating at low voltage to emit light at high intensity. For this aim, each EL element includes an anode, a cathode, a functional layer disposed between the anode and the cathode and including a light-emitting layer composed of organic material, a hole injection layer disposed between the anode and the functional layer, and a bank defining the light-emitting layer. The hole injection layer contains tungsten oxide and exhibits: by UPS measurement, a UPS spectrum having a protrusion appearing near a Fermi surface and within a region corresponding to a binding energy range lower than the top of a valence band; and by XPS measurement, that the tungsten oxide in the hole injection layer satisfies a condition that a ratio in number density of atoms other than tungsten atoms and oxygen atoms to the tungsten atoms is equal to 0.83 or smaller.

Claims

1. An organic electroluminescent (EL) element, comprising:

an anode;

a cathode;

a functional layer disposed between the anode and the cathode, and including a light-emitting layer made of organic material;

a hole injection layer disposed between the anode and the functional layer; and

a bank that defines an area in which the light-emitting layer is to be formed, wherein

the hole injection layer contains a tungsten oxide,

an Ultraviolet Photoelectron Spectroscopy (UPS) spectrum, obtained from a UPS measurement, has a protrusion appearing near a Fermi surface and within a region corresponding to a binding energy range lower than a top of a valence band,

the tungsten oxide contained in the hole injection layer satisfies a condition, determined from an X-ray Photoelectron Spectroscopy (XPS) measurement, that a ratio in a number density of atoms other than tungsten atoms and oxygen atoms to the tungsten atoms does not exceed approximately 0.83,

an inner portion of the hole injection layer is depressed to define a recess, and

an upper peripheral edge of the recess is covered with a part of the bank.

2. The organic EL element according to claim 1, wherein

in the UPS spectrum, the protrusion appears within the region corresponding to the binding energy range from approximately 1.8 eV to approximately 3.6 eV lower than the top of the valance band.

3. The organic EL element according to claim 1, wherein

the ratio in the number density of the other atoms to the tungsten atoms does not exceed approximately 0.62.

4. The organic EL element according to claim 1, wherein

the atoms other than tungsten atoms and oxygen atoms comprise carbon atoms.

5. The organic EL element according to claim 1, wherein

the hole injection layer is irradiated with ultraviolet light so that

the hole injection layer in the UPS spectrum obtained from the UPS measurement has the protrusion appearing near the Fermi surface and within the region corresponding to the binding energy range lower than the top of a valence band, and

the tungsten oxide contained in the hole injection layer satisfies the condition, as determined by the XPS measurement, that the ratio in the number density of atoms other than tungsten atoms and oxygen atoms to the tungsten atoms does not exceed approximately 0.83.

6. The organic EL element according to claim 1, wherein

the part of the bank reaches a bottom of the recess of the hole injection layer, and a side surface of the bank slopes upward from the bottom of the recess to a top of the bank.

7. The organic EL element according to claim 1, wherein

the part of the bank is out of contact with a bottom of the recess.

8. The organic EL element according to claim 1, wherein

the hole injection layer extends laterally along a bottom surface of the bank.

9. The organic EL element according to claim 1, wherein

the upper peripheral edge of the recess is a convex portion composed of (i) a part of the upper surface of the hole injection layer in which the recess is not formed and (ii) the inner side surface of the recess.

17. A display apparatus comprising the organic EL element according to claim 1.

18. A light-emitting apparatus comprising the organic EL element according to claim 1.

10. An organic EL element, comprising:

an anode;

a cathode;

a functional layer disposed between the anode and the cathode, and including a light-emitting layer made of organic material;

a hole injection layer disposed between the anode and the functional layer; and

a bank that defines an area in which the light-emitting layer is to be formed, wherein

the hole injection layer contains a tungsten oxide, an Ultraviolet Photoelectron Spectroscopy (UPS) spectrum, obtained from an UPS measurement having;

a protrusion appearing near a Fermi surface and within a region corresponding to a binding energy range lower than a top of a valence band, and

a peak appearing within a region corresponding to a binding energy range from approximately 4.5 eV to approximately 5.4 eV,

an inner portion of the hole injection layer is depressed to define a recess, and

an upper peripheral edge of the recess is covered with a part of the bank.

11. The organic EL element according to claim 10, wherein

in the UPS spectrum, the protrusion appears within the region corresponding to the binding energy range from approximately 1.8 eV to approximately 3.6 eV lower than the top of the valance band.

12. The organic EL element according to claim 10, wherein

the hole injection layer is irradiated with ultraviolet light so that

the hole injection layer, in the UPS spectrum, obtained by the UPS measurement, has:

the protrusion appearing near the Fermi surface and within the region corresponding to the binding energy range lower than the top of the valence band, and

the peak appears within the region corresponding to the binding energy range from approximately 4.5 eV to approximately 5.4 eV.

13. The organic EL element according to claim 10, wherein

the part of the bank reaches a bottom of the recess of the hole injection layer, and a side surface of the bank slopes upward from the bottom of the recess to a top of the bank.

14. The organic EL element according to claim 10, wherein

the part of the bank is out of contact with a bottom of the recess.

15. The organic EL element according to claim 10, wherein

the hole injection layer extends laterally along a bottom surface of the bank.

16. The organic EL element according to claim 10, wherein

the upper peripheral edge of the recess is a convex portion composed of (i) a part of the upper surface of the hole injection layer in which the recess is not formed and (ii) the inner side surface of the recess.