Light-emitting device and electronic device using the same

• US 8,803,853 B2
• Filed: 12/13/2005
• Issued: 08/12/2014
• Est. Priority Date: 12/16/2004
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Seo, Satoshi, Kimura, Hajime, Yamazaki, Shunpei
• Primary Examiner(s): Boddie, William
• Assistant Examiner(s): Shapiro, Leonid
• Application Number:
  US11/301,706
• Publication Number:
  US 20070008257A1
• Time in Patent Office: 3,164 Days
• Field of Search: 345/204, 345/55, 345/83
• US Class Current: 345/204
• CPC Class Codes: G09G 2330/028 Generation of voltages supplied to electrode drivers in a matrix display other than LCD
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/2077 by a combination of two or more gradation control methods
• CPC Class Codes: G09G 3/3233 with pixel circuitry controlling the current through the light-emitting element
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 59/351 comprising more than three subpixels, e.g. red-green-blue-white [RGBW]
• CPC Class Codes: H10K 59/353 characterised by the geometrical arrangement of the RGB subpixels

Abstract

It is an object to provide a light-emitting device and an electronic device which can provide an image with excellent image quality. One of the present inventions is a light-emitting device including a plurality of light-emitting elements each exhibiting a different emission color. At least one of the plurality of light-emitting elements has n light-emitting layers (n is a natural number, n≧2) between a pair of electrodes. Further, at least one of the n light-emitting layers includes a substance which provides emission from a triplet excitation state. In a light-emitting device having such a structure, an image is displayed by combining emissions from the plurality of light-emitting elements.

Claims

1. A light-emitting device comprising:

a plurality of light-emitting elements each exhibiting a different emission color;

wherein at least one of the light-emitting elements comprises n light-emitting layers (n≧

2, n is a natural number) between a pair of electrodes,

wherein each of the n light-emitting layers comprises a light-emitting substance,

wherein the light-emitting substances each exhibit different emission colors,

wherein between a m-th light-emitting layer (m is a natural number) and a (m+1)-th light-emitting layer, a first mixed layer and a second mixed layer are provided,

wherein the first mixed layer comprises a first substance and a second substance,

wherein the first substance comprises a substance having a higher mobility of electrons than that of holes or a bipolar substance,

wherein the second substance has an electron-donating property to the first substance, and

wherein the second mixed layer comprises an organic matter and a metal oxide comprising molybdenum or ruthenium.

2. The light-emitting device according to claim 1, further comprising a voltage step-up circuit electrically connected to the plurality of light-emitting elements,

wherein the voltage step-up circuit is configured to generate a plurality of power source potentials.

3. The light-emitting device according to claim 2, wherein the voltage step-up circuit is a charge pump.

4. The light-emitting device according to claim 3,

wherein the charge pump comprises:

a constant voltage source;

a first rectifying element to an N-th rectifying element (N≧

2, N is a natural number); and

a first capacitor element to an N-th capacitor element,

wherein the first rectifying element to the N-th rectifying element are connected in series,

wherein an input terminal of the first rectifying element is connected to the constant voltage source,

wherein one electrode of each of the first capacitor element to the N-th capacitor element is connected to an output terminal of each of the first rectifying element to the N-th rectifying element,

wherein a clock pulse or a clock inverted pulse is inputted alternately to the other electrode of each of the first capacitor element to the (N−

1)-th capacitor element,

wherein a predetermined potential is inputted to the other electrode of the N-th capacitor element, and

wherein a power source potential obtained from an arbitrary one electrode of each of the first capacitor element to the N-th capacitor element, is applied to each of the light-emitting elements each exhibiting a different emission color.

5. The light-emitting device according to claim 1,

wherein the number of the light-emitting layers of the light-emitting element exhibiting green emission is smaller than that exhibiting red or blue emission.

6. The light-emitting device according to claim 1, wherein an image is displayed by combining emissions from the light-emitting elements.

7. A light-emitting device comprising:

a plurality of light-emitting elements each exhibiting a different emission color;

wherein at least one of the light-emitting elements comprises n light-emitting layers (n≧

2, n is a natural number) between a pair of electrodes,

wherein each of the n light-emitting layers comprises a light-emitting substance,

wherein the light-emitting substances each exhibit different emission colors,

wherein at least one of the light-emitting substances exhibits emission from a triplet excited state,

wherein between a m-th light-emitting layer (m is a natural number) and a (m+1)-th light-emitting later, a first mixed layer and a second mixed layer are provided,

wherein the first mixed layer comprises a first substance and a second substance,

wherein the first substance comprises a substance having a higher mobility of electrons than that of holes or a bipolar substance,

wherein the second substance has an electron-donating property to the first substance, and

wherein the second mixed layer comprises an organic matter and a metal oxide comprising molybdenum or ruthenium.

8. The light-emitting device according to claim 7, further comprising a voltage step-up circuit electrically connected to the plurality of light-emitting elements,

wherein the voltage step-up circuit is configured to generate a plurality of power source potentials.

9. The light-emitting device according to claim 8,

wherein the voltage set-up circuit is a charge pump.

10. The light-emitting device according to claim 9,

wherein the charge pump comprises:

a constant voltage source;

a first rectifying element to an N-th rectifying element (N≧

2, N is a natural number); and

a first capacitor element to an N-th capacitor element,

wherein the first rectifying element to the N-th rectifying element are connected in series,

wherein an input terminal of the first rectifying element is connected to the constant voltage source,

wherein one electrode of each of the first capacitor element to the N-th capacitor element is connected to an output terminal of each of the first rectifying element to the N-th rectifying element,

wherein a clock pulse or a clock inverted pulse is inputted alternately to the other electrode of each of the first capacitor element to the (N−

1)-th capacitor element,

wherein a predetermined potential is inputted to the other electrode of the N-th capacitor element, and

wherein a power source potential obtained from an arbitrary one electrode of each of the first capacitor element to the N-th capacitor element, is applied to each of the light-emitting elements each exhibiting a different emission color.

11. The light-emitting device according to claim 7, wherein the number of the light-emitting layers of the light-emitting element exhibiting green emission is smaller than that exhibiting red or blue emission.

12. The light-emitting device according to claim 7, wherein an image is displayed by combining emissions from the light-emitting elements.

13. A light-emitting device comprising:

a light-emitting element comprising n light-emitting layers (n≧

2, n is a natural number) between a pair of electrodes,

wherein each of the n light-emitting layers comprises a light-emitting substance,

wherein the light-emitting substances each exhibit different emission colors,

wherein between a m-th light-emitting layer (m is a natural number) and a (m+1)-th light-emitting layer, a first mixed layer and a second mixed layer are provided,

wherein the first mixed layer comprises a first substance and a second substance,

wherein the first substance comprises a substance having a higher mobility of electrons than that of holes or a bipolar substance,

wherein the second substance has an electron-donating property to the first substance, and

wherein the second mixed layer comprises an organic matter and a metal oxide comprising molybdenum or ruthenium.

14. The light-emitting device according to claim 13, wherein at least one of the light-emitting substances exhibits emission from a triplet excited state.

15. The light-emitting device according to claim 13, wherein the light-emitting device emits white light.

16. A light-emitting device comprising:

a first light-emitting element comprising a light-emitting layer between a first pair of electrodes; and

a second light-emitting element comprising n light-emitting layers (n≧

2, n is a natural number) between a second pair of electrodes,

wherein each of the n light-emitting layers comprises a light-emitting substance,

wherein the light-emitting substances each exhibit different emission colors,

wherein between a m-th light-emitting layer (m is a natural number) and a (m+1)-th light-emitting layer of the n light-emitting layers, a mixed layer and a layer are provided,

wherein the mixed layer comprises a first substance and a second substance,

wherein the first substance comprises a substance having a higher mobility of electrons than that of holes or a bipolar substance,

wherein the second substance has an electron-donating property to the first substance,

wherein the layer comprises an organic matter and a metal oxide comprising molybdenum or ruthenium, and

wherein one electrode of the first pair of electrodes of the first light-emitting element and one electrode of the second pair of electrodes of the second light-emitting element are provided on a same surface of a substrate with a partition interposed therebetween.

17. The light-emitting device according to claim 16, wherein the light-emitting device is a display device.

18. A light-emitting device comprising:

a first light-emitting element comprising a light-emitting layer between a first pair of electrodes; and

a second light-emitting element comprising n light-emitting layers (n≧

2, n is a natural number) between a second pair of electrodes,

wherein each of the n light-emitting layers comprises a light-emitting substance,

wherein the light-emitting substances each exhibit different emission colors,

wherein at least one of the light-emitting substances exhibits emission from a triplet excited state,

wherein between a m-th light-emitting layer (m is a natural number) and a (m+1)-th light-emitting layer of the n light-emitting layers, a mixed layer and a layer are provided,

wherein the mixed layer comprises a first substance and a second substance,

wherein the first substance comprises a substance having a higher mobility of electrons than that of holes or a bipolar substance,

wherein the second substance has an electron-donating property to the first substance,

wherein the layer comprises an organic matter and a metal oxide comprising molybdenum or ruthenium, and

wherein one electrode of the first pair of electrodes of the first light-emitting element and one electrode of the second pair of electrodes of the second light-emitting element are provided on a same surface of a substrate with a partition interposed therebetween.

19. The light-emitting device according to claim 18, wherein the light-emitting device is a display device.

20. A light-emitting device comprising:

a first light-emitting element comprising a light-emitting layer between a first pair of electrodes; and

a second light-emitting element comprising n light-emitting layers (n≧

2, n is a natural number) between a second pair of electrodes,

wherein each of the n light-emitting layers comprises a light-emitting substance,

wherein the light-emitting substances each exhibit different emission colors,

wherein between a m-th light-emitting layer (m is a natural number) and a (m+1)-th light-emitting layer of the n light-emitting layers, a first layer and a second layer are provided,

wherein the first layer comprises a first substance and a second substance,

wherein the first substance comprises a substance having a higher mobility of electrons than that of holes or a bipolar substance,

wherein the second substance has an electron-donating property to the first substance,

wherein the second layer comprises an organic matter and a metal oxide comprising molybdenum or ruthenium, and

wherein one electrode of the first pair of electrodes of the first light-emitting element and one electrode of the second pair of electrodes of the second light-emitting element are provided on a same surface of a substrate with a partition interposed therebetween.

21. The light-emitting device according to claim 20, wherein the light-emitting device is a display device.

22. A light-emitting device comprising:

a first light-emitting element comprising a light-emitting layer between a first pair of electrodes; and

a second light-emitting element comprising n light-emitting layers (n≧

2, n is a natural number) between a second pair of electrodes,

wherein each of the n light-emitting layers comprises a light-emitting substance,

wherein the light-emitting substances each exhibit different emission colors,

wherein at least one of the light-emitting substances exhibits emission from a triplet excited state,

wherein between a m-th light-emitting layer (m is a natural number) and a (m+1)-th light-emitting layer of the n light-emitting layers, a first layer and a second layer are provided,

wherein the first layer comprises a first substance and a second substance,

wherein the first substance comprises a substance having a higher mobility of electrons than that of holes or a bipolar substance,

wherein the second substance has an electron-donating property to the first substance,

wherein the second layer comprises an organic matter and a metal oxide comprising molybdenum or ruthenium, and

wherein one electrode of the first pair of electrodes of the first light-emitting element and one electrode of the second pair of electrodes of the second light-emitting element are provided on a same surface of a substrate with a partition interposed therebetween.

23. The light-emitting device according to claim 22, wherein the light-emitting device is a display device.