ORGANIC EL ELEMENT, ORGANIC EL PANEL, ORGANIC EL LIGHT-EMITTING APPARATUS, ORGANIC EL DISPLAY APPARATUS, AND METHOD OF MANUFACTURING ORGANIC EL ELEMENT

• US 20130126840A1
• Filed: 01/08/2013
• Published: 05/23/2013
• Est. Priority Date: 07/30/2010
• Status: Active Grant

• Current Assignee: JDI Design and Development GK
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: FUJIMURA, Shinya, OHUCHI, Satoru, KOMATSU, Takahiro, FUJITA, Hirofumi, TSUKAMOTO, Yoshiaki
• Granted Patent: US 9,490,445 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• CPC Class Codes: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
• CPC Class Codes: H10K 50/17 Carrier injection layers
• CPC Class Codes: H10K 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass

Abstract

An organic EL element includes a hole injection layer that yields excellent hole conduction efficiency. The organic EL element includes an anode, a cathode, and functional layers that include organic material between the anode the cathode. The functional layers include a hole injection layer that injects holes into the functional layers. The hole injection layer is a metal oxide film that includes a metal oxide. The metal atoms constituting the metal oxide include both metal atoms at a maximum valence thereof and metal atoms at a valence less than the maximum valence, and the metal oxide film includes metal oxide crystals having a particle diameter on the order of nanometers.

Claims

1. An organic EL element, comprising:

an anode;

a cathode;

a functional layer, containing an organic material, between the anode and the cathode; and

a hole injection layer, for injecting holes to the functional layer, between the anode and the functional layer, wherein

the hole injection layer is a metal oxide film composed of a metal oxide,

metal atoms constituting the metal oxide include both metal atoms at a maximum valence thereof and metal atoms at a valence less than the maximum valence, and

the metal oxide film includes a crystal of the metal oxide, a particle diameter of the crystal being on an order of nanometers.

2. The organic EL element of claim 1, wherein

the metal oxide is tungsten oxide, so that the metal oxide film is a tungsten oxide film, and

the metal atoms at the maximum valence are tungsten atoms with a valence of six.

3. The organic EL element of claim 2, wherein

the metal atoms at the valence less than the maximum valence are tungsten atoms with a valence of five.

4. The organic EL element of claim 3, wherein

a ratio W⁵⁺/W⁶⁺ of the number of the tungsten atoms with a valence of five to the number of the tungsten atoms with a valence of six is at least 3.2%.

5. The organic EL element of claim 4, wherein

the ratio W⁵⁺/W⁶⁺ is at least 3.2% and at most 7.4%.

6. The organic EL element of claim 2, wherein

a hard X-ray photoelectron spectroscopy spectrum of a surface of the tungsten oxide film exhibits a first peak and a second peak, the first peak corresponding to a 4f_7/2 energy level of the tungsten atoms with a valence of six, and the second peak being in a region lower than the first peak in terms of binding energy.

7. The organic EL element of claim 6, wherein

the second peak is in a region between 0.3 electron volts and 1.8 electron volts lower, in terms of binding energy, than the first peak.

8. The organic EL element of claim 6, wherein

an area intensity of the second peak is between 3.2% and 7.4% of an area intensity of the first peak.

9. The organic EL element of claim 2, wherein

tungsten atoms at a valence less than the maximum valence cause a band structure of the hole injection layer to have an occupied energy level in a range between 1.8 electron volts and 3.6 electron volts lower than a lowest energy level of a valence band in terms of binding energy.

10. The organic EL element of claim 2, wherein

the tungsten oxide film includes a plurality of crystals of the tungsten oxide, each of the crystals having a particle diameter of between 3 nm and 10 nm.

11. The organic EL element of claim 2, wherein

regular linear structures at intervals of between 1.85 angstroms and 5.55 angstroms appear in a lattice image by transmission electron microscopy observation of the tungsten oxide film.

12. The organic EL element of claim 11, wherein

in a 2D Fourier transform image of the lattice image, a pattern of concentric circles centering on a center point of the 2D Fourier transform image appears.

13. The organic EL element of claim 12, wherein

in a plot of distance from the center point versus normalized luminance, the normalized luminance being a normalized value of the luminance of the 2D Fourier transform image at the corresponding distance, at least one peak of the normalized luminance appears.

14. The organic EL element of claim 13, wherein

with a peak width being a difference between the distance corresponding to a position of a peak of the normalized luminance appearing closest to the center point in the plot and the distance corresponding to a position at which the peak of the normalized luminance begins to rise, the peak width is less than 22 when a difference between the distance corresponding to the center point and the distance corresponding to the peak of the normalized luminance appearing closest to the center point is 100.

15. The organic EL element of claim 1, wherein

the functional layer includes amine-containing material.

16. The organic EL element of claim 1, wherein

the functional layer is one of a hole transfer layer that transfers holes, a light-emitting layer that emits light by recombination of electrons and holes injected thereto, and a buffer layer that one of adjusts optical characteristics and blocks electrons.

17. An organic EL panel comprising the organic EL element of claim 1.

18. An organic EL light-emitting apparatus comprising the organic EL element of claim 1.

19. An organic EL display apparatus comprising the organic EL element of claim 1.

20. A method of manufacturing an organic EL element, comprising the steps of:

preparing an anode;

forming a tungsten oxide film on the anode using a sputtering gas including argon gas and oxygen gas and using tungsten as a sputtering target, under film forming conditions such that a total pressure of the sputtering gas is at least 2.3 Pa and at most 7.0 Pa, a partial pressure of the oxygen gas in the sputtering gas is at least 50% and at most 70%, an input power density per unit area of the sputtering target is at least 1.5 W/cm² and at most 6.0 W/cm², and a value yielded by dividing the total pressure of the sputtering gas by the input power density is larger than 0.7 Pa·

cm²/W;

forming a functional layer including organic material on the tungsten oxide film; and

forming a cathode on the functional layer.

21. The method of manufacturing an organic EL element of claim 20, wherein

the tungsten oxide film is formed so that tungsten atoms constituting the tungsten oxide film include both tungsten atoms at a maximum valence thereof and tungsten atoms at a valence less than the maximum valence, and so as to include a tungsten oxide crystal having a particle diameter on an order of nanometers.

22. The method of manufacturing an organic EL element of claim 20, wherein

when forming the tungsten oxide film, the value yielded by dividing the total pressure of the sputtering gas by the input power density is less than 3.2 Pa·

cm²/W.