OLED DEVICE, DISPLAY APPARATUS AND MANUFACTURING METHOD THEREFOR

An organic light-emitting diode (OLED) device includes a first electrode, a light-emitting layer, an electron blocking layer and a second electrode. A material of the light-emitting layer includes a host material and a trap material. A lowest unoccupied molecular orbital energy level of the trap material is lower than a lowest unoccupied molecular orbital energy level of the host material, a highest occupied molecular orbital energy level of the trap type material is not higher than a highest occupied molecular orbital energy level of the host material, and the lowest unoccupied molecular orbital energy level of the trap material is lower than a lowest unoccupied molecular orbital energy level of the electron blocking layer. The first electrode, the light-emitting layer, the electron blocking layer and the second electrode are stacked in sequence.

TECHNICAL FIELD

The present disclosure relates to the field of display technologies, and in particular, to an OLED device, a display apparatus and a manufacturing method therefor.

BACKGROUND

Organic light-emitting diode (OLED) display technology is a technology that uses organic semiconductor materials and light-emitting materials to emit light and achieve display under the drive of a current. In recent years, OLED display apparatuses have received more attention as a new type of flat panel displays, and they have become mainstream display products in the market due to their advantages of active luminescence, high luminance, high resolution, wide viewing angle, fast response speed, low energy consumption and flexibility.

SUMMARY

In a first aspect, an OLED device is provided. The OLED device includes a first electrode, a light-emitting layer, an electron blocking layer and a second electrode. A material of the light-emitting layer includes a host material and a trap material. A lowest unoccupied molecular orbital energy level of the trap material is lower than a lowest unoccupied molecular orbital energy level of the host material, a highest occupied molecular orbital energy level of the trap type material is not higher than a highest occupied molecular orbital energy level of the host material, and the lowest unoccupied molecular orbital energy level of the trap material is lower than a lowest unoccupied molecular orbital energy level of the electron blocking layer. The first electrode, the light-emitting layer, the electron blocking layer and the second electrode are stacked in sequence.

In some embodiments, the light-emitting layer includes at least one first sub-layer and at least one second sub-layer that are stacked; a material of the at least one first sub-layer includes the host material, a material of the at least one second sub-layer includes the trap material.

In some embodiments, of the at least one first sub-layer and the at least one second sub-layer, a sub-layer closest to the electron blocking layer is a first sub-layer.

In some embodiments, a thickness of the first sub-layer is greater than or equal to 50% of a thickness of the light-emitting layer.

In some embodiments, the material of the at least one second sub-layer further includes the host material, and the trap material is doped in the host material.

In some embodiments, the at least one first sub-layer includes one first sub-layer, and the at least one second sub-layer includes one second sub-layer.

In some embodiments, of the light-emitting layer, a mass ratio of the trap material to the host material is 3:7 to 7:3.

In some embodiments, a total number of the at least one first sub-layer and the at least one second sub-layer is greater than two, and the first sub-layer and the second sub-layer are alternately stacked.

In some embodiments, a thickness of each second sub-layer is 3% to 10% of a thickness of the light-emitting layer.

In some embodiments, each of the at least one first sub-layer and the at least one second sub-layer further includes a guest material.

In some embodiments, of the light-emitting layer, a mass ratio of the guest material to the host material is 1:100 to 15:100; and/or of the light-emitting layer, a mass ratio of the guest material to the trap material is 1:100 to 15:100.

In some embodiments, the trap material includes one of 4,4′-Di(9H-carbazol-9-yl)-biphenyl, 1,3,5-tri(9H-carbazol-9-yl)benzene (TCP), and 3,3-Di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP).

In some embodiments, the OLED device further includes a hole blocking layer disposed between the first electrode and the light-emitting layer.

In some embodiments, the OLED device further includes: an electron injection layer disposed between the first electrode and the hole blocking layer, an electron transport layer disposed between the electron injection layer and the hole blocking layer; a hole injection layer disposed between the second electrode layer and the electron blocking layer; and a hole transport layer disposed between the hole injection layer and the electron blocking layer.

In a second aspect, an OLED display apparatus is provided. The OLED display apparatus includes a plurality of OLED devices according to any one of the above embodiments.

In a third aspect, a manufacturing method for an organic light-emitting diode (OLED) device is provided. The method includes: forming a first electrode, a light-emitting layer, an electron blocking layer and a second electrode. The first electrode, the light-emitting layer, the electron blocking layer and the second electrode are stacked in sequence, and a material of the light-emitting layer includes a host material and a trap material. A lowest unoccupied molecular orbital energy level of the trap material is lower than a lowest unoccupied molecular orbital energy level of the host material, and a highest occupied molecular orbital energy level of the trap material is not higher than a highest occupied molecular orbital energy level of the host material.

In some embodiments, forming the first electrode, the light-emitting layer, the electron blocking layer, and the second electrode, includes: forming the first electrode, the light-emitting layer, the electron blocking layer, and the second electrode in sequence; or forming the second electrode, the electron blocking layer, the light-emitting layer, and the first electrode in sequence.

In some embodiments, the light-emitting layer includes at least one first sub-layer and at least one second sub-layer that are stacked. Forming the light-emitting layer includes: forming a first sub-layer of the at least one first sub-layer and forming a second sub-layer of the at least one second sub-layer. Forming the second sub-layer includes evaporating the host material. Forming the second sub-layer includes evaporating the host material and the trap material, simultaneously.

In some embodiments, the light-emitting layer includes at least one first sub-layer and at least one second sub-layer that are stacked. A total number of layers of the at least one first sub-layer and the at least one second sub-layer is greater than two, and the first sub-layer and the second sub-layer are alternately stacked. Forming the light-emitting layer includes: forming a first sub-layer of the at least one first sub-layer and forming a second sub-layer of the at least one second sub-layer. Forming the second sub-layer includes evaporating the host material. Forming the second sub-layer includes evaporating the trap material.

In some embodiments, the light-emitting layer further includes a guest material. Forming the first sub-layer further includes: evaporating the guest material while the host material is evaporated. Forming the second sub-layer further includes: evaporating the guest material while the trap material is evaporated.

In a fourth aspect, a manufacturing method for an organic light-emitting diode (OLED) display apparatus is provided. The method includes: providing a base; and manufacturing a plurality of OLED devices on the base. Each OLED device is manufactured by the method according to any one of the above embodiments.

REFERENCE CHARACTERS

DETAILED DESCRIPTION

It will be understood that, when a layer or an element is referred to as being on another layer or substrate, it may be directly on the another layer or substrate, or intervening layer(s) may also be present.

As used herein, depending on the context, the term “if” is optionally construed as “when” or “in a case where” or “in response to determining” or “in response to detecting.” Similarly, the phrase “if it is determined that” or “if [a stated condition or event] is detected” is optionally construed as “in a case where it is determined that” or “in response to determining that” or “in a case where [the stated condition or event] is detected” or “in response to detecting [the stated condition or event],” depending on the context.

The use of the phrase “configured to” in the embodiments of the present disclosure means an open and inclusive expression, which does not exclude devices configured to perform additional tasks or steps.

Exemplary embodiments are described herein with reference to sectional views and/or plan views as idealized exemplary drawings. In the accompanying drawings, thickness of layers and regions are enlarged for clarity. Exemplary embodiments of the present disclosure should not be construed to be limited to shapes of regions shown herein, but to include deviations in shape due to, for example, manufacturing. For example, an etched area shown as a rectangle generally has a curved feature. Therefore, the areas shown in the accompanying drawings are schematic in nature, and their shapes are not intended to show actual shapes of the area in a device, and are not intended to limit the scope of the exemplary embodiments.

Some embodiments of the present disclosure provide an organic light-emitting diode (OLED) display apparatus, the OLED display apparatus may serve as any product or component with a display function such as a display, a television, a digital camera, a mobile phone, a tablet computer, an augmented reality (AR) product or a virtual reality (VR) product, and a use of the OLED display apparatus is not limited in the embodiments of the present disclosure.

In some embodiments, as shown inFIG. 1, the OLED display apparatus100includes a display panel1, a frame101, a cover plate, a circuit board and the like. The OLED display apparatus may include more or fewer components, and relative positions of these components may be changed. For example, the display panel1and the circuit board are provided in a cavity enclosed by the frame101and the cover plate.

In some examples, the circuit board is configured to provide the display panel1with signals required for display. For example, the circuit board is a printed circuit board assembly (PCBA). The PCBA includes a printed circuit board (PCB), a timing controller (TCON) disposed on the PCB, a power management integrated circuit (PMIC), and other integrated circuits (ICs) or circuitry.

As shown inFIG. 2A, the display panel1has a display area A and a peripheral region S located on at least one side of the display area A. In some examples, the peripheral area S is arranged around the display area A. In some other examples, the peripheral area S is located on only one side of the display area A. In yet some other examples, the peripheral area S is located on two opposite sides of the display area A. The peripheral area S is used for wiring, in addition, a driver circuit (e.g., a gate driver circuit) may also be provided in the peripheral area S.FIG. 2Ashows an example in which the peripheral area S is arranged around the display area A.

As shown inFIG. 2A, the display panel2includes a plurality of sub-pixels P disposed in the display area A.FIG. 2Ashows an example in which the plurality of sub-pixels P are arranged in a matrix with a plurality of rows and a plurality of columns. Herein, sub-pixels P arranged in a line in an X direction are referred to as sub-pixels in a row, and sub-pixels P arranged in a line in a Y direction are referred to as sub-pixels in a column.

In some embodiments, the plurality of sub-pixels P include at least sub-pixels of a first color, sub-pixels of a second color, and sub-pixels of a third color. For example, the first color sub-pixels, the second color sub-pixels, and the third color sub-pixels are red sub-pixels, green sub-pixels, and blue sub-pixels, respectively. A distribution of the first color sub-pixels, the second color sub-pixels, and the third color sub-pixels is, for example, that first color sub-pixels, second color sub-pixels, and third color sub-pixels in sub-pixels in each row are alternately arranged in sequence.

As shown inFIGS. 2A and 2B, the display panel1includes a base11. Each sub-pixel P includes an OLED device2disposed on the base11and a pixel driving circuit3electrically connected to the OLED device2.

In some examples, the base11may be a flexible base or a rigid base. A material of the flexible base is, for example, polyimide. A material of the rigid base is, for example, glass.

In some examples, as shown inFIG. 2B, the display panel1further includes a pixel defining layer13. The pixel defining layer13includes a plurality of openings, and one OLED device is disposed in one opening.

In some examples, as shown inFIG. 3A, the pixel driving circuit3includes a driving transistor Td, a first switching transistor T1and a storage capacitor Cst. That is, a circuit structure of the pixel driving circuit3is a 2T1C circuit structure. It will be understood by those skilled in the art that in the pixel driving circuit3, a width-length ratio of a channel of the driving transistor Td is greater than width-length ratios of channels of other transistors that function as switches.

As shown inFIG. 3A, a gate of the first switching transistor T1is electrically connected to a scanning signal line GL, a first electrode of the first switching transistor T1is electrically connected to a data signal line DL, and a second electrode of the first switching transistor T1is electrically connected to a gate of the driving transistor Td. A first electrode of the driving transistor Td is electrically connected to a first power line VDD, and a second electrode of the driving transistor Td is electrically connected to an anode of the OLED device2. A cathode of the OLED device2is electrically connected to a second power line VSS. A terminal of the storage capacitor Cst is electrically connected to the gate of the driving transistor Td, and the other terminal of the storage capacitor Cst is electrically connected to the second electrode of the driving transistor Td. For example, the first power line VDD is configured to provide a high voltage signal, and the second power line VSS is configured to provide a low voltage signal.

In some other examples, as shown inFIG. 3B, the pixel driving circuit3includes a driving transistor Td, a second switching transistor T2, a third switching transistor T3, a fourth switching transistor T4, a fifth switching transistor T5, a sixth switching transistor T6, a seventh switching transistor T7and a storage capacitor Cst. That is, the circuit structure of the pixel driving circuit3is a7T1C circuit structure.

As shown inFIG. 3B, a gate of the second switching transistor T2is electrically connected to a scanning signal line GL, a first electrode of the second switching transistor T2is electrically connected to a data signal line DL, and a second electrode of the second switching transistor T2is electrically connected to a gate of the driving transistor Td. A gate of the third switching transistor T3is electrically connected to the scanning signal line GL, and a first electrode and a second electrode of the third switching transistor T3are electrically connected to a second electrode and a gate of the driving transistor Td, respectively. A gate of the fourth switching transistor T4is electrically connected to an enable signal line EM, a first electrode of the fourth switching transistor T4is electrically connected to a first power line VDD, and a second electrode of the fourth switching transistor T4is electrically connected to the first electrode of the driving transistor Td. A gate of the fifth switching transistor T5is electrically connected to the enable signal line EM, a first electrode of the fifth switching transistor T5is electrically connected to the second electrode of the driving transistor Td, and a second electrode of the fifth switching transistor T5is electrically connected to an anode of the OLED device2. A gate of the sixth switching transistor T6is electrically connected to a reset signal line RST(N), a first electrode of the sixth switching transistor T6is electrically connected to an initialization signal line VIN, and a second electrode of the sixth switching transistor T4is electrically connected to the gate of the driving transistor Td. A gate of the seventh switching transistor T7is electrically connected to a reset signal line RST(N+1) that is connected to a sixth switching transistor T6of a pixel driving circuit3in a next row, a first electrode of the seventh switching transistor T7is electrically connected to the initialization signal line VIN, and a second electrode of the seventh switching transistor T7is electrically connected to the anode of the OLED device2. A terminal of the storage capacitor Cst is electrically connected to the gate of the driving transistor Td, and the other terminal of the storage capacitor Cst is electrically connected to the first power line VDD. A cathode of the OLED device2is electrically connected to a second power line VSS. For example, the first power line VDD is configured to provide a high voltage signal, and the second power line VSS is configured to provide a low voltage signal.

The above is merely examples for the pixel driving circuit3. The circuit structure of the pixel driving circuit3is not limited to the two structures described above, and may be other types of circuit structure, which will not be listed herein. However, it will be understood that, regardless of which circuit structure the pixel driving circuit3has, it includes at least a driving transistor, a switching transistor function as a switch, and a storage capacitor.

Transistors used in the embodiments of the present disclosure may all be thin film transistors or field-effect transistors or other devices with same characteristics. In the embodiments of the present disclosure, a first electrode is one of a source and a drain of a transistor, and a second electrode is the other of the source and the drain of the transistor. Since the source and the drain of the transistor may be symmetrical in structure, there may be no difference in structure between the source and the drain of the transistor. That is, there may be no difference in structures between the first electrode and the second electrode of the transistor in the embodiments of the present disclosure. For example, for a P-type transistor, the second electrode is referred to as the drain, and the first electrode is referred to as the source. For another example, for an N-type transistor, the first electrode is referred to as the drain, and the second electrode is referred to as the source.

In some examples, as shown inFIG. 2B, the display panel1further includes a planarization layer12disposed between the pixel driving circuit3and an OLED device2corresponding thereto, and the driving transistor Td is electrically connected to a second electrode25(e.g., the anode) of the OLED device2through a via hole disposed in the planarization layer12. For example, the planarization layer12may be formed by forming an insulating film through a chemical vapor deposition after the pixel driving circuit3is formed, and then the required via hole may be formed by performing a patterning process on the insulating film.

For example, a material of the planarization layer12includes, but is not limited to, a polysiloxane-based material, an acrylic-based material or a polyimide-based material.

In some examples, as shown inFIG. 2B, the display panel1further includes an encapsulation layer14.

As shown inFIG. 4A, some embodiments of the present disclosure provide an OLED device2including a first electrode21, a light-emitting layer (EML)23, an electron blocking layer (EBL)24and a second electrode25that are stacked in sequence. For example, a thickness of the light-emitting layer23is in a range of 20 nm to 40 nm. For example, a thickness of the electron blocking layer24is in a range of 5 nm to 10 nm.

In some examples, as shown inFIGS. 4B and 4C, the OLED device2is formed on a substrate20. “being stacked” means that the above are stacked in a thickness direction of the substrate20. For example, as shown inFIG. 4B, the second electrode25, the electron blocking layer24, the light-emitting layer23and the first electrode21are sequentially stacked on the substrate20in the thickness direction of the substrate20. For another example, as shown inFIG. 4C, the first electrode21, the light-emitting layer23, the electron blocking layer24and the second electrode25are sequentially stacked on the substrate20in the thickness direction of the substrate20.

For example, a material of the substrate20is glass. For another example, the material of the substrate20is polyimide.

In some examples, the OLED device is applied to the display panel1, and the substrate20for the OLED device is the base in the display panel1.

In some examples, the first electrode21is a cathode and the second electrode25is an anode. Holes injected through the second electrode25and electrons injected through the first electrode21both move to the light-emitting layer23due to an action of an electric field, and the holes and the electrons recombine in the light-emitting layer23to form excitons. The excitons activate organic molecules in the light-emitting layer, which in turn makes electrons in the outermost layer of the organic molecules jump to an excited state from a ground state. Since the electrons in the excited state are extremely unstable and may return to the ground state, and energy may be released in a form of light during the transition process, the luminescence of the OLED device is achieved.

In some examples, as shown inFIG. 4B, the second electrode25is disposed on the substrate20, and the first electrode21is disposed on a side of the second electrode25away from the substrate20.

For example, in a case where the OLED device has a top-emission structure, the first electrode21is a transparent electrode or a translucent electrode, and the second electrode25is a translucent electrode or a reflective electrode. For example, the first electrode21is a transparent electrode, and a material of the first electrode21includes indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), zinc oxide (ZnO) or any combination thereof. Alternatively, the first electrode21is a translucent electrode, and the material of the first electrode21includes SnO2, ITO, IZO, ZnO, indium oxide (In2O3), indium gallium oxide (IGO), aluminum oxide zinc (AZO) or any combination thereof. The second electrode25is a reflective electrode, and a material of the second electrode25includes magnesium (Mg), silver (Ag), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), magnesium-silver (Mg—Ag) or a combination thereof. The embodiments of the present disclosure are not limited thereto.

For example, in a case where the OLED device has a bottom-emission structure, the first electrode21is a translucent electrode or a reflective electrode, and the second electrode25is a transparent electrode or a translucent electrode. For example, the first electrode21is a reflective electrode, and a material of the first electrode21includes Mg, Ag, Al, Al—Li, Ca, Mg—In, Mg—Ag or a combination thereof. The embodiments of the present disclosure are not limited thereto. The second electrode25is a transparent electrode, and the material of the second electrode25includes ITO, IZO, SnO2, ZnO or any combination thereof. Alternatively, the second electrode25is a translucent electrode, and the material of the first electrode25includes SnO2, ITO, IZO, ZnO, In2O3, IGO, AZO or any combination thereof. The embodiments of the present disclosure are not limited thereto.

A material of the light-emitting layer23includes a host material and a trap material. As shown inFIGS. 5 to 12, a lowest unoccupied molecular orbital (LUMO) energy level LUMO1of the trap material is lower than a lowest unoccupied molecular orbital energy level LUMO2of a host material, and the lowest unoccupied molecular orbital energy level LUMO1of the trap material is lower than a lowest unoccupied molecular orbital energy level LUMO24of a material of the electron blocking layer24. A highest occupied molecular orbital (HOMO) energy level HOMO1of the trap type material is not higher than a highest occupied molecular orbital energy level HOMO2of the host material. The host material of the light-emitting layer23has a property of transporting carriers, and the trap material has a property of trapping electrons.

In some examples, as shown inFIGS. 5 to 12, the lowest unoccupied molecular orbital energy level LUMO2of the host material is lower than the lowest unoccupied molecular orbital energy level LUMO24of the material of the electron blocking layer24. In this way, the electron blocking layer24blocks electrons from the cathode at an interface between the light-emitting layer23and the electron blocking layer24of the OLED device, so that a concentration of electrons at the interface between the light-emitting layer23and the electron blocking layer24of the OLED device is increased.

In some other examples, as shown inFIGS. 5 to 12, the highest occupied molecular orbital energy level HOMO2of the host material is lower than a highest occupied molecular orbital energy level HOMO24of the material of the electron blocking layer24.

In some examples, the host material of the light-emitting layer23includes one of 4,4′,4″-Tris(carbazol-9-yl)-triphenylamine (TCTA), N,N′-Dimethylquinacridone (DMQA) and 3,3′-(1,3-phenyl)-Bis(7-ethoxy-4-methyl-3-coumarinyl) benzene (mEMCB). The embodiments of the present disclosure are not limited thereto.

In some examples, the trap material of the light-emitting layer23includes one of 4,4′-Di(9H-carbazol-9-yl)-biphenyl (CBP), 1,3,5-tri(9H-carbazol-9-yl)benzene (TCP) and 3,3-Di(9H-carbazol-9-yl)-1,1′-biphenyl (mCBP). The embodiments of the present disclosure are not limited thereto, as long as it is ensured that the lowest unoccupied molecular orbital energy level LUMO1of the trap material is lower than the lowest unoccupied molecular orbital energy level LUMO2of the host material, and the highest occupied molecular orbital energy level HOMO1of the trap material is not higher than the highest occupied molecular orbital energy level HOMO2of the host material.

In some examples, the material of the electron blocking layer24includes one of mCBP and 3,6-Bis(N-phenyloxazol-3-yl)-N-phenylcarbazole (Tris-PCz). The embodiments of the present disclosure are not limited thereto, as long as it is ensured that the lowest unoccupied molecular orbital energy level LUMO1of the trap material is lower than the lowest unoccupied molecular orbital energy level LUMO24of the material of the electron blocking layer24, and the highest occupied molecular orbital energy level HOMO1of the trap material is lower than the highest occupied molecular orbital energy level HOMO24of the material of the electron blocking layer24. It is understood that, in a case where the trap material of the light-emitting layer23is mCBP, the material of the electron blocking layer24is not mCBP.

As shown inFIG. 13, electrons and holes recombine to form more excitons in a region proximate to an electron blocking layer (EBL)24of a light-emitting layer (EML)23of an OLED device. That is to say, transmission of the electrons in the OLED device is excessive, and the electrons are easier to be transmitted and accumulated at an interface of the EML and EBL. Since a material of the EBL is generally an electron-rich material and contains a structure of aniline, if too many electrons accumulate at the interface between the EML and the EBL, these electrons may generate a repulsive force with surplus electrons in the material of the EBL, and this repulsive force may distort a δ-bond of a benzene ring of aniline in the material of the EBL (as shown inFIG. 14). The distortion of the δ-bond may cause the δ-bond to break, and a defect caused by the breaking of the δ-bond may cause the material of the EBL to deteriorate, and further causing a service life of the OLED device to decrease. Reduction of the service life of the OLED device may cause a white balance shift of a product having the display panel after long-term use, and a color of the white picture may be reddish, greenish or pinkish visually.

In the OLED device2provided by the embodiments of the present disclosure, the material of the light-emitting layer23includes the trap material and the host material. The LUMO energy level of the trap material is lower than the LUMO energy level of the host material, and the HOMO energy level of the trap material is not higher than HOMO energy level of the host material. In this way, the electrons injected from the cathode may be trapped by the trap material of the light-emitting layer23, and the holes injected from the anode may not be trapped by the trap material of the light-emitting layer23. Therefore, under the premise of ensuring a luminous efficiency of the OLED device, a case where excessive electrons are transmitted and accumulated at an interface of the EML and the EBL may be reduced.

Therefore, in the embodiments of the present disclosure, the trap material is added to the material of the light-emitting layer23to trap excessive electrons, thereby avoiding the accumulation of excessive electrons at the interface between the EML and the EBL, reducing the deterioration of the material of the EBL, improving stability of the material of the EBL, and prolonging the service life of the OLED device.

In some embodiments, as shown inFIGS. 8 to 12, the light-emitting layer23includes at least one first sub-layer231and at least one second sub-layer232that are stacked. A material of the at least one first sub-layer231includes the host material, and a material of at least one second sub-layer232includes the trap material.

In some embodiments, as shown inFIGS. 8 to 12, of the at least one first sub-layer231and the at least one second sub-layer232, a sub-layer closest to the electron blocking layer24is a first sub-layer231. In this way, in the light-emitting layer23, compared to the first sub-layer231closest to the electron blocking layer24, the material of the second sub-layer232away from the electron blocking layer24includes the trap material that can trap electrons, so that electrons transmitted to the interface between the EML and the EBL may be reduced, so as to prevent excessive electrons from accumulating at the interface between the EML and EBL.

In some embodiments, as shown inFIGS. 8 to 12, a thickness of the first sub-layer231closest to the electron blocking layer24is greater than or equal to 50% of a thickness of the light-emitting layer23.

As shown inFIG. 13, in the light-emitting layer23and in a thickness direction of the light-emitting layer23, in a region with a distance to the interface between the EML and the EBL greater than 50% of the thickness of the light-emitting layer23, intensity of excitons formed by recombination of electrons and holes is small. Therefore, the thickness of the first sub-layer231closest to the electron blocking layer24is greater than or equal to 50% of the thickness of the light-emitting layer23. That is to say, the second sub-layer232is located in the region with the distance to the interface between the EML and the EBL greater than 50% of the thickness of the light-emitting layer23. In this way, the trap material of the second sublayer232traps electrons, which has a small influence on the intensity of excitons in the EML, thereby ensuring the luminous intensity of the OLED device2.

In some examples, as shown inFIG. 8, the material of the at least one second sub-layer232further includes the host material, and the trap material is doped in the host material.

For example, as shown inFIGS. 8 to 10, the light-emitting layer23includes one first sub-layer231and one second sub-layer232. For example, a thickness of the second sub-layer232is in a range of 10 nm to 20 nm.

For another example, the light-emitting layer23may also include a plurality of first sub-layers231and a plurality of second sub-layers232, which are not limited in the embodiments of the present disclosure.

For example, of the light-emitting layer23, a mass ratio of a total mass of the trap material to a total mass of the host material is 3:7 to 7:3.

In some examples, as shown inFIGS. 11 and 12, a total number of the at least one first sub-layer231and the at least one second sub-layer232is greater than two, and the first sub-layer231and the second sub-layer232are alternately stacked.

For example, the light-emitting layer23includes two or three second sub-layers. For example, as shown inFIGS. 11 and 12, the light-emitting layer23includes two first sub-layers231and two second sub-layers232, and the first sub-layers231and the second sub-layers232are alternately stacked in the thickness direction of the light-emitting layer23. A sub-layer closest to the electron blocking layer24is a first sub-layer231, and the thickness of the first sub-layer is greater than 50% of the thickness of the light-emitting layer23.

For example, a thickness of each second sub-layer232is 3% to 10% of the thickness of the light-emitting layer23.

In the case where the light-emitting layer23includes a plurality of second sub-layers232, thicknesses of the plurality of second sub-layers232may be exactly equal, for example, the thicknesses of the plurality of second sub-layers232are each 5% of the thickness of the light-emitting layer23. The thicknesses of the plurality of second sub-layers232may not be exactly equal. Herein, “not exactly equal” means that part are equal and part are not equal; or all are not equal. The embodiments of the present disclosure do not limit thereto, as long as the thickness of the first sub-layer231in the light-emitting layer23closest to the electron blocking layer24is greater than or equal to 50% of the thickness of the light-emitting layer23.

In some embodiments, as shown inFIGS. 6, 8,10 and 12, the material of the light-emitting layer23further includes a guest material. The guest material of the light-emitting layer23receives energy of the host material to achieve light emission, thereby ensuring the luminous efficiency of the OLED device.

In some embodiments, as shown inFIGS. 8, 10, and 12, the material of each first sub-layer231and the material of each second sub-layer232in the light-emitting layer23further includes the guest material.

In some examples, of the light-emitting layer23, a mass ratio of a total mass of the guest material to a total mass of the host material is 1:100 to 15:100.

In some other examples, of the light-emitting layer23, a mass ratio of the total mass of the guest material to a total mass of the trap material is 1:100 to 15:100.

For example, the guest material includes Tris(2-phenylpyridine)iridium (Ir(ppy)3) and Bis[2-(2-hydroxyphenyl)-pyridine]beryllium (Be(PP)2).

In some examples, a relationship of energy levels of the host material, the trap material and the guest material is shown inFIGS. 6, 8, 10 and 12, a lowest unoccupied molecular orbital energy level HOMO3of the guest material is lower than the lowest unoccupied molecular orbital energy level LUMO1of the trap material, and a highest occupied molecular orbital energy level HOMO3of the guest material is higher than the highest occupied molecular orbital energy level HOMO2of the host material.

In some embodiments, as shown inFIG. 15A, the OLED device2further includes a hole blocking layer (HBL)22disposed between the first electrode21and the light-emitting layer23. For example, a thickness of the HBL22is in a range of 10 nm to 80 nm.

In some examples, as shown inFIGS. 5 to 12, the lowest unoccupied molecular orbital energy level LUMO2of the host material is lower than a lowest unoccupied molecular orbital energy level LUMO22of a material of the HBL22. The highest occupied molecular orbital energy level HOMO2of the host material is higher than a highest occupied molecular orbital energy level HOMO22of the material of the hole blocking layer22. In this way, the hole blocking layer22blocks holes from the anode at an interface between the light-emitting layer23and the hole blocking layer22of the OLED device, so that a recombination probability of electrons and holes in the light-emitting layer of the OLED device is improved, and the luminous efficiency of the OLED device is increased.

For example, the material of the hole blocking layer22includes one of 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 1,10-Phenanthroline (Bphen) and 1,3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI). The embodiments of the present disclosure are not limited thereto.

In some embodiments, as shown inFIG. 15B, the OLED device2further includes an electron injection layer (EIL)26, an electron transport layer (ETL)27, and a hole injection layer (HIL)28and a hole transport layer (HTL)29.

The electron injection layer26is located between the first electrode21(e.g., the cathode) and the hole blocking layer22. The electron injection layer26modifies the cathode, and transmits electrons to the electron transport layer27, so that a speed and amount of electron injection from the first electrode21may be adjusted. For example, a thickness of the electron injection layer26is in a range of 1 nm to 3 nm.

For example, a material of the electron injection layer26includes one of lithium fluoride (LiF), ytterbium (Yb) and quinolinolato lithium (8-hydroxy-quinolinolato lithium (LIQ)) complex. The embodiments of the present disclosure do not limit thereto.

The electron transport layer27is located between the electron injection layer26and the hole blocking layer22, and transports electrons from the cathode to the light-emitting layer23of the OLED device. For example, a thickness of the electron transport layer27is in a range of 20 nm to 35 nm.

For example, a material of the electron transport layer27includes one of BCP, Bphen, and TPBI. For example, the materials of the electron transport layer27and the hole blocking layer22are the same. For another example, the materials of the electron transport layer27and the hole blocking layer22are different. The embodiments of the present disclosure are not limited thereto.

The hole injection layer29is located between the second electrode25(e.g. the anode) and the electron blocking layer24. The hole injection layer29modifies the anode of the OLED device, so that holes from the anode may be smoothly injected into the hole transport layer29, and an injection rate and amount of the holes from the second electrode25may be adjusted. For example, a thickness of the hole transport layer29is in a range of 5 nm to 30 nm.

For example, a material of the hole injection layer29includes one of molybdenum trioxide (MoO3), 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) and 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN). However, the embodiments of the present disclosure are not limited thereto.

The hole transport layer29is located between the hole injection layer28and the electron blocking layer24, and transports holes to the light-emitting layer23. For example, a thickness of the hole transport layer29is in a range of 1000 nm to 1300 nm.

A material of the hole transport layer29includes at least one of N,N′-Bis(naphthalen-1-yl)-N,N′-bis(phenyl)benzidine (NPB), 4,4′,4″-Tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA) or N,N′-Bis(3-methylphenyl)-N,N′-bis(phenyl)benzidine (TPD). However, the embodiments of the present disclosure are not limited thereto.

Some embodiments of the present disclosure provide a manufacturing method for an OLED device. The method includes forming a first electrode21, a light-emitting layer23, an electron blocking layer24and a second electrode25, and the first electrode21, the light-emitting layer23, the electron blocking layer24and the second electrode25being stacked in sequence.

In some embodiments, forming a first electrode21, a light-emitting layer23, an electron blocking layer24and a second electrode25, includes S01to S04.

S01, in which a first electrode21is formed on a substrate20;

S02, in which a light-emitting layer23is formed on a side of the first electrode21in a thickness direction of the substrate20;

S03, in which an electron blocking layer24is formed on a side of the light-emitting layer23away from the first electrode21; and

S04, in which a second electrode25is formed on a side of the electron blocking layer24away from the light-emitting layer23.

That is, the first electrode21, the light-emitting layer23, the electron blocking layer24and the second electrode25are sequentially formed on a side of the substrate20, in the thickness direction of the substrate20, to form an OLED device as shown inFIG. 4C.

In some other embodiments, forming a first electrode21, a light-emitting layer23, an electron blocking layer24and a second electrode25, includes: forming the second electrode25, the electron blocking layer24, the light-emitting layer23, and the first electrode21sequentially on a side of the substrate20, in the thickness direction of the substrate20, to form an OLED device as shown inFIG. 4B.

S021, in which a first sub-layer is formed, includes S0212, evaporating a host material; and

S022, in which a second sub-layer is formed, includes S0222, evaporating the host material and a trap material, simultaneously.

The embodiments of the present disclosure are not limit an order of S021and S022. For example, in a case where the second electrode25and the electron blocking layer24are formed first, S021may be performed first, and then S022may be performed. For another example, in a case of the first electrode21is formed first, S022may be performed first, and then S021may be performed, so as to form the light-emitting layer23including the first sub-layer231and the second sub-layer232as shown inFIG. 8.

In some other embodiments, S02includes S021′ and S202′.

S021′, in which a first sub-layer is formed, includes S0212′, evaporating a host material; and

S022′, in which a second sub-layer is formed, includes S0222′, evaporating a trap material. S021′ and S022′ are alternately performed to form the light-emitting layer23including a plurality of first sub-layers231and a plurality of second sub-layers232.

The embodiments of the present disclosure are not limit an order of S021′ and S022′, as long as it is ensured that a sub-layer closest to the electron blocking layer24in the light-emitting layer23is a first sub-layer231. For example, in the case where the first electrode21is formed first, S021′ may be performed first, or S022′ may be performed first. For example, S022′, S021′, S022′ and S021′ are sequentially performed to form the light-emitting layer23including two first sub-layers231and two second sub-layers232as shown inFIG. 11. As another example, in the case where the second electrode25and the electron blocking layer24are formed first, S021′ is performed first, and then S022′ is performed.

In some embodiments, S021further includes S0211, and S022further includes S0221.

S0211, in which a guest material is evaporated while the host material is evaporated; and

S0221, in which the guest material is evaporated while the host material and the trap material are evaporated simultaneously.

The embodiments of the present disclosure are not limit an order of S0211and S0221, as long as it is ensured that S0212and S0211are performed simultaneously, and S0222and S0221are performed simultaneously. For example, in the case where the second electrode25and the electron blocking layer24are formed first, S0212and S0211are performed simultaneously, and then S0222and S0221are performed simultaneously. For another example, in the case where the first electrode21is formed first, S0222and S0221are performed simultaneously and then S0212and S0211are performed simultaneously, so as to form the light-emitting layer23including one first sub-layer231and one second sub-layer232as shown inFIG. 8.

In yet some other embodiments, S021′ further includes S0211′, and S022′ further includes S0221′.

S0211′, in which the guest material is evaporated while the host material is evaporated; and

S0221′, in which the guest material is evaporated while the trap material is evaporated.

The embodiments of the present disclosure are not limit the order of S0211′ and S0221′, as long as it is ensured that S0212′ and S0211′ are performed simultaneously.

For example, in the case where the first electrode21is formed first, S0212′ and S0211′ may be performed simultaneously, or S0222′ and S0221′ may be performed simultaneously. For example, S0222′ and S0221′ are performed simultaneously first, then S0212′ and S0211′ are performed simultaneously, then S0222′ and S0221′ are performed simultaneously, and then S0212′ and S0211′ are performed simultaneously, so as to form the light-emitting layer23including two first sub-layers231and two second sub-layers232as shown inFIG. 12.

Two specific examples of OLED devices are provided below to illustrate an effect of adding the trap material to the material of the light-emitting layer on performance of an OLED device.

Example 1: the second electrode25is an anode, and a material of the second electrode25is ITO; a material of the hole injection layer is MoO3, and a thickness thereof is 5 nm to 30 nm; a material of the hole transport layer is NPB, and a thickness thereof is 1000 nm to 1300 nm; a material of the electron blocking layer is mCBP, and a thickness thereof is 10 nm to 80 nm; a material of the light-emitting layer includes mEMCB, Ir(ppy)3and CBP, and a light-emitting layer includes one first sub-layer and one second sub-layer, a material of the first sub-layer includes the host material (mEMCB) and the guest material (Ir(ppy)3), a material of the second sub-layer includes the host material (mEMCB), the trap material (CBP) and the guest material (Ir(ppy)3), and a thickness of the light-emitting layer is 20 nm to 40 nm, and a thickness of the second sub-layer is 10 nm to 20 nm; a material of the hole blocking layer is BCP, and a thickness thereof is 5 nm to 10 nm; a material of the electron transport layer is a mixture of Bephen and LIQ, and a thickness thereof is 20 nm to 35 nm; a material of the electron injection layer is LIQ, and a thickness thereof is 1 nm to 3 nm; and the first electrode21is a cathode, and a material of the first electrode21is Mg—Ag alloy.

Example 2: the light-emitting layer is a single-layer, and the material of the light-emitting layer includes the host material (mEMCB) and the guest material (Ir(ppy)3). Except that the material of the light-emitting layer is different from that of the OLED device of Example 1, the materials of other layers are each completely the same as those of the OLED device of Example 1, the thicknesses of the other layers are each completely the same as those of the OLED device of Example 1, and the thickness of the light-emitting layer is the same as that of the OLED device of Example 1.

FIG. 16shows distributions of excitons in light-emitting layers23, due to an action of an electric field, in an OLED device in which a material of a light-emitting layer23includes the trap material and in an OLED device in which a material of a light-emitting layer23does not include the trap material. It may be seen fromFIG. 16that, compared with the OLED device in which the material of the light-emitting layer23does not include the trap material, in the OLED device in which the material of the light-emitting layer23includes the trap material, excitons are most distributed at a position with a distance to an interface of the light emitting layer23and the electron blocking layer24being 25% of a thickness of the light emitting layer23due to the action of the electric field, thereby preventing excessive electrons from being transmitted and accumulated at the interface of the EML and the EBL.

Some embodiments of the present disclosure provide a manufacturing method for an OLED display apparatus, including S100and S200.

S100, in which a base11is provided; and

S200, in which a plurality of OLED devices are manufactured on the base11, and each OLED device is manufactured by the manufacturing method for the OLED device in any one of the above embodiments.

Herein, the substrate20in S01of any of the above embodiments is the base11in S100.