US2016104855A1PendingUtilityA1

Light-Emitting Element, Display Device, Electronic Device, and Lighting Device

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Assignee: SEMICONDUCTOR ENERGY LABPriority: Oct 10, 2014Filed: Oct 8, 2015Published: Apr 14, 2016
Est. expiryOct 10, 2034(~8.2 yrs left)· nominal 20-yr term from priority
Inventors:Nobuharu OhsawaSatoshi Seo
H01L 27/3244H01L 51/5016H01L 51/5237H01L 2251/5376H01L 2251/5384H01L 27/323H01L 51/0058H01L 27/322H10K 85/615H10K 2101/10C09K 11/06C09K 2211/1003F21Y 2105/00C07C 15/28H10K 59/40H10K 50/11H10K 59/38H10K 85/633H10K 85/6572H10K 50/8426H10K 50/805H10K 2101/27H10K 2101/30H10K 2101/90H10K 2101/20H10K 50/121
53
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Claims

Abstract

A light-emitting element including a fluorescent material as a light-emitting material and having high emission efficiency is provided. The light-emitting element includes a pair of electrodes and an EL layer provided between the pair of electrodes. The EL layer includes a host material and a guest material. The host material is capable of exhibiting thermally activated delayed fluorescence at room temperature. The guest material is capable of exhibiting fluorescence. The second triplet excitation energy level of the guest material is higher than or equal to the lowest singlet excitation energy level of the guest material.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
         1 . A light-emitting element comprising:
 a pair of electrodes; and   an EL layer provided between the pair of electrodes,   wherein the EL layer comprises a first host material and a guest material,   wherein the first host material is capable of exhibiting thermally activated delayed fluorescence at room temperature,   wherein the guest material is capable of exhibiting fluorescence, and   wherein a second triplet excitation energy level of the guest material is higher than or equal to a lowest singlet excitation energy level of the guest material.   
     
     
         2 . The light-emitting element according to  claim 1 ,
 wherein the EL layer further comprises a second host material which is capable of forming an exciplex, and   wherein the exciplex is capable of exhibiting thermally activated delayed fluorescence at room temperature.   
     
     
         3 . The light-emitting element according to  claim 1 , wherein the first host material has a difference of more than 0 eV and less than or equal to 0.2 eV between a lowest singlet excitation energy level and a lowest triplet excitation energy level. 
     
     
         4 . The light-emitting element according to  claim 1 , wherein the guest material comprises at least one skeleton selected from anthracene, tetracene, chrysene, pyrene, perylene and acridine, and at least one substituent bonded to the skeleton. 
     
     
         5 . The light-emitting element according to  claim 1 ,
 wherein the guest material comprises a skeleton, a first substituent and a second substituent,   wherein the skeleton is selected from anthracene, tetracene, chrysene, pyrene, perylene and acridine, and   wherein a structure of the first substituent is same as that of the second substituent.   
     
     
         6 . A display device comprising:
 the light-emitting element according to  claim 1 ; and   any one of a color filter, a seal and a transistor.   
     
     
         7 . An electronic device comprising:
 the display device according to  claim 6 ; and   a housing or a touch sensor.   
     
     
         8 . A lighting device comprising:
 the light-emitting element according to  claim 1 ; and   a housing or a touch sensor.   
     
     
         9 . A light-emitting element comprising:
 a pair of electrodes; and   an EL layer provided between the pair of electrodes,   wherein the EL layer comprises a host material and a guest material,   wherein the host material is capable of exhibiting thermally activated delayed fluorescence at room temperature,   wherein the guest material is capable of exhibiting fluorescence,   wherein a second triplet excitation energy level of the guest material is higher than or equal to a lowest triplet excitation energy level of the host material, and   wherein the lowest triplet excitation energy level of the host material is higher than or equal to a lowest triplet excitation energy level of the guest material.   
     
     
         10 . The light-emitting element according to  claim 9 ,
 wherein the second triplet excitation energy level of the guest material is higher than or equal to a lowest singlet excitation energy level of the host material.   
     
     
         11 . The light-emitting element according to  claim 9 , wherein the lowest triplet excitation energy level of the host material is higher than or equal to a lowest singlet excitation energy level of the guest material. 
     
     
         12 . The light-emitting element according to  claim 9 ,
 wherein a difference between the lowest triplet excitation energy level of the host material and that of the guest material is higher than or equal to 0.5 eV.   
     
     
         13 . The light-emitting element according to  claim 9 ,
 wherein a thermally activated delayed fluorescence emission energy of the host material is higher than or equal to a phosphorescence emission energy of the guest material.   
     
     
         14 . The light-emitting element according to  claim 9 ,
 wherein a difference between a thermally activated delayed fluorescence emission energy of the host material and a phosphorescence emission energy of the guest material is higher than or equal to 0.5 eV.   
     
     
         15 . The light-emitting element according to  claim 9 , wherein the host material has a difference of more than 0 eV and less than or equal to 0.2 eV between a lowest singlet excitation energy level and the lowest triplet excitation energy level. 
     
     
         16 . The light-emitting element according to  claim 9 , wherein the guest material comprises at least one skeleton selected from anthracene, tetracene, chrysene, pyrene, perylene and acridine, and at least one substituent bonded to the skeleton. 
     
     
         17 . The light-emitting element according to  claim 9 ,
 wherein the guest material comprises a skeleton, a first substituent and a second substituent,   wherein the skeleton is selected from anthracene, tetracene, chrysene, pyrene, perylene and acridine, and   wherein a structure of the first substituent is same as that of the second substituent.   
     
     
         18 . A display device comprising:
 the light-emitting element according to  claim 9 ; and   any one of a color filter, a seal and a transistor.   
     
     
         19 . An electronic device comprising:
 the display device according to  claim 18 ; and   a housing or a touch sensor.   
     
     
         20 . A lighting device comprising:
 the light-emitting element according to  claim 9 ; and   a housing or a touch sensor.   
     
     
         21 . A light-emitting element comprising:
 a pair of electrodes; and   an EL layer provided between the pair of electrodes,   wherein the EL layer comprises a host material and a guest material,   wherein the host material comprises a first organic compound and a second organic compound,   wherein an exciplex formed by the first organic compound and the second organic compound is capable of exhibiting thermally activated delayed fluorescence at room temperature,   wherein the guest material is capable of exhibiting fluorescence,   wherein a second triplet excitation energy level of the guest material is higher than or equal to a lowest triplet excitation energy level of the exciplex, and   wherein the lowest triplet excitation energy level of the exciplex is higher than or equal to a lowest triplet excitation energy level of the guest material.   
     
     
         22 . The light-emitting element according to  claim 21 ,
 wherein the second triplet excitation energy level of the guest material is higher than or equal to a lowest singlet excitation energy level of the exciplex.   
     
     
         23 . The light-emitting element according to  claim 21 , wherein the lowest triplet excitation energy level of the exciplex is higher than or equal to a lowest singlet excitation energy level of the guest material. 
     
     
         24 . The light-emitting element according to  claim 21 ,
 wherein a difference between the lowest triplet excitation energy level of the exciplex and the lowest triplet excitation energy level of the guest material is higher than or equal to 0.5 eV.   
     
     
         25 . The light-emitting element according to  claim 21 ,
 wherein a thermally activated delayed fluorescence emission energy of the exciplex is higher than or equal to a phosphorescence emission energy of the guest material.   
     
     
         26 . The light-emitting element according to  claim 21 ,
 wherein a difference between a thermally activated delayed fluorescence emission energy of the exciplex and a phosphorescence emission energy of the guest material is higher than or equal to 0.5 eV.   
     
     
         27 . The light-emitting element according to  claim 21 ,
 wherein the exciplex has a difference of more than 0 eV and less than or equal to 0.2 eV between a lowest singlet excitation energy level and the lowest triplet excitation energy level.   
     
     
         28 . The light-emitting element according to  claim 21 , wherein the guest material comprises at least one skeleton selected from anthracene, tetracene, chrysene, pyrene, perylene and acridine, and at least one substituent bonded to the skeleton. 
     
     
         29 . The light-emitting element according to  claim 21 ,
 wherein the guest material comprises a skeleton, a first substituent and a second substituent,   wherein the skeleton is selected from anthracene, tetracene, chrysene, pyrene, perylene and acridine, and   wherein a structure of the first substituent is same as that of the second substituent.   
     
     
         30 . A display device comprising:
 the light-emitting element according to  claim 21 ; and   any one of a color filter, a seal and a transistor.   
     
     
         31 . An electronic device comprising:
 the display device according to  claim 30 ; and   a housing or a touch sensor.   
     
     
         32 . A lighting device comprising:
 the light-emitting element according to  claim 21 ; and   a housing or a touch sensor.

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