US 11,672,177 B2
Light-emitting element, light-emitting device, electronic appliance, and lighting device
Hiromi Seo, Kanagawa (JP); Satoshi Seo, Kanagawa (JP); and Satoko Shitagaki, Kanagawa (JP)
Assigned to Semiconductor Energy Laboratory Co., Ltd.
Filed by Semiconductor Energy Laboratory Co., Ltd., Kanagawa-ken (JP)
Filed on Dec. 30, 2020, as Appl. No. 17/138,394.
Application 17/138,394 is a continuation of application No. 16/819,547, filed on Mar. 16, 2020, granted, now 11,183,644.
Application 16/819,547 is a continuation of application No. 15/377,019, filed on Dec. 13, 2016, granted, now 10,600,972, issued on Mar. 24, 2020.
Application 15/377,019 is a continuation of application No. 14/790,613, filed on Jul. 2, 2015, granted, now 9,525,149, issued on Dec. 20, 2016.
Application 14/790,613 is a continuation of application No. 13/864,407, filed on Apr. 17, 2013, granted, now 9,076,976, issued on Jul. 7, 2015.
Claims priority of application No. JP2012-096887 (JP), filed on Apr. 20, 2012.
Prior Publication US 2021/0119150 A1, Apr. 22, 2021
Int. Cl. H01L 29/08 (2006.01); H01L 35/24 (2006.01); H01L 51/00 (2006.01); H01L 51/50 (2006.01)
CPC H01L 51/0074 (2013.01) [H01L 51/006 (2013.01); H01L 51/0061 (2013.01); H01L 51/0072 (2013.01); H01L 51/0085 (2013.01); H01L 51/5004 (2013.01); H01L 51/5016 (2013.01); H01L 51/5056 (2013.01); H01L 51/0052 (2013.01); H01L 51/5072 (2013.01); H01L 2251/5384 (2013.01); H01L 2251/552 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A light-emitting device comprising:
a hole-transport layer and a light-emitting layer between a pair of electrodes,
wherein the light-emitting layer includes a first organic compound, a second organic compound, and a third organic compound that converts triplet excitation energy into light emission,
wherein a combination of the first organic compound and the second organic compound forms an exciplex,
wherein a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound,
wherein a LUMO level of the first organic compound is lower than a LUMO level of the second organic compound,
wherein the hole-transport layer comprises a fourth organic compound whose HOMO level is higher than the HOMO level of the second organic compound,
wherein an emission spectrum of the exciplex overlaps with an absorption spectrum of the third organic compound,
wherein a difference between an energy value of a peak of the emission spectrum of the exciplex and an energy value of a peak of an absorption band on the lowest energy side of the absorption spectrum of the third organic compound is 0.2 eV or less, and
wherein the hole-transport layer is in contact with the light-emitting layer.