Light-emitting device comprising an organic compound
First Claim
1. A light-emitting device comprising:
- a light-emitting layer comprising at least a first organic compound, a second organic compound, and a third organic compound,wherein the first organic compound is guest material,wherein a T1 level of the first organic compound is equal to or higher than a T1 level of the second organic compound,wherein the T1 level of the first organic compound is equal to or lower than a T1 level of the third organic compound,wherein emission time-dependence of emission intensity of the light-emitting device is represented by a multicomponent decay curve, andwherein an emission time of a longest lifetime component of the multicomponent decay curve is less than or equal to 15 μ
sec where the emission time is a time required for a value of initial emission intensity to become 1/100.
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Abstract
A light-emitting element of the present invention can have sufficiently high emission efficiency with a structure including a host material being able to remain chemically stable even if a phosphorescent compound having higher emission energy is used as a guest material. The relation between the relative emission intensity and the emission time of light emission obtained from the host material and the guest material contained in a light-emitting layer is represented by a multicomponent decay curve. The relative emission intensity of the slowest component of the multicomponent decay curve becomes 1/100 for a short time within a range where the slowest component is not interfered with by quenching of the host material (the emission time of the slowest component is preferably less than or equal to 15 μsec); thus, sufficiently high emission efficiency can be obtained.
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Citations
20 Claims
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1. A light-emitting device comprising:
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a light-emitting layer comprising at least a first organic compound, a second organic compound, and a third organic compound, wherein the first organic compound is guest material, wherein a T1 level of the first organic compound is equal to or higher than a T1 level of the second organic compound, wherein the T1 level of the first organic compound is equal to or lower than a T1 level of the third organic compound, wherein emission time-dependence of emission intensity of the light-emitting device is represented by a multicomponent decay curve, and wherein an emission time of a longest lifetime component of the multicomponent decay curve is less than or equal to 15 μ
sec where the emission time is a time required for a value of initial emission intensity to become 1/100. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A light-emitting device comprising:
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a light-emitting layer comprising at least a first organic compound, a second organic compound, and a third organic compound, wherein the first organic compound is guest material, wherein each of the second organic compound and the third organic compound is host material, wherein a T1 level of the first organic compound is equal to or higher than a T1 level of the second organic compound, wherein the T1 level of the first organic compound is equal to or lower than a T1 level of the third organic compound, wherein the first organic compound and the second organic compound are selected so that emission time-dependence of emission intensity of the light-emitting device is represented by a multicomponent decay curve, and wherein an emission time of a longest lifetime component of the multicomponent decay curve is less than or equal to 15 μ
sec where the emission time is a time required for a value of initial emission intensity to become 1/100. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A light-emitting device comprising:
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a light-emitting layer comprising a guest material, a first host material, and a second host material, wherein a T1 level of the guest material is equal to or higher than a T1 level of the first host material, wherein the T1 level of the guest material is equal to or lower than a T1 level of the second host material, wherein the guest material, the first host material and the second host material are selected so that emission time-dependence of emission intensity of the light-emitting device is represented by a multicomponent decay curve, and wherein an emission time of a longest lifetime component of the multicomponent decay curve is less than or equal to 15 μ
sec where the emission time is a time required for a value of initial emission intensity to become 1/100. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification