Abstract:
A light-emitting element having low driving voltage and high emission efficiency is provided. In the light-emitting element, a combination of a guest material and a host material forms an exciplex. The guest material is capable of converting triplet excitation energy into light emission. Light emission from the light-emitting layer includes light emission from the guest material and light emission from the exciplex. The percentage of the light emission from the exciplex to the light emission from the light-emitting layer is greater than 0 percent and less than or equal to 60 percent. The energy after subtracting the energy of light emission from the exciplex from the energy of light emission from the guest material is greater than 0 eV and less than or equal to 0.23 eV.
Abstract:
Providing a light-emitting element emitting light in a broad emission spectrum. A combination of a first organic compound and a second organic compound forms an exciplex. The first organic compound has a function of converting triplet-excitation energy into light emission. The lowest triplet excitation level of the second organic compound is higher than or equal to the lowest triplet excitation level of the first organic compound, and the lowest triplet excitation level of the first organic compound is higher than or equal to the lowest triplet excitation level of the exciplex. Light emission from a light-emitting layer includes light emission from the first organic compound and light emission from the exciplex.
Abstract:
Provided is a light-emitting element having a light-emitting layer which contains at least a host material and a plurality of guest materials, where the host material has a lower T1 level than that of at least one of the plurality of guest materials. The emission of the one of the plurality of guest materials exhibits a multicomponent decay curve, and the lifetime thereof is less than or equal to 15 μsec, preferably less than or equal to 10 μsec, more preferably less than or equal to 5 μsec, where the lifetime is defined as a time for the emission to decrease in intensity to 1/100 of its initial intensity.
Abstract:
To increase emission efficiency of a fluorescent light-emitting element by efficiently utilizing a triplet exciton generated in a light-emitting layer. The light-emitting layer of the light-emitting element includes at least a host material and a guest material. The triplet exciton generated from the host material in the light-emitting layer is changed to a singlet exciton by triplet-triplet annihilation (TTA). The guest material (fluorescent dopant) is made to emit light by energy transfer from the singlet exciton. Thus, the emission efficiency of the light-emitting element is improved.
Abstract:
An organic semiconductor device with low driving voltage is provided. The organic semiconductor device includes a layer containing an organic compound between a pair of electrodes. The layer containing an organic compound includes a hole-transport region. The hole-transport region includes a first layer and a second layer. The first layer is positioned between the anode and the second layer. When a potential gradient of a surface potential of an evaporated film is set as GSP (mV/nm), a value obtained by subtracting GSP of an organic compound in the second layer from GSP of an organic compound in the first layer is less than or equal to 20 (mV/nm).
Abstract:
A light-emitting apparatus with high emission efficiency is provided. The light-emitting apparatus includes light-emitting devices A and B each including an anode, a cathode, and an EL layer. An EL layer A includes a first layer A to a third layer A and a light-emitting layer A. An EL layer B includes a first layer B to a fourth layer B and a light-emitting layer B. The light-emitting layer A includes a light-emitting substance A and the light-emitting layer B includes a light-emitting substance B. An emission peak wavelength (wavelength A) of the light-emitting substance A is shorter than an emission peak wavelength (wavelength B) of the light-emitting substance B. The first layers A and B have similar structures, the second layers A and B have similar structures, and the third layers A and B have similar structures. The ordinary refractive index (no) of each of the first layer A and the third layer A is lower than the no of the second layer A at the wavelength A. The no of each of the first layer B and the third layer B is lower than the no of the second layer B at the wavelength B. The fourth layer B is positioned between the anode B and the first layer B, between the first layer B and the second layer B, between the first layer B and the third layer B, or between the third layer B and the light-emitting layer B.
Abstract:
A display apparatus having a function of emitting visible light and infrared light and a light detection function is provided. The display apparatus includes a first light-emitting device, a second light-emitting device, and a light-receiving device in a display portion. The first light-emitting device emits both visible light and infrared light and the second light-emitting device emits visible light. The light-receiving device has a function of absorbing at least part of visible light and infrared light. The first light-emitting device includes a first pixel electrode, a first light-emitting layer, a second light-emitting layer, and a common electrode. The second light-emitting device includes a second pixel electrode, a third light-emitting layer, and the common electrode. The light-receiving device includes a third pixel electrode, an active layer, and the common electrode. The first light-emitting layer includes a light-emitting material emitting infrared light. The second light-emitting layer and the third light-emitting layer include light-emitting materials emitting visible light with different wavelengths. The active layer includes an organic compound.
Abstract:
Provided is a light-emitting element which has an anode, a light-emitting layer over the anode, an electron-transport layer over and in contact with the light-emitting layer, an electron-injection layer over and in contact with the electron-transport layer, and a cathode over and in contact with the electron-injection layer. The light-emitting layer has an electron-transport property, and the electron-transport layer includes an anthracene derivative. The light-emitting layer further includes a phosphorescent substance. This device structure allows the formation of a highly efficient blue-emissive light-emitting element even though the phosphorescent substance has higher triplet energy than the anthracene derivative which directly contacts with the light-emitting layer.
Abstract:
A display device that has a function of emitting visible light and infrared light and a function of detecting light. The display device is a display device including a first light-emitting device, a second light-emitting device, and a light-receiving device, in a display portion. The first light-emitting device includes a first pixel electrode, a first optical adjustment layer, a first light-emitting layer, a second light-emitting layer, and a common electrode. The second light-emitting device includes a second pixel electrode, a second optical adjustment layer, the first light-emitting layer, the second light-emitting layer, and the common electrode. The light-receiving device includes a third pixel electrode, an active layer, and the common electrode. The active layer includes an organic compound. The first light-emitting device emits infrared light emitted by the first light-emitting layer. The second light-emitting device emits visible light emitted by the second light-emitting layer. The light-receiving device has a function of absorbing at least part of visible light and infrared light.
Abstract:
A light-emitting element having low driving voltage and high emission efficiency is provided. In the light-emitting element, a combination of a guest material and a host material forms an exciplex. The guest material is capable of converting triplet excitation energy into light emission. Light emission from the light-emitting layer includes light emission from the guest material and light emission from the exciplex. The percentage of the light emission from the exciplex to the light emission from the light-emitting layer is greater than 0 percent and less than or equal to 60 percent. The energy after subtracting the energy of light emission from the exciplex from the energy of light emission from the guest material is greater than 0 eV and less than or equal to 0.23 eV.