LIGHT EMITTING ELEMENT AND LIGHT EMITTING DEVICE USING THE SAME
First Claim
1. A light emitting device comprising:
- an anode comprising a metal;
a light emitting layer over the anode;
a second layer over the light emitting layer, the second layer comprising a first substance with an electron transporting property and a second substance with an electron donating property with respect to the first substance;
a first layer over the second layer, the first layer comprising a third substance with a hole transporting property and a fourth substance with an electron accepting property with respect to the third substance; and
a transparent cathode over the first layer.
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Abstract
An object of the present invention is to provide a light emitting element having slight increase in driving voltage with accumulation of light emitting time. Another object of the invention is to provide a light emitting element having slight increase in resistance value with increase in film thickness. A light emitting element of the invention includes a first layer for generating holes, a second layer for generating electrons and a third layer comprising a light emitting substance between first and second electrodes. The first and third layers are in contact with the first and second electrodes, respectively. The second and third layers are connected to each other so as to inject electrons generated in the second layer into the third layer when applying the voltage to the light emitting element such that a potential of the second electrode is higher than that of the first electrode.
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Citations
37 Claims
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1. A light emitting device comprising:
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an anode comprising a metal; a light emitting layer over the anode; a second layer over the light emitting layer, the second layer comprising a first substance with an electron transporting property and a second substance with an electron donating property with respect to the first substance; a first layer over the second layer, the first layer comprising a third substance with a hole transporting property and a fourth substance with an electron accepting property with respect to the third substance; and a transparent cathode over the first layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A light emitting device comprising:
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a reflecting electrode capable of reflecting light; a first layer over the reflecting electrode, the first layer comprising a first substance with a hole transporting property and a second substance with an electron accepting property with respect to the first substance; a light emitting layer over the first layer; a second layer over the light emitting layer, the second layer comprising a third substance with a hole transporting property and a fourth substance with an electron accepting property with respect to the third substance; and a transparent electrode capable of transmitting visible light. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A light emitting device comprising:
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a first electrode comprising a metal; a first layer over the first electrode, the first layer comprising a first substance with a hole transporting property and a second substance with an electron accepting property with respect to the first substance; a second layer over the first layer, the second layer comprising a third substance with an electron transporting property and a fourth substance with an electron donating property with respect to the third substance; a light emitting layer over the second layer; and a second electrode over the light emitting layer. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification