Organic light emitting diode and organic light emitting device comprising the same

Abstract

The present disclosure relates to an organic light-emitting diode and an organic light-emitting device including the same. The organic light-emitting diode includes a first electrode; a second electrode facing the first electrode; and a first light-emitting material layer including a first compound, a second compound, and a third compound and located between the first electrode and the second electrode, wherein a starting wavelength of the second compound is greater than a starting wavelength of the first compound and less than a starting wavelength of the third compound, wherein a maximum emission wavelength of the second compound is less than a maximum emission wavelength of the first compound, and a maximum emission wavelength of the third compound is equal to or less than the maximum emission wavelength of the first compound, and wherein a full width at half maximum of each of the second compound and the third compound is less than a full width at half maximum of the first compound.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0186092, filed in the Republic of Korea on December 29, 2020, which is hereby incorporated by reference in its entirety. Technical Field

[0003] The present disclosure relates to an organic light emitting diode, and more particularly, to an organic light emitting diode having excellent light emitting characteristics and an organic light emitting device including the same. Background Art

[0004] Recently, demand for flat panel display devices with a small footprint has increased. Among flat panel display devices, technology for organic light emitting display devices, which include organic light emitting diodes (OLEDs) and may be referred to as organic electroluminescent devices, has rapidly developed.

[0005] OLEDs emit light by injecting electrons from a cathode serving as an electron injection electrode and holes from an anode serving as a hole injection electrode into a light-emitting material layer, combining the electrons with the holes to generate excitons, and converting the excitons from an excited state to a ground state.

[0006] The light-emitting materials in the light-emitting material layer of the OLED can be classified into phosphorescent materials, fluorescent materials and delayed fluorescent materials. Delayed fluorescent materials and phosphorescent materials each have a wider full width at half maximum (FWHM) than fluorescent materials, while fluorescent materials have lower luminous efficiency than delayed fluorescent materials and phosphorescent materials. Summary of the Invention

[0007] Accordingly, embodiments of the present disclosure are directed to OLEDs and organic light emitting devices that substantially obviate one or more of the problems associated with limitations and disadvantages of the related art.

[0008] Additional features and aspects will be set forth in the following description, and in part will be apparent from the description, or may be learned by practicing the inventive concepts provided herein. Other features and aspects of the inventive concepts may be realized and obtained by the structures particularly pointed out in or derived from the written description, and in the claims and drawings.

[0009] To achieve these advantages and other advantages according to embodiments of the present disclosure, as embodied and broadly described herein, an organic light emitting diode includes a first electrode; a second electrode facing the first electrode; and a first light emitting material layer including a first compound, a second compound, and a third compound and located between the first electrode and the second electrode, wherein a starting wavelength of the second compound is greater than a starting wavelength of the first compound and less than a starting wavelength of the third compound, wherein a maximum emission wavelength of the second compound is less than a maximum emission wavelength of the first compound, and a maximum emission wavelength of the third compound is equal to or less than the maximum emission wavelength of the first compound, and wherein a half-full width of each of the second compound and the third compound is less than a half-full width of the first compound.

[0010] In another aspect, an organic light emitting device includes a substrate; and an organic light emitting diode disposed on or over the substrate, the organic light emitting diode including a first electrode; a second electrode facing the first electrode; and a first light emitting material layer including a first compound, a second compound, and a third compound and located between the first electrode and the second electrode, wherein a starting wavelength of the second compound is greater than a starting wavelength of the first compound and less than a starting wavelength of the third compound, wherein a maximum emission wavelength of the second compound is less than a maximum emission wavelength of the first compound, and a maximum emission wavelength of the third compound is equal to or less than the maximum emission wavelength of the first compound, and wherein a half-full width of each of the second compound and the third compound is less than a half-full width of the first compound.

[0011] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the present inventive concept claimed. BRIEF DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings, which are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure.

[0013] Figure 1 is a schematic circuit diagram of an organic light emitting display device of the present disclosure.

[0014] Figure 2 is a schematic cross-sectional view of an organic light emitting display device according to a first embodiment of the present disclosure.

[0015] Figure 3 is a schematic cross-sectional view of an OLED according to a second embodiment of the present disclosure.

[0016] Figure 4 is a schematic view showing a light emitting mechanism in a light emitting material layer of an OLED according to the second embodiment of the present disclosure.

[0017] Figure 5 is a schematic cross-sectional view of an OLED according to a third embodiment of the present disclosure.

[0018] Figure 6 is a schematic diagram illustrating a light emitting mechanism in a light emitting material layer of an OLED according to a third embodiment of the present disclosure.

[0019] Figure 7 is a schematic cross-sectional view of an OLED according to a fourth embodiment of the present disclosure.

[0020] Figures 8A to 8G is a graph of EL spectra of OLEDs according to the second to fourth embodiments of the present disclosure.

[0021] Figure 9 is a schematic cross-sectional view of an OLED according to a fifth embodiment of the present disclosure.

[0022] Figure 10 is a schematic diagram showing the relationship between compounds in the light-emitting material layer of an OLED according to a fifth embodiment of the present disclosure.

[0023] Figure 11 is a schematic diagram illustrating a light emitting mechanism in a light emitting material layer of an OLED according to a fifth embodiment of the present disclosure.

[0024] Figure 12 is a graph of PL spectra of a first compound, a second compound, and a third compound used in an OLED according to the present disclosure.

[0025] Figures 13A to 13L is used Figure 12 Graph of the EL spectrum of OLEDs containing the compounds in FIG.

[0026] Figure 14 is a graph of PL spectra of a first compound, a second compound, and a third compound used in an OLED according to the present disclosure.

[0027] Figures 15A to 15J is used Figure 14 Graph of the EL spectrum of OLEDs containing the compounds in FIG.

[0028] Figure 16 is a graph of PL spectra of a first compound, a second compound, and a third compound used in an OLED according to the present disclosure.

[0029] Figures 17A to 17E is used Figure 16 Graph of the EL spectrum of OLEDs containing the compounds in FIG.

[0030] Figure 18is a schematic cross-sectional view of an OLED according to a sixth embodiment of the present disclosure.

[0031] Figure 19 is a schematic cross-sectional view of an organic light emitting display device according to a seventh embodiment of the present disclosure.

[0032] Figure 20 is a schematic cross-sectional view of an OLED according to an eighth embodiment of the present disclosure.

[0033] Figure 21 is a schematic cross-sectional view of an OLED according to a ninth embodiment of the present disclosure.

[0034] Figure 22 is a schematic cross-sectional view of an OLED according to a tenth embodiment of the present disclosure.

[0035] Figure 23 is a schematic cross-sectional view of an OLED according to an eleventh embodiment of the present disclosure. DETAILED DESCRIPTION

[0036] Reference will now be made in detail to some examples and preferred embodiments which are illustrated in the accompanying drawings.

[0037] The present disclosure relates to an organic light-emitting device (OLED) in which a delayed fluorescent material, a phosphorescent material, and a fluorescent material are applied to a single light-emitting material layer or adjacent light-emitting material layers, and an organic light-emitting device including the OLED. For example, the organic light-emitting device may be an organic light-emitting display device or an organic lighting device. As an example, the organic light-emitting display device, which is a display device including the OLED of the present disclosure, will be primarily described.

[0038] Figure 1 is a schematic circuit diagram of an organic light emitting display device disclosed herein.

[0039] like Figure 1 As shown in FIG, the organic light emitting display device includes a gate line GL, a data line DL, a power line PL, a switching thin film transistor TFT Ts, a driving TFT Td, a storage capacitor Cst, and an OLED D. The gate line GL and the data line DL cross each other to define a pixel region P. The pixel region may include a red pixel region, a green pixel region, and a blue pixel region.

[0040] The switching TFT Ts is connected to the gate line GL and the data line DL, and the driving TFT Td and the storage capacitor Cst are connected to the switching TFT Ts and the power line PL. The OLED D is connected to the driving TFT Td.

[0041] In the organic light emitting display device, when the switch TFT Ts is turned on by a gate signal applied through the gate line GL, a data signal from the data line DL is applied to one electrode of the storage capacitor Cst and the gate electrode of the drive TFT Td.

[0042] When the drive TFT Td is turned on by the data signal, a current is supplied from the power supply line PL to the OLED D. Thus, the OLED D emits light. In this case, when the drive TFT Td is turned on, the level of the current applied from the power supply line PL to the OLED D is determined so that the OLED D can generate a gray scale.

[0043] The storage capacitor Cst is used to maintain the voltage of the gate electrode of the drive TFT Td when the switch TFT Ts is turned off. Thus, even if the switch TFT Ts is turned off, the level of the current applied from the power supply line PL to the OLED D is maintained to the next frame.

[0044] As a result, the organic light emitting display device displays a desired image.

[0045] Figure 2 is a schematic cross-sectional view of an organic light emitting display device according to a first embodiment of the disclosure.

[0046] As Figure 2 As shown in FIG. 1, the organic light emitting display device 100 includes a substrate 110, a TFT Tr, and an OLED D connected to the TFT Tr.

[0047] The substrate 110 can be a glass substrate or a flexible substrate. For example, the flexible substrate can be a polyimide (PI) substrate, a polyether sulfone (PES) substrate, a polyethylene naphthalate (PEN) substrate, a polyethylene terephthalate (PET) substrate, or a polycarbonate (PC) substrate.

[0048] A buffer layer 122 is formed on the substrate, and the TFT Tr is formed on the buffer layer 122. The buffer layer 122 can be omitted.

[0049] A semiconductor layer 120 is formed on the buffer layer 122. The semiconductor layer 120 can include an oxide semiconductor material or polysilicon.

[0050] When the semiconductor layer 120 includes the oxide semiconductor material, a light-shielding pattern (not shown) can be formed under the semiconductor layer 120. Light reaching the semiconductor layer 120 is shielded or blocked by the light-shielding pattern, so that thermal degradation of the semiconductor layer 120 can be prevented. On the other hand, when the semiconductor layer 120 includes polysilicon, impurities can be doped in both sides of the semiconductor layer 120.

[0051] A gate insulating layer 124 is formed over the semiconductor layer 120. The gate insulating layer 124 can be formed of an inorganic insulating material such as silicon oxide or silicon nitride.

[0052] A gate electrode 130 formed of a conductive material (e.g., metal) is formed over the gate insulating layer 124 in correspondence with the center of the semiconductor layer 120. In Figure 2 In the present embodiment, the gate insulating layer 124 is formed over the entire surface of the substrate 110. Alternatively, the gate insulating layer 124 can be patterned to have the same shape as the gate electrode 130.

[0053] An interlayer insulating layer 132 formed of an insulating material is formed over the gate electrode 130. The interlayer insulating layer 132 can be formed of an inorganic insulating material (e.g., silicon oxide or silicon nitride) or an organic insulating material (e.g., benzocyclobutene or photo-acryl).

[0054] The interlayer insulating layer 132 includes a first contact hole 134 and a second contact hole 136 that expose both sides of the semiconductor layer 120. The first contact hole 134 and the second contact hole 136 are located on both sides of the gate electrode 130 so as to be spaced apart from the gate electrode 130. The first contact hole 134 and the second contact hole 136 are formed so as to pass through the gate insulating layer 124. Alternatively, when the gate insulating layer 124 is patterned to have the same shape as the gate electrode 130, the first contact hole 134 and the second contact hole 136 are formed so as to pass through only the interlayer insulating layer 132.

[0055] A source electrode 144 and a drain electrode 146 formed of a conductive material (e.g., metal) are formed over the interlayer insulating layer 132. The source electrode 144 and the drain electrode 146 are spaced apart from each other with respect to the gate electrode 130 and contact both sides of the semiconductor layer 120 through the first contact hole 134 and the second contact hole 136, respectively.

[0056] The semiconductor layer 120, the gate electrode 130, the source electrode 144, and the drain electrode 146 constitute a TFT Tr. The TFT Tr functions as a driving element. That is, the TFT Tr is a (driving) TFT Td. Figure 1

[0057] In the TFT Tr, the gate electrode 130, the source electrode 144, and the drain electrode 146 are located above the semiconductor layer 120. That is, the TFT Tr has a coplanar structure. Alternatively, in the TFT Tr, the gate electrode can be located below the semiconductor layer, and the source electrode and the drain electrode can be located above the semiconductor layer, so that the TFT Tr can have a reverse staggered structure. In this case, the semiconductor layer can include amorphous silicon.

[0058] ​Although not shown, gate lines and data lines cross each other to define pixel areas, and switching TFTs are formed connected to the gate lines and the data lines. The switching TFTs are connected to the TFT Tr as a driving element. Further, a power supply line which can be formed in parallel with and spaced apart from one of the gate lines and the data lines and a storage capacitor for maintaining a voltage of a gate electrode of the TFT Tr in one frame can also be formed.

[0059] A planarization layer 150 is formed on the entire surface of the substrate 110 to cover the source electrode 144 and the drain electrode 146. The planarization layer 150 provides a flat top surface and has a drain contact hole 152 exposing the drain electrode 146 of the TFT Tr.

[0060] The OLED D is disposed on the planarization layer 150 and includes a first electrode 210 connected to the drain electrode 146 of the TFT Tr, a light-emitting layer 220, and a second electrode 230. The light-emitting layer 220 and the second electrode 230 are sequentially stacked on the first electrode 210. The OLED D is located in each of the red, green, and blue pixel areas and emits red, green, and blue light, respectively.

[0061] The first electrode 210 is formed in each pixel area, respectively. The first electrode 210 can be an anode and can be formed of a conductive material having a relatively high work function, such as a transparent conductive oxide (TCO). For example, the first electrode 210 can be formed of indium-tin-oxide (ITO), indium-zinc-oxide (IZO), indium-tin-zinc-oxide (ITZO), tin oxide (SnO), zinc oxide (ZnO), indium-copper-oxide (ICO), or aluminum-zinc-oxide (Al:ZnO, AZO).

[0062] When the organic light-emitting display device 100 operates in a bottom emission type, the first electrode 210 can have a single-layer structure of a transparent conductive material layer. When the organic light-emitting display device 100 operates in a top emission type, a reflective electrode or a reflective layer can be formed under the first electrode 210. For example, the reflective electrode or the reflective layer can be formed of silver (Ag) or an aluminum-palladium-copper (APC) alloy. In this case, the first electrode 210 can have a three-layer structure of ITO / Ag / ITO or ITO / APC / ITO.

[0063] Further, a bank layer 160 is formed on the planarization layer 150 to cover edges of the first electrode 210. That is, the bank layer 160 is located at boundaries of the pixel areas and exposes centers of the first electrode 210 in the pixel areas.

[0064] A light-emitting layer 220, which is a light-emitting unit, is formed on the first electrode 210. The light-emitting layer 220 can have a single layer structure including an emission material layer (EML) containing an emission material. To improve the light-emitting efficiency of the organic light-emitting display device, the light-emitting layer 220 can have a multi-layer structure. For example, the light-emitting layer 220 can further include a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), a hole blocking layer (HBL), an electron transport layer (ETL), and an electron injection layer (EIL). The HIL, the HTL, and the EBL are sequentially disposed between the first electrode 210 and the EML, and the HBL, the ETL, and the EIL are sequentially disposed between the EML and the second electrode 230. Further, the EML can have a single layer structure or a multi-layer structure. Further, two or more light-emitting layers can be disposed to be spaced apart from each other such that the OLED D can have a tandem structure.

[0065] The second electrode 230 is formed over the substrate 110 on which the light-emitting layer 220 is formed. The second electrode 230 covers the entire surface of the display area and can be formed of a conductive material having a relatively low work function to serve as a cathode. For example, the second electrode 230 can be formed of aluminum (Al), magnesium (Mg), calcium (Ca), silver (Ag), or an alloy or a combination thereof. In the top emission type organic light-emitting display device 100, the second electrode 230 can have a thin profile (small thickness) to provide a light-transmitting property (or a semi-transmissive property).

[0066] Although not shown, the organic light-emitting display device 100 can include color filters corresponding to red, green, and blue pixel areas. For example, when the OLED D having a tandem structure and emitting white light is formed in all of the red, green, and blue pixel areas, a red color filter pattern, a green color filter pattern, and a blue color filter pattern can be formed in the red, green, and blue pixel areas, respectively, so that full-color display is provided. When the organic light-emitting display device 100 operates in a bottom emission type, the color filters can be disposed between the OLED D and the substrate 110, for example, between the interlayer insulating layer 132 and the planarization layer 150. Alternatively, when the organic light-emitting display device 100 operates in a top emission type, the color filters can be disposed above the OLED D, for example, above the second electrode 230.

[0067] An encapsulation film 170 is formed on the second electrode 230 to prevent moisture from penetrating into the OLED D. The encapsulation film 170 includes a first inorganic insulating layer 172, an organic insulating layer 174, and a second inorganic insulating layer 176, which are sequentially stacked, but is not limited thereto.

[0068] The organic light emitting display device 100 can further include a polarizing plate (not shown) for reducing reflection of ambient light. For example, the polarizing plate can be a circular polarizing plate. In the bottom emission type organic light emitting display device 100, the polarizing plate can be disposed under the substrate 110. In the top emission type organic light emitting display device 100, the polarizing plate can be disposed on or above the encapsulation film 170.

[0069] Further, in the top emission type organic light emitting display device 100, a cover window (not shown) can be attached to the encapsulation film 170 or the polarizing plate. In this case, the substrate 110 and the cover window have a flexible property, so that a flexible organic light emitting display device can be provided.

[0070] Figure 3 is a schematic cross-sectional view of an OLED according to a second embodiment of the disclosure.

[0071] As Figure 3 As shown in FIG. 1A, the OLED D1 includes a first electrode 210 and a second electrode 230 facing each other and a light emitting layer 220 therebetween. The light emitting layer 220 includes an emitting material layer (EML) 240. Figure 2 The organic light emitting display device 100 (of FIG. 1A) can include a red pixel region, a green pixel region, and a blue pixel region, and the OLED D1 can be located in each of the red pixel region, the green pixel region, and the blue pixel region.

[0072] The first electrode 210 can be an anode, and the second electrode 230 can be a cathode.

[0073] The light emitting layer 220 can further include at least one of a hole transport layer (HTL) 260 between the first electrode 210 and the EML 240 and an electron transport layer (ETL) 270 between the second electrode 230 and the EML 240.

[0074] Further, the light emitting layer 220 can further include at least one of a hole injection layer (HIL) 250 between the first electrode 210 and the HTL 260 and an electron injection layer (EIL) 280 between the second electrode 230 and the ETL 270.

[0075] Also, the light emitting layer 220 can further include at least one of an electron blocking layer (EBL) 265 between the HTL 260 and the EML 240 and a hole blocking layer (HBL) 275 between the EML 240 and the ETL 270.

[0076] For example, the HIL 250 may include at least one compound selected from the group consisting of 4,4',4"-tris(3-methylphenylamino)triphenylamine (MTDATA), 4,4',4"-tris(N,N-diphenylamino)triphenylamine (NATA), 4,4',4"-tris(N-(naphthalen-1-yl)-N-phenylamino)triphenylamine (1T-NATA), 4,4',4"-tris(N-(naphthalen-2-yl)-N-phenylamino)triphenylamine (2T-NATA), copper phthalocyanine (CuPc), tris(4-carbazolyl-9-yl-phenyl)amine (TCTA), N,N'-diphenyl-N,N'-bis(1-naphthyl) -1,1'-biphenyl-4,4"-diamine (NPB or NPD), 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (dipyrazino[2,3-f:2'3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile; HAT-CN), 1,3,5-tris[4-(diphenylamino)phenyl]benzene (TDAPB), poly(3,4-ethylenedioxythiophene)polystyrenesulfonate (PEDOT / PSS), and N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine, but are not limited thereto. The HIL 250 may have a thickness of about 1 nm to 30 nm.

[0077] The HTL 260 may include at least one compound selected from the group consisting of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), NPB (or NPD), 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] (poly-TPD), poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)-1,1'-biphenyl)]] The HTL 260 may include, but is not limited to, bis-[4-(N,N-di-p-tolylamino)-phenyl]cyclohexane (TAPC), 3,5-bis(9H-carbazol-9-yl)-N,N-diphenylaniline (DCDPA), N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine, and N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl-4-amine. The thickness of the HTL 260 may be approximately 10 nm to 100 nm.

[0078] The ETL 270 may include at least one of the following: Compounds based on oxadiazole, compounds based on triazole, compounds based on phenanthroline, compounds based on benzophenone Compounds of azole, compounds based on benzothiazole, compounds based on benzimidazole, and compounds based on triazine. For example, the ETL 270 can include at least one compound selected from the group consisting of tris-(8-hydroxyquinoline) aluminum (Alq3), 2-biphenyl-4-yl-5-(4-tert-butylphenyl)-1,3,4- oxadiazole (PBD), spiro-PBD, lithium quinolate (Liq), 1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBi), bis(2-methyl-8-hydroxyquinoline-N1,O8)-(1,1'-biphenyl-4-hydroxy)aluminum (BAlq), 4,7-diphenyl-1,10-phenanthroline (Bphen), 2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (NBphen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), 4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ), 1,3,5-tris(p-pyridin-3-yl-phenyl)benzene (TpPyPB), 2,4,6-tris(3'-(pyridin-3-yl)biphenyl-3-yl)1,3,5-triazine (TmPPPyTz), poly[9,9-bis(3'-(N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene-alternate-2,7-(9,9-dioctylfluorene)] dibromide (PFNBr), tris(phenylquinoxaline) (TPQ), and diphenyl-4-triphenylsilyl-phenylphosphine oxide (TSPO1), but is not limited thereto. The thickness of the ETL 270 can be about 10 nm to 100 nm.

[0079] The EIL 280 can include at least one of an alkali halide compound, such as LiF, CsF, NaF, or BaF2, and an organic metal compound, such as Liq, lithium benzoate, or sodium stearate, but is not limited thereto. The thickness of the EIL 280 can be about 0.1 nm to 10 nm.

[0080] The EBL 265 located between the HTL 260 and the EML 240 to block the transfer of electrons from the EML 240 into the HTL 260 can include at least one compound selected from the group consisting of TCTA, tris[4-(diethylamino)phenyl]amine, N-(diphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluoren-2-amine, TAPC, MTDATA, 1,3-bis(carbazol-9-yl)benzene (mCP), 3,3'-bis(N-carbazolyl)-1,1'-biphenyl (mCBP), CuPc, N,N'-bis[4-[bis(3-methylphenyl)amino]phenyl]-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (DNTPD), TDAPB, DCDPA, and 2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene, but is not limited thereto. The thickness of the EBL 265 can be about 5 nm to 30 nm.

[0081] The HBL 275 located between the EML 240 and the ETL 270 to block the transfer of holes from the EML 240 into the ETL 270 can include the above-described material of the ETL 270. For example, the material of the HBL 275 has a lower HOMO energy level than the material of the EML 240 and can be at least one compound selected from the group consisting of BCP, BAlq, Alq3, PBD, Spiro-PBD, Liq, bis-4,6-(3,5-di-3-pyridylphenyl)-2-methylpyrimidine (B3PYMPM), bis[2-(diphenylphosphino)phenyl]ether oxide (DPEPO), 9-(6-9H-carbazol-9-yl)pyridin-3-yl)-9H-3,9'-bicarbazole, and TSPO1, but is not limited thereto. The thickness of the HBL 275 can be about 1 nm to 30 nm.

[0082] The EML 240 includes a first compound 241 having a delayed fluorescence characteristic (or feature) and a second compound 243 having a fluorescent characteristic. In addition, the EML 240 can further include a compound (not shown) as a host.

[0083] The first compound 241 having a delayed fluorescence characteristic has high luminous efficiency. However, the first compound 241 has a wide FWHM. Thus, when the first compound 241 in the EML 240 acts as a dopant (i.e., an emitter), the OLED has a disadvantage in color purity.

[0084] To overcome the above color purity problem, the EML 240 of the OLED D1 further includes the second compound 243 having a fluorescent characteristic.

[0085] The difference between the singlet energy level and the triplet energy level of the first compound 241 is very small (less than about 0.3 eV). The energy of the triplet exciton of the first compound 241 is converted into a singlet exciton through reverse intersystem crossing (RISC), so that the first compound 241 has a high quantum efficiency. The singlet exciton of the first compound 241 is transported into the second compound, and luminescence is generated by the second compound 243. Accordingly, the OLED D1 provides luminescence having a narrow FWHM through the second compound 243 and high luminescent efficiency through the first compound 241.

[0086] That is, referring to Figure 4 (the schematic diagram showing a luminescence mechanism in a luminescent material layer of an OLED according to a second embodiment of the disclosure), the singlet energy level S1 and the triplet energy level T1 generated in the compound as a host are transported into the TD as the first compound 241. Since the difference between the singlet energy level and the triplet energy level of the first compound 241 is small, the energy of the triplet energy level T1 of the first compound 241 is converted into the singlet energy level S1 of the first compound 241 through RISC. Then, the singlet energy level S1 of the first compound 241 is transported into the singlet energy level S1 of the FD as the second compound 243, and the second compound 243 provides luminescence.

[0087] However, the triplet exciton remains in the first compound 241 during RISC, so that thermal degradation of the EML 240 and non-luminescent quenching of the triplet exciton can occur. Accordingly, the lifespan and the luminescent efficiency of the OLED D1 can be reduced. In addition, when luminescence is generated by the first compound 241, the FWHM of the OLED D1 is increased.

[0088] Figure 5 is a schematic cross-sectional view of an OLED according to a third embodiment of the disclosure.

[0089] As Figure 5 shown in Figure 2 The organic light emitting display device 100 can include a red pixel region, a green pixel region, and a blue pixel region, and the OLED D2 can be located in each of the red pixel region, the green pixel region, and the blue pixel region.

[0090] The first electrode 310 can be an anode, and the second electrode 330 can be a cathode.

[0091] The light-emitting layer 320 can further include at least one of an HTL 360 between the first electrode 310 and the EML 340 and an ETL 370 between the second electrode 330 and the EML 340.

[0092] Further, the light-emitting layer 320 can further include at least one of an HIL 350 between the first electrode 310 and the HTL 360 and an EIL 380 between the second electrode 330 and the ETL 370.

[0093] Also, the light-emitting layer 320 can further include at least one of an EBL 365 between the HTL 360 and the EML 340 and an HBL 375 between the EML 340 and the ETL 370.

[0094] The EML 340 contains the first compound 341 and the third compound 345 each having a delayed fluorescence property, the second compound 343 having a fluorescent property or a delayed fluorescent property, and the fourth compound 347 having a phosphorescent property. The EML 340 includes a first layer 340a and a second layer 340b between the first layer 340a and the second electrode 330. That is, the second layer 340b is disposed on the first layer 340a. One of the first layer 340a and the second layer 340b contains the first compound 341 and the second compound 343, and the other of the first layer 340a and the second layer 340b contains the third compound 345 and the fourth compound 347. That is, the third compound 345 and the fourth compound 347 are not present in the layer containing the first compound 341 and the second compound 343 among the first layer 340a and the second layer 340b, and the first compound 341 and the second compound 343 are not present in the other layer containing the third compound 345 and the fourth compound 347 among the first layer 340a and the second layer 340b. The first compound 341 and the third compound 345 can be the same.

[0095] The second compound 343 has a fluorescent property or a delayed fluorescent property and a multi-resonance structure. Therefore, RISC exists in the second compound 343, so that the second compound 343 has a narrow FWHM.

[0096] An OLED D2 in which the first layer 340a as a lower layer contains the first compound 341 and the second compound 343, and the second layer 340b as an upper layer contains the third compound 345 and the fourth compound 347 will be explained.

[0097] The EML 340 includes a first compound 341 and a third compound 345 each having a delayed fluorescence property, a second compound 343 having a fluorescent property or a delayed fluorescent property, and a fourth compound 347 having a phosphorescent property, and the second compound 343 and the fourth compound 347 are included in separate first and second layers 340a and 340b, respectively.

[0098] The thickness of the first layer 340a can be less than that of the second layer 340b. For example, the thickness of the first layer 340a can be about 1 nm to 10 nm, preferably about 2 nm to 5 nm. to The thickness of the second layer 340b can be about 10 nm to 50 nm, preferably about 20 nm to 30 nm. to The weight % of the second compound 343 in the first layer 340a can be equal to or greater than that of the fourth compound 347 in the second layer 340b. For example, the weight % of the second compound 343 in the first layer 340a can be about 1 wt% to 5 wt%, preferably about 3 wt% to 5 wt%. The weight % of the fourth compound 347 in the second layer 340b can be about 1 wt% to 3 wt%.

[0099] Each of the first compound 341 and the third compound 345 can be represented by Formula 1-1.

[0100] [Formula 1-1]

[0101]

[0102] In Formula 1-1, R1 and R2 are each independently selected from the group consisting of hydrogen (H), C1 to C10 alkyl, and C6 to C30 aryl. For example, each of R1 and R2 can be a tert-butyl group.

[0103] Alternatively, each of the first compound 341 and the third compound 345 can be represented by Formula 1-2.

[0104] [Formula 1-2]

[0105]

[0106] In Formula 1-2, R3 to R6 are each independently selected from the group consisting of H, C1 to C10 alkyl, and C6 to C30 aryl. For example, each of R3 to R6 can be H.

[0107] For example, each of the first compound 341 and the third compound 345 can be one of the compounds of Formula 2.

[0108] [Formula 2]

[0109]

[0110] The second compound 343 can be represented by Formula 3.

[0111] [Formula 3]

[0112]

[0113] In Formula 3, R11to R14are each independently selected from the group consisting of H, deuterium (D), C1to C10alkyl, C6to C30aryl, and C6to C30arylamino.

[0114] For example, R11may be diphenylamino, R12may be H, and R13and R14may each be phenyl. The second compound 343 can be a compound of Formula 4.

[0115] [Formula 4]

[0116]

[0117] The fourth compound 347 can be represented by Formula 5-1 or Formula 5-2.

[0118] [Formula 5-1]

[0119]

[0120] [Formula 5-2]

[0121]

[0122] In each of Formulas 5-1 and 5-2, R21to R24are each independently selected from the group consisting of H, C1to C10alkyl, and C6to C30aryl.

[0123] For example, R21and R22may each be t-butyl, and R23and R24may each independently be H, methyl, or terphenyl. The fourth compound 347 can be a compound of Formula 6.

[0124] [Formula 6]

[0125]

[0126] The starting wavelength of the second compound 343 is greater (longer) than the starting wavelength of each of the first compound 341 and the third compound 345 and is less (shorter) than the starting wavelength of the fourth compound 347. In addition, the maximum emission wavelength (λmax) of the second compound 343 is less than the maximum emission wavelength of each of the first compound 341 and the third compound 345, and the maximum emission wavelength of the fourth compound 347 is equal to or less than the maximum emission wavelength of each of the first compound 341 and the third compound 345. Furthermore, the FWHM of the second compound 343 is less than the FWHM of each of the first compound 341 and the third compound 345, and the FWHM of the fourth compound 347 is less than the FWHM of each of the first compound 341 and the third compound 345.

[0127] The starting wavelength is a wavelength value at a point where a line extrapolated in a linear region of a short wavelength region in a PL spectrum intersects an X axis, i.e., a wavelength. More specifically, the starting wavelength can be defined as a wavelength corresponding to a shorter wavelength of two wavelengths corresponding to 1 / 10 of a maximum value of a light emission intensity in the PL spectrum.

[0128] In the EML 340, each of the first layer 340a and the second layer 340b can further include a host. A triplet energy level of the host can be equal to or greater (higher) than a triplet energy level of each of the first compound 341 and the third compound 345 which are delayed fluorescence compounds. When the triplet energy level of the host is less (lower) than the triplet energy level of each of the first compound 341 and the third compound 345, triplet excitons of the first compound 341 and the third compound 345 are transported into the host, so that improvement in quantum efficiency (or light emission efficiency) and / or lifetime caused by RISC in the first compound 341 and the third compound 345 cannot be provided.

[0129] In addition, the triplet energy level of the host can be greater than a triplet energy level of the fourth compound 347 having a phosphorescent property. When the triplet energy level of the host is less than the triplet energy level of the fourth compound 347, most of triplet excitons are quenched (non-emission quenching) in the host, so that improvement in light emission efficiency cannot be provided.

[0130] The host in each of the first layer 340a and the second layer 340b can include a p-type host and an n-type host.

[0131] The first to fourth compounds 341, 343, 345, and 347 satisfy the above conditions (relationships), so that the second compound 343 and the fourth compound 347 respectively act as emitters (dopants) in the first layer 340a and the second layer 340b.

[0132] For example, when the starting wavelength of the first compound 341 is greater than the starting wavelength of the second compound 343, energy transfer from the first compound 341 into the second compound 343 cannot be ensured (insufficiently generated), so that light emission is provided by the first compound 341. Thus, color purity of the OLED D2 is reduced due to a wide FWHM of the first compound 341. In other words, a CIEy value of light from the OLED D2 is increased.

[0133] However, in the OLED D2 of the present disclosure, the first to fourth compounds 341, 343, 345, and 347 satisfy the above conditions, such that the energy of the first compound 341 and the third compound 345 is transferred into the second compound 343 and the fourth compound 347, respectively, and the light emission is provided from the second compound 343 and the fourth compound 347. Accordingly, the problem of the decrease in the lifetime and / or the luminous efficiency caused by the triplet excitons in the first compound 341 and the third compound 345 having the delayed fluorescence characteristics is prevented.

[0134] Further, since the second compound 343 and the fourth compound 347 are included in the first layer 340a and the second layer 340b, respectively, the energy transfer from the fourth compound 347 into the second compound 343 is prevented. That is, the transfer of the triplet excitons from the fourth compound 347 into the second compound 343 and the non-emission quenching of the triplet excitons are prevented.

[0135] Referring to Figure 6 (being a schematic diagram showing the light emission mechanism in the light emission material layer of the OLED according to the third embodiment of the present disclosure), in the first layer EML1 (EML2), the excitons are generated in the host and the TD as the third compound, and the excitons in the host are transferred into the TD as the third compound. In the TD as the third compound, the intersystem crossing (ISC) occurs. That is, in the TD as the third compound, a part of the triplet excitons is converted into the singlet excitons, and a part of the singlet excitons is converted into the triplet excitons. Further, in the second layer EML2 (EML1), the excitons are generated in the host and the TD as the third compound, and the excitons in the host are transferred into the TD as the first compound. In the TD as the first compound, the intersystem crossing (ISC) occurs. That is, in the TD as the first compound, a part of the triplet excitons is converted into the singlet excitons, and a part of the singlet excitons is converted into the triplet excitons.

[0136] Meanwhile, the singlet excitons of the TD as the first compound and the TD as the third compound are transferred into the singlet excitons of the FD as the second compound (i.e., Forster Energy Transfer (FET)), and the triplet excitons of the TD as the third compound are transferred into the triplet excitons of the PD as the fourth compound (i.e., Dexter Energy Transfer (DET)). Accordingly, the light emission occurs in the FD as the second compound and the PD as the fourth compound.

[0137] On the other hand, since the FD as the second compound and the PD as the fourth compound are included in the first and second layers of the EML, respectively, energy transfer from the PD as the fourth compound to the FD as the second compound is suppressed. Accordingly, the quantum efficiency (luminous efficiency) of the OLED is improved.

[0138] Figure 7 is a schematic cross-sectional view of an OLED according to a fourth embodiment of the disclosure.

[0139] As shown in FIG. 1A, the OLED D1 includes a first electrode 410 and a second electrode 430 facing each other and a light-emitting layer 420 therebetween. Figure 7 As shown in FIG. 1A, the OLED D1 includes a first electrode 410 and a second electrode 430 facing each other and a light-emitting layer 420 therebetween. Figure 2 The organic light-emitting display device 100 can include a red pixel region, a green pixel region, and a blue pixel region, and the OLED D3 can be located in each of the red pixel region, the green pixel region, and the blue pixel region.

[0140] The first electrode 410 can be an anode, and the second electrode 430 can be a cathode.

[0141] The light-emitting layer 420 can further include at least one of an HTL 460 between the first electrode 410 and the EML 440 and an ETL 470 between the second electrode 430 and the EML 440.

[0142] Further, the light-emitting layer 420 can further include at least one of an HIL 450 between the first electrode 410 and the HTL 460 and an EIL 480 between the second electrode 430 and the ETL 470.

[0143] Also, the light-emitting layer 420 can further include at least one of an EBL 465 between the HTL 460 and the EML 440 and an HBL 475 between the EML 440 and the ETL 470.

[0144] The EML 440 includes the first to sixth compounds 441, 443, 445a, 447a, 445b, and 447b. The first, third, and fifth compounds 441, 445a, and 445b each have delayed fluorescence characteristics, and the second compound 443 has fluorescence characteristics or delayed fluorescence characteristics. The fourth and sixth compounds 447a and 447b each have phosphorescence characteristics. The EML 440 includes a first layer 440a, a second layer 440b between the first layer 440a and the first electrode 410, and a third layer 440c between the first layer 440a and the second electrode 430. That is, the first layer 440a and the third layer 440c are sequentially disposed on the second layer 440b. The first layer 440a includes the first compound 441 and the second compound 443, and the second layer 440b includes the third compound 445a and the fourth compound 447a. The third layer 440c includes the fifth compound 445b and the sixth compound 447b. That is, the third to sixth compounds 445a, 447a, 445b, and 447b are not present in the first layer 440a, and the first, second, fifth, and sixth compounds 441, 443, 445b, and 447b are not present in the second layer 440b. Further, the first to fourth compounds 441, 443, 445a, and 447a are not present in the third layer 440c. The first, third, and fifth compounds 441, 445a, and 445b can be the same. The fourth and sixth compounds 447a and 447b can be the same.

[0145] The first to third layers 440a, 440b, and 440c can have the same thickness. For example, the thickness of each of the first to third layers 440a, 440b, and 440c can be about 1 nm to 10 nm, preferably about 2 nm to 5 nm, and more preferably about 3 nm. to The weight % of the second compound 443 in the first layer 440a can be equal to or greater than each of the weight % of the fourth compound 447a in the second layer 440b and the weight % of the sixth compound 447b in the third layer 440c. For example, the weight % of the second compound 443 in the first layer 440a can be about 1 wt% to 5 wt%, preferably about 3 wt% to 5 wt%, and the weight % of the fourth compound 447a in the second layer 440b and the weight % of the sixth compound 447b in the third layer 440c can each be about 1 wt% to 3 wt%.

[0146] The EML 440 includes a first compound 441, a third compound 445a, and a fifth compound 445b each having a delayed fluorescence property, a second compound 443 having a fluorescent property or a delayed fluorescent property, and a fourth compound 447a and a sixth compound 447b each having a phosphorescent property, and the second compound 443, the fourth compound 447a, and the sixth compound 447b are present in different layers, i.e., a first layer 440a, a second layer 440b, and a third layer 440c.

[0147] The starting wavelength of the second compound 443 is greater than the starting wavelength of each of the first compound 441, the third compound 445a, and the fifth compound 445b and is less than the starting wavelength of each of the fourth compound 447a and the sixth compound 447b. In addition, the maximum emission wavelength (λmax) of the second compound 443 is less than the maximum emission wavelength of each of the first compound 441, the third compound 445a, and the fifth compound 445b, and the maximum emission wavelength of each of the fourth compound 447a and the sixth compound 447b is equal to or less than the maximum emission wavelength of each of the first compound 441, the third compound 445a, and the fifth compound 445b. In addition, the FWHM of the second compound 443 is less than the FWHM of each of the first compound 441, the third compound 445a, and the fifth compound 445b, and the FWHM of each of the fourth compound 447a and the sixth compound 447b is less than the FWHM of each of the first compound 441, the third compound 445a, and the fifth compound 445b.

[0148] In the OLED D3, the first to sixth compounds 441, 443, 445a, 447a, 445b, and 447b satisfy the above conditions, and the energy of the first compound 441, the third compound 445a, and the fifth compound 445b is transferred into the second compound 443, the fourth compound 447a, and the sixth compound 447b, respectively, so that light emission is provided by the second compound 443, the fourth compound 447a, and the sixth compound 447b. Accordingly, the problem of the decrease in the lifetime and / or the light emission efficiency caused by the triplet exciton in the first compound 441, the third compound 445a, and the fifth compound 445b having a delayed fluorescent property is prevented.

[0149] In addition, since the second compound 443, the fourth compound 447a, and the sixth compound 447b are included in the first layer 440a, the second layer 440b, and the third layer 440c, respectively, the energy transfer from the fourth compound 447a and the sixth compound 447b into the second compound 443 is prevented. That is, the transfer of the triplet exciton from the fourth compound 447a and the sixth compound 447b into the second compound 443 and the non-emission quenching of the triplet exciton are prevented.

[0150] [OLED1]

[0151] Anode (ITO, 50 nm), HIL (Formula 7, 7 nm), HTL (Formula 8, 78 nm), EBL (Formula 9, 10 nm), EML (30 nm), HBL (Formula 10, 10 nm), ETL (Formula 11, 25 nm), EIL (LiF, 1 nm), and cathode (Al, 100 nm) were sequentially deposited to form an OLED.

[0152] 1. Comparative Example

[0153] (1) Comparative Example 1 (Ref1)

[0154] A host (Formula 12, 59 wt%), a compound “TD1” in Formula 2 (40 wt%), and a compound “PD” in Formula 6 (1 wt%) were used to form an EML.

[0155] (2) Comparative Example 2 (Ref2)

[0156] A host (Formula 12, 59 wt%), a compound “TD1” in Formula 2 (40 wt%), and a compound “FD1” in Formula 4 (1 wt%) were used to form an EML.

[0157] 2. Examples

[0158] (1) Example 1 (Ex1)

[0159] A host (Formula 12, 59 wt%), a compound “TD1” in Formula 2 (40 wt%), and a compound “PD” in Formula 6 (1 wt%) were used to form a lower EML, and a host (Formula 12, 59 wt%), a compound “TD1” in Formula 2 (40 wt%), and a compound “FD1” in Formula 4 (1 wt%) were used to form an upper EML.

[0160] (2) Example 2 (Ex2)

[0161] A host (Formula 12, 59 wt%), a compound “TD1” in Formula 2 (40 wt%), and a compound “PD” in Formula 6 (1 wt%) were used to form a lower EML, and a host (Formula 12, 57 wt%), a compound “TD1” in Formula 2 (40 wt%), and a compound “FD1” in Formula 4 (3 wt%) were used to form an upper EML.

[0162] (3) Example 3 (Ex3)

[0163] The lower EML was formed using the host (Formula 12, 59 wt%) and the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (1 wt%), and the upper EML was formed using the host (Formula 12, 55 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "FD1" in Formula 4 (5 wt%).

[0164] (4) Example 4 (Ex4)

[0165] The lower EML was formed using the host (Formula 12, 59 wt%) and the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (1 wt%), and the upper EML was formed using the host (Formula 12, 55 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "FD1" in Formula 4 (5 wt%).

[0166] (5) Example 5 (Ex5)

[0167] The lower EML was formed using the host (Formula 12, 59 wt%) and the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (1 wt%), and the upper EML was formed using the host (Formula 12, 55 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "FD1" in Formula 4 (5 wt%).

[0168] (6) Example 6 (Ex6)

[0169] The lower EML was formed using the host (Formula 12, 59 wt%) and the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (1 wt%), and the upper EML was formed using the host (Formula 12, 55 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "FD1" in Formula 4 (5 wt%).

[0170] (7) Example 7 (Ex7)

[0171] The lower EML was formed using the host (Formula 12, 59 wt%) and the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (1 wt%), and the upper EML was formed using the host (Formula 12, 55 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "FD1" in Formula 4 (5 wt%).

[0172] (8) Example 8 (Ex8)

[0173] The lower EML was formed using the host (Formula 12, 59 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (1 wt%), the middle EML was formed using the host (Formula 12, 55 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "FD1" in Formula 4 (5 wt%), and the upper EML was formed using the host (Formula 12, 59 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (1 wt%).

[0174] (9) Example 9 (Ex9)

[0175] The lower EML was formed using the host (Formula 12, 59 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (1 wt%), the middle EML was formed using the host (Formula 12, 55 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "FD1" in Formula 4 (5 wt%), and the upper EML was formed using the host (Formula 12, 59 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (1 wt%).

[0176] [Formula 7]

[0177]

[0178] [Formula 8]

[0179]

[0180] [Formula 9]

[0181]

[0182] [Formula 10]

[0183]

[0184] [Formula 11]

[0185]

[0186] [Formula 12]

[0187]

[0188] The light emitting properties of the OLEDs in Comparative Examples 1 and 2 and Examples 1 to 9 were measured and are listed in Table 1, and the EL spectra of the OLEDs are shown in Figures 8A to 8G Table 1. (EQE = external quantum efficiency)

[0189]

[0190] As shown in Table 1 and Figures 8A to 8G As shown in FIG, in the OLED of Ref1, luminescence is provided by the phosphorescent compound, namely compound "PD," resulting in a wide full width at half maximum (FWHM). On the other hand, in the OLED of Ref2, luminescence is provided by the first compound, namely compound "TD1," and the fluorescent compound, namely compound "FD1," because triplet excitons are retained in the first compound. As a result, in the OLED of Ref2, the FWHM becomes relatively narrow, and luminous efficiency decreases.

[0191] However, the OLEDs of Ex1 to Ex9 offer narrow full width at half maximum (FWHM) and relatively high luminous efficiency. In particular, in the OLEDs of Ex4 to Ex6, which include the second compound in the first layer adjacent to the anode, luminescence from the first compound is minimized or prevented, resulting in OLEDs of Ex4 to Ex6 offering equivalent or narrower full width at half maximum (FWHM) than the OLED of Ref2. Furthermore, in the OLEDs of Ex5 and Ex6, the weight percentage of the second compound, compound "FD1," in the first layer (lower EML) is greater than the weight percentage of the fourth compound, compound "PD," in the second layer (upper EML), further narrowing the FWHM and improving color purity.

[0192] Furthermore, in the OLEDs of Ex4 to Ex9, the OLEDs have lower CIEy values ​​to provide high color purity.

[0193] That is, in the OLEDs according to the third and fourth embodiments of the present disclosure, the second layer containing the fourth compound is disposed on one side of the second electrode, which serves as a cathode, and the first layer containing the second compound is disposed between the first electrode, which serves as an anode, and the second layer. As a result, the optical properties of the OLED are improved. Furthermore, the third layer containing the fourth compound is further disposed between the first layer and the first electrode, further improving the color purity and luminous efficiency of the OLED. In the OLEDs according to the fourth embodiment of the present disclosure, such as those of Ex7 to Ex9, luminous efficiency is significantly increased, FWHM is reduced, and lifetime is increased.

[0194] When the weight % of the second compound in the first layer is greater than the weight % of the fourth compound in the second layer, the color purity of the OLED is further improved.

[0195] Figure 9 is a schematic cross-sectional view of an OLED according to a fifth embodiment of the present disclosure.

[0196] like Figure 9As illustrated in the middle, the OLED D4 includes a first electrode 510 and a second electrode 530 facing each other and a light-emitting layer 520 therebetween. The light-emitting layer 520 includes an emitting material layer (EML) 540. Figure 2 The organic light-emitting display device 100 can include a red pixel region, a green pixel region, and a blue pixel region, and the OLED D4 can be located in each of the red pixel region, the green pixel region, and the blue pixel region.

[0197] The first electrode 510 can be an anode, and the second electrode 530 can be a cathode.

[0198] The light-emitting layer 520 can further include at least one of a hole transport layer (HTL) 560 between the first electrode 510 and the EML 540 and an electron transport layer (ETL) 570 between the second electrode 530 and the EML 540.

[0199] Further, the light-emitting layer 520 can further include at least one of a hole injection layer (HIL) 550 between the first electrode 510 and the HTL 560 and an electron injection layer (EIL) 580 between the second electrode 530 and the ETL 570.

[0200] Also, the light-emitting layer 520 can further include at least one of an electron blocking layer (EBL) 565 between the HTL 560 and the EML 540 and a hole blocking layer (HBL) 575 between the EML 540 and the ETL 570.

[0201] The EML 540 contains a first compound 541 having a delayed fluorescence characteristic, a second compound 543 having a fluorescent characteristic or a delayed fluorescent characteristic, and a third compound 547 having a phosphorescent characteristic. The first to third compounds 541, 543, and 547 are mixed and contained in one layer (a single layer).

[0202] As described above, the second compound 543 has a fluorescent characteristic or a delayed fluorescent characteristic and a multi-resonance structure. Thus, RISC exists in the second compound 543, so that the second compound 543 has a narrow FWHM.

[0203] In the EML 540, the weight % of the second compound 543 can be equal to or less than the weight % of the third compound 547. For example, the weight % of the third compound 547 is about 100 to 1200 weight % with respect to the second compound 543.

[0204] The first compound 541 can be represented by Formula 1-1 or Formula 1-2 and can be one of the compounds in Formula 2. The second compound 543 can be represented by Formula 3 and can be the compound in Formula 4. The third compound 547 can be represented by Formula 5-1 or Formula 5-2 and can be the compound in Formula 6.

[0205] The starting wavelength of the second compound 543 is greater (longer) than the starting wavelength of the first compound 541 and is less (shorter) than the starting wavelength of the third compound 547. In addition, the maximum emission wavelength (λmax) of the second compound 543 is less than the maximum emission wavelength of the first compound 541, and the maximum emission wavelength of the third compound 547 is equal to or less than the maximum emission wavelength of the first compound 541. The maximum emission wavelength of the second compound 543 is less than the maximum emission wavelength of the third compound 547. In addition, the FWHM of the second compound 543 is less than the FWHM of the first compound 541, and the FWHM of the third compound 547 is less than the FWHM of the first compound 541.

[0206] Referring to Figure 10 Referring to

[0207] For example, the difference between the starting wavelength of the second compound 543 and the starting wavelength of the first compound 541 can be about 1 nm to 30 nm, preferably about 5 nm to 25 nm, the difference between the starting wavelength of the second compound 543 and the starting wavelength of the third compound 547 can be about 1 nm to 20 nm, preferably about 5 nm to 15 nm. The difference between the maximum emission wavelength of the second compound 543 and the maximum emission wavelength of the first compound 541 can be about 1 nm to 20 nm, preferably about 3 nm to 15 nm, the difference between the maximum emission wavelength of the third compound 547 and the maximum emission wavelength of the first compound 541 can be about 0.1 nm to 10 nm, preferably about 0.1 nm to 5 nm. In addition, the difference between the maximum emission wavelength of the second compound 543 and the maximum emission wavelength of the third compound 547 can be about 1 nm to 5 nm, preferably about 1 nm to 3 nm.

[0208] The EML 540 can further include a host. The triplet energy level of the host can be equal to or greater than (higher than) the triplet energy level of the first compound 541 which is a delayed fluorescence compound. When the triplet energy level of the host is less than (lower than) the triplet energy level of the first compound 541, triplet excitons of the first compound 541 are transferred into the host, so that improvement in quantum efficiency (or luminous efficiency) and / or lifetime caused by RISC in the first compound 541 cannot be provided.

[0209] Further, the triplet energy level of the host can be greater than the triplet energy level of the third compound 547 having phosphorescent properties. When the triplet energy level of the host is less than the triplet energy level of the third compound 547, most of the triplet excitons are quenched (non-emission quenching) in the host, so that improvement in luminous efficiency cannot be provided.

[0210] The host of the EML 540 can be the same material as that of the EBL 565. In this case, the EML 540 can have a light-emitting function and an electron-blocking function. That is, the EML 540 can function as a buffer layer for blocking electrons. When the EBL 565 is omitted, the EML 540 can function as a light-emitting material layer and an electron-blocking layer.

[0211] Alternatively, the host of the EML 540 can be the same material as that of the HBL 575. In this case, the EML 540 can have a hole-blocking function and a light-emitting function. That is, the EML 540 can function as a buffer layer for blocking holes. When the HBL 575 is omitted, the EML 540 can function as a light-emitting material layer and a hole-blocking layer.

[0212] The host in the EML 540 can include a p-type host and an n-type host.

[0213] The first to third compounds 541, 543, and 547 satisfy the above conditions (relationships), so that the second compound 543 and the third compound 547 act as emitters (dopants) in the EML 540.

[0214] For example, when the starting wavelength of the first compound 541 is greater than the starting wavelength of the second compound 543, energy transfer from the first compound 541 into the second compound 543 cannot be ensured (insufficiently generated), so that light emission is provided by the first compound 541. Thus, the color purity of the OLED D4 is reduced due to the wide FWHM of the first compound 541. In other words, the CIEy value of light from the OLED D4 increases.

[0215] However, in the OLED D4 of the present disclosure, the first to third compounds 541, 543, and 547 satisfy the above conditions, such that the energy of the first compound 541 is transferred into the second compound 543 and the third compound 547, respectively, and the light emission is provided by the second compound 543 and the third compound 547. Accordingly, the problem of the decrease in the lifetime and / or the luminous efficiency caused by the triplet exciton in the first compound 541 having the delayed fluorescence characteristics is prevented.

[0216] Further, since the second compound 543 and the third compound 547 are included in a single layer, i.e., the EML 540, the singlet exciton and the triplet exciton of the first compound 541 are transferred into the second compound 543 and the third compound 547, respectively. Accordingly, the problem of the non-emission quenching of the triplet exciton in the first compound 541 and / or the second compound 543 is prevented.

[0217] Also, the maximum emission wavelength of the second compound 543 is less than that of the third compound 547, which prevents or minimizes the energy transfer from the third compound 547 into the second compound 543.

[0218] Accordingly, the OLED D4 provides high luminous efficiency and high color purity.

[0219] Figure 11 is a schematic diagram illustrating a light emission mechanism in a light emission material layer of an OLED according to a fifth embodiment of the present disclosure.

[0220] Referring to Figure 11 Singlet excitons and triplet excitons are generated in the first compound TD. A part of the triplet excitons is converted into singlet excitons by ISC, and a part of the singlet excitons is converted into triplet excitons. At the same time, the singlet excitons of the first compound TD are transferred into singlet excitons of the second compound FD (i.e., Foster energy transfer, FET), and the triplet excitons of the first compound TD are transferred into triplet excitons of the third compound PD (i.e., Dexter energy transfer, DET).

[0221] Further, when the EML further includes a host, the singlet excitons generated in the host are transferred into singlet excitons of the first compound TD (i.e., FET), and the triplet excitons are transferred into triplet excitons of the first compound TD (i.e., DET). Accordingly, the luminous efficiency can be further improved.

[0222] Therefore, since the light emission is provided by the second compound FD and the third compound PD, and the triplet exciton of the first compound TD is transferred to the triplet exciton of the third compound PD, the triplet exciton is not reserved (or maintained) in the first compound TD. Therefore, the thermal degradation, non-emissive quenching, and short lifetime caused by the triplet exciton in the first compound TD are prevented.

[0223] That is, when the first compound TD and the second compound FD are included in the EML without the third compound PD, a part of the triplet exciton is reserved in the first compound TD, making it possible to generate the thermal degradation, non-emissive quenching, and short lifetime. However, in the OLED D4 of the present disclosure, the EML includes the first to third compounds TD, FD, and PD, making it possible to minimize or prevent the above problems.

[0224] Further, the second compound FD and the third compound PD satisfy the above conditions, preventing the transfer of the triplet exciton from the third compound PD to the second compound FD.

[0225] [OLED2]

[0226] An anode (ITO, 50 nm), a HIL (Formula 7, 10 nm), a HTL (Formula 8, 45 nm), an EBL (Formula 9, 15 nm), an EML (30 nm), a HBL (Formula 10, 5 nm), an ETL (Formula 11, 35 nm), an EIL (LiF, 1 nm), and a cathode (Al, 100 nm) were sequentially deposited to form an OLED.

[0227] 1. Comparative Example

[0228] (1) Comparative Example 1 (Ref1)

[0229] A host (Formula 12, 60 wt%) and a compound "TD1" in Formula 2 (40 wt%) were used to form an EML.

[0230] (2) Comparative Example 2 (Ref2)

[0231] A host (Formula 12, 59 wt%), a compound "TD1" in Formula 2 (40 wt%), and a compound "PD" in Formula 6 (1 wt%) were used to form an EML.

[0232] (3) Comparative Example 3 (Ref3)

[0233] A host (Formula 12, 57 wt%), a compound "TD1" in Formula 2 (40 wt%), and a compound "PD" in Formula 6 (3 wt%) were used to form an EML.

[0234] (4) Comparative Example 4 (Ref4)

[0235] The EML was formed using the host (Formula 12, 48 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (12 wt%).

[0236] (5) Comparative Example 5 (Ref5)

[0237] The EML was formed using the host (Formula 12, 48 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "PD" in Formula 6 (12 wt%).

[0238] (6) Comparative Example 6 (Ref6)

[0239] The EML was formed using the host (Formula 12, 59 wt%), the compound "TD1" in Formula 2 (40 wt%), and the compound "FD1" in Formula 4 (1 wt%).

[0240] 2. Example

[0241] (1) Example 1 (Ex1)

[0242] The EML was formed using the host (Formula 12, 58 wt%), the compound "TD1" in Formula 2 (40 wt%), the compound "FD1" in Formula 4 (1 wt%), and the compound "PD" in Formula 6 (1 wt%).

[0243] (2) Example 2 (Ex2)

[0244] The EML was formed using the host (Formula 12, 56 wt%), the compound "TD1" in Formula 2 (40 wt%), the compound "FD1" in Formula 4 (1 wt%), and the compound "PD" in Formula 6 (3 wt%).

[0245] (3) Example 3 (Ex3)

[0246] The EML was formed using the host (Formula 12, 51 wt%), the compound "TD1" in Formula 2 (40 wt%), the compound "FD1" in Formula 4 (1 wt%), and the compound "PD" in Formula 6 (8 wt%).

[0247] (4) Example 4 (Ex4)

[0248] The EML was formed using the host (Formula 12, 47 wt%), the compound "TD1" in Formula 2 (40 wt%), the compound "FD1" in Formula 4 (1 wt%), and the compound "PD" in Formula 6 (12 wt%).

[0249] (5) Example 5 (Ex5)

[0250] An EML was formed using the host (Formula 12, 54 wt%), the compound "TD1" in Formula 2 (40 wt%), the compound "FD1" in Formula 4 (5 wt%), and the compound "PD" in Formula 6 (1 wt%).

[0251] (6) Example 6 (Ex6)

[0252] An EML was formed using the host (Formula 12, 54 wt%), the compound "TD1" in Formula 2 (40 wt%), the compound "FD1" in Formula 4 (5 wt%), and the compound "PD" in Formula 6 (1 wt%).

[0253] The PL spectra of the compounds "TD1", "FD1", and "PD" used in the EML of the above OLEDs were measured and shown in Figure 12 . The maximum emission wavelengths (λmax) and the starting wavelengths of the compounds "TD1", "FD1", and "PD" were measured and listed in Table 2. The characteristics of the OLEDs in Comparative Examples 1 to 6 and Examples 1 to 6 were measured and listed in Table 3, and the EL spectra of the OLEDs are shown in Figures 13A to 13L .

[0254] Table 2

[0255] λmax (nm) Onset (nm) TD1 469 430 FD1 461 440 PD 467 450

[0256] Table 3

[0257]

[0258] As Figure 12 and Table 2, the first to third compounds "TD1", "FD1", and "PD" satisfy the above-mentioned relationship of the starting wavelength and the maximum emission wavelength. As a result, the light emission is provided by the compounds "FD1" and "PD", so that the OLEDs have high light emission efficiency and excellent color purity.

[0259] That is, as shown in Table 3 and Figures 13A to 13L , the OLEDs of Ex1 to Ex6 have a narrow FWHM and / or a long lifetime compared to the OLEDs of Ref1 to Ref6. In addition, in the OLEDs of Ex1 to Ex6, the "cd / A / CIEy" value, which can be called "blue index", is increased. This means that the light emission efficiency based on visibility is improved.

[0260] For example, when the wt% of the third compound "PD" in the EML is greater than the wt% of the second compound "FD1" in the EML, the OLED has an advantage in color purity, light emission efficiency, and lifetime.

[0261] [OLED3]

[0262] An anode (ITO, 50 nm), HIL (Formula 7, 10 nm), HTL (Formula 8, 45 nm), EBL (Formula 9, 15 nm), EML (30 nm), HBL (Formula 10, 5 nm), ETL (Formula 11, 35 nm), EIL (LiF, 1 nm), and a cathode (Al, 100 nm) were sequentially deposited to form an OLED.

[0263] 1. Comparative Examples 7 to 12 (Ref7 to Ref12)

[0264] The compound "TD2" in Formula 2 was used instead of the compound "TD1" in Comparative Examples 1 to 6 in OLED2.

[0265] 2. Examples 7 to 10 (Ex7 to Ex10)

[0266] The compound "TD2" in Formula 2 was used instead of the compound "TD1" in Examples 1 to 4 in OLED2.

[0267] The PL spectra of the compounds "TD2", "FD1", and "PD" used in the EML of the above OLEDs were measured and shown in Figure 14 The maximum emission wavelength (λmax) and the starting wavelength of the compounds "TD2", "FD1", and "PD" were measured and listed in Table 4. The characteristics of the OLEDs in Comparative Examples 7 to 12 and Examples 7 to 10 were measured and listed in Table 5, and the EL spectra of the OLEDs are shown in Figures 15A to 15J .

[0268] Table 4

[0269] λmax (nm) Onset (nm) TD2 467 420 FD1 461 440 PD 467 450

[0270] Table 5

[0271]

[0272] As Figure 14 and Table 4, the first to third compounds "TD2", "FD1", and "PD" satisfy the above-mentioned relationship of the starting wavelength and the maximum emission wavelength. As a result, the light emission is provided by the compounds "FD1" and "PD" so that the OLEDs have high light emission efficiency and excellent color purity.

[0273] That is, as shown in Table 5 and Figures 15A to 15J , the OLEDs of Ex7 to Ex10 have a narrow FWHM and / or a long lifetime compared to the OLEDs of Ref7 to Ref12. In addition, in the OLEDs of Ex7 to Ex10, the "cd / A / CIEy" value, which can be called "blue index", is increased. This means that the light emission efficiency based on visibility is improved.

[0274] For example, when the weight % of the third compound "PD" in the EML is greater than the weight % of the second compound "FD1" in the EML, the OLED has an advantage in color purity, luminous efficiency, and lifetime.

[0275] [OLED4]

[0276] An anode (ITO, 50 nm), a HIL (Formula 7, 10 nm), an HTL (Formula 8, 45 nm), an EBL (Formula 9, 15 nm), an EML (30 nm), a HBL (Formula 10, 5 nm), an ETL (Formula 11, 35 nm), an EIL (LiF, 1 nm), and a cathode (Al, 100 nm) were sequentially deposited to form an OLED.

[0277] 1. Comparative Examples 13 to 17 (Ref13 to Ref17)

[0278] The compound "FD2" in Formula 13 was used instead of the compound "FD1" in Comparative Example 6 and Examples 1 to 4 in OLED2.

[0279] [Formula 13]

[0280]

[0281] The PL spectra of the compounds "TD1", "FD2", and "PD" used in the EML of the above OLEDs were measured and shown in Figure 16 . The maximum emission wavelength (λmax) and the starting wavelength of the compounds "TD1", "FD2", and "PD" were measured and listed in Table 6. The characteristics of the OLEDs in Comparative Examples 13 to 17 were measured and listed in Table 7, and the EL spectra of the OLEDs are shown in Figures 17A to 17E .

[0282] Table 6

[0283] λmax (nm) Onset (nm) TD1 469 430 FD2 537 513 PD 467 450

[0284] Table 7

[0285]

[0286] As Figure 16 and Table 6, the first to third compounds "TD1", "FD2", and "PD" do not satisfy the above relationship of the starting wavelength and the maximum emission wavelength. That is, the starting wavelength and the maximum emission wavelength of the second compound "FD2" are greater than those of the third compound "PD", so that the energy transfer is concentrated to the second compound "FD2". Therefore, the triplet excitons are quenched at the second compound "FD2", and the luminous efficiency and the color sense are significantly reduced, as shown in Table 7 and Figures 17A to 17E .

[0287] Figure 18 is a schematic cross-sectional view of an OLED according to a sixth embodiment of the disclosure.

[0288] As shown in FIG. 6A, Figure 18 OLED D5 includes a first electrode 610 and a second electrode 630 facing each other and a light-emitting layer 620 therebetween. Figure 2 The organic light-emitting display device 100 can include a red pixel area, a green pixel area, and a blue pixel area, and the OLED D5 can be located in each of the red pixel area, the green pixel area, and the blue pixel area.

[0289] The first electrode 610 can be an anode, and the second electrode 630 can be a cathode.

[0290] The light-emitting layer 620 includes a first light-emitting part 640 including a first EML 650 and a second light-emitting part 660 including a second EML 670. In addition, the light-emitting layer 620 can further include a charge generation layer (CGL) 680 between the first light-emitting part 640 and the second light-emitting part 660.

[0291] The CGL 680 is located between the first light-emitting part 640 and the second light-emitting part 660, such that the first light-emitting part 640, the CGL 680, and the second light-emitting part 660 are sequentially stacked on the first electrode 610. That is, the first light-emitting part 640 is located between the first electrode 610 and the CGL 680, and the second light-emitting part 660 is located between the second electrode 630 and the CGL 680.

[0292] The first light-emitting part 640 includes the first EML 650.

[0293] In addition, the first light-emitting part 640 can further include at least one of a first HTL 640b between the first electrode 610 and the first EML 650, a HIL 640a between the first electrode 610 and the first HTL 640b, and a first ETL 640e between the first EML 650 and the CGL 680.

[0294] Also, the first light-emitting part 640 can further include at least one of a first EBL 640c between the first HTL 640b and the first EML 650 and a first HBL 640d between the first EML 650 and the first ETL 640e.

[0295] The second light-emitting part 660 includes the second EML 670.

[0296] Further, the second light emitting part 660 can further include at least one of a second HTL 660a between the CGL 680 and the second EML 670, a second ETL 660d between the second EML 670 and the second electrode 630, and an EIL 660e between the second ETL 660d and the second electrode 630.

[0297] Further, the second light emitting part 660 can further include at least one of a second EBL 660b between the second HTL 660a and the second EML 670, and a second HBL 660c between the second EML 670 and the second ETL 660d.

[0298] The CGL 680 is located between the first light emitting part 640 and the second light emitting part 660. That is, the first light emitting part 640 and the second light emitting part 660 are connected to each other through the CGL 680. The CGL 680 can be a P-N junction type CGL of an N-type CGL 682 and a P-type CGL 684.

[0299] The N-type CGL 682 is located between the first ETL 640e and the second HTL 660a, and the P-type CGL 684 is located between the N-type CGL 682 and the second HTL 660a. The N-type CGL 682 provides electrons to the first EML 650 of the first light emitting part 640, and the P-type CGL 684 provides holes to the second EML 670 of the second light emitting part 660.

[0300] The first EML 650 and the second EML 670 are blue ELMLs. Alternatively, the first EML 650 is one of a blue EML, a green EML, and a red EML, and the second EML 670 is a blue EML. At least one of the first EML 650 and the second EML 670 has the same structure or configuration as the EML 540 of the illustrated OLED. Figure 9

[0301] That is, at least one of the first EML 650 and the second EML 670 includes a first compound having a delayed fluorescence property, a second compound having a fluorescent property or a delayed fluorescent property, and a third compound having a phosphorescent property. The first compound to the third compound are mixed in a single EML.

[0302] The first compound can be represented by Formula 1-1 or Formula 1-2 and can be one of the compounds in Formula 2. The second compound can be represented by Formula 3 and can be the compound in Formula 4. The third compound can be represented by Formula 5-1 or Formula 5-2 and can be the compound in Formula 6.

[0303] ​As described above, the second compound has a starting wavelength that is greater (longer) than the starting wavelength of the first compound and that is less (shorter) than the starting wavelength of the third compound. Also, the second compound has a maximum emission wavelength (λmax) that is less than the maximum emission wavelength of the first compound, and the third compound has a maximum emission wavelength that is equal to or less than the maximum emission wavelength of the first compound. The maximum emission wavelength of the second compound is less than the maximum emission wavelength of the third compound. Also, the FWHM of the second compound is less than the FWHM of the first compound, and the FWHM of the third compound is less than the FWHM of the first compound.

[0304] In each of the first EML 650 and the second EML 670, the weight % of the second compound can be equal to or less than the weight % of the third compound. For example, the weight % of the third compound with respect to the second compound is about 100 wt% to 1200 wt%.

[0305] Each of the first EML 650 and the second EML 670 can further include a host. The triplet energy level of the host can be equal to or greater (higher) than the triplet energy level of the first compound which is a delayed fluorescence compound. Also, the triplet energy level of the host can be greater than the triplet energy level of the third compound which has a phosphorescent property.

[0306] In the OLED D5, since the first compound to the third compound satisfy the above conditions (or relationships), the energy of the first compound is transferred into each of the second compound and the third compound, so that light emission is provided by each of the second compound and the third compound. Accordingly, the reduction in the lifetime and the luminous efficiency caused by the triplet exciton in the first compound is prevented.

[0307] Also, since the second compound and the third compound are included in a single layer (i.e., each of the first EML 650 and the second EML 670), the singlet exciton and the triplet exciton of the first compound are transferred into the second compound and the third compound, respectively. Accordingly, the non-emission quenching problem of the triplet exciton in the first compound and / or the second compound is prevented.

[0308] Also, the maximum emission wavelength of the second compound is less than the maximum emission wavelength of the third compound, which prevents or minimizes the energy transfer from the third compound into the second compound.

[0309] Accordingly, the OLED D5 provides high luminous efficiency and high color purity.

[0310] Figure 19 is a schematic cross-sectional view of an organic light emitting display device according to a seventh embodiment of the present disclosure.

[0311] As Figure 19As illustrated in FIG. 10, the organic light emitting display device 1000 includes a substrate 1010 in which first to third pixel areas P1, P2, and P3 are defined, a TFT Tr over the substrate 1010, and an OLED D6. The OLED D6 is disposed over the TFT Tr and connected to the TFT Tr. For example, the first to third pixel areas P1, P2, and P3 can be blue, green, and red pixel areas, respectively.

[0312] The substrate 1010 can be a glass substrate or a flexible substrate. For example, the flexible substrate can be a polyimide (PI) substrate, a polyether sulfone (PES) substrate, a polyethylene naphthalate (PEN) substrate, a polyethylene terephthalate (PET) substrate, or a polycarbonate (PC) substrate.

[0313] A buffer layer 1012 is formed on the substrate 1010, and the TFT Tr is formed on the buffer layer 1012. The buffer layer 1012 can be omitted.

[0314] As illustrated in FIG. 10, the organic light emitting display device 1000 includes a substrate 1010 in which first to third pixel areas P1, P2, and P3 are defined, a TFT Tr over the substrate 1010, and an OLED D6. The OLED D6 is disposed over the TFT Tr and connected to the TFT Tr. For example, the first to third pixel areas P1, P2, and P3 can be blue, green, and red pixel areas, respectively. Figure 2 As illustrated in FIG. 10, the organic light emitting display device 1000 includes a substrate 1010 in which first to third pixel areas P1, P2, and P3 are defined, a TFT Tr over the substrate 1010, and an OLED D6. The OLED D6 is disposed over the TFT Tr and connected to the TFT Tr. For example, the first to third pixel areas P1, P2, and P3 can be blue, green, and red pixel areas, respectively.

[0315] A planarization layer (or a passivation layer) 1050 is formed on the TFT Tr. The planarization layer 1050 has a planar top surface and includes a drain contact hole 1052 that exposes the drain electrode of the TFT Tr.

[0316] The OLED D6 is disposed on the planarization layer 1050 and includes a first electrode 1060, a light emitting layer 1062, and a second electrode 1064. The first electrode 1060 is connected to the drain electrode of the TFT Tr, and the light emitting layer 1062 and the second electrode 1064 are sequentially stacked on the first electrode 1060. The OLED D6 is disposed in each of the first to third pixel areas P1, P2, and P3, and emits different colors of light in the first to third pixel areas P1, P2, and P3. For example, the OLED D6 in the first pixel area P1 can emit blue light, the OLED D6 in the second pixel area P2 can emit green light, and the OLED D6 in the third pixel area P3 can emit red light.

[0317] The first electrode 1060 is formed to be separate in the first to third pixel areas P1, P2, and P3, and the second electrode 1064 is formed to be integral to cover the first to third pixel areas P1, P2, and P3.

[0318] The first electrode 1060 is one of an anode and a cathode, and the second electrode 1064 is the other of the anode and the cathode. Also, one of the first electrode 1060 and the second electrode 1064 can be a light-transmitting electrode (or a semi-transmissive electrode), and the other of the first electrode 1060 and the second electrode 1064 can be a reflective electrode.

[0319] For example, the first electrode 1060 can be an anode and can include a transparent conductive oxide (TCO) material layer formed of a TCO material having a relatively high work function. The second electrode 1064 can be a cathode and can include a metal material layer formed of a low-resistance metal material having a relatively low work function. For example, the TCO material layer of the first electrode 1060 includes at least one of indium-tin-oxide (ITO), indium-zinc-oxide (IZO), indium-tin-zinc-oxide (ITZO), tin oxide (SnO), zinc oxide (ZnO), indium-copper-oxide (ICO), and aluminum-zinc oxide alloy (Al:ZnO), and the second electrode 1064 can include Al, Mg, Ca, Ag, an alloy thereof (e.g., Mg-Ag alloy), or a combination thereof.

[0320] In the bottom emission type organic light emitting display device 1000, the first electrode 1060 can have a single layer structure of a transparent conductive oxide material layer.

[0321] On the other hand, in the top emission type organic light emitting display device 1000, a reflective electrode or a reflective layer can be formed under the first electrode 1060. For example, the reflective electrode or the reflective layer can be formed of Ag or an aluminum-palladium-copper (APC) alloy. In this case, the first electrode 1060 can have a three layer structure of ITO / Ag / ITO or ITO / APC / ITO. Also, the second electrode 1064 can have a thin profile (small thickness) to provide a light-transmitting property (or a semi-transmissive property).

[0322] A bank layer 1066 is formed on the planarization layer 1050 to cover edges of the first electrode 1060. That is, the bank layer 1066 is located at boundaries of the first to third pixel regions P1 to P3 and exposes centers of the first electrode 1060 in the first to third pixel regions P1 to P3.

[0323] A light emitting layer 1062 as a light emitting unit is formed on the first electrode 1060. The light emitting layer 1062 can have a single layer structure of an EML. Alternatively, the light emitting layer 1062 can further include at least one of an HIL, an HTL, an EBL, sequentially stacked between the first electrode 1060 and the EML, and a HBL, an ETL, and an EIL, sequentially stacked between the EML and the second electrode 1064.

[0324] In the first pixel region P1 which is a blue pixel region, the EML of the light-emitting layer 1062 contains a first compound having a delayed fluorescence property, a second compound having a fluorescent property or a delayed fluorescent property, and a third compound having a phosphorescent property. The first compound to the third compound are mixed in a single layer.

[0325] The first compound can be represented by Formula 1-1 or Formula 1-2 and can be one of the compounds in Formula 2. The second compound can be represented by Formula 3 and can be the compound in Formula 4. The third compound can be represented by Formula 5-1 or Formula 5-2 and can be the compound in Formula 6.

[0326] As described above, the second compound has a starting wavelength that is greater (longer) than that of the first compound and is less (shorter) than that of the third compound. In addition, the second compound has a maximum emission wavelength (λmax) that is less than that of the first compound, and the third compound has a maximum emission wavelength that is equal to or less than that of the first compound. The second compound has a maximum emission wavelength that is less than that of the third compound. In addition, the second compound has a FWHM that is less than that of the first compound, and the third compound has a FWHM that is less than that of the first compound.

[0327] In the EML of the light-emitting layer 1062, the weight % of the second compound can be equal to or less than that of the third compound. For example, the weight % of the third compound with respect to the second compound is about 100 to 1200 weight %.

[0328] In the first pixel region P1, the EML of the light-emitting layer 1062 can further contain a host. The triplet energy level of the host can be equal to or greater (higher) than that of the first compound which is a delayed fluorescent compound. In addition, the triplet energy level of the host can be greater than that of the third compound having a phosphorescent property.

[0329] An encapsulation film 1070 is formed on the second electrode 1064 to prevent moisture from penetrating into the OLED D6. The encapsulation film 1070 can have a three-layer structure including a first inorganic insulating layer, an organic insulating layer, and a second inorganic insulating layer, but is not limited thereto.

[0330] The organic light-emitting display device 1000 can further include a polarizing plate (not shown) for reducing reflection of ambient light. For example, the polarizing plate can be a circular polarizing plate. In a bottom emission type organic light-emitting display device 1000, the polarizing plate can be disposed below the substrate 1010. In a top emission type organic light-emitting display device 1000, the polarizing plate can be disposed on or above the encapsulation film 1070.

[0331] Figure 20 is a schematic cross-sectional view of an OLED according to an eighth embodiment of the disclosure.

[0332] Referring to Figure 20 and Figure 19 OLED D6 is located in each of the first to third pixel areas P1 to P3 and includes the first and second electrodes 1060 and 1064 facing each other and the light-emitting layer 1062 therebetween. The light-emitting layer 1062 includes the EML 1090.

[0333] The first electrode 1060 can be an anode, and the second electrode 1064 can be a cathode. For example, the first electrode 1060 can be a reflective electrode, and the second electrode 1064 can be a transmissive electrode (or a semi-transmissive electrode).

[0334] The light-emitting layer 1062 can further include the HTL 1082 between the first electrode 1060 and the EML 1090 and the ETL 1094 between the EML 1090 and the second electrode 1064.

[0335] In addition, the light-emitting layer 1062 can further include the HIL 1080 between the first electrode 1060 and the HTL 1082 and the EIL 1096 between the ETL 1094 and the second electrode 1064.

[0336] Also, the light-emitting layer 1062 can further include the EBL 1086 between the EML 1090 and the HTL 1082 and the HBL 1092 between the EML 1090 and the ETL 1094.

[0337] In addition, the light-emitting layer 1062 can further include the auxiliary HTL 1084 between the HTL 1082 and the EBL 1086. The auxiliary HTL 1084 can include the first auxiliary HTL 1084a in the first pixel area P1, the second auxiliary HTL 1084b in the second pixel area P2, and the third auxiliary HTL 1084c in the third pixel area P3.

[0338] The first auxiliary HTL 1084a has a first thickness, the second auxiliary HTL 1084b has a second thickness, and the third auxiliary HTL 1084c has a third thickness. The second thickness is greater than the first thickness and less than the third thickness, so that the OLED D6 provides a microcavity structure.

[0339] That is, by having the first to third auxiliary HTLs 1084a, 1084b, and 1084c having a difference in thickness, in which the distance between the first electrode 1060 and the second electrode 1064 in the second pixel region P2 that emits light of a first wavelength range, for example, green light, is smaller than the distance between the first electrode 1060 and the second electrode 1064 in the third pixel region P3 that emits light of a second wavelength range larger than the first wavelength range, for example, red light, and is larger than the distance between the first electrode 1060 and the second electrode 1064 in the first pixel region P1 that emits light of a third wavelength range smaller than the first wavelength range, for example, blue light. Thus, the light-emitting efficiency of the OLED D6 is improved.

[0340] In Figure 20 the first auxiliary HTL 1084a is formed in the first pixel region P1. Alternatively, the microcavity structure can be provided without the first auxiliary HTL 1084a.

[0341] A cap layer (not shown) for improving light extraction characteristics can be further formed on the second electrode 1064.

[0342] The EML 1090 includes a first EML 1090a in the first pixel region P1, a second EML 1090b in the second pixel region P2, and a third EML 1090c in the third pixel region P3. The first to third EMLs 1090a, 1090b, and 1090c can be a blue EML, a green EML, and a red EML, respectively.

[0343] The first EML 1090a contains a first compound having a delayed fluorescence characteristic, a second compound having a fluorescent characteristic or a delayed fluorescent characteristic, and a third compound having a phosphorescent characteristic. The first to third compounds are mixed in a single EML.

[0344] The first compound can be represented by Formula 1-1 or Formula 1-2 and can be one of the compounds in Formula 2. The second compound can be represented by Formula 3 and can be the compound in Formula 4. The third compound can be represented by Formula 5-1 or Formula 5-2 and can be the compound in Formula 6.

[0345] As described above, the second compound has a starting wavelength that is greater (longer) than the starting wavelength of the first compound and that is less (shorter) than the starting wavelength of the third compound. Also, the second compound has a maximum emission wavelength (λmax) that is less than the maximum emission wavelength of the first compound, and the third compound has a maximum emission wavelength that is equal to or less than the maximum emission wavelength of the first compound. The maximum emission wavelength of the second compound is less than the maximum emission wavelength of the third compound. Also, the FWHM of the second compound is less than the FWHM of the first compound, and the FWHM of the third compound is less than the FWHM of the first compound.

[0346] In the first EML 1090a in the first pixel area P1, the weight % of the second compound can be equal to or less than the weight % of the third compound. For example, the weight % of the third compound can be about 100 to 1200 weight % with respect to the second compound.

[0347] The first EML 1090a in the first pixel area P1 can further include a host. The triplet energy level of the host can be equal to or greater (higher) than the triplet energy level of the first compound that is a delayed fluorescent compound. Also, the triplet energy level of the host can be greater than the triplet energy level of the third compound having a phosphorescent property.

[0348] The second EML 1090b in the second pixel area P2 and the third EML 1090c in the third pixel area P3 can each include a host and a dopant. For example, in each of the second EML 1090b in the second pixel area P2 and the third EML 1090c in the third pixel area P3, the dopant can include at least one of a phosphorescent compound, a fluorescent compound, and a delayed fluorescent compound.

[0349] Figure 20 The OLED D6 in Equation 1 can emit blue light, green light, and red light in the first pixel area P1 to the third pixel area P3, respectively, such that the organic light emitting display device 1000 can provide a full-color image. Figure 19 The organic light emitting display device 1000 can provide a full-color image.

[0350] The organic light emitting display device 1000 can further include a color filter layer corresponding to the first pixel area P1 to the third pixel area P3 to improve color purity. For example, the color filter layer can include a first color filter layer (e.g., a blue color filter layer) corresponding to the first pixel area P1, a second color filter layer (e.g., a green color filter layer) corresponding to the second pixel area P2, and a third color filter layer (e.g., a red color filter layer) corresponding to the third pixel area P3.

[0351] In the bottom emission type organic light emitting display device 1000, a color filter layer can be disposed between the OLED D6 and the substrate 1010. On the other hand, in the top emission type organic light emitting display device 1000, the color filter layer can be disposed on or above the OLED D6.

[0352] Figure 21 is a schematic cross-sectional view of an organic light emitting display device according to a ninth embodiment of the disclosure.

[0353] As Figure 21 As shown in FIG. 11A, the organic light emitting display device 1100 includes a substrate 1110 in which first to third pixel areas P1, P2, and P3 are defined, a TFT Tr over the substrate 1110, an OLED D disposed over the TFT Tr and connected to the TFT Tr, and a color filter layer 1120 corresponding to the first to third pixel areas P1 to P3. For example, the first to third pixel areas P1, P2, and P3 can be a blue pixel area, a green pixel area, and a red pixel area, respectively.

[0354] The substrate 1110 can be a glass substrate or a flexible substrate. For example, the flexible substrate can be a polyimide (PI) substrate, a polyether sulfone (PES) substrate, a polyethylene naphthalate (PEN) substrate, a polyethylene terephthalate (PET) substrate, or a polycarbonate (PC) substrate.

[0355] The TFT Tr is formed on the substrate 1110. Alternatively, a buffer layer (not shown) can be formed on the substrate 1110, and the TFT Tr can be formed on the buffer layer.

[0356] As described above, Figure 2 The TFT Tr can include a semiconductor layer, a gate electrode, a source electrode, and a drain electrode and can function as a driving element.

[0357] Further, the color filter layer 1120 is disposed on the substrate 1110. For example, the color filter layer 1120 can include a first color filter layer 1122 corresponding to the first pixel area P1, a second color filter layer 1124 corresponding to the second pixel area P2, and a third color filter layer 1126 corresponding to the third pixel area P3. The first to third color filter layers 1122, 1124, and 1126 can be a blue color filter layer, a green color filter layer, and a red color filter layer, respectively. For example, the first color filter layer 1122 can include at least one of a blue dye and a blue pigment, the second color filter layer 1124 can include at least one of a green dye and a green pigment. The third color filter layer 1126 can include at least one of a red dye and a red pigment.

[0358] A planarization layer (or a passivation layer) 1150 is formed on the TFT Tr and the color filter layer 1120. The planarization layer 1150 has a flat top surface and includes a drain contact hole 1152 that exposes the drain electrode of the TFT Tr.

[0359] The OLED D is disposed on the planarization layer 1150 and corresponds to the color filter layer 1120. The OLED D includes a first electrode 1160, a light-emitting layer 1162, and a second electrode 1164. The first electrode 1160 is connected to the drain electrode of the TFT Tr, and the light-emitting layer 1162 and the second electrode 1164 are sequentially stacked on the first electrode 1160. The OLED D emits white light in each of the first to third pixel regions P1 to P3.

[0360] The first electrode 1160 is formed to be separate in the first to third pixel regions P1 to P3, and the second electrode 1164 is formed to be integrated to cover the first to third pixel regions P1 to P3.

[0361] The first electrode 1160 is one of an anode and a cathode, and the second electrode 1164 is the other of the anode and the cathode. In addition, the first electrode 1160 can be a light-transmissive electrode (or a semi-transmissive electrode), and the second electrode 1164 can be a reflective electrode.

[0362] For example, the first electrode 1160 can be an anode and can include a transparent conductive oxide (TCO) material layer formed of a TCO material having a relatively high work function. The second electrode 1164 can be a cathode and can include a metal material layer formed of a low-resistance metal material having a relatively low work function. For example, the TCO material layer of the first electrode 1160 contains at least one of indium-tin-oxide (ITO), indium-zinc-oxide (IZO), indium-tin-zinc-oxide (ITZO), tin oxide (SnO), zinc oxide (ZnO), indium-copper-oxide (ICO), and aluminum-zinc oxide alloy (Al:ZnO), and the second electrode 1164 can contain Al, Mg, Ca, Ag, an alloy thereof (e.g., a Mg-Ag alloy), or a combination thereof.

[0363] The light-emitting layer 1162 as a light-emitting unit is formed on the first electrode 1160. The light-emitting layer 1162 includes at least two light-emitting portions that emit different colors of light. Each light-emitting portion can have a single-layer structure of an EML. Alternatively, each light-emitting portion can further include at least one of a HIL, a HTL, an EBL, a HBL, an ETL, and an EIL. In addition, the light-emitting layer 1162 can further include a charge generation layer (CGL) between the light-emitting portions.

[0364] The EML of one of the light emitting parts includes a first compound having a delayed fluorescence property, a second compound having a fluorescent property or a delayed fluorescent property, and a third compound having a phosphorescent property.

[0365] A bank layer 1166 is formed on the planarization layer 1150 to cover edges of the first electrode 1160. That is, the bank layer 1166 is located at boundaries of the first to third pixel regions P1 to P3 and exposes centers of the first electrode 1160 in the first to third pixel regions P1 to P3. As described above, since the OLED D emits white light in the first to third pixel regions P1 to P3, the light emitting layer 1162 can be formed as a common layer in the first to third pixel regions P1 to P3 without being separated in the first to third pixel regions P1 to P3. The bank layer 1166 can be formed to prevent current leakage at edges of the first electrode 1160, and the bank layer 1166 can be omitted.

[0366] Although not shown, the organic light emitting display device 1100 can further include an encapsulation film formed on the second electrode 1164 to prevent moisture from penetrating into the OLED D. In addition, the organic light emitting display device 1100 can further include a polarizing plate under the substrate 1110 for reducing reflection of ambient light.

[0367] In the organic light emitting display device 1100 of FIG. 11A, Figure 21 In the organic light emitting display device 1100 of FIG. 11A,

[0368] Alternatively, in the organic light emitting display device 1100, the first electrode 1160 can be a reflective electrode and the second electrode 1164 can be a transparent electrode (or a semi-transparent electrode). In this case, the color filter layer 1120 is located on or above the OLED D.

[0369] In the organic light emitting display device 1100, the OLED D in the first to third pixel regions P1 to P3 emits white light, and the white light passes through the first to third color filter layers 1122, 1124, and 1126. Accordingly, blue light, green light, and red light are displayed in the first to third pixel regions P1 to P3, respectively.

[0370] Although not shown, a color conversion layer can be formed between the OLED D and the color filter layer 1120. The color conversion layer can include a blue color conversion layer, a green color conversion layer, and a red color conversion layer corresponding to the first to third pixel regions P1 to P3, respectively, and white light from the OLED D can be converted into blue light, green light, and red light. The color conversion layer can include quantum dots. Accordingly, color purity of the OLED D can be further improved.

[0371] A color conversion layer can be included instead of the color filter layer 1120.

[0372] Figure 22 is a schematic cross-sectional view of an OLED according to a tenth embodiment of the disclosure.

[0373] As Figure 22 As shown in FIG. 11B, the OLED D7 includes a first electrode 1160 and a second electrode 1164 facing each other and a light emitting layer 1162 therebetween.

[0374] The first electrode 1160 can be an anode, and the second electrode 1164 can be a cathode. The first electrode 1160 is a transparent electrode (light-transmitting electrode), and the second electrode 1164 is a reflective electrode.

[0375] The light emitting layer 1162 includes a first light emitting part 1210 including a first EML 1220, a second light emitting part 1230 including a second EML 1240, and a third light emitting part 1250 including a third EML 1260. In addition, the light emitting layer 1162 can further include a first CGL 1270 between the first light emitting part 1210 and the second light emitting part 1230 and a second CGL 1280 between the second light emitting part 1230 and the third light emitting part 1250.

[0376] The first CGL 1270 is located between the first light emitting part 1210 and the second light emitting part 1230 and includes an N-type CGL 1270a and a P-type CGL 1270b, and the second CGL 1280 is located between the second light emitting part 1230 and the third light emitting part 1250 and includes an N-type CGL 1280a and a P-type CGL 1280b. That is, the first light emitting part 1210, the first CGL 1270, the second light emitting part 1230, the second CGL 1280, and the third light emitting part 1250 are sequentially stacked on the first electrode 1160. In other words, the first light emitting part 1210 is located between the first electrode 1160 and the first CGL 1270, the second light emitting part 1230 is located between the first CGL 1270 and the second CGL 1280. The third light emitting part 1250 is located between the second CGL 1280 and the second electrode 1164.

[0377] The first light emitting part 1210 can further include a HIL 1210a and a first HTL 1210b under the first EML 1220, and a first ETL 1210c over the first EML 1220. That is, the HIL 1210a and the first HTL 1210b are located between the first electrode 1160 and the first EML 1220, and the first ETL 1210c is located between the first EML 1220 and the first CGL 1270.

[0378] Further, the first light emitting part 1210 can further include an EBL (not shown) between the first HTL 1210b and the first EML 1220, and an HBL (not shown) between the first ETL 1210c and the first EML 1220.

[0379] The second light emitting part 1230 can further include a second HTL 1230a under the second EML 1240, and a second ETL 1230b over the second EML 1240. That is, the second HTL 1230a is located between the second EML 1240 and the first CGL 1270, and the second ETL 1230b is located between the second EML 1240 and the second CGL 1280.

[0380] Further, the second light emitting part 1230 can further include an EBL (not shown) between the second HTL 1230a and the second EML 1240, and an HBL (not shown) between the second ETL 1230b and the second EML 1240.

[0381] The third light emitting part 1250 can further include a third HTL 1250a under the third EML 1260, and a third ETL 1250b and an EIL 1250c over the third EML 1260. That is, the third HTL 1250a is located between the third EML 1260 and the second CGL 1280, and the third ETL 1250b and the EIL 1250c are located between the third EML 1260 and the second electrode 1164.

[0382] Further, the third light emitting part 1250 can further include an EBL (not shown) between the third HTL 1250a and the third EML 1260, and an HBL (not shown) between the third ETL 1250b and the third EML 1260.

[0383] One of the first to third EMLs 1220, 1240, and 1260 may be a blue EML, another one of the first to third EMLs 1220, 1240, and 1260 may be a green EML, and the remaining one of the first to third EMLs 1220, 1240, and 1260 may be a red EML.

[0384] For example, the first EML 1220 may be a red EML, the second EML 1240 may be a green EML, and the third EML 1260 may be a blue EML. Alternatively, the first EML 1220 may be a green EML, the second EML 1240 may be a red EML, and the third EML 1260 may be a blue EML.

[0385] The third EML 1260, which is a blue EML, has the same Figure 9 The third EML 1260 has the same structure or configuration as the EML 540 of the OLED described above. That is, the third EML 1260 includes a first compound having delayed fluorescence characteristics, a second compound having fluorescent characteristics or delayed fluorescence characteristics, and a third compound having phosphorescent characteristics. The first to third compounds are mixed in a single EML.

[0386] The first compound may be represented by Formula 1-1 or Formula 1-2 and may be one of the compounds in Formula 2. The second compound may be represented by Formula 3 and may be a compound in Formula 4. The third compound may be represented by Formula 5-1 or Formula 5-2 and may be a compound in Formula 6.

[0387] As described above, the starting wavelength of the second compound is greater than (longer than) the starting wavelength of the first compound and less than (shorter than) the starting wavelength of the third compound. Furthermore, the maximum emission wavelength (λmax) of the second compound is less than the maximum emission wavelength of the first compound, and the maximum emission wavelength of the third compound is equal to or less than the maximum emission wavelength of the first compound. The maximum emission wavelength of the second compound is less than the maximum emission wavelength of the third compound. Furthermore, the full width at half maximum (FWHM) of the second compound is less than the FWHM of the first compound, and the FWHM of the third compound is less than the FWHM of the first compound.

[0388] In the third EML 1260, wt% of the second compound may be equal to or less than wt% of the third compound. For example, wt% of the third compound is about 100 wt% to 1200 wt% with respect to the second compound.

[0389] The third EML 1260 may further include a host. The triplet energy level of the host may be equal to or greater than (higher than) the triplet energy level of the first compound, which is a delayed fluorescent compound. In addition, the triplet energy level of the host may be greater than the triplet energy level of the third compound having phosphorescent properties.

[0390] The first EML 1220 includes a host and a green dopant (or a red dopant), and the second EML 1240 includes a host and a red dopant (or a green dopant). For example, in each of the first EML 1220 and the second EML 1240, the dopant may be one of a phosphorescent compound, a fluorescent compound, and a delayed fluorescent compound.

[0391] ( Figure 21 The OLED D7 in the first to third pixel regions P1 to P3 emits white light, and the white light passes through the OLEDs in the first to third pixel regions P1 to P3 ( Figure 21 ) color filter layer 1120. Therefore, ( Figure 21 The organic light-emitting display device 1100 can provide full-color images.

[0392] In OLED D7, since the first to third compounds satisfy the above conditions (or relationships), energy from the first compound is transferred to each of the second and third compounds, resulting in each of the second and third compounds providing luminescence. This prevents reductions in lifetime and luminous efficiency caused by triplet excitons in the first compound.

[0393] In addition, since the second and third compounds are contained in a single layer (i.e., the third EML 1260), the singlet excitons and triplet excitons of the first compound are transferred to the second and third compounds, respectively. Therefore, the non-luminescent quenching problem of triplet excitons in the first and / or second compounds is prevented.

[0394] Furthermore, the maximum emission wavelength of the second compound is smaller than the maximum emission wavelength of the third compound, preventing or minimizing energy transfer from the third compound to the second compound.

[0395] Therefore, the OLED D7 offers high luminous efficiency and high color purity.

[0396] Figure 23 is a schematic cross-sectional view of an OLED according to an eleventh embodiment of the present disclosure.

[0397] like Figure 23 As shown in FIG, the OLED D8 includes a first electrode 1360 and a second electrode 1364 facing each other with a light emitting layer 1362 therebetween.

[0398] The first electrode 1360 may be an anode, and the second electrode 1364 may be a cathode. The first electrode 1360 is a transparent electrode (light-transmitting electrode), and the second electrode 1364 is a reflective electrode.

[0399] The light-emitting layer 1362 includes a first light-emitting part 1410 including a first EML 1420, a second light-emitting part 1430 including a second EML 1440, and a third light-emitting part 1450 including a third EML 1460. In addition, the light-emitting layer 1362 can further include a first CGL 1470 between the first light-emitting part 1410 and the second light-emitting part 1430 and a second CGL 1480 between the first light-emitting part 1410 and the third light-emitting part 1450.

[0400] The first light-emitting part 1420 includes a lower EML 1420a and an upper EML 1420b. That is, the lower EML 1420a is positioned closer to the first electrode 1360, and the upper EML 1420b is positioned closer to the second electrode 1364.

[0401] The first CGL 1470 is located between the first light-emitting part 1410 and the second light-emitting part 1430 and includes an N-type CGL 1470a and a P-type CGL 1470b, and the second CGL 1480 is located between the first light-emitting part 1410 and the third light-emitting part 1450 and includes an N-type CGL 1480a and a P-type CGL 1480b. That is, the third light-emitting part 1450, the second CGL 1480, the first light-emitting part 1410, the first CGL 1470, and the second light-emitting part 1430 are sequentially stacked on the first electrode 1360. In other words, the first light-emitting part 1410 is located between the first CGL 1470 and the second CGL 1480, and the second light-emitting part 1430 is located between the first CGL 1470 and the second electrode 1364. The third light-emitting part 1450 is located between the second CGL 1480 and the first electrode 1360.

[0402] The first light-emitting part 1410 can further include a first HTL 1410a below the first EML 1420 and a first ETL 1410b above the first EML 1420. That is, the first HTL 1410a can be located between the first EML 1420 and the second CGL 1480, and the first ETL 1410b can be located between the first EML 1420 and the first CGL 1470.

[0403] In addition, the first light-emitting part 1410 can further include an EBL (not shown) between the first HTL 1410a and the first EML 1420 and an HBL (not shown) between the first ETL 1410b and the first EML 1420.

[0404] The second light emitting part 1430 can further include a second HTL 1430a under the second EML 1440, a second ETL 1430b over the second EML 1440, and an EIL 1430c on the second ETL 1430b. That is, the second HTL 1430a can be located between the second EML 1440 and the first CGL 1470, and the second ETL 1430b and the EIL 1430c can be located between the second EML 1440 and the second electrode 1364.

[0405] Further, the second light emitting part 1430 can further include an EBL (not shown) between the second HTL 1430a and the second EML 1440, and an HBL (not shown) between the second ETL 1430b and the second EML 1440.

[0406] The third light emitting part 1450 can further include a third HTL 1450b under the third EML 1460, a HIL 1450a under the third HTL 1450b, and a third ETL 1450c over the third EML 1460. That is, the HIL 1450a and the third HTL 1450b can be located between the first electrode 1360 and the third EML 1460, and the third ETL 1450c can be located between the third EML 1460 and the second CGL 1480.

[0407] Further, the third light emitting part 1450 can further include an EBL (not shown) between the third HTL 1450b and the third EML 1460, and an HBL (not shown) between the third ETL 1450c and the third EML 1460.

[0408] One of the lower EML 1420a and the upper EML 1420b of the first EML 1420 is a red EML, and the other of the lower EML 1420a and the upper EML 1420b of the first EML 1420 can be a green EML. That is, the red EML (or the green EML) and the green EML (or the red EML) are sequentially stacked to form the first EML 1420.

[0409] The second EML 1440 and the third EML 1460 can each be a blue EML. At least one of the second EML 1440 and the third EML 1460 has the same structure or configuration as the EML 540 of the OLED described above. Figure 9

[0410] ​That is, at least one of the second EML 1440 and the third EML 1460 includes a first compound having delayed fluorescence characteristics, a second compound having fluorescence characteristics or delayed fluorescence characteristics, and a third compound having phosphorescence characteristics. The first to third compounds are mixed in a single EML.

[0411] The first compound may be represented by Formula 1-1 or Formula 1-2 and may be one of the compounds in Formula 2. The second compound may be represented by Formula 3 and may be a compound in Formula 4. The third compound may be represented by Formula 5-1 or Formula 5-2 and may be a compound in Formula 6.

[0412] As described above, the starting wavelength of the second compound is greater than (longer than) the starting wavelength of the first compound and less than (shorter than) the starting wavelength of the third compound. Furthermore, the maximum emission wavelength (λmax) of the second compound is less than the maximum emission wavelength of the first compound, and the maximum emission wavelength of the third compound is equal to or less than the maximum emission wavelength of the first compound. The maximum emission wavelength of the second compound is less than the maximum emission wavelength of the third compound. Furthermore, the full width at half maximum (FWHM) of the second compound is less than the FWHM of the first compound, and the FWHM of the third compound is less than the FWHM of the first compound.

[0413] In at least one of the second EML 1440 and the third EML 1460, the wt % of the second compound may be equal to or less than that of the third compound. For example, the wt % of the third compound relative to the second compound is approximately 100 wt % to 1200 wt %.

[0414] At least one of the second EML 1440 and the third EML 1460 may further include a host. The triplet energy level of the host may be equal to or greater than (higher than) the triplet energy level of the first compound, which is a delayed fluorescence compound. In addition, the triplet energy level of the host may be greater than the triplet energy level of the third compound having phosphorescent properties.

[0415] ( Figure 21 The OLED D8 in the first to third pixel regions P1 to P3 emits white light, and the white light passes through the OLEDs in the first to third pixel regions P1 to P3 ( Figure 21 ) color filter layer 1120. Therefore, ( Figure 21 The organic light-emitting display device 1100 can provide full-color images.

[0416] exist Figure 23In the present embodiment, the OLED D8 has a triple stack structure in which the second EML 1440 and the third EML 1460 are blue EMLs. Alternatively, the OLED D8 can have a double stack structure in which the light-emitting portion including one of the second EML 1440 and the third EML 1460 is not included.

[0417] In at least one of the second EML 1440 and the third EML 1460 of the OLED D8, since the first compound to the third compound satisfy the above condition (or relation), the energy of the first compound is transferred into each of the second compound and the third compound, so that light emission is provided by each of the second compound and the third compound. Thus, reduction in the lifetime and the light emission efficiency caused by the triplet exciton in the first compound is prevented.

[0418] Further, since the second compound and the third compound are included in a single layer, the singlet exciton and the triplet exciton of the first compound are transferred into the second compound and the third compound, respectively. Thus, the non-emission quenching problem of the triplet exciton in the first compound and / or the second compound is prevented.

[0419] Further, the maximum emission wavelength of the second compound is smaller than the maximum emission wavelength of the third compound, which prevents or minimizes the energy transfer from the third compound into the second compound.

[0420] Thus, the OLED D8 provides high light emission efficiency and high color purity.

[0421] It will be obvious to those skilled in the art that various modifications and changes can be made in the present application without departing from the spirit or scope thereof. Accordingly, the present disclosure is intended to encompass all modifications and changes which can come within the scope of the following claims and their equivalents.

Claims

1. An organic light emitting diode comprising: a first electrode; a second electrode facing the first electrode; and a first light emitting material layer comprising a first compound, a second compound, and a third compound and located between the first electrode and the second electrode, wherein an onset wavelength of the second compound is greater than an onset wavelength of the first compound and less than an onset wavelength of the third compound, wherein a maximum emission wavelength of the second compound is less than a maximum emission wavelength of the first compound, and a maximum emission wavelength of the third compound is equal to or less than the maximum emission wavelength of the first compound, such that singlet excitons of the first compound are transferred into singlet excitons of the second compound and triplet excitons of the first compound are transferred into triplet excitons of the third compound, and light emission is provided by the second compound and the third compound, wherein a full width at half maximum of each of the second compound and the third compound is less than a full width at half maximum of the first compound, wherein the first compound is represented by Formula 1-1 or Formula 1-2: [Formula 1-1] [Formula 1-2] wherein R 1 and R 2 are each independently selected from the group consisting of hydrogen (H), C 1 to C 10 alkyl, and C 6 to C 30 aryl, and wherein R 3 to R 6 are each independently selected from the group consisting of H, C 1 to C 10 alkyl, and C 6 to C 30 aryl; wherein the second compound is represented by Formula 3: [Formula 3] wherein R 11 to R 14 are each independently selected from the group consisting of H, deuterium (D), C 1 to C 10 alkyl, C 6 to C 30 aryl, and C 6 to C 30 arylamino; and wherein the third compound is represented by Formula 5-1 or Formula 5-2: [Formula 5-1] [Formula 5-2] wherein R 21 to R 24 are each independently selected from the group consisting of H, C 1 to C 10 alkyl, and C 6 to C 30 aryl. 2.The organic light emitting diode according to claim 1, wherein the first compound to the third compound are contained in a single layer. 3.The organic light emitting diode according to claim 2, wherein a maximum emission wavelength of the second compound is less than a maximum emission wavelength of the third compound. 4.The organic light emitting diode according to claim 2, wherein a weight % of the second compound is equal to or less than a weight % of the third compound. 5.The organic light emitting diode according to claim 2, wherein the first light emitting material layer further comprises a host, and wherein a triplet energy level of the host is equal to or greater than a triplet energy level of the first compound. 6.The organic light emitting diode according to claim 2, wherein the first light emitting material layer further comprises a host, and wherein a triplet energy level of the host is greater than a triplet energy level of the third compound. a hole blocking layer between the second electrode and the first light emitting material layer, 7. The organic light emitting diode of claim 2, further comprising: wherein the first light emitting material layer further comprises a host, and the host is the same material as the hole blocking layer. an electron blocking layer between the first electrode and the first light emitting material layer, 8. The organic light emitting diode of claim 2, further comprising: wherein the first light emitting material layer further comprises a host, and the host is the same material as the electron blocking layer. ​ 9. The organic light emitting diode of claim 1, wherein the first light emitting material layer comprises a first layer and a second layer between the first layer and the second electrode, and wherein the first layer comprises the first compound and the second compound, and the second layer comprises the first compound and the third compound.

10. The organic light emitting diode of claim 9, wherein a thickness of the first layer is less than a thickness of the second layer.

11. The organic light emitting diode of claim 9, wherein a weight % of the second compound in the first layer is equal to or greater than a weight % of the third compound in the second layer.

12. The organic light emitting diode of claim 9, wherein the first light emitting material layer further comprises a third layer, the third layer comprising the first compound and the third compound and being located between the first electrode and the first layer.

13. The organic light emitting diode of claim 9, wherein the second layer further comprises a host, and wherein a triplet energy level of the host is greater than a triplet energy level of the third compound.

14. The organic light emitting diode of claim 1, further comprising: a second light emitting material layer between the first electrode and the first light emitting material layer; and a charge generation layer between the first light emitting material layer and the second light emitting material layer, wherein the second light emitting material layer is one of a red light emitting material layer, a green light emitting material layer, and a blue light emitting material layer.

15. An organic light emitting device comprising: a substrate; and an organic light emitting diode disposed on or over the substrate, the organic light emitting diode comprising: a first electrode; a second electrode facing the first electrode; and a first light emitting material layer comprising a first compound, a second compound, and a third compound and being located between the first electrode and the second electrode, wherein an onset wavelength of the second compound is greater than an onset wavelength of the first compound and less than an onset wavelength of the third compound, wherein a maximum emission wavelength of the second compound is less than a maximum emission wavelength of the first compound, and a maximum emission wavelength of the third compound is equal to or less than the maximum emission wavelength of the first compound, such that singlet excitons of the first compound are transferred into singlet excitons of the second compound and triplet excitons of the first compound are transferred into triplet excitons of the third compound, and light emission is provided by the second compound and the third compound, wherein a full width at half maximum of each of the second compound and the third compound is less than a full width at half maximum of the first compound, wherein the first compound is represented by Formula 1-1 or Formula 1-2: [Formula 1-1] [Formula 1-2] wherein R1and R2are each independently selected from hydrogen (H), C1to C10alkyl, and C6to C30aryl, and wherein R3to R6are each independently selected from H, C1to C10alkyl, and C6to C30aryl; wherein the second compound is represented by Formula 3: [Formula 3] wherein R11to R14are each independently selected from the group consisting of H, deuterium (D), C1to C10alkyl, C6to C30aryl, and C6to C30arylamino; and wherein the third compound is represented by Formula 5-1 or Formula 5-2: [Formula 5-1] [Formula 5-2] wherein R21to R24are each independently selected from the group consisting of H, C1to C10alkyl, and C6to C30aryl.

16. The organic light emitting device of claim 15, wherein the first compound through the third compound are included in a single layer, and wherein a maximum emission wavelength of the second compound is less than a maximum emission wavelength of the third compound.

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