A two-component blue polymer light emitting diode and a preparation method thereof

Abstract

The application belongs to the technical field of photoelectric devices, and discloses a two-component blue polymer light-emitting diode and a preparation method thereof. The two-component blue polymer light-emitting diode comprises a glass substrate, an anode layer, a hole injection layer, a light-emitting layer, an electron injection layer and a metal cathode, and the light-emitting layer is a two-component blue polyfluorene material thin film prepared by a spin coating method. One of the two-component blue polyfluorene materials is a polymer PFA-a (a=1~4) containing a styryl triphenylamine unit, and the other is a PFB-b (b=1~4) containing a 7H-benzo[b]benzo[5,6]fluorene[2,3-d]thiophene unit. By using the two-component polyfluorene material as the light-emitting layer, an effective energy transfer process between the two polymer materials is utilized, the exciton utilization rate in the device is significantly improved, and thus a blue PLED with a current efficiency as high as 7.30 cd A ‑1 is realized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optoelectronic devices, and particularly relates to a two-component blue polymer light-emitting diode and a preparation method thereof. BACKGROUND

[0002] Polymer light-emitting diodes (PLEDs) have shown good application prospects in full-color display and solid-state lighting fields due to their self-luminescence, low cost, flexibility and large-area device preparation, and have attracted extensive attention. In full-color display screens, red, green and blue three primary colors play a crucial role in display quality, and the development of standard light-emitting polymer materials is the key to realizing high-efficiency full-color display. Among the three primary colors of the display, the blue light PLED is far behind the devices based on the other two primary colors in terms of device efficiency and device stability. Since blue light emission requires a large band gap, this characteristic leads to a large injection barrier in the device, which is not conducive to the injection and transport of carriers, and exciton quenching is more likely to occur in the device, thus leading to problems such as low luminous efficiency, short service life and poor stability. At present, the optimization of the polymer blue light-emitting layer is mainly carried out from two aspects, one of which is to realize the optimization of the material by modifying the main chain of the polymer, adjusting the side chain unit, adjusting the structure and proportion of the monomer, etc., and the other of which is to appropriately dope the polymer light-emitting layer to improve the carrier mobility and exciton utilization rate of the light-emitting layer material. It can be seen that optimizing the polymer light-emitting layer and realizing the improvement of the exciton utilization rate in the device to improve the efficiency of the blue light PLED has important significance for breaking through the development bottleneck of PLED and promoting PLED to practical application. SUMMARY

[0003] In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present application is to provide a two-component blue polymer light-emitting diode. By using a two-component polyfluorene material as the light-emitting layer, the effective energy transfer process between the two polymer materials is utilized, the exciton utilization rate in the device is significantly improved, and a blue light PLED with a current efficiency of 7.30 cdA -1 is realized.

[0004] Another purpose of the present application is to provide a preparation method of the two-component blue polymer light-emitting diode.

[0005] The purpose of the present application is realized by the following scheme:

[0006] A two-component blue polymer light-emitting diode comprises a glass substrate, an anode layer, a hole injection layer, a light-emitting layer, an electron injection layer and a metal cathode, and the light-emitting layer is a thin film of a two-component blue light polyfluorene material prepared by a spin coating method.

[0007] The two-component blue light polyfluorene material is a polymer PFA-a (a = 1-4) containing styryl triphenylamine unit, wherein the chemical structure of PFA-a is specifically as follows:

[0008]

[0009] In the chemical structure of PFA-a, x = 0.005-0.02, n = 10-300;

[0010] Preferably, in the chemical structure of PFA-a, x is 0.005, 0.01 or 0.02, and n is an integer of 10-300.

[0011] The two-component blue light polyfluorene material is a polymer PFB-b (b = 1-4) containing 7H-benzo[b]benzo[5,6]fluorene[2,3-d]thiophene unit, wherein the chemical structure of PFB-b is specifically as follows:

[0012]

[0013] In the chemical structure of PFB-b, x = 0.01-0.2, n = 10-300, and R is one of linear alkyl groups with a total number of carbon atoms of 1-4;

[0014] Preferably, in the chemical structure of PFB-b, x is 0.01, 0.03, 0.05, 0.07, 0.1 or 0.2, and n is an integer of 10-300; R is methyl.

[0015] The light-emitting layer is a PFA-a: PFB-b two-component polymer thin film with a mass ratio of (20-1):1; the polymer light-emitting layer has a thickness of 60-130 nm.

[0016] The anode layer is at least one of metal, metal oxide (such as indium tin oxide conductive film, doped tin dioxide zinc oxide, indium gallium zinc oxide, etc.) and graphene and its derivatives;

[0017] The anode substrate formed by the glass substrate and the anode layer is preferably one of ITO glass substrate, IZO glass substrate or FTO glass substrate.

[0018] The hole injection layer is poly 3,4-ethylenedioxythiophene / polystyrene sulfonate (PEDOT:PSS); the film thickness of the hole injection layer is in the range of 10-50 nm.

[0019] The electron injection layer is CsF; the thickness of the electron injection layer is 0.5-2 nm.

[0020] The cathode is metal, metal alloy or metal oxide; the thickness of the cathode is 80-150nm.

[0021] A preparation method of the above-mentioned two-component blue polymer light-emitting diode comprises the following steps:

[0022] A glass substrate material with an anode layer is taken, and then a hole injection layer, a light-emitting layer, an electron injection layer and a cathode layer are prepared on the anode layer in sequence to obtain the two-component blue polymer light-emitting diode.

[0023] The processing method of the anode includes but is not limited to sputtering, chemical vapor deposition, spray pyrolysis and the like.

[0024] The glass substrate material with an anode layer is preferably one of ITO glass substrate, IZO glass substrate or FTO glass substrate.

[0025] The glass substrate material with an anode layer is preferably cleaned before use, and the specific steps are as follows: the glass substrate material with an anode layer is sequentially placed in isopropyl alcohol, glass cleaning solution, deionized water and isopropyl alcohol for ultrasonic cleaning, and the ultrasonic time is 15 min each time. After the ultrasonic cleaning is completed, the anode substrate is placed in an oven for drying for more than 2h, and then the substrate is subjected to 1-2min of UV or O2-Plasma surface treatment.

[0026] The hole injection layer is formed by a solution spin coating process; the spin coating speed is 2000-4000rpm, the spin coating time is 20-40s, and the spin coating is annealed at 150-180℃ in an atmospheric environment for 5-15min.

[0027] The light-emitting layer is formed by a solution spin coating process, the spin coating speed is 1000-3000rpm, the spin coating time is 30-60s, and the spin coating is annealed at 80-120℃ in a nitrogen environment for 15-25min.

[0028] The electron injection layer adopts CsF; the electron injection layer is prepared by a vacuum evaporation method.

[0029] The cathode is metal, metal alloy or metal oxide; the processing method of the cathode includes but is not limited to electrode evaporation, solution processing, inkjet printing and the like.

[0030] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0031] The application adopts two kinds of polyfluorene blue light materials to prepare a two-component polymer film by blending, uses the energy transfer process between the two components to effectively improve the exciton utilization rate, and thus realizes a high-efficiency two-component blue polymer light emitting diode. The two polymer materials have similar stability and solubility, and it is easy to realize a uniform blending system. There is effective and thorough energy transfer between the two components, and the exciton on the component with a larger band gap can be effectively transferred to the light-emitting component, the quenching probability of the exciton is reduced, the utilization rate of the exciton is significantly improved, and thus the device current efficiency and device brightness are significantly improved under the condition of blue light emission. The blue PLED provided by the application can be prepared by using a spin coating process, the manufacturing process is simple, the repeatability is good, the cost is low, and the application potential in the fields of flexible devices and large-area devices is good. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a device structure schematic diagram of the application.

[0033] Figure 2 It is a nuclear magnetic spectrum diagram of PFA-1 prepared in Example 1. DETAILED DESCRIPTION

[0034] The application will be further described in detail below in combination with examples and drawings, but the implementation manner of the application is not limited to this. The specific conditions are not indicated in the examples, and the conventional conditions or the conditions suggested by the manufacturer are used. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products that can be purchased on the market.

[0035] The reagents used in the examples can be purchased on the market unless otherwise specified.

[0036] The application provides a method for preparing a blue polymer light emitting diode by a two-component polymer solution spin coating process, which comprises the following steps:

[0037] (1) cleaning the anode substrate;

[0038] (2) preparing a hole injection layer;

[0039] The hole injection solution is added dropwise on the upper anode substrate, and annealing treatment is carried out after spin coating;

[0040] (3) preparing a polymer light-emitting layer

[0041] The polymer organic solution is added dropwise on the hole injection layer film, and annealing treatment is carried out after spin coating;

[0042] (4) preparing an electron injection layer

[0043] CsF is evaporated on the upper polymer light-emitting layer under high vacuum to obtain an electron injection layer;

[0044] (5) Preparation of cathode

[0045] Evaporate a certain thickness of cathode on the electron injection layer.

[0046] Further, the step (1) anode substrate is one of ITO substrate, IZO substrate or FTO substrate. Preferably, the anode substrate is sequentially placed in isopropyl alcohol, washing liquid, deionized water for cleaning, and then placed in clean isopropyl alcohol for ultrasonic cleaning, each time for 10-20 min; after ultrasonic cleaning is completed, the substrate is placed in an oven for drying for more than 2 h, and then the substrate is subjected to 1-2 min of UV or O2-Plasma surface treatment.

[0047] Further, the step (2) hole injection layer preparation method is: taking the PEDOT: PSS aqueous solution out of the 4℃ refrigerator, placing it for half an hour to wait for the solution to warm up to room temperature. The solution after warming up is filtered through a 0.22 μm water filter head, and then added dropwise on the anode substrate to form a hole injection layer film by spin coating process, the spin coating speed is 2000-4000 rpm, the spin coating time is 20-40 s, and the annealing is carried out in the atmosphere at 150-180℃ for 5-15 min. Preferably, the spin coating speed is 3000 rpm, the amount is 100 μl, the spin coating time is 30 s, and the annealing is carried out at 150℃ for 10 min.

[0048] Further, the polymer solution in step (3) is prepared from PFA-a and PFB-b, wherein the mass ratio of PFA-a: PFB-b is 20-1:1, preferably the mass ratio is 19:1, 4:1, 1:1. The total concentration of the mixed solution is 8-15 mg / ml -1 . The solvent can be selected from xylene, p-xylene, o-xylene and chlorobenzene, preferably p-xylene.

[0049] The spin coating speed of the polymer organic solution is 1000-3000 rpm, and the preferred spin coating speed is 2000 rpm. The spin coating time is 30-60 s, and the preferred spin coating time is 40 s. Then annealing is carried out at 80-120℃ for 15-25 min under nitrogen atmosphere in the glove box. The preferred annealing temperature is 100℃, and the annealing time is 20 min. Preferably, the amount of polymer organic solution is 20 μl.

[0050] Further, steps (4), (5) and (6) all need to be transferred into a vacuum evaporation chamber to evaporate the electron injection layer and the cathode. The thickness of the evaporated electron injection layer is 0.5-2 nm, and the preferred thickness is 1 nm. The thickness of the evaporated cathode is 80-150 nm, and the preferred thickness is 100 nm.

[0051] A two-component blue polymer light-emitting diode prepared by spin-coating process, the light-emitting device comprises, from bottom to top, a substrate, an anode layer, a hole injection layer, a polymer light-emitting layer, an electron injection layer and a metal cathode.

[0052] Example 1

[0053] Preparation of polymer PFA-1 (x = 0.02)

[0054]

[0055] F-Bpin2 (192.8 mg, 0.3 mmol), F-Br2 (158.0 mg, 0.288 mmol), TD-Br2 (3.0 mg, 0.006 mmol), DPAVBi-Br2 (3.0 mg, 0.006 mmol), palladium acetate (2.0 mg), tricyclohexylphosphine (4.0 mg) were weighed in sequence using an electronic balance, and then put into a 50 mL three-necked flask with a clean stirring bar. Then the two bottle openings were plugged with rubber plugs, the reaction flask was protected by nitrogen using a three-way stopcock and a nitrogen balloon, and 9 mL of toluene and 1 mL of 20% tetraethylammonium hydroxide aqueous solution were added using a syringe. The reaction device was fixed on a magnetic stirrer, and slowly heated to 85°C, and reacted at this temperature for 24 hours. Then 30 mg of phenylboronic acid was added to the polymer using a syringe to cap it, and after 12 hours of reaction, 0.2 mL of bromobenzene was added to remove excess phenylboronic acid, and the reaction continued for another 12 hours. After the reaction was completed, the post-treatment was carried out, and the reaction material in the bottle was poured into a beaker containing 100 mL of methanol while hot, and yellow-white flocculent solid was precipitated. After standing for 10 min, the solid was filtered, and the obtained solid was wrapped in filter paper and loaded into a Soxhlet extractor, and methanol, acetone and n-hexane were used in sequence to extract and purify the reaction material for 24 hours respectively to remove small molecular impurities and catalysts. Finally, the remaining flocculent solid was placed in a vacuum oven and dried, and then loaded into a brown reagent bottle and sealed for use.

[0056] The number average molecular weight of the obtained polymer PFA-1 was 206 kDa, and the PDI value was 1.71.

[0057] The nuclear magnetic resonance spectrum of the obtained polymer PFA-1 is shown in Figure 2 .

[0058] Example 2

[0059] Preparation of polymer PFB-1 (x = 0.2)

[0060]

[0061] Under nitrogen gas protection, monomers 2,7-dibromo-9,9-di(4-(2- ethylhexyloxy)phenyl)fluorene (43.9 mg, 0.06 mmol), 2,7-di(4,4,5,5-s tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-di(4-(2-ethylhexyloxy)phenyl)fluorene (82.7 mg, 0.1 mmol), 5,11-dibromo-7,7-dimethyl-7H-benzo[b]benzo[5,6]fluorene[2,3-d]thiophene (20.4 mg, 0.04 mmol), 5 mL of toluene, 0.9 mL of 20 wt% aqueous tetraethylammonium hydroxide solution, tricyclohexylphosphine (2 mg) and palladium acetate (1 mg) were added into a 50 mL two-necked flask. The reaction was carried out at 85°C for 24 hours, 25 mg of phenylboronic acid was added to terminate the reaction for 12 hours, and then 0.2 mL of bromobenzene was added to terminate the reaction for 12 hours. After the reaction was stopped, the reaction solution was added dropwise into a large amount of methanol, and the polymer was precipitated and filtered. The polymer was preliminarily purified by Soxhlet extraction using methanol, acetone and n-hexane as the solvents, respectively. The preliminarily purified polymer was redissolved in 10 mL of toluene, and the product was separated by using a chromatographic column (eluent: toluene, filler: neutral alumina). The purified polymer was dissolved in a small amount of toluene, and the polymer was precipitated and filtered in methanol again, and dried to obtain a yellow-green filamentous solid.

[0062] The number average molecular weight of the polymer PFB-1 was 70 kDa, and the width of the molecular weight distribution was 2.43.

[0063] Example 3

[0064] The device structure of this example was: anode (ITO) / hole injection layer (PEDOT:PSS) / bicomponent blue light-emitting polymer layer of PFA-1:PFB-1 (19:1) / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 .

[0065] The preparation process was as follows:

[0066] a. The ITO substrate used was sequentially subjected to ultrasonic cleaning in isopropanol, glass cleaning solution, deionized water and isopropanol, with each ultrasonic cleaning time being 15 min. After the ultrasonic cleaning was completed, the ITO substrate was placed in an oven and dried for more than 2 h for standby use.

[0067] b. A bicomponent polymer solution was prepared. PFA-1 and PFB-1 were respectively dissolved in p-xylene at a concentration of 10 mg / ml -1 and 15 mg / ml -1 , respectively. After complete dissolution, the two were mixed at a volume ratio of 57:2 to obtain a bicomponent polymer solution.

[0068] c. Before spin-coating the hole injection layer, the ITO substrate was treated by plasma for 2 min to improve the wettability on ITO. The hole injection layer solution was filtered by a 0.22 μm water filter head and then dropped on the ITO substrate. The spin-coating process was performed at a speed of 3000 rpm for 30 s, followed by annealing at 150 °C in air for 15 min. The thickness of the hole injection layer was 35 nm;

[0069] d. The substrate was transferred into a glove box for spin-coating the polymer light-emitting layer. The spin-coating amount was 20 μl, the spin-coating speed was 2000 rpm, and the spin-coating time was 40 s. Then, the substrate was heated at 100 °C for 20 min. The thickness of the polymer light-emitting layer was 80 nm.

[0070] e. After spin-coating all the functional layers, the device was transferred into a vacuum evaporation chamber for the evaporation of the electron injection layer and the cathode. The thickness of the evaporated electron injection layer was 1 nm, and the thickness of the evaporated cathode was 100 nm.

[0071] f. After the evaporation of the aluminum electrode, the device was encapsulated by epoxy resin and glass cover plate. The electrical properties (current, voltage, brightness, efficiency, color coordinates, etc.) of the device were characterized outside the glove box.

[0072] Example 4

[0073] The device structure of this example was: anode (ITO) / hole injection layer (PEDOT:PSS) / bicomponent polymer light-emitting layer of PFA-1:PFB-1 (4:1) / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 .

[0074] The preparation process was as follows:

[0075] a. The ITO substrate was sequentially cleaned by ultrasonic treatment in isopropanol, glass cleaning solution, deionized water, and isopropanol, each for 15 min. After the ultrasonic treatment, the ITO substrate was dried in an oven for more than 2 h for standby.

[0076] b. The bicomponent polymer solution was prepared by dissolving PFA-1 and PFB-1 in p-xylene at concentrations of 10 mg / ml and 15 mg / ml, respectively. After complete dissolution, the two solutions were mixed at a volume ratio of 6:1 to obtain the bicomponent polymer solution. -1 -1

[0077] ​​c. Before spin-coating the hole injection layer, the ITO substrate was treated by plasma for 2 min to improve the wettability on ITO. The hole injection layer solution was filtered by a 0.22 μm water filter head and then dropped on the ITO substrate. The spin-coating process was performed at a speed of 3000 rpm for 30 s, followed by annealing at 150 °C in air for 15 min. The thickness of the hole injection layer was 35 nm;

[0078] d. The substrate was transferred into a glove box for spin-coating the polymer light-emitting layer. The spin-coating amount was 20 μl, the spin-coating speed was 2000 rpm, and the spin-coating time was 40 s. Then, the substrate was heated at 100 °C for 20 min. The thickness of the polymer light-emitting layer was 80 nm.

[0079] e. After spin-coating all the functional layers, the device was transferred into a vacuum evaporation chamber for evaporation of the electron injection layer and the cathode. The thickness of the evaporated electron injection layer was 1 nm, and the thickness of the evaporated cathode was 100 nm.

[0080] f. After evaporation of the aluminum electrode, the device was encapsulated with epoxy resin and a glass cover plate. The electrical properties (current, voltage, brightness, efficiency, and color coordinates) of the device were characterized outside the glove box.

[0081] Example 5

[0082] The device structure of this example was: anode (ITO) / hole injection layer (PEDOT:PSS) / bicomponent blue polymer light-emitting layer of PFA-1:PFB-1 (1:1) / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 .

[0083] The preparation process was as follows:

[0084] a. The ITO substrate was sequentially subjected to ultrasonic cleaning in isopropanol, glass cleaning solution, deionized water, and isopropanol, with each ultrasonic cleaning time being 15 min. After the ultrasonic cleaning was completed, the ITO substrate was placed in an oven and dried for more than 2 h for standby use.

[0085] b. A bicomponent polymer solution was prepared. PFA-1 and PFB-1 were respectively dissolved in p-xylene at a concentration of 10 mg ml -1 and 15 mg ml -1 , respectively. After complete dissolution, the two solutions were mixed at a volume ratio of 3:2 to obtain the bicomponent polymer solution.

[0086] c. Before spin-coating the hole injection layer, the ITO substrate was treated by plasma for 2 min to improve the wettability on ITO. The hole injection layer solution was filtered by a 0.22 μm water filter head and then dropped on the ITO substrate. The spin-coating process was performed at a speed of 3000 rpm for 30 s, followed by annealing at 150 °C in air for 15 min. The thickness of the hole injection layer was 35 nm;

[0087] d. The substrate was transferred into a glove box for spin-coating the polymer light-emitting layer. The spin-coating amount was 20 μl, the spin-coating speed was 2000 rpm, and the spin-coating time was 40 s. Then, the substrate was heated at 100 °C for 20 min. The thickness of the polymer light-emitting layer was 80 nm.

[0088] e. After spin-coating all the functional layers, the device was transferred into a vacuum evaporation chamber for electron injection layer and cathode evaporation. The thickness of the evaporated electron injection layer was 1 nm, and the thickness of the evaporated cathode was 100 nm.

[0089] f. After evaporation of the aluminum electrode, the device was encapsulated with epoxy resin and glass cover plate. The electrical properties (current, voltage, brightness, efficiency, color coordinates, etc.) of the device were characterized outside the glove box.

[0090] Example 6

[0091] The device structure of this example was: anode (ITO) / hole injection layer (PEDOT:PSS) / bicomponent blue polymer light-emitting layer of PFA-2:PFB-2 (4:1) / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 .

[0092] The preparation process was as follows:

[0093] a. The ITO substrate was sequentially cleaned by ultrasonic treatment in isopropanol, glass cleaning solution, deionized water, and isopropanol, each for 15 min. After the ultrasonic treatment, the ITO substrate was dried in an oven for more than 2 h for standby.

[0094] b. The bicomponent polymer solution was prepared by dissolving PFA-2 and PFB-2 in p-xylene at concentrations of 10 mg / ml and 15 mg / ml, respectively. After complete dissolution, the two solutions were mixed at a volume ratio of 6:1 to obtain the bicomponent polymer solution. -1 -1 b. The bicomponent polymer solution was prepared by dissolving PFA-2 and PFB-2 in p-xylene at concentrations of 10 mg / ml and 15 mg / ml, respectively. After complete dissolution, the two solutions were mixed at a volume ratio of 6:1 to obtain the bicomponent polymer solution.

[0095] ​c. Before spin-coating the hole injection layer, the ITO substrate was treated by plasma for 2 min to improve the wettability on ITO. The hole injection layer solution was filtered by a 0.22 μm water filter head and then dropped on the ITO substrate. The spin-coating process was performed at a speed of 3000 rpm for 30 s, followed by annealing at 150 °C in air for 15 min. The thickness of the hole injection layer was 35 nm;

[0096] d. The substrate was transferred into a glove box for spin-coating the polymer light-emitting layer. The spin-coating amount was 20 μl, the spin-coating speed was 2000 rpm, and the spin-coating time was 40 s. Then, the substrate was heated at 100 °C for 20 min. The thickness of the polymer light-emitting layer was 80 nm.

[0097] e. After spin-coating all the functional layers, the device was transferred into a vacuum evaporation chamber for electron injection layer and cathode evaporation. The thickness of the evaporated electron injection layer was 1 nm, and the thickness of the evaporated cathode was 100 nm.

[0098] f. After evaporation of the aluminum electrode, the device was encapsulated with epoxy resin and glass cover plate. The electrical properties (current, voltage, brightness, efficiency, color coordinates, etc.) of the device were characterized outside the glove box. The structural formula of PFA-2 and PFB-2 is as follows:

[0099]

[0100] The preparation of PFA-2 was according to the preparation of PFA-1 in Reference Example 1, and the preparation of PFB-2 was according to the preparation of PFB-1 in Reference Example 2. The structures and amounts of the corresponding monomers were adjusted according to the actual structural formula. The number average molecular weight of PFA-2 was 188.7 kDa, and the PDI value was 1.90. The number average molecular weight of the polymer PFB-2 was 44 kDa, and the molecular weight distribution width was 2.53.

[0101] Example 7

[0102] The device structure of this example was: anode (ITO) / hole injection layer (PEDOT:PSS) / PFA-2:PFB-3 (4:1) two-component blue light-emitting polymer light-emitting layer / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 .

[0103] The preparation process was as follows:

[0104] a. The ITO substrate was sequentially subjected to ultrasonic cleaning in isopropanol, glass cleaning solution, deionized water, and isopropanol, with each ultrasonic cleaning time being 15 min. After the ultrasonic cleaning was completed, the ITO substrate was placed in an oven for drying for more than 2 h for standby use.

[0105] b. Formulating the two-component polymer solution, PFA-2 and PFB-3 are dissolved in p-xylene respectively at the concentration of 10 mg / ml and 15 mg / ml respectively, after complete dissolution, mixing them with the volume ratio of 6:1 to obtain the two-component polymer solution. -1 and 15 mg / ml -1 respectively. After complete dissolution, mixing them with the volume ratio of 6:1 to obtain the two-component polymer solution.

[0106] c. Before spin-coating the hole injection layer, the ITO substrate used is subjected to Plasma treatment for 2 min to improve the wettability on ITO. The hole injection layer solution is filtered through a 0.22 μm aqueous filter head and then dropped on the ITO substrate, spin-coating process is adopted with the speed of 3000 rpm for 30 s, followed by annealing at 150 °C in air for 15 min, the thickness of the hole injection layer is 35 nm;

[0107] d. The substrate is transferred into the glove box for spin-coating the polymer light-emitting layer, the spin-coating amount is 20 μl, the spin-coating speed is 2000 rpm, the spin-coating time is 40 s, followed by thermal treatment process at the temperature of 100 °C for 20 min, the thickness of the polymer light-emitting layer is 80 nm.

[0108] e. After spin-coating all the functional layers, the device is transferred into the vacuum evaporation chamber for electron injection layer and cathode evaporation. The thickness of the evaporated electron injection layer is 1 nm, the thickness of the evaporated cathode is 100 nm;

[0109] f. After evaporation of the aluminum electrode, the device is encapsulated with epoxy resin and glass cover plate, and the electrical properties (current, voltage, brightness, efficiency, color coordinates and other electrical properties of the device) are characterized outside the glove box.

[0110] The structure of PFB-3 is shown as follows:

[0111]

[0112] The preparation of PFB-3 refers to the preparation of PFB-1 in Reference Example 2. The structure and amount of the corresponding monomer are adjusted according to the actual structure. The number average molecular weight of PFB-3 is 64 kDa, and the molecular weight distribution width is 2.47.

[0113] Example 8

[0114] The device structure of this example is: anode (ITO) / hole injection layer (PEDOT:PSS) / two-component blue light polymer light-emitting layer of PFA-2:PFB-4 (4:1) / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 .

[0115] The preparation process is as follows:

[0116] a. The ITO substrate was sequentially cleaned by ultrasonic cleaning in isopropanol, glass cleaning solution, deionized water, and isopropanol, each for 15 min. After the ultrasonic cleaning, the ITO substrate was dried in an oven for more than 2 h and was ready for use.

[0117] b. The two-component polymer solution was prepared by dissolving PFA-2 and PFB-4 in p-xylene at a concentration of 10 mg / ml and 15 mg / ml, respectively. After complete dissolution, the two-component polymer solution was obtained by mixing the two solutions at a volume ratio of 6:1. -1 -1 b. The two-component polymer solution was prepared by dissolving PFA-2 and PFB-4 in p-xylene at a concentration of 10 mg / ml and 15 mg / ml, respectively. After complete dissolution, the two-component polymer solution was obtained by mixing the two solutions at a volume ratio of 6:1.

[0118] c. Before spin-coating the hole injection layer, the ITO substrate was subjected to plasma treatment for 2 min to improve the wettability of the ITO. The hole injection layer solution was filtered through a 0.22 μm water filter and was then dropped onto the ITO substrate. The spin-coating process was performed at a speed of 3000 rpm for 30 s, followed by annealing at 150 °C in air for 15 min. The thickness of the hole injection layer was 35 nm.

[0119] d. The substrate was transferred into a glove box for spin-coating the polymer light-emitting layer. The spin-coating amount was 20 μl, the spin-coating speed was 2000 rpm, and the spin-coating time was 40 s. Then, the polymer light-emitting layer was subjected to thermal treatment at a temperature of 100 °C for 20 min. The thickness of the polymer light-emitting layer was 80 nm.

[0120] e. After spin-coating all the functional layers, the device was transferred into a vacuum evaporation chamber for electron injection layer and cathode evaporation. The thickness of the evaporated electron injection layer was 1 nm, and the thickness of the evaporated cathode was 100 nm.

[0121] f. After the evaporation of the aluminum electrode, the device was encapsulated with epoxy resin and a glass cover plate. The electrical properties (current, voltage, brightness, efficiency, and color coordinates) of the device were characterized outside the glove box.

[0122] The structure of PFB-4 is shown below:

[0123]

[0124] PFB-4 was prepared according to the preparation of PFB-1 in Reference Example 2. The structure and amount of the corresponding monomer were adjusted according to the actual structure. The number average molecular weight of PFB-4 was 57 kDa, and the molecular weight distribution width was 1.91.

[0125] Example 9

[0126] ​The device structure of this embodiment is: anode (ITO) / hole injection layer (PEDOT:PSS) / bicomponent blue light polymer light-emitting layer of PFA-3:PFB-3 (4:1) / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 .

[0127] The preparation process is as follows:

[0128] a. The ITO substrate used was sequentially subjected to ultrasonic cleaning in isopropanol, glass cleaning solution, deionized water, and isopropanol, with each ultrasonic cleaning time being 15 min. After the ultrasonic cleaning was completed, the ITO substrate was placed in an oven and dried for more than 2 h for standby use.

[0129] b. The bicomponent polymer solution was prepared. PFA-3 and PFB-3 were respectively dissolved in p-xylene at a concentration of 10 mg / ml -1 and 15 mg / ml -1 , respectively. After complete dissolution, the two were mixed at a volume ratio of 6:1 to obtain the bicomponent polymer solution.

[0130] c. Before spin-coating the hole injection layer, the ITO substrate used was subjected to Plasma treatment for 2 min to improve the wettability on the ITO. The hole injection layer solution was filtered through a 0.22 μm aqueous filter head and then dropped on the ITO substrate. A spin-coating process was adopted, with a spin-coating speed of 3000 rpm and a spin-coating time of 30 s. Subsequently, the hole injection layer was annealed in air at 150°C for 15 min, and the thickness of the hole injection layer was 35 nm;

[0131] d. The substrate was transferred into a glove box for spin-coating of the polymer light-emitting layer. The spin-coating amount was 20 μl, the spin-coating speed was 2000 rpm, and the spin-coating time was 40 s. Subsequently, thermal treatment was performed, with a temperature of 100°C and a heating time of 20 min. The thickness of the polymer light-emitting layer was 80 nm.

[0132] e. After spin-coating of all the functional layers, the device was transferred into a vacuum evaporation chamber for electron injection layer and cathode evaporation. The thickness of the evaporated electron injection layer was 1 nm, and the thickness of the evaporated cathode was 100 nm;

[0133] f. After evaporation of the aluminum electrode, the device was encapsulated with epoxy resin and a glass cover plate, and the electrical properties (current, voltage, brightness, efficiency, color coordinates, and other electrical properties of the device) were characterized outside the glove box.

[0134] The structure of PFA-3 is as follows:

[0135]

[0136] PFA-3 was prepared according to the preparation of PFA-1 in Reference Example 1. The structure and amount of the corresponding monomer were adjusted according to the actual structure. The number average molecular weight of PFA-3 was 220 kDa, and the molecular weight distribution width was 1.78.

[0137] Example 10

[0138] The device structure of this example is: anode (ITO) / hole injection layer (PEDOT:PSS) / PFA-3:PFB-4 (4:1) two-component blue light polymer light-emitting layer / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 .

[0139] The preparation process is as follows:

[0140] a. The ITO substrate used was sequentially subjected to ultrasonic cleaning in isopropanol, glass cleaning solution, deionized water, and isopropanol, with an ultrasonic time of 15 min each time. After the ultrasonic cleaning was completed, the ITO substrate was placed in an oven and dried for more than 2 h for standby use.

[0141] b. The two-component polymer solution was prepared. PFA-3 and PFB-4 were respectively dissolved in p-xylene at a concentration of 10 mg / ml -1 and 15 mg / ml -1 , respectively. After complete dissolution, the two were mixed at a volume ratio of 6:1 to obtain the two-component polymer solution.

[0142] c. Before spin-coating the hole injection layer, the ITO substrate used was subjected to Plasma treatment for 2 min to improve the wettability on the ITO. The hole injection layer solution was filtered through a 0.22 μm aqueous filter head and then dropped onto the ITO substrate. A spin-coating process was adopted, with a speed of 3000 rpm for 30 s, followed by annealing at 150°C in air for 15 min, and the thickness of the hole injection layer was 35 nm;

[0143] d. The substrate was transferred into a glove box for spin-coating of the polymer light-emitting layer. The spin-coating amount was 20 μl, and the spin-coating speed was 800 rpm. The thickness of the polymer light-emitting layer was 80 nm.

[0144] e. After spin-coating all the functional layers, the device was transferred into a vacuum evaporation chamber for electron injection layer and cathode evaporation. The thickness of the evaporated electron injection layer was 1 nm, and the thickness of the evaporated cathode was 100 nm;

[0145] f. After evaporation of the aluminum electrode, the device was packaged with epoxy resin and a glass cover plate, and the electrical properties (current, voltage, brightness, efficiency, and color coordinates of the device) were characterized outside the glove box.

[0146] Example 11

[0147] The device structure of this embodiment is: anode (ITO) / hole injection layer (PEDOT:PSS) / PFA-4:PFB-4 (4:1) two-component blue light polymer light-emitting layer / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 .

[0148] The preparation process is as follows:

[0149] a. The ITO substrate used was sequentially subjected to ultrasonic cleaning in isopropanol, glass cleaning solution, deionized water, and isopropanol, with each ultrasonic cleaning time being 15 min. After the ultrasonic cleaning was completed, the ITO substrate was placed in an oven and dried for more than 2 h for standby use.

[0150] b. The two-component polymer solution was prepared. PFA-4 and PFB-4 were respectively dissolved in p-xylene at a concentration of 10 mg / ml -1 and 15 mg / ml -1 , respectively. After complete dissolution, the two-component polymer solution was obtained by mixing the two solutions at a volume ratio of 6:1.

[0151] c. Before spin-coating the hole injection layer, the ITO substrate used was subjected to Plasma treatment for 2 min to improve the wettability on the ITO. The hole injection layer solution was filtered through a 0.22 μm aqueous filter head and then dropped on the ITO substrate. The spin-coating process was performed at a speed of 3000 rpm for 30 s, followed by annealing at 150°C in air for 15 min. The thickness of the hole injection layer was 35 nm.

[0152] d. The substrate was transferred into a glove box for spin-coating the polymer light-emitting layer. The spin-coating amount was 20 μl, and the spin-coating speed was 800 rpm. The thickness of the polymer light-emitting layer was 80 nm.

[0153] e. After spin-coating all the functional layers, the device was transferred into a vacuum evaporation chamber for electron injection layer and cathode evaporation. The thickness of the evaporated electron injection layer was 1 nm, and the thickness of the evaporated cathode was 100 nm.

[0154] f. After the aluminum electrode was evaporated, the device was packaged with epoxy resin and a glass cover plate, and the electrical properties (current, voltage, brightness, efficiency, and color coordinates of the device) were characterized outside the glove box.

[0155] The structure of PFA-4 is as follows:

[0156]

[0157] The preparation of PFA-4 refers to the preparation of PFA-1 in Example 1. The structure and amount of the corresponding monomer were adjusted according to the actual structure. The number average molecular weight of PFA-4 was 191.9 kDa, and the molecular weight distribution width was 1.85.

[0158] Example 12

[0159] The device structure of this example is: anode (ITO) / hole injection layer (PEDOT:PSS) / bicomponent blue light polymer light-emitting layer of PFA-4:PFB-1 (4:1) / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 .

[0160] The preparation process is as follows:

[0161] a. The ITO substrate used was sequentially subjected to ultrasonic cleaning in isopropanol, glass cleaning solution, deionized water, and isopropanol, with each ultrasonic cleaning time being 15 min. After the ultrasonic cleaning was completed, the ITO substrate was placed in an oven and dried for more than 2 h for standby use.

[0162] b. The bicomponent polymer solution was prepared by dissolving PFA-4 and PFB-1 in p-xylene at concentrations of 10 mg / ml and 15 mg / ml, respectively, mixing them at a volume ratio of 6:1 after complete dissolution, and obtaining the bicomponent polymer solution. -1 -1 b. The bicomponent polymer solution was prepared by dissolving PFA-4 and PFB-1 in p-xylene at concentrations of 10 mg / ml and 15 mg / ml, respectively, mixing them at a volume ratio of 6:1 after complete dissolution, and obtaining the bicomponent polymer solution.

[0163] c. Before the spin coating of the hole injection layer, the ITO substrate used was subjected to Plasma treatment for 2 min to improve the wettability on the ITO. After the hole injection layer solution was filtered through a 0.22 μm aqueous filter head, it was added dropwise to the ITO substrate, and a spin coating process was performed at a speed of 3000 rpm for 30 s, followed by annealing at 150°C in air for 15 min, and the thickness of the hole injection layer was 35 nm;

[0164] d. The substrate was transferred into a glove box for spin coating of the polymer light-emitting layer, with a spin coating amount of 20 μl, a spin coating speed of 2000 rpm, and a spin coating time of 40 s, followed by thermal treatment processing at a temperature of 100°C for 20 min, and the thickness of the polymer light-emitting layer was 80 nm.

[0165] e. After all the functional layers were spin coated, the device was transferred into a vacuum evaporation chamber for electron injection layer and cathode evaporation. The thickness of the evaporated electron injection layer was 1 nm, and the thickness of the evaporated cathode was 100 nm;

[0166] f. After the aluminum electrode was evaporated, the device was packaged with epoxy resin and a glass cover plate, and the electrical properties (current, voltage, brightness, efficiency, and color coordinates of the device) were characterized outside the glove box.

[0167] Comparative Example 1

[0168] ​The device structure of the comparative example is: anode (ITO) / hole injection layer (PEDOT: PSS) / PFA-1 single-component blue light polymer light-emitting layer / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 The only difference between the comparative example and the example is the polymer solution in step b. In the comparative example, 15 mg / ml of PFB-1 single-component solution is used as the light-emitting layer solution, and the other steps are the same as those of the example, which will not be repeated here. -1 The only difference between the comparative example and the example is the polymer solution in step b. In the comparative example, 15 mg / ml of PFB-1 single-component solution is used as the light-emitting layer solution, and the other steps are the same as those of the example, which will not be repeated here.

[0169] Comparative Example 2

[0170] The device structure of the comparative example is: anode (ITO) / hole injection layer (PEDOT: PSS) / PFA-1 single-component blue light polymer light-emitting layer / electron injection layer (CsF) / cathode (Al), as shown in Figure 1 The only difference between the comparative example and the example is the polymer solution in step b. In the comparative example, 15 mg / ml of PFB-1 single-component solution is used as the light-emitting layer solution, and the other steps are the same as those of the example, which will not be repeated here. -1 The only difference between the comparative example and the example is the polymer solution in step b. In the comparative example, 15 mg / ml of PFB-1 single-component solution is used as the light-emitting layer solution, and the other steps are the same as those of the example, which will not be repeated here.

[0171] Performance test:

[0172] The electrical properties such as current density, voltage, brightness, EQE and color coordinates of the polymer light-emitting diodes of Examples 3-12 and Comparative Examples 1-2 were tested, and the device performance data are shown in Table 1.

[0173] Table 1: PLEDs performance parameters

[0174]

[0175] It can be seen from the test results that the turn-on voltage of the two-component PLEDs is lower than that of the PFA-1 single-component PLED, which is because the carrier injection barrier is reduced after the addition of PFB-b, and the current density and brightness of the device are also improved. The current efficiency of the two-component PLEDs is significantly better than that of the PFA-a single-component PLED and the PFB-b single-component PLED, and has a good synergistic effect. This is because PFB-b has a larger band gap and can act as a ladder for energy transfer in the two-component polymer device, transferring excitons to PFA-a. The utilization rate of excitons in the PLED is improved, and the probability of exciton quenching is reduced, thereby improving the performance of the device.

[0176] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A two-component blue polymer light emitting diode, characterized in that The double-component blue light polyfluorene material is prepared by spin coating method, and the glass substrate, anode layer, hole injection layer, light emitting layer, electron injection layer and metal cathode are prepared. One of the double-component blue light polyfluorene materials is a polymer PFA-a containing styryl triphenylamine unit, wherein a=1, 2, 3 or 4, and the chemical structure of PFA-a is shown in the following formula: In the chemical structure of PFA-a, x=0.005-0.02, and n=10-300. The other double-component blue light polyfluorene material is PFB-b containing 7H-benzo[b]benzo[5,6]fluorene[2,3-d]thiophene unit, wherein b=1, 2, 3 or 4, and the chemical structure of PFB-b is shown in the following formula: In the chemical structure of PFB-b, x=0.01-0.2, n=10-300, and R is independently one of straight-chain alkyl with a total number of carbon atoms of 1-4.

2. The double-component blue light polyfluorene material according to claim 1, wherein: in the chemical structure of PFA-a, x is independently 0.005, 0.01 or 0.02; and n is independently an integer of 10-300; and in the chemical structure of PFB-b, x is independently 0.01, 0.03, 0.05, 0.07, 0.1 or 0.2, and n is independently an integer of 10-300; and R is methyl.

3. The double-component blue light polyfluorene material according to claim 1 or 2, wherein: the light emitting layer is a double-component polymer film of PFA-a and PFB-b with a mass ratio of (20-1) : 1; and the thickness of the polymer light emitting layer is 60-130 nm.

4. The double-component blue light polyfluorene material according to claim 1, wherein: the anode is at least one of metal, metal oxide and graphene and derivatives thereof.

5. The double-component blue light polyfluorene material according to claim 1, wherein: the hole injection layer is poly 3,4-ethylenedioxythiophene / poly (styrenesulfonate); and the thickness of the hole injection layer is 10-50 nm.

6. The double-component blue light polyfluorene material according to claim 1, wherein: the electron injection layer is CsF; and the thickness of the electron injection layer is 0.5-2 nm.

7. The double-component blue light polyfluorene material according to claim 1, wherein: the cathode is metal, metal alloy or metal oxide; and the thickness of the cathode is 80-150 nm. The preparation method comprises the following steps: The glass substrate material with anode layer is taken, and then the hole injection layer, light emitting layer, electron injection layer and cathode layer are prepared on the anode layer to obtain the double-component blue light polyfluorene material.

9. The preparation method of the double-component blue light polyfluorene material according to claim 8, wherein: ​ ​ ​ ​ ​ 8. A method of preparing a two-component blue polymer light emitting diode according to any one of claims 1 to 7, characterized in that ​ ​ ​ The light-emitting layer is formed by a solution spin-coating process, the spin-coating speed is 1000-3000 rpm, the spin-coating time is 30-60 s, and after spin-coating, annealing is carried out at 80-120 ℃ for 15-25 min in a nitrogen environment; The total concentration of the two-component blue light polyfluorene material in the spin-coated solution is 8-15 mg ml -1 .

10. The method of claim 8, wherein the two-component blue polymer light-emitting diode is prepared by the steps of: The hole injection layer is formed by a solution spin-coating process, the spin-coating speed is 2000-4000 rpm, the spin-coating time is 20-40 s, and after spin-coating, annealing is carried out at 150-180 ℃ for 5-15 min in an atmospheric environment.

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