Light-emitting device and electronic apparatus including the same
A light-emitting device includes a first electrode, a second electrode, m emitting units, and m−1 charge generation layers. The m emitting units each include a hole transport region, an emission layer, and an electron transport region. At least one emission layer of the m emitting units includes a first emission layer and a second emission layer, and at least one hole transport region adjacent to a p-type charge generation layer includes a multi-layered hole transport layer consisting of a first non-doped layer, a doped layer, and a second non-doped layer. The first non-doped layer and the second non-doped layer each independently consist of a hole transport material, the doped layer includes a hole transport material and a p-dopant, and the hole transport region adjacent to the first electrode does not include the multi-layered hole transport layer. An electronic apparatus including the light-emitting device is also provided.
1 . A light-emitting device comprising:
an anode;
a cathode facing the anode;
m emitting units disposed between the anode and the cathode; and
m−1 charge generation layers disposed between two adjacent ones of the m emitting units and each including an n-type charge generation layer and a p-type charge generation layer, wherein
m is an integer of 2 or more,
each of the m emitting units comprises a hole transport region, an emission layer, and an electron transport region that are sequentially disposed,
at least one emission layer of the m emitting units comprises a first emission layer and a second emission layer that are sequentially disposed between the anode and the cathode,
at least one hole transport region adjacent to the p-type charge generation layer of each of the m−1 charge generation layers comprises a multi-layered hole transport layer consisting of a first non-doped layer, a doped layer, and a second non-doped layer that are sequentially stacked,
the first non-doped layer and the second non-doped layer each independently consist of a hole transport material,
the doped layer comprises a hole transport material and a p-dopant,
a hole transport region adjacent to the anode does not comprise the multi-layered hole transport layer, and
the p-dopant is a quinone derivative or a cyano group-containing compound.
2 . The light-emitting device of claim 1 , wherein m is an integer of 3 or more.
3 . The light-emitting device of claim 1 , wherein
each hole transport region comprises a hole injection layer, a hole transport layer, an emission auxiliary layer, an electron blocking layer, or a combination thereof,
each electron transport region comprises a buffer layer, a hole blocking layer, an electron transport layer, an electron injection layer, or a combination thereof, and
the at least one hole transport region comprising the multi-layered hole transport layer does not comprise an emission auxiliary layer and an electron blocking layer.
4 . The light-emitting device of claim 1 , wherein a highest occupied molecular orbital (HOMO) energy level of the multi-layered hole transport layer is in a range of about −5.5 eV to about −5.25 eV.
5 . The light-emitting device of claim 1 , wherein the multi-layered hole transport layer is adjacent to an emission layer.
6 . The light-emitting device of claim 5 , wherein the emission layer adjacent to the multi-layered hole transport layer comprises the first emission layer and the second emission layer.
7 . The light-emitting device of claim 1 , wherein an amount of the p-dopant included in the doped layer of the multi-layered hole transport layer is in a range of about 0.1 wt % to about 20 wt % based on the total weight of the doped layer.
8 . The light-emitting device of claim 1 , wherein a thickness of the doped layer of the multi-layered hole transport layer is less than about 80% of a total thickness of the multi-layered hole transport layer.
9 . The light-emitting device of claim 1 , wherein
the second non-doped layer of the multi-layered hole transport layer is adjacent to an emission layer, and
a thickness of the second non-doped layer is equal to or greater than about 20% of a total thickness of the multi-layered hole transport layer.
10 . The light-emitting device of claim 1 , wherein the hole transport materials included in the first non-doped layer, the doped layer, and the second non-doped layer are identical to or different from each other.
11 . The light-emitting device of claim 1 , wherein
the first emission layer comprises a first compound comprising at least one deuterium, and
the second emission layer comprises a second compound that does not comprise deuterium.
12 . The light-emitting device of claim 1 , wherein
the first emission layer comprises a first dopant,
the second emission layer comprises a second dopant, and
the first dopant and the second dopant are identical to or different from each other.
13 . The light-emitting device of claim 1 , wherein a maximum luminescence wavelength of light emitted from at least one emitting unit of the m emitting units is different from a maximum luminescence wavelength of light emitted from at least one emitting unit of the remaining emitting units.
14 . The light-emitting device of claim 1 , wherein light emitted from each of the m emitting units have the same maximum luminescence wavelength.
15 . The light-emitting device of claim 1 , wherein the at least one emission layer of the m emitting units that comprises the first emission layer and the second emission layer emits blue light having a maximum luminescence wavelength in a range of about 440 nm to about 510 nm.
16 . The light-emitting device of claim 1 , wherein the emitting unit comprising the multi-layered hole transport layer emits blue light having a maximum luminescence wavelength in a range of about 440 nm to about 510 nm.
17 . The light-emitting device of claim 1 , further comprising at least one of:
a first capping layer disposed outside the anode; and
a second capping layer disposed outside the cathode, wherein
at least one of the first capping layer and the second capping layer has a refractive index of greater than or equal to about 1.6 at a wavelength of 589 nm.
18 . An electronic apparatus comprising the light-emitting device of claim 1 .
19 . The electronic apparatus of claim 18 , further comprising:
a sealing portion disposed on the light-emitting device; and
a touch screen layer, a polarizing layer, a color filter, a color conversion layer, or a combination thereof, disposed on the sealing portion.
20 . The electronic apparatus of claim 18 , further comprising quantum dots or an optical member comprising the quantum dots, wherein
the quantum dots or the optical member comprising the quantum dots are disposed on at least one traveling direction of light emitted from the light-emitting device.
21 . The electronic apparatus of claim 18 , wherein the electronic apparatus is a display, a light source, lighting, a personal computer, a mobile personal computer, a mobile phone, a digital camera, an electronic organizer, an electronic dictionary, an electronic game machine, a medical instrument, an electronic thermometer, a sphygmomanometer, a blood glucose meter, a pulse measurement apparatus, a pulse wave measurement apparatus, an electrocardiogram display, an ultrasonic diagnostic apparatus, an endoscope display, a fish finder, a measuring instrument, a meter for a vehicle, a meter for an aircraft, a meter for a vessel, or a projector.