Semiconductor Energy Laboratory Co., Ltd.

Shunsuke Hosoumi

Satoshi Seo

Takahiro Ishisone

Tatsuyoshi Takahashi

Nobuharu Ohsawa

Kunihiko Suzuki

Harue Osaka

Takeyoshi Watabe

Ryohei Yamaoka

Nozomi Komatsu

A light-emitting element having high emission efficiency which includes a fluorescent material as a light-emitting substance is provided. A light-emitting element includes a pair of electrodes and an EL layer between the pair of electrodes. The EL layer includes a light-emitting layer. The light-emitting layer includes a host material and a guest material. The host material has a difference of more than 0 eV and less than or equal to 0.2 eV between a singlet excitation energy level and a triplet excitation energy level. The guest material is capable of emitting fluorescence. The triplet excitation energy level of the host material is higher than a triplet excitation energy level of the guest material.

Light-emitting element, display device, electronic device, and lighting device

Light-emitting element with fluorescent material, display device, electronic device, and lighting device

A light-emitting element containing a fluorescent material and having high emission efficiency is provided. The light-emitting element contains the fluorescent material and a host material. The host material contains a first organic compound and a second organic compound. The first organic compound and the second organic compound can form an exciplex. The minimum value of a distance between centroids of the fluorescent material and at least one of the first organic compound and the second organic compound is 0.7 nm or more and 5 nm or less.

A light-emitting element containing a fluorescent material and having high emission efficiency is provided. The light-emitting element contains the fluorescent material and a host material. The host material contains a first organic compound and a second organic compound. The first organic compound and the second organic compound can form an exciplex. The proportion of a delayed fluorescence component in light emitted from the exciplex is higher than or equal to 5%, and the delayed fluorescence component contains a delayed fluorescence component whose fluorescence lifetime is 10 ns or longer and 50 μs or shorter.

Light-emitting element with light-emitting layer including first and second organic compounds, display device, electronic device, and lighting device

A light-emitting element containing a fluorescent material and having high emission efficiency is provided. The light-emitting element contains the fluorescent material and a host material. The host material contains a first organic compound and a second organic compound. The first organic compound and the second organic compound can form an exciplex. The proportion of a delayed fluorescence component in light emitted from the exciplex is higher than or equal to 5%, and the delayed fluorescence component contains a delayed fluorescence component whose fluorescence lifetime is 10 ns or longer and 50 &#x3bc;s or shorter.

A highly reliable light-emitting element having high emission efficiency is provided. The light-emitting element includes a light-emitting layer including a first organic compound and a guest material. The first organic compound has a substituted or unsubstituted carbazole skeleton. In the light-emitting layer, the weight ratio of a hydrocarbon group substitution product in which at least one of hydrogen atoms in the first organic compound is substituted by a hydrocarbon group having 1 to 6 carbon atoms to the first organic compound is greater than 0 and less than or equal to 0.1.

Light-emitting element, light-emitting device, electronic device, and lighting device including a nitrogen-containing six-membered heteroaromatic skeleton

A highly reliable light-emitting element that shows a novel degradation curve when driven is provided. The degradation curve of a light-emitting element with a long lifetime is represented by a function composed of two exponential functions, which is a linear combination of an exponential function expressing an initial degradation component and an exponential function expressing a long-term degradation component. The initial degradation component is represented by a stretched exponential function, and the long-term degradation component is represented by a single exponential function. When the proportion of the initial degradation component of the degradation curve represented by the function composed of two exponential functions is less than or equal to 0.25, preferably less than or equal to 0.20, and further preferably less than or equal to 0.15; a highly reliable light-emitting element is obtained.

Light-emitting element, light-emitting device, electronic device, and lighting device

A light-emitting element having high emission efficiency is provided. A light-emitting element which has high emission efficiency without using a rare metal as a light-emitting material is provided. A light-emitting element includes a first electrode, a second electrode, and a layer between the first electrode and the second electrode. The layer contains a first organic compound and a second organic compound. The second organic compound has a carbazole skeleton and a substituted or unsubstituted bivalent aromatic hydrocarbon group. The second organic compound further has a benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton. The aromatic hydrocarbon group is bonded to the carbazole skeleton. The aromatic hydrocarbon group is bonded to the benzofuropyrimidine skeleton or the benzothienopyrimidine skeleton. The first organic compound and the second organic compound can form an exciplex.

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Kanagawa, Japan

Shunsuke Hosoumi