A silicon-based OLED device structure with a hole transport layer

Abstract

A silicon-based OLED device structure with a hole transport layer, comprising a composite hole transport layer structure composed of a hole injection layer, a hole transport layer, and an electron blocking layer. The hole injection layer structure is composed of a hole transport host material and a P-type doping material. The hole transport layer is composed of a hole transport host material and a hole transport sub-host material. The electron blocking layer is composed of a hole transport sub-host material and an electron blocking material, and the HOMO energy levels of the hole transport host material and the hole transport sub-host material that constitute the hole transport layer are different. The HOMO energy level of the hole transport sub-host material is greater than the HOMO energy level of the electron blocking material. The present invention generates two hole transport channels through material design, thereby respectively improving the hole injection and transport efficiency of the two light-emitting units and reducing the barrier effect caused by different HOMO energy levels of materials. By reducing the hole transport barrier, the thermal effect is reduced, thereby achieving a high lifetime performance of the OLED device.

Description

Technical Field

[0001] The present invention belongs to the field of micro-display technology, and specifically relates to a silicon-based OLED device structure with a hole transport layer. Background Art

[0002] Silicon-based OLED (Organic Light Emitting Display) is being called the dark horse of next-generation display technology. Unlike conventional AMOLED devices, which utilize amorphous silicon, microcrystalline silicon, or low-temperature polycrystalline silicon thin-film transistors as backplanes, it is an active organic light-emitting diode display device made with single-crystal silicon as the active drive backplane. Its pixel size is 1 / 10 or even smaller than that of traditional displays, and its resolution far exceeds that of traditional devices. It boasts numerous advantages, including high resolution, high integration, low power consumption, compact size, and light weight. Even ordinary silicon-based OLEDs can achieve display effects that exceed the resolution limit of the human eye. Silicon-based OLED microdisplays are now widely used in military applications such as helmets, rifle scopes, and night vision goggles. With the adoption of new technologies such as AR / VR and autonomous driving, silicon-based OLED microdisplays are poised for explosive growth.

[0003] Silicon-based OLEDs used in VR applications need to meet the requirements of high brightness and long lifespan. The minimum brightness required for VR optical systems must exceed 5000cd / m 2 Indicators. Limited by the standard voltage limit of silicon-based CMOS driving technology, the higher device brightness requirement in the silicon-based OLED device structure based on multiple light-emitting layers requires a certain voltage adjustment range for the long-term operation of the device. Based on this requirement, higher requirements are placed on the low operating voltage of the device. Research on reducing device driving voltage, improving device luminous efficiency, and increasing device service life has become the main research direction in the field of silicon-based OLEDs. In order to achieve continuous improvement in the performance of silicon-based OLED devices, in addition to manufacturing higher-performance materials in the field of organic light-emitting materials to meet high luminous efficiency, it is also necessary to innovate in the structure of silicon-based OLED devices based on multiple light-emitting layers.

[0004] In existing technologies, both the hole transport layer and the electron blocking layer are typically composed of a single material. After charge transfer between the hole transport material and the P-type dopant, charge accumulation tends to form at the interface between the hole injection layer and the hole transport layer. Simultaneously, a second region of accumulated charge forms at the interface between the hole transport layer and the electron blocking layer. The presence of accumulated charge leads to decreased OLED device efficiency and increased voltage, which in turn shortens the device's lifespan. Furthermore, single hole transport and electron blocking materials place higher demands on energy level matching, often failing to meet the requirements for device structures matching multiple luminescent materials.

[0005] Therefore, to improve the driving voltage and service life of OLED devices, we can start from optimizing the combination of the hole transport structure of the devices. A silicon-based OLED device solution based on the combination of hole transport layers can overcome the above technical problems and become the research direction of those skilled in the art. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the technical solution of the present invention aims to provide a silicon-based OLED device with improved low voltage and high service life. By optimizing the combination of the interlayer structure and materials of the hole transport layers in the multi-light-emitting unit silicon-based OLED structure, the present invention reduces the interlayer barrier for hole carrier transport, improves the stability of carrier transport, enables the light-emitting layer to emit light more stably, reduces the operating voltage of the device, and improves the service life of high-brightness devices.

[0007] The technical solution of the present invention is as follows:

[0008] A silicon-based OLED device structure with a combination of hole transport layers, comprising a silicon-based CMOS driving substrate, a reflective anode array, an organic functional layer, a semi-transparent cathode layer, and a thin film encapsulation layer arranged in sequence from bottom to top. The organic functional layer includes: a first organic functional layer and a second organic functional layer located on the first organic functional layer; the first organic functional layer includes a first composite hole transport structure, a first light-emitting layer, a first electron transport layer, and a first electron injection layer, and the second organic functional layer includes a second composite hole transport structure, a second light-emitting layer, a second electron transport layer, and a second electron injection layer.

[0009] Preferably, the first composite hole transport structure of the present invention includes a first hole injection layer, a first hole transport layer, and a first electron blocking layer. The first hole injection layer is composed of a first hole transport host material and a P-type doping material; the first hole transport layer is composed of a first hole transport host material and a first hole transport sub-host material, and the first electron blocking layer is composed of a first hole transport sub-host material and a first electron blocking material. The HOMO energy level of the first hole transport host material is different from that of the first hole transport sub-host material, and the HOMO energy level of the first hole transport sub-host material is greater than that of the first electron blocking material.

[0010] Preferably, the second composite hole transport structure of the present invention includes a second hole injection layer, a second hole transport layer, and a second electron blocking layer. The second hole injection layer is composed of a second hole transport host material and a P-type doping material; the second hole transport layer structure is composed of the aforementioned second hole transport host material and a second hole transport sub-host material, and the second electron blocking layer is composed of the aforementioned second hole transport sub-host material and a second electron blocking material. Moreover, the HOMO energy level of the second hole transport host material that constitutes the second hole transport layer is different from the HOMO energy level of the second hole transport sub-host material, and the HOMO energy level of the second hole transport sub-host material is greater than the HOMO energy level of the second electron blocking material.

[0011] Preferably, in the first hole transport layer of the present invention, the ratio of the first hole transport host material to the first hole transport sub-host material is 8:2 to 2:8; the thickness of the first hole transport layer is 10 - 40 nm; in the second hole transport layer, the ratio of the second hole transport host material to the second hole transport sub-host material is 8:2 to 2:8; the thickness of the second hole transport layer structure is 10 - 20 nm.

[0012] Preferably, in the first hole injection layer of the present invention, the proportion of the p-type doping material in the first hole transport material is 1% to 3%; the thickness of the first hole injection layer is 1 - 10 nm; in the second hole injection layer structure, the proportion of the p-type doping material in the second hole transport material is 1% to 3%; the thickness of the first hole injection layer structure is 10 - 20 nm.

[0013] Preferably, the first light-emitting layer of the present invention is one or a combination of red, green, blue, or yellow organic light-emitting materials, and different organic light-emitting material layers are longitudinally stacked and combined; the second light-emitting layer is one or a combination of red, green, blue, or yellow organic light-emitting materials, and different organic light-emitting material layers are longitudinally stacked and combined; to form a light-emitting color structure based on one of red, green, blue, yellow, cyan, purple, and white.

[0014] The beneficial technical effects of the present invention are as follows:

[0015] In the present invention, in a multi-light-emitting unit silicon-based OLED device, between the first hole injection layer, the first hole transport layer, and the first electron blocking layer, and between the second hole injection layer, the second hole transport layer, and the second electron blocking layer, different transport layer structures with low hole transport barriers are respectively formed. By designing the energy level matching of the first hole transport host material and the second hole transport sub-host material, a stepped hole transport channel is formed to reduce the accumulation effect of the injected holes in the hole injection layer at the interface of the first hole transport layer. At the same time, by designing the material energy level matching of the first hole transport layer and the first electron blocking layer, a second stepped hole transport channel is further formed to reduce the hole transport barrier at the interface of the electron blocking layer. Similarly, for the second light-emitting unit, through the design of the stepped hole transport channel, the hole transport barriers at the interfaces of the second hole transport layer and the second electron blocking layer are respectively reduced. Thereby, the hole utilization rate of the device is improved, the driving voltage is reduced, and the device stability is enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the accompanying drawings:

[0017] Figure 1 is a schematic structural diagram of a silicon-based OLED device provided in a preferred embodiment of the present invention;

[0018] Figure 2 is a schematic structural diagram of a hole transport layer of a silicon-based OLED display device provided in a preferred embodiment of the present invention;

[0019] Figure 3 is a schematic diagram of a hole transport energy transfer mechanism provided in a preferred embodiment of the present invention.

[0020] Figure 4 is the result of the lifetime test of a silicon-based OLED device and a traditional device fabricated according to a preferred embodiment of the present invention.

[0021] Explanation of the accompanying symbols: 100, silicon-based driving backplane, 200, reflective anode layer, 300, first composite hole transport structure, 301, first hole injection layer, 301a, first P-type doping material, 301b, first hole transport main material, 302, first hole transport layer, 302a, first hole transport main material, 302b, first hole transport sub-main material, 303, first hole transport sub-functional layer, 303a, first hole transport sub-main material, 303b, first electron blocking material, 400, first light-emitting layer, 500 , first electron transport layer, 600, second composite hole transport structure, 601, first hole injection layer, 601a, second P-type doping material, 601b, second hole transport main material, 602, second hole transport layer, 602a, second hole transport main material, 602b, second hole transport sub-main material, 603, second hole transport sub-functional layer, 603a, second hole transport sub-main material, 603b, second electron blocking material, 700, second light-emitting layer, 800, second electron transport layer, 900, semi-transparent cathode layer. DETAILED DESCRIPTION

[0022] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0023] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper" and "lower" is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0024] See Figure 1 The present invention provides a silicon-based OLED device structure with a low-voltage, long-life hole transport layer. The structure includes a silicon-based driver backplane 100, on which an OLED driver circuit is fabricated. The driver circuit is connected to a reflective anode layer 200 via a tungsten via in a standard CMOS process. A first composite hole transport structure 300 is located above the reflective anode layer 200. A first light-emitting layer 400 and a first electron transport layer 500 are sequentially located above the first composite hole transport structure 300. A second composite hole transport structure 600 is located above the first electron transport layer 500. A second light-emitting layer 700 and a second electron transport layer 800 are sequentially located above the second hole transport layer 600. A semi-transparent cathode layer 900 is located above the electron transport layer 800. Together, these structures constitute the silicon-based OLED light-emitting device structure from bottom to top.

[0025] refer to Figure 2, the first composite hole transport structure 300 of the present invention sequentially includes a first hole injection layer 301, a first hole transport layer 302, and a first electron blocking layer 303 from bottom to top. The second composite hole transport structure 600 is sequentially composed of a second hole injection layer 601, a second hole transport layer 602, and a second electron blocking layer 603 from bottom to top.

[0026] As Figure 3 shown, the first hole injection layer 301 and the second hole injection layer 601 of the present invention are respectively doped with a first hole transport host material 301b and a P-type doping material 301a, and a second hole transport host material 601b and a P-type doping material 601a. The first hole transport layer 302 is doped with a first hole transport host material 302a and a first hole transport sub-host material 302b. The second hole transport layer 602 is doped with a second hole transport host material 602a and a second hole transport sub-host material 602b. The first electron blocking layer 303 is doped with a first hole transport sub-host material 303a and a first electron blocking material 303b. The second electron blocking layer 603 is doped with a second hole transport sub-host material 603a and a second electron blocking material 603b.

[0027] The first hole transport host material 301b and the second hole transport host material 601b of the present invention can be the same or different types of hole transport materials. The first hole transport sub-host material 302b and the second hole transport sub-host material 602b can be the same or different types of hole transport materials. The first electron blocking layer material 303b and the second electron blocking layer material 603b can be the same or different types of electron blocking materials.

[0028] Further, referring to the example Figure 3 , the HOMO energy level of the first hole transport host material 301b is higher than that of the first hole transport sub-host material 302b. Similarly for the second layer, forming a double hole transport channel from the hole injection layer to the hole transport layer. The first hole transport host material 301b and the first hole transport host material 302a are the same material. The first hole transport sub-host material 302b and the first hole transport sub-host material 303a are the same material. Similarly for the second layer.

[0029] The HOMO energy level of the first hole transport sub-host material 302b of the present invention is lower than that of the first electron blocking layer 303b. Similarly for the second layer, forming the hole transport characteristic of a low-barrier double transport channel from the hole transport layer to the resistance blocking layer.

[0030] In the first hole transport layer 302 of the present invention, the ratio of the first hole transport host material 301b to the first hole transport sub-host material 302b is 8:2 to 2:8, calculated based on the rate. The thickness of the first hole transport layer 302 is 10 - 40 nm. In the second hole transport layer 602, the ratio of the second hole transport host material 601b to the second hole transport sub-host material 602b is 8:2 to 2:8, calculated based on the rate. The thickness of the second hole transport layer 602 is 10 - 20 nm.

[0031] In the first hole injection layer 301 of the present invention, the proportion of the p-type doping material 301a in the first hole transport material 301b is 1% to 3%, calculated based on the rate. The thickness of the first hole injection layer 301 is 1 - 10 nm. In the second hole injection layer 601, the proportion of the p-type doping material 601a in the second hole transport material 601b is 1% to 3%, calculated based on the rate. The thickness of the first hole injection layer 601 is 10 - 20 nm.

[0032] Figure 4 A comparison chart of the lifetime test results of the silicon-based OLED device (New structure) and the traditional device (Ref) of the present invention is shown. It can be intuitively seen that the silicon-based OLED device of the present invention improves the hole energy density of the composite layer, enhances the light emission efficiency, and thus improves the device lifetime.

[0033] In summary, the low-voltage and high-lifetime silicon-based OLED hole transport layer device structure provided by the present invention can achieve two hole transport channels through material design in a multi-light-emitting layer OLED device system, thereby respectively improving the hole injection and transport efficiency of the two light-emitting units and reducing the barrier effect caused by different HOMO energy levels of the materials. By reducing the hole transport barrier, the thermal effect is reduced, thereby achieving the high-lifetime performance of the OLED device.

Claims

1. A silicon-based OLED device structure with a hole transport layer, characterized in that: It includes a silicon-based CMOS driving substrate, a reflective anode array, an organic functional layer, a semi-transparent cathode layer, and a thin film encapsulation layer arranged in sequence from bottom to top. The organic functional layer includes: a first organic functional layer and a second organic functional layer located on the first organic functional layer; the first organic functional layer includes a first composite hole transport structure, a first light-emitting layer, a first electron transport layer, and a first electron injection layer, and the second organic functional layer includes a second composite hole transport structure, a second light-emitting layer, a second electron transport layer, and a second electron injection layer; The second composite hole transport structure of the second organic functional layer includes a second hole injection layer, a second hole transport layer, and a second electron blocking layer. The second hole injection layer is composed of a second hole transport host material and a P-type doping material; the second hole transport layer structure is composed of the aforementioned second hole transport host material and a second hole transport sub-host material, and the second electron blocking layer is composed of the aforementioned second hole transport sub-host material and a second electron blocking material. The HOMO energy level of the second hole transport host material that constitutes the second hole transport layer is different from the HOMO energy level of the second hole transport sub-host material, and the HOMO energy level of the second hole transport sub-host material is greater than the HOMO energy level of the second electron blocking material.

2. The structure of the silicon-based OLED device with a hole transport layer according to claim 1, characterized in that: The first composite hole transport structure of the first organic functional layer includes a first hole injection layer, a first hole transport layer, and a first electron blocking layer. The first hole injection layer is composed of a first hole transport host material and a P-type doping material; the first hole transport layer is composed of a first hole transport host material and a first hole transport sub-host material, and the first electron blocking layer is composed of a first hole transport sub-host material and a first electron blocking material. The HOMO energy level of the first hole transport host material that constitutes the first hole transport layer is different from the HOMO energy level of the first hole transport sub-host material, and the HOMO energy level of the first hole transport sub-host material is greater than the HOMO energy level of the first electron blocking material.

3. The silicon-based OLED device structure with a hole transport layer according to claim 2, characterized in that: The ratio of the first hole transport host material to the first hole transport sub-host material in the first hole transport layer is 8:2 to 2:8; the thickness of the first hole transport layer is 10 - 40 nm; the ratio of the second hole transport host material to the second hole transport sub-host material in the second hole transport layer is 8:2 to 2:8; the thickness of the second hole transport layer structure is 10 - 20 nm.

4. The silicon-based OLED device structure with a hole transport layer according to claim 2, characterized in that: In the first hole injection layer, the proportion of the p-type doping material in the first hole transport material is 1% to 3%; the thickness of the first hole injection layer is 1 - 10 nm; in the second hole injection layer structure, the proportion of the p-type doping material in the second hole transport material is 1% to 3%; the thickness of the first hole injection layer structure is 10 - 20 nm.

5. The silicon-based OLED device structure with a hole transport layer according to claim 1, characterized in that: The first light-emitting layer is one or a combination of red, green, blue, or yellow organic light-emitting materials, and different organic light-emitting material layers are longitudinally stacked and combined; the second light-emitting layer is one or a combination of red, green, blue, or yellow organic light-emitting materials, and different organic light-emitting material layers are longitudinally stacked and combined; to form a light-emitting color structure based on one of red, green, blue, yellow, cyan, purple, and white.

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