Display device, display module, electronic device, and television device
A display device having a long lifetime is provided. A large-sized display device is provided. A display device includes a first light-emitting device and a second light-emitting device. The first light-emitting device includes a hole-injection layer, a first light-emitting layer, and an electron-transport layer. The second light-emitting device includes a second light-emitting layer. The hole-injection layer contains a first compound and a second compound. The first light-emitting layer contains a third compound that emits light of a first color. The second light-emitting layer contains a fourth compound that emits light of a second color. The electron-transport layer contains a fifth compound. The first compound has a property of accepting electrons from the second compound. The second compound has a HOMO level higher than or equal to −5.7 eV and lower than or equal to −5.4 eV. The fifth compound has a HOMO level higher than or equal to −6.0 eV and an electron mobility higher than or equal to 1×10{circumflex over ( )}−7 cm{circumflex over ( )}/Vs and lower than or equal to 5×10{circumflex over ( )}−5 cm{circumflex over ( )}/Vs when the square root of electric field strength [V/cm] is 600.
1. A display device comprising:
a first light-emitting device; and
a second light-emitting device,
wherein the first light-emitting device comprises a first electrode and a common electrode,
wherein the second light-emitting device comprises a second electrode and the common electrode,
wherein the first light-emitting device comprises a hole-injection layer, a first light-emitting layer, and an electron-transport layer in this order from a side of one of the first electrode and the common electrode that functions as an anode,
wherein the second light-emitting device comprises a second light-emitting layer between the second electrode and the common electrode,
wherein the hole-injection layer is in contact with the one of the first electrode and the common electrode that functions as the anode,
wherein the hole-injection layer comprises a first compound and a second compound,
wherein the first light-emitting layer comprises a third compound that emits light of a first color,
wherein the second light-emitting layer comprises a fourth compound that emits light of a second color,
wherein the electron-transport layer comprises a fifth compound,
wherein the first compound has a property of accepting an electron from the second compound,
wherein the second compound has a HOMO level higher than or equal to −5.7 eV and lower than or equal to −5.4 eV, and
wherein the fifth compound has a HOMO level higher than or equal to −6.0 eV and an electron mobility higher than or equal to 1×10 −7 cm 2 /Vs and lower than or equal to 5×10 −5 cm 2 /Vs when a square root of electric field strength [V/cm] is 600.
2. The display device according to claim 1 ,
wherein the second light-emitting device comprises a layer shared with the first light-emitting device between the second electrode and the common electrode.
3. The display device according to claim 1 ,
wherein the second light-emitting device comprises the hole-injection layer and the electron-transport layer.
4. The display device according to claim 1 ,
wherein the first light-emitting device further comprises a first hole-transport layer,
wherein the first hole-transport layer comprises a sixth compound,
wherein a HOMO level of the sixth compound is lower than or equal to a HOMO level of the second compound, and
wherein a difference between the HOMO level of the sixth compound and the HOMO level of the second compound is 0.2 eV or less.
5. The display device according to claim 4 ,
wherein the second compound and the sixth compound each comprise at least one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton.
6. The display device according to claim 4 ,
wherein the first light-emitting device further comprises a second hole-transport layer,
wherein the second hole-transport layer comprises a seventh compound, and
wherein a HOMO level of the seventh compound is lower than the HOMO level of the sixth compound.
7. The display device according to claim 6 ,
wherein the second compound, the sixth compound, and the seventh compound each comprise at least one of a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton.
8. The display device according to claim 1 ,
wherein the electron-transport layer further comprises an eighth compound, and
wherein the eighth compound is an organic complex comprising an alkali metal or an alkaline earth metal.
9. The display device according to claim 8 ,
wherein a ratio of the fifth compound to the eighth compound in the electron-transport layer differs between the first light-emitting layer side and the common electrode side.
10. The display device according to claim 8 ,
wherein the electron-transport layer comprises a first region on the first light-emitting layer side and a second region on the common electrode side, and
wherein an amount of the eighth compound in the second region is smaller than an amount of the eighth compound in the first region.
11. The display device according to claim 1 ,
wherein each of the third compound and the fourth compound is a fluorescent substance.
12. The display device according to claim 1 ,
wherein the first color is blue.
13. The display device according to claim 1 ,
wherein a decay curve expressed as a change in luminance of light emission obtained when a certain amount of current flows through the first light-emitting device has a local maximum value.
14. A display module comprising the display device according to claim 1 , and a connector or an integrated circuit.
15. An electronic device comprising the display module according to claim 14 , and at least one of an antenna, a battery, a housing, a camera, a speaker, a microphone, and an operation button.
16. A television device comprising the display module according to claim 14 , and a communication control portion,
wherein the television device is capable of being connected to a computer network using the communication control portion.
17. A display device comprising:
a first light-emitting device;
a second light-emitting device; and
a third light-emitting device,
wherein the first light-emitting device comprises a first electrode and a common electrode,
wherein the second light-emitting device comprises a second electrode and the common electrode,
wherein the third light-emitting device comprises a third electrode and the common electrode,
wherein the first light-emitting device comprises a hole-injection layer, a first light-emitting layer, and an electron-transport layer in this order from a side of one of the first electrode and the common electrode that functions as an anode,
wherein the second light-emitting device comprises a second light-emitting layer between the second electrode and the common electrode,
wherein the third light-emitting device comprises a third light-emitting layer between the third electrode and the common electrode,
wherein the hole-injection layer is in contact with the one of the first electrode and the common electrode that functions as the anode,
wherein the hole-injection layer comprises a first compound and a second compound,
wherein the electron-transport layer comprises a third compound,
wherein the first compound has a property of accepting an electron from the second compound,
wherein the second compound has a HOMO level higher than or equal to −5.7 eV and lower than or equal to −5.4 eV,
wherein the third compound has a HOMO level higher than or equal to −6.0 eV and an electron mobility higher than or equal to 1×10 −7 cm 2 /Vs and lower than or equal to 5×10 −5 cm 2 /Vs when a square root of electric field strength [V/cm] is 600,
wherein a maximum peak wavelength of an emission spectrum of the first light-emitting device is shorter than a maximum peak wavelength of an emission spectrum of the second light-emitting device,
wherein the maximum peak wavelength of the emission spectrum of the second light-emitting device is shorter than a maximum peak wavelength of an emission spectrum of the third light-emitting device,
wherein in a top view, an area of a light-emitting region of the second light-emitting device is larger than an area of a light-emitting region of the third light-emitting device, and
wherein in the top view, an area of a light-emitting region of the first light-emitting device is larger than or equal to the area of the light-emitting region of the third light-emitting device and smaller than or equal to the area of the light-emitting region of the second light-emitting device.
18. The display device according to claim 17 ,
wherein the first light-emitting device exhibits fluorescence, and
wherein the second light-emitting device and the third light-emitting device each exhibit phosphorescence.
19. The display device according to claim 17 ,
wherein the second light-emitting device comprises a layer shared with the first light-emitting device between the second electrode and the common electrode.
20. A display device comprising:
a first light-emitting device;
a second light-emitting device; and
a third light-emitting device,
wherein the first light-emitting device comprises a first electrode and a common electrode,
wherein the second light-emitting device comprises a second electrode and the common electrode,
wherein the third light-emitting device comprises a third electrode and the common electrode,
wherein the first light-emitting device comprises a first light-emitting layer and an electron-transport layer in this order from a side of one of the first electrode and the common electrode that functions as an anode,
wherein the second light-emitting device comprises a second light-emitting layer between the second electrode and the common electrode,
wherein the third light-emitting device comprises a third light-emitting layer between the third electrode and the common electrode,
wherein the electron-transport layer comprises an electron-transport material and an organometallic complex of an alkali metal or an alkaline earth metal,
wherein the electron-transport layer comprises a first region and a second region that is positioned closer to the common electrode than the first region is,
wherein the first region and the second region differ in a concentration of the electron-transport material,
wherein a maximum peak wavelength of an emission spectrum of the first light-emitting device is shorter than a maximum peak wavelength of an emission spectrum of the second light-emitting device,
wherein the maximum peak wavelength of the emission spectrum of the second light-emitting device is shorter than a maximum peak wavelength of an emission spectrum of the third light-emitting device,
wherein in a top view, an area of a light-emitting region of the second light-emitting device is larger than an area of a light-emitting region of the third light-emitting device, and
wherein in the top view, an area of a light-emitting region of the first light-emitting device is larger than or equal to the area of the light-emitting region of the third light-emitting device and smaller than or equal to the area of the light-emitting region of the second light-emitting device.
21. The display device according to claim 20 ,
wherein the concentration of the electron-transport material in the second region is lower than the concentration of the electron-transport material in the first region.
22. The display device according to claim 20 ,
wherein the first light-emitting device exhibits fluorescence, and
wherein the second light-emitting device and the third light-emitting device each exhibit phosphorescence.
23. The display device according to claim 20 ,
wherein the second light-emitting device comprises a layer shared with the first light-emitting device between the second electrode and the common electrode.