Patent Publication Number: US-2023157140-A1

Title: Oled device structure and manufacturing method thereof

Description:
FIELD OF INVENTION 
     The present invention relates to the field of organic light emitting diodes (OLEDs), and in particular, to an OLED device structure and a manufacturing method thereof. 
     BACKGROUND OF INVENTION 
     Organic light emitting diode (OLED) devices have been considered as the next generation of new display technologies in the display industry because of their advantages of light weight, wide viewing angles, fast response times, low temperature resistance, and high luminous efficiency compared with traditional liquid crystal display (LCD). In particular, OLEDs can be made into flexible displays that can be bent on flexible substrates, which are a huge advantage of OLED display panels. 
       FIG.  1   a    is a basic structure of a current OLED panel  10 , comprising a foam copper foil  11 , a backplane  12  (used to protect an OLED display panel), a flexible substrate layer  2 , an array segment film layer  3 , an organic light emitting layer  4 , a thin film packing layer  5 , a touch layer  6 , a polarizer  7 , and a glass cover  8 . 
     However, during a manufacturing process, the current OLED panel has following problems: 
     1. The commonly used backplane  12  has poor light penetration (average penetration rate is less than 60%) and cannot meet high light transmittance requirements for OLED devices of future under-screen cameras ( FIG.  1   b   ). 
     2. Adhesion between the backplane  12  and the flexible substrate  2  is poor, which causes the OLED panels to easily peel off after module manufacturing processes. 
     3. The backplane  12  is a polymer material, and its thermal conductivity is poor, and the thermal conductivity is about 0.1 to 0.2 W/mK. It is impossible to dissipate heat generated by circuits under the OLED devices while operating, which can easily cause the OLED device to entirely fail. 
     4. When bonding with the glass cover  8  (such as a hyperboloid or quadric surface), because of a low mechanical strength of backplane materials, it is easy to break at a bending area. 
     Therefore, it is necessary to solve the above problems and enhance competitiveness and yield of the OLED devices. 
     Technical Problem 
     Current OLED panels have following problems: 
     1. A commonly used backplane  12  has poor light penetration (average penetration rate is less than 60%) and cannot meet high light transmittance requirements for OLED devices of future under-screen cameras ( FIG.  1   b   ). 
     2. Adhesion between a backplane  12  and a flexible substrate  2  is poor, which causes the OLED panels to easily peel off after module manufacturing processes. 
     3. The backplane  12  is a polymer material, and its thermal conductivity is poor, and the thermal conductivity is about 0.1 to 0.2 W/mK. It is impossible to dissipate heat generated by circuits under the OLED devices while operating, which can easily cause the OLED device to entirely fail. 
     4. When bonding with a glass cover  8  (such as a hyperboloid or quadric surface), because of a low mechanical strength of backplane materials, it is easy to break at a bending area. 
     Therefore, it is necessary to solve the above problems and enhance competitiveness and yield of the OLED devices. 
     Technical Solution 
     In order to solve the above technical problems, an objective of the present invention is to provide an organic light emitting diode (OLED) device structure and a manufacturing method thereof, which can solve the problems of low penetration rate, poor heat dissipation, buffer layers are easy to peel, and easy breakage in backplane layers of current OLED panels. 
     In order to achieve the above objective, the present invention provides an OLED device structure comprising a base layer, an array segment film layer, an organic light emitting layer, and a thin film packing layer disposed sequentially from bottom to top; a touch layer, a polarizer, and a cover glass sequentially disposed above the thin film packing layer; a composite material layer disposed under the base layer; and a foam copper foil layer disposed under the composite material layer. 
     In an embodiment of the present invention, the base layer is a flexible base layer. 
     In an embodiment of the present invention, the composite material layer comprises a boron nitride nanosheet-nanocellulose composite material. 
     In an embodiment of the present invention, a boron nitride nanosheet is present in the boron nitride nanosheet-nanocellulose composite material by an amount greater than 0.1 wt % and less than 7 wt %. 
     In an embodiment of the present invention, a material of the composite material layer is formed by spraying, spin coating or inkjet printing processes. 
     In order to achieve the above objective, the present invention further provides a manufacturing method of the OLED device structure, comprising following steps: 
     providing a base layer; 
     forming an array segment film layer, an organic light emitting layer, and a thin film packing layer on the base layer sequentially; 
     forming a touch layer and a polarizer on the thin film packing layer sequentially; 
     forming a composite material layer under the base layer; and 
     forming a foam copper foil layer under the composite material layer and forming a cover glass on the polarizer. 
     In an embodiment of the present invention, the base layer is a flexible base layer. 
     In an embodiment of the present invention, the composite material layer comprises a boron nitride nanosheet-nanocellulose composite material. 
     In an embodiment of the present invention, a boron nitride nanosheet is present in the boron nitride nanosheet-nanocellulose composite material by an amount greater than 0.1 wt % and less than 7 wt %. 
     In an embodiment of the present invention, a material of the composite material layer is formed by spraying, spin coating or inkjet printing processes. 
     In order to make the above contents of the present invention more comprehensible, preferred embodiments are described below in conjunction with attached drawings, which are described in detail as follows. 
     Beneficial Effect 
     The present invention provides an organic light emitting diode (OLED) device structure and a manufacturing method thereof, which can solve problems of low penetration rate, poor heat dissipation, buffer layers are easy to peel, and easy breakage in backplane layers of current OLED panels. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       In order to more clearly illustrate the embodiments or the technical solutions in the prior art, a brief introduction of the drawings used in the embodiments or the prior art description will be briefly described below. Obviously, the drawings in the following description are only some of the embodiments of the invention, and those skilled in the art can obtain other drawings according to the drawings without any creative work. 
         FIG.  1   a    is a schematic structural view of a current organic light emitting diode (OLED) panel. 
         FIG.  1   b    is a schematic view of the current OLED panel used to install an under-screen camera. 
         FIG.  2    is a schematic structural view of a structure of an OLED device of the present invention. 
         FIG.  3    is a flowchart of a manufacturing method of the OLED device structure of the present invention. 
         FIG.  4    is a schematic view of a manufacturing process of the OLED device structure of the present invention. 
         FIG.  5    is a schematic view of another embodiment of the structure of the OLED device of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of the present invention. 
     In the figures, units having similar structures are used for the same reference numbers. 
     As shown in  FIG.  2   , an objective of the present invention is to provide an organic light emitting diode (OLED) device structure  20  comprising a base layer  21 , an array segment film layer  22 , an organic light emitting layer  23 , and a thin film packing layer  24  disposed sequentially from bottom to top; a touch layer  25 , a polarizer  26 , and a cover glass  27  sequentially disposed above the thin film packing layer  24 ; a composite material layer  28  disposed under the base layer  21 ; and a foam copper foil layer  29  disposed under the composite material layer  28 . 
     The base layer  21  is a flexible base layer. The composite material layer  28  comprises a boron nitride nanosheet-nanocellulose composite material. A boron nitride nanosheet is present in the boron nitride nanosheet-nanocellulose composite material by an amount greater than 0.1 wt % and less than 7 wt %, and with less than 5 wt % being best. 
     In detail, replacing a backplane  12  used in the prior art with the composite material layer  28  of the present invention will have following advantages: 
     1. When the amount of the boron nitride nanosheets is 5%, a penetration of the composite material layer  28  can reach more than 80%. Therefore, the penetration of the composite material layer  28  will be more than 33.3% higher than that of a traditional backplane material (backplane material penetration is less than 60%), which can greatly improve an overall light transmittance of the OLED device, making it more suitable for a development trend of under-screen cameras. 
     In addition, a light transmittance of traditional backplane materials in a blue light band (400 nm to 450 nm) is basically 0, which cannot meet a requirement of the under-screen cameras for full-band light, that is, the under-screen cameras cannot perceive blue light, and cannot generate images normally. However, the boron nitride nanosheet-nanocellulose composite material of the composite material layer  28  of the present invention has a high light transmittance (more than 60%) in the blue light band, so normal imaging of the under-screen cameras can be guaranteed. 
     2. The base layer  21  is an organic substance, and a surface is rich in hydrophilic groups. However, a nano-cellulose surface of the boron nitride nanosheet-nanocellulose composite material in the composite material layer  28  is also rich with a large number of hydrophilic group hydroxyl groups, which can greatly improve adhesion between the two at an interface of the film layer, thereby effectively avoiding peeling problems of flexible substrates and backplane materials in the prior art. 
     3. The boron nitride nanosheet of the boron nitride nanosheet-nanocellulose composite material in the composite material layer  28  has a high thermal conductivity. When the amount of the boron nitride nanosheet is 5%, the thermal conductivity of the boron nitride nanosheet-nanocellulose can reach 26.2 W/mK, which is much higher than a thermal conductivity of the backplane material (about 0.1 to 0.2 W/mK), which can effectively solve heat dissipation problems of the OLED devices. 
     4. When the amount of the boron nitride nanosheet of the boron nitride nanosheet-nanocellulose composite material in the composite material layer  28  is 5%, it still maintains ultra-high mechanical properties, and its tensile stress is close to 200 MPa, so that it will not break during bending and fitting. 
     As shown in  FIG.  3    and  FIG.  4   , which are flowcharts of a manufacturing method of the OLED device structure  20  of the present invention and a schematic view of a manufacturing process of the OLED device structure of the present invention, the manufacturing method of the OLED device structure comprises following steps: 
     S1. Providing the base layer  21 ; 
     S2. Forming the array segment film layer  22 , the organic light emitting layer  23 , and the thin film packing layer  24  on the base layer  21  sequentially; 
     S3. Forming the touch layer  25  and the polarizer  26  on the thin film packing layer  24  sequentially; 
     S4. Forming the composite material layer  28  under the base layer  21 ; and 
     S5. Forming the foam copper foil layer  29  under the composite material layer  28  and forming the cover glass  27  on the polarizer  26 . 
     The base layer  21  is a flexible base layer. The composite material layer  28  comprises boron nitride nanosheet-nanocellulose composite material. The boron nitride nanosheet is present in the boron nitride nanosheet-nanocellulose composite material by an amount greater than 0.1 wt % and less than 7 wt %, and with less than 5 wt % being best. 
     When the composite material layer  28  is formed under the base layer  21 , the processes used include, but are not limited to, spraying, spin coating or inkjet printing, etc. 
     On the other hand, structures of the touch layer  25 , the polarizer  26 , the foam copper foil layer  29 , and the cover glass  27  can be formed according to current procedures, so the present invention can be introduced into current manufacturing processes in a most economical manner. 
     As shown in  FIG.  5   , in another embodiment of the present invention, the base layer  21  may be further configured as a double flexible base layer and a single buffer layer. That is, the base layer  21  is distinguished into a first flexible base layer  211 , a buffer layer  212 , and a second flexible base layer  213 , and the present invention can also be introduced into the current manufacturing processes in the most economical manner. 
     Replacing the backplane  12  used in the prior art with the composite material layer  28  of the present invention will have following advantages: 
     1. When the amount of the boron nitride nanosheets is 5%, a penetration of the composite material layer  28  can reach more than 80%. Therefore, the penetration of the composite material layer  28  will be more than 33.3% higher than that of a traditional backplane material (backplane material penetration is less than 60%), which can greatly improve an overall light transmittance of the OLED device, making it more suitable for a development trend of under-screen cameras. 
     In addition, a light transmittance of traditional backplane materials in a blue light band (400 nm to 450 nm) is basically 0, which cannot meet a requirement of the under-screen cameras for full-band light, that is, the under-screen cameras cannot perceive blue light, and cannot generate images normally. However, the boron nitride nanosheet-nanocellulose composite material of the composite material layer  28  of the present invention has a high light transmittance (more than 60%) in the blue light band, so normal imaging of the under-screen cameras can be guaranteed. 
     2. The base layer  21  is an organic substance, and a surface is rich in hydrophilic groups. However, a nano-cellulose surface of the boron nitride nanosheet-nanocellulose composite material in the composite material layer  28  is also rich with a large number of hydrophilic group hydroxyl groups, which can greatly improve adhesion between the two at an interface of the film layer, thereby effectively avoiding peeling problems of flexible substrates and backplane materials in the prior art. 
     3. The boron nitride nanosheet of the boron nitride nanosheet-nanocellulose composite material in the composite material layer  28  has a high thermal conductivity. When the amount of the boron nitride nanosheet is 5%, the thermal conductivity of the boron nitride nanosheet-nanocellulose can reach 26.2 W/mK, which is much higher than the thermal conductivity of the backplane material (about 0.1 to 0.2 W/mK), which can effectively solve heat dissipation problems of the OLED devices. 
     4. When the amount of the boron nitride nanosheet of the boron nitride nanosheet-nanocellulose composite material in the composite material layer  28  is 5%, it still maintains ultra-high mechanical properties, and its tensile stress is close to 200 MPa, so that it will not break during bending and fitting. 
     In this way, the OLED device structure and the manufacturing method thereof of the present invention can solve the problems of low penetration rate, poor heat dissipation, buffer layers are easy to peel, and easy breakage in backplane layers of current OLED panels. 
     The above are only preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from principles of the present invention, a number of improvements and retouches can be made, and these improvements and retouches should also be considered as the scope of protection of the present invention.