Charge generation layer and stacked organic light emitting device

Abstract

The embodiment of the present application provides a charge generation layer and a laminated organic light-emitting device, the charge generation layer comprises a first charge layer and a second charge layer arranged in layers, one of the first charge layer and the second charge layer is doped with a P-type dopant, and the other is doped with an N-type dopant, wherein, in the direction from the first charge layer to the second charge layer, the dopant concentration of at least part of the first charge layer has an increasing trend, and the dopant concentration of at least part of the second charge layer has a decreasing trend. The present application can improve the problem of the stability reduction of the first light-emitting device layer and the second light-emitting device layer caused by the instability of the charge generation layer.

Description

Technical Field

[0001] This application relates to the field of display device technology, and more particularly to a charge generation layer and a stacked organic light-emitting device. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are self-emissive display devices. Compared to traditional liquid crystal displays (LCDs), OLED technology does not require a backlight and is self-emissive. OLEDs use a thin layer of organic material and a glass substrate; when current flows through, the organic material emits light. Therefore, OLED display panels can significantly save energy, be made lighter and thinner, withstand a wider range of temperature variations than LCD panels, and have a wider viewing angle. OLED display panels are expected to become the next-generation flat panel display technology after LCDs and are currently one of the most watched technologies in the flat panel display field.

[0003] In the prior art, in order to improve the lifespan of OLED display panels, multiple OLED devices are stacked and connected in series through a charge generation layer. Different types of metals need to be doped into the charge generation layer. As the usage time increases, metal diffusion will lead to a decrease in the stability of OLED devices. Summary of the Invention

[0004] This application provides a charge generation layer and a stacked organic light-emitting device, aiming to solve the problem of reduced device stability in multilayer light-emitting devices.

[0005] An embodiment of the first aspect of this application provides a charge generation layer, which includes a first charge layer and a second charge layer disposed along a stack. One of the first charge layer and the second charge layer is doped with a P-type dopant, and the other is doped with an N-type dopant. In the direction from the first charge layer to the second charge layer, the dopant concentration of at least a portion of the first charge layer has an increasing trend, and the dopant concentration of at least a portion of the second charge layer has a decreasing trend.

[0006] According to an embodiment of the first aspect of this application, there is a contact interface between the first charge layer and the second charge layer, and the dopant concentration of at least a portion of the first charge layer tends to increase along the direction close to the contact interface, and the dopant concentration of at least a portion of the second charge layer tends to increase along the direction close to the contact interface.

[0007] According to any of the foregoing embodiments of the first aspect of this application, the first charge layer has a first interface on the side opposite to the second charge layer, and the dopant concentration of the first charge layer has an increasing trend along the direction from the first interface to the contact interface.

[0008] According to any of the foregoing embodiments of the first aspect of this application, the second charge layer has a second interface on a side opposite to the first charge layer, and the dopant concentration of the second charge layer tends to increase along the direction from the second interface to the contact interface.

[0009] According to any of the foregoing embodiments of the first aspect of this application, the first charge layer has a first interface on the side opposite to the second charge layer and a first intermediate interface located between the first interface and the contact interface. The dopant concentration of the first charge layer has an increasing trend along the direction from the first intermediate interface to the contact interface.

[0010] According to any of the foregoing embodiments of the first aspect of this application, the second charge layer has a second interface on a side away from the first charge layer and a second intermediate interface located between the second interface and the contact interface. The dopant concentration of the second charge layer tends to increase along the direction from the second intermediate interface to the contact interface.

[0011] According to any of the foregoing embodiments of the first aspect of this application, a contact interface is provided between the first charge layer and the second charge layer. The dopant concentration of a portion of the first charge layer tends to increase along the direction near the contact interface, while the dopant concentration of another portion of the first charge layer tends to decrease along the direction near the contact interface. The dopant concentration of a portion of the second charge layer tends to decrease along the direction near the contact interface, while the dopant concentration of another portion of the first charge layer tends to increase along the direction near the contact interface.

[0012] According to any of the foregoing embodiments of the first aspect of this application, the first charge layer has a first interface on the side opposite to the second charge layer and a first intermediate interface located between the first interface and the contact interface, and the dopant concentration of the first charge layer has a decreasing trend along the direction from the first intermediate interface to the contact interface or the first interface.

[0013] According to any of the foregoing embodiments of the first aspect of this application, the second charge layer has a second interface on the side opposite to the first charge layer and a second intermediate interface located between the second interface and the contact interface. The dopant concentration of the second charge layer has a decreasing trend along the direction from the second intermediate interface to the contact interface and the direction from the second intermediate interface to the first interface.

[0014] According to any of the foregoing embodiments of the first aspect of this application, along the direction close to the contact interface between the first charge layer and the second charge layer, at least a portion of the dopant concentration of one of the first charge layer and the second charge layer tends to increase, while at least a portion of the dopant concentration of the other tends to decrease.

[0015] According to any of the foregoing embodiments of the first aspect of this application, the dopant concentration of at least a portion of the first charge layer tends to increase along the direction close to the contact interface; the second charge layer has a second interface away from the first charge layer and a second intermediate interface located between the contact interface and the second interface, and the dopant concentration of the second charge layer tends to decrease along the direction from the second intermediate interface to the contact interface or the second interface.

[0016] According to any of the foregoing embodiments of the first aspect of this application, the first charge layer has a first interface on the side opposite to the second charge layer and a first intermediate interface located between the first interface and the contact interface. Along the direction from the first intermediate interface to the contact interface or the first interface, the dopant concentration of the first charge layer tends to decrease, and along the direction close to the contact interface, the dopant concentration of at least a portion of the second charge layer tends to increase.

[0017] According to any of the foregoing embodiments of the first aspect of this application, the first charge layer is doped with a P-type dopant, the second charge layer is doped with an N-type dopant, a contact interface is provided between the first charge layer and the second charge layer, the first charge layer has a first interface on the side opposite to the second charge layer, the first interface is used to dock with the hole transport layer, and the dopant concentration of at least a portion of the first charge layer has an increasing trend along the direction close to the first interface.

[0018] According to any of the foregoing embodiments of the first aspect of this application, the first charge layer has a first intermediate interface located between the first interface and the contact interface, and the dopant concentration of the first charge layer has an increasing trend along the direction from the first intermediate interface to the contact interface, and the dopant concentration of the first charge layer has an increasing trend along the direction from the first intermediate interface toward the first interface.

[0019] According to any of the foregoing embodiments of the first aspect of this application, the second charge layer has a second interface on a side opposite to the first charge layer, and the dopant concentration of the second charge layer tends to increase along the direction from the second interface to the contact interface.

[0020] According to any of the foregoing embodiments of the first aspect of this application, the dopant concentration of the P-type dopant in the first charge layer is 0 to 20%.

[0021] According to any of the foregoing embodiments of the first aspect of this application, the dopant concentration of the P-type dopant in the first charge layer is 2 to 20%.

[0022] According to any of the foregoing embodiments of the first aspect of this application, the dopant concentration of the N-type dopant in the second charge layer is 0 to 10%.

[0023] According to any of the foregoing embodiments of the first aspect of this application, the dopant concentration of the N-type dopant in the second charge layer is 1 to 10%.

[0024] An embodiment of the second aspect of this application also provides a stacked organic light-emitting device, including a first light-emitting device layer, a second light-emitting device layer and a charge-generating layer of any one of the above, wherein the first light-emitting device layer and the second light-emitting device layer are connected in series through the charge-generating layer.

[0025] In the charge generation layer provided in this application embodiment, the charge generation layer includes a first charge layer and a second charge layer. One of the first charge layer and the second charge layer is doped with a P-type dopant, and the other is doped with an N-type dopant, enabling the charge generation layer to generate corresponding charge carriers. Along the direction from the first charge layer to the second charge layer, the dopant concentration of at least a portion of the first charge layer shows an increasing trend, while the dopant concentration of at least a portion of the second charge layer shows a decreasing trend. That is, the dopant concentration change trends of at least a portion of the first charge layer and the second charge layer are different. While ensuring sufficient electron supply, the ability of the interface to be bombarded by electrons is improved, thereby improving the problem of reduced device stability of the first light-emitting device layer and the second light-emitting device layer due to the instability of the charge generation layer, and extending the lifespan of the stacked organic light-emitting device. Attached Figure Description

[0026] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings, wherein the same or similar reference numerals denote the same or similar features.

[0027] Figure 1 This is a schematic diagram of the structure of a stacked organic light-emitting device provided in an embodiment of the present invention;

[0028] Figure 2 This is an energy diagram of the layer structure of a stacked organic light-emitting device provided in an embodiment of the present invention;

[0029] Figures 3 to 10 This is a graph showing the variation trend of dopant concentration in the first and second charge layers of a charge generation layer in some different embodiments, as provided by the present invention.

[0030] Figure 11 This is a schematic diagram of a stacked organic light-emitting device structure provided in another embodiment of the present invention;

[0031] Figures 12 to 19 This is a trend diagram showing the variation of dopant concentrations in the first and second charge layers of a charge generation layer in some other different embodiments, as provided by the present invention.

[0032] Figure 20 This is a schematic diagram of a fabrication method for a stacked organic light-emitting device provided in an embodiment of the present invention.

[0033] Explanation of reference numerals in the attached figures:

[0034] 10. Stacked organic light-emitting device; 11. First light-emitting device layer; 111. First electron transport layer; 112. First light-emitting material layer; 113. First hole transport layer; 12. Second light-emitting device layer; 121. Second electron transport layer; 122. Second light-emitting material layer; 123. Second hole transport layer; 13. Charge generation layer; 131. First charge layer; 131a. First interface; 131b. First intermediate interface; 132. Second charge layer; 132a. Second interface; 132b. Second intermediate interface; 133. Contact interface; 14. First electrode; 15. Second electrode. Detailed Implementation

[0035] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description in order to provide a thorough understanding of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the present application. In the accompanying drawings and the following description, at least some well-known structures and techniques have not been shown in order to avoid unnecessarily obscuring the invention; and, for clarity, the dimensions of some structures may be exaggerated. Furthermore, the features, structures, or characteristics described below can be combined in any suitable manner in one or more embodiments.

[0036] In the description of this invention, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of the embodiments of the present invention. It should also be noted in the description of the present invention that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0038] To better understand this invention, the following is combined with... Figures 1 to 20The charge generation layer and the stacked organic light-emitting device of the present invention will be described in detail.

[0039] Please see Figure 1 , Figure 2 and Figure 11 , Figure 1 This is a schematic diagram of a stacked organic light-emitting device provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the layer structure of a stacked organic light-emitting device provided in an embodiment of the present invention. Figure 11 This is a schematic diagram of a stacked organic light-emitting device structure provided in another embodiment of the present invention.

[0040] like Figure 1 , Figure 2 and Figure 11 As shown, the stacked organic light-emitting device 10 provided by the present invention includes a first light-emitting device layer 11, a second light-emitting device layer 12 and a charge-generating layer 13 located between the first light-emitting device layer 11 and the second light-emitting device layer 12, which are stacked along the thickness direction.

[0041] In the embodiments provided by the present invention, the stacked organic light-emitting device 10 includes a first light-emitting device layer 11 and a second light-emitting device layer 12 stacked together. Both the first light-emitting device layer 11 and the second light-emitting device layer 12 can emit light to realize the display of the stacked organic light-emitting device 10. By setting the first light-emitting device layer 11 and the second light-emitting device layer 12 stacked together, the lifespan and luminous efficiency of the stacked organic light-emitting device 10 can be improved. A charge-generating layer 13 is disposed between the first light-emitting device layer 11 and the second light-emitting device layer 12, and the charge-generating layer 13 is used to connect the first light-emitting device layer 11 and the second light-emitting device layer 12.

[0042] The charge generation layer 13 can be referred to as an "intermediate connecting layer" because it controls the balance of holes and electrons between the first light-emitting device layer 11 and the second light-emitting device layer 12. The charge generation layer 13 includes a P-type charge generation layer doped with P-type dopant and an N-type charge generation layer doped with N-type dopant. The P-type charge generation layer helps inject holes into one of the first light-emitting device layer 11 and the second light-emitting device layer 12, while the N-type charge generation layer helps inject electrons into the other of the first light-emitting device layer 11 and the second light-emitting device layer 12.

[0043] There are various ways to set the charge generation layer 13. This embodiment of the invention also provides a charge generation layer, such as... Figure 1 and Figure 11 As shown, the charge generation layer 13 includes a first charge layer 131 and a second charge layer 132 stacked along the thickness direction.

[0044] like Figure 1As shown, the first charge layer 131 is doped with an N-type dopant, and the second charge layer 132 is doped with a P-type dopant. Along the direction from the first charge layer 131 to the second charge layer 132, the dopant concentration of at least a portion of the first charge layer 131 shows an increasing trend, while the dopant concentration of at least a portion of the second charge layer 132 shows a decreasing trend. Figure 11 As shown, the first charge layer 131 is doped with a P-type dopant, and the second charge layer 132 is doped with an N-type dopant. That is, the charge generation layer 13 includes a first charge layer 131 and a second charge layer 132 stacked together. One of the first charge layer 131 and the second charge layer 132 is doped with a P-type dopant, and the other is doped with an N-type dopant. Along the direction from the first charge layer 131 to the second charge layer 132, the dopant concentration of at least a portion of the first charge layer 131 shows an increasing trend, and the dopant concentration of at least a portion of the second charge layer 132 shows a decreasing trend.

[0045] In the charge generation layer 13 provided in this embodiment of the invention, the charge generation layer 13 includes a first charge layer 131 and a second charge layer 132. One of the first charge layer 131 and the second charge layer 132 is doped with a P-type dopant, and the other is doped with an N-type dopant, so that the charge generation layer 13 can generate corresponding charge carriers. Along the direction from the first charge layer 131 to the second charge layer 132, the dopant concentration of at least a portion of the first charge layer 131 has an increasing trend, and the dopant concentration of at least a portion of the second charge layer 132 has a decreasing trend. That is, the dopant concentration change trends of at least a portion of the first charge layer 131 and the second charge layer 132 are different, which can improve the problem of reduced device stability of the first light-emitting device layer 11 and the second light-emitting device layer 12 due to the instability of the charge generation layer 13.

[0046] The first light-emitting device layer 11 and the second light-emitting device layer 12 can be OLED light-emitting device layers. Optionally, the first light-emitting device layer 11 may include a first electron transport layer 111, a first light-emitting material layer 112 and a first hole transport layer 113, and the second light-emitting device layer 12 may include a second electron transport layer 121, a second light-emitting material layer 122 and a second hole transport layer 213.

[0047] Optionally, the stacked organic light-emitting device 10 further includes a first electrode 14 and a second electrode 15. The first electrode 14 and the second electrode 15 are respectively disposed on both sides of the first light-emitting device layer 11 and the second light-emitting device layer 12. One of the first electrode 14 and the second electrode 15 is an anode and the other is a cathode. The first electrode 14, the second electrode 15 and the charge generation layer 13 together drive the first light-emitting device layer 11 and the second light-emitting device layer 12 to emit light.

[0048] Optionally, both the first light-emitting material layer 112 and the second light-emitting material layer 122 may include red light-emitting units, green light-emitting units and blue light-emitting units to achieve color display of the stacked organic light-emitting device 10.

[0049] according to Figure 1 The structure of the stacked organic light-emitting device 10 shown is as follows: Figures 3 to 10 The embodiments described herein use an example where the first charge layer 131 is doped with an N-type dopant and the second charge layer 132 is doped with a P-type dopant to illustrate the variation trend of the dopant concentrations of the first charge layer 131 and the second charge layer 132 in the charge generation layer 13 in some different embodiments. In the above embodiments, the first charge layer 131 is adjacent to the first electron transport layer 111, and the second charge layer 132 is adjacent to the second hole transport layer 123.

[0050] Optionally, the increasing dopant concentration of at least a portion of the first charge layer 131 along the direction from the first charge generation layer 131 to the second charge generation layer 132 includes: all the first charge layers 131 exhibiting an increasing dopant concentration along the direction from the first charge generation layer 131 to the second charge generation layer 132; or, a portion of the first charge layers 131 exhibiting an increasing dopant concentration, while another portion of the first charge layers 131 exhibits a decreasing or unchanged dopant concentration. When the dopant of the first charge layer 131 is an N-type dopant, the N-type dopant concentration of the first charge layer 131 exhibits an increasing trend along the direction from the first light-emitting device layer 11 to the second light-emitting device layer 12; or, a portion of the first charge layers 131 exhibits an increasing N-type dopant concentration, while another portion of the first charge layers 131 exhibits a decreasing N-type dopant concentration.

[0051] Optionally, when the dopant of the first charge layer 131 is an N-type dopant, the dopant concentration of the N-type dopant can vary between 0% and 10%. For example, the dopant concentration of the N-type dopant can vary between 1% and 10%. In this invention, the dopant concentration refers to the proportion of the dopant volume to the total volume.

[0052] Optionally, the decreasing dopant concentration of at least a portion of the second charge layer 132 along the direction from the first charge layer 131 to the second charge layer 132 includes: all the second charge layers 132 exhibiting a decreasing dopant concentration along the direction from the first charge layer 131 to the second charge layer 132; or, a portion of the second charge layers 132 exhibiting a decreasing dopant concentration while the dopant concentration of another portion of the second charge layers 132 increases or remains unchanged. When the dopant of the second charge layer 132 is a P-type dopant, the decreasing dopant concentration of all the second charge layers 132 along the direction from the first light-emitting device layer 11 to the second light-emitting device layer 12; or, a portion of the second charge layers 132 exhibiting a decreasing dopant concentration while the P-type dopant concentration of another portion of the second charge layers 132 exhibits an increasing dopant concentration.

[0053] Optionally, when the dopant of the second charge layer 132 is a P-type dopant, the volume ratio of the P-type dopant concentration can vary between 0% and 20%. For example, when the dopant of the second charge layer 132 is a P-type dopant, the volume ratio of the P-type dopant concentration can vary between 2% and 20%.

[0054] Optionally, the thickness of the first charge layer 131 ranges from 5 nm to 30 nm. The thickness of the second charge layer 132 also ranges from 5 nm to 30 nm.

[0055] Optionally, p-type dopants are a class of deep LUMO materials with strong electron-withdrawing properties, while n-type dopants can be alkali metals, alkaline earth metals, lanthanides, transition metals, and their compounds.

[0056] In some optional embodiments, along the contact interface 133 near the first charge layer 131 and the second charge layer 132, the dopant concentration of at least a portion of the first charge layer 131 and the second charge layer 132 exhibits an increasing trend. That is, the dopant concentration of at least a portion of the first charge layer 131 exhibits an increasing trend along the direction near the contact interface 133, and the dopant concentration of at least a portion of the second charge layer 132 exhibits an increasing trend along the direction near the contact interface 133.

[0057] like Figure 1 , 3 to Figure 10 As shown, with the direction from the first light-emitting device layer 11 to the second light-emitting device layer 12 as a reference, the dopant of the first charge layer 131 is an N-type dopant, the dopant of the second charge layer 132 is a P-type dopant, the surface of the first light-emitting device layer 11 near the first charge layer 131 is the first reference surface, and the surface of the second light-emitting device layer 12 near the second charge layer 132 is the second reference surface. Figures 3 to 10The x-coordinate is the distance H between the first interface 131a and the first reference surface. The distance from the first interface 131a to the first reference surface is defined as 0, the distance from the contact interface to the first reference surface is H1, the distance from the second interface 132a to the first reference surface is H2, the distance from the first intermediate interface 131b to the first reference surface is H3, and the distance from the second intermediate interface 132b to the first reference surface is H4. Figures 3 to 10 The vertical axis represents the dopant concentration P in the first charge layer 131 and the second charge layer 132. The dopant concentration in the first charge layer 131 varies between 0 and P1, and the dopant concentration in the second charge layer varies between 0 and P2. The value of P1 ranges from 0 to 10%, and the value of P2 ranges from 0 to 20%, and neither P1 nor P2 takes the value 0.

[0058] In this embodiment of the invention, the thickness of both the first charge layer 131 and the second charge layer 132 is 15 nm, i.e., H1 is 15 nm, H2 is 30 nm, H3 is 7.5 nm, and H4 is 22.5 nm. The dopant concentration of the first charge layer 131 gradually varies between 0% and 10%. The dopant concentration of the second charge layer 132 varies between 0% and 20%, i.e., P1 is 10% and H2 is 20%.

[0059] Depend on Figures 3 to 6 It can be seen that the dopant concentration of at least part of the first charge layer 131 and the second charge layer 132 both show an increasing trend in the direction near the contact interface 133.

[0060] In these optional embodiments, the dopant concentrations of at least a portion of the first charge layer 131 and the second charge layer 132 exhibit an increasing trend near the contact interface 133. That is, the dopant concentrations of the first charge layer 131 and the second charge layer 132 are relatively high near the contact interface 133. This reduces the charge barrier between the first charge layer 131 and the second charge layer 132, allowing carrier transport between them to be achieved with a smaller voltage. In other words, a smaller voltage is needed to illuminate the first light-emitting device layer 11 and the second light-emitting device layer 12, thereby reducing the power consumption of the stacked organic light-emitting device 10. Optionally, in the above embodiments, the dopant concentration of the first charge layer 131 and the second charge layer 132 is highest at the contact interface 133, further reducing the power consumption of the stacked organic light-emitting device 10.

[0061] In some alternative embodiments, such as Figure 1 , Figure 3 and Figure 4As shown, the first charge layer 131 has a first interface 131a on the side opposite to the second charge layer 132. Along the direction from the first interface 131a to the contact interface 133, the dopant concentration of the first charge layer 131 shows an increasing trend. That is, the overall dopant concentration of the first charge layer 131 increases in the direction close to the contact interface 133, which simplifies the doping complexity of the first charge layer 131, facilitates the fabrication of the first charge layer 131, and improves the fabrication efficiency of the stacked organic light-emitting device 10.

[0062] In some alternative embodiments, such as Figure 1 , Figure 5 and Figure 6 As shown, the first charge layer 131 has a first interface 131a on the side opposite to the second charge layer 132, and a first intermediate interface 131b located between the first interface 131a and the contact interface 133. Along the direction from the first intermediate interface 131b to the contact interface 133, the dopant concentration of the first charge layer 131 has an increasing trend.

[0063] In these alternative embodiments, the dopant concentration of the first charge layer 131 is relatively high near the contact interface 133, which can reduce the charge barrier between the first charge layer 131 and the second charge layer 132 and reduce the power consumption of the stacked organic light-emitting device 10.

[0064] Optionally, the dopant concentration of the first charge layer 131 increases along the direction from the first intermediate interface 131b to the first interface 131a. That is, the dopant concentration of the first charge layer 131 is lower near the first interface 131a.

[0065] In some alternative embodiments, such as Figure 1 , Figure 3 and Figure 6 As shown, the second charge layer 132 has a second interface 132a on the side opposite to the first charge layer 131. Along the direction from the second interface 132a to the contact interface 133, the dopant concentration of the second charge layer 132 shows an increasing trend. That is, the overall dopant concentration of the second charge layer 132 decreases towards the contact interface 133, which simplifies the doping complexity of the second charge layer 132, facilitates its fabrication, and improves the fabrication efficiency of the stacked organic light-emitting device 10.

[0066] In some alternative embodiments, such as Figure 1 , Figure 4 and Figure 5As shown, the second charge layer 132 has a second interface 132a on the side opposite to the first charge layer 131, and a second intermediate interface 132b located between the second interface 132a and the contact interface 133. The dopant concentration of the second charge layer 132 has an increasing trend along the direction from the second intermediate interface 132b to the contact interface 133.

[0067] In these alternative embodiments, the dopant concentration of the second charge layer 132 is relatively high near the contact interface 133, which can reduce the charge barrier between the first charge layer 131 and the second charge layer 132 and reduce the power consumption of the stacked organic light-emitting device 10.

[0068] Optionally, the dopant concentration of the second charge layer 132 increases along the direction from the second intermediate interface 132b to the second interface 132a. That is, the dopant concentration of the second charge layer 132 is lower near the second interface 132a, which can reduce the charge barrier between the second charge layer 132 and the second light-emitting device layer 12 and reduce the power consumption of the stacked organic light-emitting device 10.

[0069] In some alternative embodiments, such as Figure 1 and Figure 7 As shown, along the contact interface 133 near the first charge layer 131 and the second charge layer 132, the dopant concentration in a portion of the first charge layer 131 tends to decrease, while the dopant concentration in another portion of the first charge layer 131 tends to increase. Similarly, the dopant concentration in the second charge layer 132 tends to decrease, while the dopant concentration in another portion of the second charge layer 132 tends to increase. In other words, the dopant concentration in a portion of the first charge layer 131 tends to increase along the direction near the contact interface 133, while the dopant concentration in another portion of the first charge layer 131 tends to decrease along the direction near the contact interface 133. Conversely, the dopant concentration in a portion of the second charge layer 132 tends to decrease along the direction near the contact interface 133, while the dopant concentration in another portion of the first charge layer 132 tends to increase along the direction near the contact interface 133.

[0070] In these optional embodiments, the dopant concentrations of at least a portion of the first charge layer 131 and the second charge layer 132 decrease along the contact interface 133. By reasonably setting the dopant concentrations of the first charge layer 131 and the second charge layer 132, it is possible to ensure that the potential barrier between the first charge layer 131 and the second charge layer 132 is low, as well as that between the first charge layer 131 and the first light-emitting device layer 11, and between the second charge layer 132 and the second light-emitting device layer, thereby reducing the power consumption of the stacked organic light-emitting device 10.

[0071] Optional, as described above, such as Figure 1 and Figure 7As shown, the first charge layer 131 has a first interface 131a and a first intermediate interface 131b. Along the direction from the first intermediate interface 131b to the contact interface 133 or the first interface 131a, the dopant concentration of the first charge layer 131 has a decreasing trend.

[0072] In these alternative embodiments, the dopant concentration of the first charge layer 131 is low near the first intermediate interface 131b, and the dopant concentration of the first charge layer 131 increases from the first intermediate interface 131b toward the contact interface 133 or the first interface 131a, which can improve the problem of reduced device stability of the first light-emitting device layer 11 and the second light-emitting device layer 12 caused by the instability of the charge generation layer 130.

[0073] Optionally, as described above, the second charge layer 132 has a second interface 132a and a second intermediate interface 132b, and the direction along the second intermediate interface 132b to the contact interface 133 or the second interface 132a is as follows: Figure 1 and Figure 7 As shown, the dopant concentration of the second charge layer 132 has a decreasing trend.

[0074] In these alternative embodiments, the dopant concentration of the second charge layer 132 is low near the second intermediate interface 132b, and the dopant concentration of the second charge layer 132 increases from the second intermediate interface 132b toward the contact interface 133 or the second interface 132a, which can improve the problem of reduced device stability of the first light-emitting device layer 11 and the second light-emitting device layer 12 caused by metal diffusion.

[0075] In some alternative embodiments, such as Figure 1 , Figures 8 to 10 As shown, along the direction near the contact interface 133 of the first charge layer 131 and the second charge layer 132, at least a portion of the dopant concentration in one of the first charge layer 131 and the second charge layer 132 tends to increase, while at least a portion of the dopant concentration in the other tends to decrease. That is, in the first charge layer 131 and the second charge layer 132, at least a portion of the dopant concentration in one tends to increase along the direction near the contact interface 133, while at least a portion of the dopant concentration in the other tends to decrease along the direction near the contact interface 133.

[0076] In these alternative embodiments, the dopant concentrations of the first charge layer 131 and the second charge layer 132 change differently along the direction close to the contact interface 133, such that one of the first charge layer 131 and the second charge layer 132 has a higher dopant concentration near the contact interface 133 and the other has a lower dopant concentration. This can improve the problem that the instability of the charge generation layer 130 leads to a decrease in the device stability of the first light-emitting device layer 11 and the second light-emitting device layer 12.

[0077] Optional, such as Figure 1 , Figure 8 and Figure 9 As shown, along the direction close to the contact interface 133, the dopant concentration of at least part of the first charge layer 131 tends to increase; the second charge layer 132 has a second interface 132a away from the first charge layer 131 and a second intermediate interface 132b located between the contact interface 133 and the second interface 132a, and along the direction from the second intermediate interface 132b to the contact interface 133 or the second interface 132a, the dopant concentration of the second charge layer 132 tends to decrease.

[0078] In these embodiments, along the direction close to the contact interface 133, the dopant concentration of the first charge layer 131 may generally increase, or a portion of the dopant concentration of the first charge layer 131 may increase. Along the direction from the second intermediate interface 132b to the contact interface 133 or the second interface 132a, the dopant concentration of the second charge layer 132 may decrease, i.e., the dopant concentration of the second charge layer 132 near the second intermediate interface 132b is higher, while the dopant concentration of the second charge layer 132 near the second interface 132a and the contact interface 133 is lower. This can mitigate the problem of reduced device stability of the first light-emitting device layer 11 and the second light-emitting device layer 12 due to metal diffusion.

[0079] In some other alternative embodiments, such as Figure 10 As shown, the first charge layer 131 has a first interface 131a on the side opposite to the second charge layer 132, and a first intermediate interface 131b located between the first interface 131a and the contact interface 133. Along the direction from the first intermediate interface 131b to the contact interface 133 or the first interface 131a, the dopant concentration of the first charge layer 131 tends to decrease. Along the direction close to the contact interface 133, the dopant concentration of at least a portion of the second charge layer 132 tends to increase.

[0080] In these embodiments, along the direction close to the contact interface 133, the dopant concentration of the second charge layer 132 may generally increase, or a portion of the dopant concentration of the second charge layer 132 may increase. Along the direction from the first intermediate interface 131b to the contact interface 133 or the first interface 131a, the dopant concentration of the second charge layer 132 generally decreases; that is, the dopant concentration of the second charge layer 132 is higher near the first intermediate interface 131b, and lower near the first interface 131a or the contact interface 133. This can mitigate the problem of reduced device stability of the first light-emitting device layer 11 and the second light-emitting device layer 12 due to metal diffusion.

[0081] like Figures 11 to 19 As shown, with the direction from the first light-emitting device layer 11 to the second light-emitting device layer 12 as a reference, the dopant of the first charge layer 131 is a P-type dopant, the dopant of the second charge layer 132 is an N-type dopant, the surface of the first light-emitting device layer 11 near the first charge layer 131 is the first reference surface, and the surface of the second light-emitting device layer 12 near the second charge layer 132 is the second reference surface. Figures 11 to 19 The horizontal coordinate is the distance H between the first interface 131a and the first reference surface. The distance from the first interface 131a to the first reference surface is defined as 0, the distance from the contact interface 133 to the first reference surface is H1, the distance from the second interface 132a to the first reference surface is H2, the distance from the first intermediate interface 131b to the first reference surface is H3, and the distance from the second intermediate interface 132b to the first reference surface is H4. Figures 11 to 19 The vertical axis represents the dopant concentration P in the first charge layer 131 and the second charge layer 132. The dopant concentration in the first charge layer 131 varies between 0 and P1, and the dopant concentration in the second charge layer varies between 0 and P2. The value of P1 ranges from 0 to 20%, and the value of P2 ranges from 0 to 10%, and neither P1 nor P2 takes the value 0.

[0082] like Figure 12 As shown, along the direction close to the contact interface 133 of the first charge layer 131 and the second charge layer 132, the dopant concentration of at least part of one of the first charge layer 131 and the second charge layer 132 has an increasing trend, and the dopant concentration of at least part of the other has a decreasing trend, further including: Figure 12 As shown, in the first charge layer 131, the dopant concentration increases from the first intermediate interface 131b toward the first interface 131a and / or the contact interface 133; in the second charge layer 132, the dopant concentration increases from the contact interface 133 toward the second interface 132a. Alternatively, as... Figure 13 As shown, in the first charge layer 131, the dopant concentration increases from the first intermediate interface 131b toward the first interface 131a and / or the contact interface 133; in the second charge layer 132, the dopant concentration decreases from the second intermediate interface 132b toward the contact interface 133 and / or the second interface 132a. Alternatively, as... Figure 14 As shown, in the first charge layer 131, the concentration of dopant increases from the first interface 131a to the contact interface 133; in the second charge layer 132, the concentration of dopant decreases from the second intermediate interface 132b to the second interface 132a and / or the contact interface 133.

[0083] like Figure 12As shown, when the dopant of the first charge layer 131 is a P-type dopant, the concentration of the P-type dopant in the first charge layer 131 tends to increase along the direction from the first light-emitting device layer 12 to the second light-emitting device layer 12. Alternatively, the concentration of the P-type dopant in a portion of the first charge layer 131 tends to increase, while the concentration of the P-type dopant in another portion of the first charge layer 131 decreases or remains unchanged.

[0084] like Figure 12 As shown, when the dopant of the first charge layer 131 is a P-type dopant, the volume ratio of the P-type dopant concentration can vary between 0% and 20%. For example, the volume ratio of the P-type dopant concentration can vary between 2% and 20%.

[0085] like Figure 12 As shown, when the dopant of the second charge layer 132 is an N-type dopant, the N-type dopant concentration of all parts of the second charge layer 132 tends to decrease along the direction from the first light-emitting device layer 12 to the second light-emitting device layer 12. Alternatively, the N-type dopant concentration of a portion of the second charge layer 132 tends to decrease, while the N-type dopant concentration of another portion of the second charge layer 132 either increases or remains unchanged.

[0086] like Figure 12 As shown, when the dopant of the second charge layer 132 is an N-type dopant, the volume ratio of the N-type dopant concentration can vary between 0% and 10%. For example, when the dopant of the second charge layer 132 is an N-type dopant, the volume ratio of the N-type dopant concentration can vary between 1% and 10%.

[0087] In other embodiments, such as Figure 11 and Figure 12 As shown, when the dopant of the first charge layer 131 is a P-type dopant and the dopant of the second charge layer 132 is an N-type dopant, along the contact interface 133 near the first charge layer 131 and the second charge layer 132, the dopant concentration of at least a portion of the first charge layer 131 tends to decrease, while the dopant concentration of at least another portion of the first charge layer 131 tends to increase. The dopant concentration of at least a portion of the second charge layer 132 tends to decrease, while the dopant concentration of at least another portion of the second charge layer 132 tends to increase. This further includes: Figure 15 As shown, in the first charge layer 131, the concentration of directional dopant decreases from the first interface 131a to the contact interface 133; in the second charge layer 132, the concentration of directional dopant decreases from the second intermediate interface 132b to the contact interface 133 and / or the second interface 132a; or, as Figure 16As shown, in the first charge layer 131, the concentration of directional dopant decreases from the first interface 131a to the contact interface 133; in the second charge layer 132, the concentration of directional dopant decreases from the contact interface 133 to the second interface 132a; or, as Figure 17 As shown, in the first charge layer 131, the concentration of directional dopant decreases from the first intermediate interface 131b to the contact interface 133 and / or the first interface 131a; in the second charge layer 132, the concentration of directional dopant decreases from the contact interface 133 to the second interface 132a.

[0088] In some other embodiments, such as Figure 11 and Figure 18 As shown, the first charge layer 131 is doped with a P-type dopant, and the second charge layer 132 is doped with an N-type dopant. The first light-emitting device layer 11 includes a first hole transport layer 113 located on its side facing the first charge layer 131. Along the direction close to the first hole transport layer 113, the dopant concentration of at least a portion of the first charge layer 131 shows an increasing trend. That is, there is a contact interface 133 between the first charge layer 131 and the second charge layer 132. The first charge layer 131 has a first interface 131a on the side facing away from the second charge layer 132. The first interface 131a is used to dock the hole transport layer (i.e., the first hole transport layer 113). Along the direction close to the first interface 131a, the dopant concentration of at least a portion of the first charge layer 131 shows an increasing trend.

[0089] In these optional embodiments, the first charge layer 131 is adjacent to the first hole transport layer 113 through the first interface 131a. Along the direction close to the first interface 131a, the dopant concentration of at least part of the first charge layer 131 has an increasing trend, that is, the P-type dopant concentration of the first charge layer 131 near the first hole transport layer 113 is higher, which can reduce the potential barrier between the first hole transport layer 113 and the first charge layer 131 and reduce the power consumption of the stacked organic light-emitting device 10.

[0090] As described above, the first charge layer 131 has a first interface 131a and a first intermediate interface 131b. When the first charge layer 131 is doped with a P-type dopant, optionally, as shown below, Figure 1 and Figure 19 As shown, the dopant concentration of the first charge layer 131 increases along the direction from the first intermediate interface 131b to the contact interface 133, and the dopant concentration of the first charge layer 131 also increases along the direction from the first intermediate interface 131b toward the first hole transport layer 113.

[0091] In these alternative embodiments, the first charge layer 131 doped with P-type dopant has a high dopant concentration near the first interface 131a and the contact interface 133, which can reduce the potential barrier between the first charge layer 131 and the first hole transport layer 113, as well as the potential barrier between the first charge layer 131 and the second charge layer 132, thereby better reducing the power consumption of the stacked organic light-emitting device 10.

[0092] As described above, the second charge layer 132 has a second interface 132a. When the second charge layer 132 is doped with an N-type dopant, the dopant concentration of the second charge layer 132 tends to increase along the direction from the second interface 132a to the contact interface 133. This simplifies the complexity of the second charge layer 132 and facilitates its fabrication. Furthermore, the higher dopant concentration near the contact interface 133 reduces the potential barrier between the first charge layer 131 and the second charge layer 132, thereby reducing the power consumption of the stacked organic light-emitting device 10.

[0093] In any of the above embodiments, optionally, the dopant concentration of the first charge layer 131 has an increasing trend along the direction from the first charge layer 131 to the second charge layer 132, and the dopant concentration at the first intermediate interface 131b is the average dopant concentration of the first charge layer 131. This makes it less likely that the concentration change of the first charge layer 131 will be abrupt.

[0094] In any of the above embodiments, optionally, when the dopant concentration of the second charge layer 132 has a decreasing trend along the direction from the first charge layer 131 to the second charge layer 132, the dopant concentration at the second intermediate interface 132b is the average dopant concentration of the second charge layer 132, so that the concentration change of the second charge layer 132 is not prone to sudden changes.

[0095] A second aspect of the present invention also provides a display device including the stacked organic light-emitting device 10 of any of the first aspect embodiments described above. Since the display device provided by the second aspect of the present invention includes the stacked organic light-emitting device 10 of any of the first aspect embodiments described above, the display device provided by the second aspect of the present invention has the beneficial effects of the stacked organic light-emitting device 10 of any of the first aspect embodiments described above, which will not be elaborated further here.

[0096] The display devices in the embodiments of the present invention include, but are not limited to, mobile phones, personal digital assistants (PDAs), tablet computers, e-books, televisions, access control systems, smart landline phones, control consoles, and other devices with display functions.

[0097] like Figure 20As shown, an embodiment of the third aspect of the present invention also provides a method for fabricating a stacked organic light-emitting device 10, wherein the stacked organic light-emitting device 10 can be any of the stacked organic light-emitting devices 10 described in the first aspect embodiment above, and the fabrication method includes:

[0098] Step S01: A first charge layer 131 is formed on the first light-emitting device layer 11. The first charge layer 131 is doped with a first dopant, and the dopant concentration of at least a portion of the first charge layer 131 has an increasing trend along the direction away from the first light-emitting device layer 11.

[0099] Step S02: A second charge layer 132 is disposed on the side of the first charge layer 131 away from the first light-emitting device layer 11. The second charge layer 132 is doped with a second dopant. One of the first dopant and the second dopant is a P-type dopant and the other is an N-type dopant. The first charge layer 131 and the second charge layer 132 are combined to form a charge generation layer 13. Along the direction away from the first light-emitting device layer 11, the dopant concentration of at least part of the second charge layer 132 has a decreasing trend.

[0100] Step S03: A second light-emitting device layer 12 is disposed on the side of the second charge layer 132 away from the first charge layer 131 to form a stacked organic light-emitting device 10.

[0101] In the multilayer organic light-emitting device 10 fabricated by the method provided in this embodiment of the invention, the multilayer organic light-emitting device 10 includes a first light-emitting device layer 11 and a second light-emitting device layer 12 stacked together. Both the first light-emitting device layer 11 and the second light-emitting device layer 12 can emit light to realize the display of the multilayer organic light-emitting device 10. By setting the first light-emitting device layer 11 and the second light-emitting device layer 12 stacked together, the lifespan and luminous efficiency of the multilayer organic light-emitting device 10 can be improved. A charge generation layer 13 is disposed between the first light-emitting device layer 11 and the second light-emitting device layer 12. The charge generation layer 13 is used to drive the first light-emitting device layer 11 and the second light-emitting device layer 12 to emit light. The charge generation layer 13 includes a first charge layer 131 and a second charge layer 132. One of the first charge layer 131 and the second charge layer 132 is doped with a P-type dopant, and the other is doped with an N-type dopant, so that the charge generation layer 13 can generate corresponding charge carriers. Along the direction from the first light-emitting device layer 11 to the second light-emitting device layer 12, the dopant concentration of at least a portion of the first charge layer 131 has an increasing trend, and the dopant concentration of at least a portion of the second charge layer 132 has a decreasing trend. That is, the dopant concentration change trends of at least a portion of the first charge layer 131 and the second charge layer 132 are different, which can improve the problem of reduced device stability of the first light-emitting device layer 11 and the second light-emitting device layer 12 caused by metal diffusion.

[0102] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A stacked organic light-emitting device, characterized in that, It includes a first light-emitting device layer, a second light-emitting device layer, and a charge-generating layer located between the first light-emitting device layer and the second light-emitting device layer; The first light-emitting device layer includes a first electron transport layer, a first light-emitting material layer, and a first hole transport layer; the second light-emitting device layer includes a second electron transport layer, a second light-emitting material layer, and a second hole transport layer. The charge generation layer is disposed between the second hole transport layer and the first electron transport layer; The charge generation layer includes a first charge layer and a second charge layer stacked together, wherein one of the first charge layer and the second charge layer is doped with a P-type dopant and the other is doped with an N-type dopant. Specifically, along the direction from the first charge layer to the second charge layer, at least a portion of the dopant concentration in the first charge layer shows an increasing trend, and at least a portion of the dopant concentration in the second charge layer shows a decreasing trend. There is a contact interface between the first charge layer and the second charge layer. In the first charge layer and the second charge layer, at least a portion of the dopant concentration of one has an increasing trend along the direction close to the contact interface, and at least a portion of the dopant concentration of the other has a decreasing trend along the direction close to the contact interface.

2. The stacked organic light-emitting device according to claim 1, characterized in that, The first charge layer has a first interface on the side opposite to the second charge layer and a first intermediate interface located between the first interface and the contact interface. The dopant concentration of the first charge layer has an increasing trend along the direction from the first intermediate interface to the contact interface. And / or, the second charge layer has a second interface on a side opposite to the first charge layer, and a second intermediate interface located between the second interface and the contact interface. The dopant concentration of the second charge layer tends to increase along the direction from the second intermediate interface to the contact interface.

3. The stacked organic light-emitting device according to claim 1, characterized in that, The dopant concentration of a portion of the first charge layer tends to increase along the direction close to the contact interface, the dopant concentration of another portion of the first charge layer tends to decrease along the direction close to the contact interface, the dopant concentration of a portion of the second charge layer tends to decrease along the direction close to the contact interface, and the dopant concentration of another portion of the second charge layer tends to increase along the direction close to the contact interface.

4. The stacked organic light-emitting device according to claim 3, characterized in that, The first charge layer has a first interface on the side opposite to the second charge layer and a first intermediate interface located between the first interface and the contact interface. Along the direction from the first intermediate interface to the contact interface or the first interface, the dopant concentration of the first charge layer has a decreasing trend. And / or, the second charge layer has a second interface on a side opposite to the first charge layer, and a second intermediate interface located between the second interface and the contact interface, and the dopant concentration of the second charge layer has a decreasing trend along the direction from the second intermediate interface to the contact interface and the direction from the second intermediate interface to the second interface.

5. The stacked organic light-emitting device according to claim 1, characterized in that, Along the direction close to the contact interface, the dopant concentration of at least a portion of the first charge layer tends to increase; the second charge layer has a second interface away from the first charge layer and a second intermediate interface located between the contact interface and the second interface, and along the direction from the second intermediate interface to the contact interface or the second interface, the dopant concentration of the second charge layer tends to decrease.

6. The stacked organic light-emitting device according to claim 1, characterized in that, The first charge layer has a first interface on the side opposite to the second charge layer and a first intermediate interface located between the first interface and the contact interface. Along the direction from the first intermediate interface to the contact interface or the first interface, the dopant concentration of the first charge layer tends to decrease. Along the direction close to the contact interface, the dopant concentration of at least a portion of the second charge layer tends to increase.

7. The stacked organic light-emitting device according to claim 1, characterized in that, The first charge layer is doped with a P-type dopant, the second charge layer is doped with an N-type dopant, the first charge layer has a first interface on the side opposite to the second charge layer, the first interface is used to dock a hole transport layer, and the dopant concentration of at least a portion of the first charge layer has an increasing trend along the direction close to the first interface.

8. The stacked organic light-emitting device according to claim 7, characterized in that, The first charge layer has a first intermediate interface located between the first interface and the contact interface. The dopant concentration of the first charge layer tends to increase along the direction from the first intermediate interface to the contact interface. The dopant concentration of the first charge layer tends to increase along the direction from the first intermediate interface toward the first interface.

9. The stacked organic light-emitting device according to claim 7, characterized in that, The second charge layer has a second interface on the side opposite to the first charge layer, and the dopant concentration of the second charge layer tends to increase along the direction from the second interface to the contact interface.

10. The stacked organic light-emitting device according to claim 7, characterized in that, The dopant concentration of the P-type dopant in the first charge layer is 0~20%; And / or, the dopant concentration of the N-type dopant in the second charge layer is 0~10%.

11. The stacked organic light-emitting device according to claim 7, characterized in that, The dopant concentration of the P-type dopant in the first charge layer is 2-20%; and / or, the dopant concentration of the N-type dopant in the second charge layer is 1-10%.

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