Intrinsic flexible polymer composite light-emitting film and application thereof in intrinsic flexible polymer light-emitting diode

Abstract

The invention discloses an intrinsic flexible polymer composite light-emitting film and application thereof in an intrinsic flexible polymer light-emitting diode. The intrinsic flexible polymer composite luminescent film is prepared from a blend of a luminescent conjugated polymer and an elastomer dopant, and the elastomer dopant is polycaprolactone polyurethane or thermoplastic polyurethane obtained by block copolymerization of polycaprolactone diol and 4, 4-diphenylmethane diisocyanate. The maximum brightness of a PLED prepared by using the polymer composite light-emitting film as a light-emitting layer reaches 21072Cd / m < 2 >, the turn-on voltage is 2.7 V, and the polymer composite light-emitting film also has good performance stability and is easy to process and prepare in a large area. The polymer composite light-emitting film is applied to an IFPLED, the maximum brightness is 1621Cd / m < 2 >, the turn-on voltage is 4V, meanwhile, a 4 * 6 light-emitting display array is prepared, good uniformity is shown, and it is proved that the IFPLED has wide application prospects in the emerging science and technology field of intrinsic flexible display in the future.

Description

Technical Field

[0001] The invention relates to an intrinsic flexible polymer composite luminescent film and application thereof in an intrinsic flexible polymer light emitting diode, belonging to the technical field of intrinsic flexible display. Background Art

[0002] The display industry is an important cornerstone of the national information industry. In the future, the display industry will develop towards the form of "intrinsic flexible display", that is, the screen can be folded or stretched along any axis (Natl Sci Rev, 2022, Vol. 9, nwac090). Based on the "disruptive" display form of intrinsic flexible display that deforms on any surface and direction, future display screens can truly realize ubiquitous display, such as smart windows, wearable electronics, optical medical and other fields. Therefore, this field has become a new high ground for companies and institutions around the world to compete. In order to overcome this problem, it is first necessary to improve the intrinsic flexibility of light-emitting devices. Among them, PLED based on the advantages of polymer semiconductor materials has the characteristics of good flexible display, adjustable functions and solution processing, so it can be used as a basic component of intrinsic flexible display. In recent years, with the efforts of researchers, the functional materials and solution processing technology of IFPLED devices have also been steadily developing.

[0003] The light-emitting functional layer in IFPLED is one of the key functional layers. According to current reports, in order to improve the stretchability of polymer light-emitting materials, the main method used by researchers is to add elastomers to polymer light-emitting materials, such as hydrogenated styrene-butadiene block copolymer (SEBS), polyurethane elastomer (TPU) and polydimethylsiloxane (PDMS). However, this method has two main problems. On the one hand, it has high selectivity for polymers, and usually requires polymer materials to have good self-assembly properties, which can self-assemble with elastomers at the microscopic scale into an interpenetrating network structure to improve stretchability. However, the elastomer dopants reported so far are not universal, and the effects on different polymer light-emitting materials vary greatly; on the other hand, the materials will form a relatively serious phase separation after compounding, which has a great impact on the performance of the light-emitting material. Therefore, how to select a universal elastomer dopant to prepare a polymer composite light-emitting film is of great research significance for realizing intrinsic flexible display. Summary of the invention

[0004] The purpose of the present invention is to provide an intrinsic flexible polymer composite light-emitting film. The present invention prepares a light-emitting layer by blending a universal elastomer dopant with a light-emitting polymer. The light-emitting layer has high brightness and a stretchability of more than 100%.

[0005] The elastomer dopant used in the present invention is polycaprolactone polyurethane (PU / PCL) or thermoplastic polyurethane (Lubrizol SG-80A, Lubrizol SG-80A) obtained by block copolymerization of polycaprolactone diol (PCL) and 4,4-diphenylmethane diisocyanate (MDI), preferably PU / PCL.

[0006] The present invention uses PU / PCL as an elastomer dopant to achieve the following effects:

[0007] 1. The PCL group enhances the hydrophobicity of the polyurethane material and reduces its polarity. At the same time, the semi-crystalline polycaprolactone enhances the structural regularity of the polyurethane molecular chain, thereby enhancing its interaction with the longer hydrophobic alkyl chains in the polymer semiconductor chain. During the microphase separation process, the elastomer itself is not easy to aggregate, thereby better forming a nano-interpenetrating network structure with the polymer semiconductor chain.

[0008] 2. The PCL group has good biocompatibility and biodegradability. As a soft segment in the polyurethane elastomer, the PCL group enhances the flexibility of the polymer chain and reduces its elastic modulus (0.1-3MPa), which is close to the elastic modulus of human skin (0.5-1.95MPa). This makes it have a better mechanical compatibility interface with human skin and has broad application prospects in the fields of biological implantation, health monitoring, and bionic electronics.

[0009] Specifically, the polymer composite luminescent film provided by the present invention is prepared from a blend of a luminescent conjugated polymer and an elastomer dopant;

[0010] The elastomer dopant is a polycaprolactone polyurethane (PU / PCL, M n About 20000~80000) or thermoplastic polyurethane (Lubrizol SG-80A, Lubrizol SG-80A);

[0011] In the blend, the mass content of the elastomer dopant is 10-50%, preferably any value among 10%, 30% and 50% or a range consisting of any values.

[0012] The polymer composite light-emitting film is prepared by solution spin coating using the blend under the following conditions:

[0013] The solvent used is any one of toluene, xylene, chlorobenzene, dichlorobenzene, chloroform, dichloromethane, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide (DMF) and water, the concentration of the blend is 5-15 mg / mL, the specific conditions of spin coating are: rotation speed 2000-7000 rpm, time 40-60 s. Annealing conditions are: temperature 80-160°C, time 5-30 min;

[0014] The thickness of the polymer composite luminescent film is 30-100 nm.

[0015] Preferably, the luminescent conjugated polymer may be poly[{2,5-bis(3',7'-dimethyloctyloxy)-1,4-phenylethynyl}-co-{3-(4'-(3",7"-dimethyloctyloxy)phenyl)-1,4-phenylethynyl}-co-{3-(3'-(3",7"-dimethyloctyloxy)phenyl)-1,4-phenylethynyl}] (SY-PPV), poly(9,9-di-n-octylfluorenyl-2,7-diyl), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylethynyl] (MEH-PPV), poly[(9,9-di-n-octylfluorenyl-2,7-diyl) At least one of poly[(2-methoxy-5-(2-ethylhexyloxy)-1,4-diyl)], poly[(N,N'-(4-n-butylphenyl)-N,N'-diphenyl-1,4-phenylenediamine)-alt-(9,9-di-n-octylfluorenyl-2,7-diyl)], poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] and poly[2-methoxy-5-[(3,7-dimethyloctyloxy)-1,4-phenyl]-1,2-ethylenediyl].

[0016] The polymer composite light-emitting film provided by the present invention can be used in a high-flexibility display device, a stretchable display device and an intrinsically flexible display device, and the polymer composite light-emitting film serves as a light-emitting layer.

[0017] Based on the polymer composite light-emitting film, the present invention also provides a polymer light-emitting diode, comprising an ITO anode electrode, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode electrode arranged in sequence;

[0018] The light-emitting layer is the polymer composite light-emitting film of the present invention.

[0019] The ITO anode electrode is sputtered on a substrate such as a silicon wafer, glass or quartz, and the substrate is ultrasonically cleaned with detergent, deionized water, acetone, and isopropanol in sequence, blown dry with a nitrogen gun, and then subjected to oxygen plasma treatment to obtain a clean substrate. The specific ultrasonic conditions are: ultrasonic power of 30 to 100 W, ultrasonic time of 10 to 20 min, and ultrasonic frequency of 20 to 50 kHz; the conditions for oxygen plasma treatment are: treatment time of 5 to 20 min, pressure of 0.2 mbar, and power of 100%.

[0020] Wherein, the material of the hole transport layer is any one of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, poly(9-vinylcarbazole), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-n-butyl)phenyl)-diphenylamine)], 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine and 4,4',4"-tri(carbazole-9-yl)triphenylamine;

[0021] Depositing the hole transport layer by solution deposition or vacuum evaporation deposition;

[0022] The thickness of the hole transport layer is 30-60 nm.

[0023] Wherein, the material of the electron transport layer is any one of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, 1,3,5-tris[(3-pyridyl)-3-phenyl]benzene, zinc oxide nanoparticles, polyethoxyethyleneimine, 4,6-bis(3,5-di(3-pyridyl)phenyl)-2-methylpyrimidine and 4,7-diphenyl-1,10-phenanthroline and poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide;

[0024] The electron transport layer is prepared by solution spin coating or vacuum evaporation deposition;

[0025] The conditions of the vacuum evaporation deposition method are as follows: a small molecule electron transport layer material is placed in a crucible, and a layer of electron transport layer material is deposited on the surface of the polymer light-emitting composite film by heating and evaporation. The vacuum thermal evaporation rate is The thickness of the deposited film is between 20 and 100 nm;

[0026] The thickness of the electron transport layer is 10 to 50 nm.

[0027] Wherein, the material of the electron injection layer is lithium fluoride or 8-hydroxyquinoline lithium;

[0028] The electron injection layer is deposited by vacuum evaporation deposition: an inorganic material is placed in a crucible, and a layer of electron injection layer material is deposited on the surface of the electron transport layer by heating and evaporation. The vacuum thermal evaporation rate is between;

[0029] The thickness of the electron injection layer is 1 to 2 nm;

[0030] The cathode electrode is Al or Ag;

[0031] The cathode electrode is prepared by vacuum evaporation: a mask is placed on the surface of the prepared device, fixed by a clamp, a metal material is placed in a ceramic boat, and a layer of metal electrode material is deposited on the surface of the electron injection layer material by heating and evaporation. The vacuum thermal evaporation rate is The thickness of the deposited film is between 100 and 300 nm.

[0032] On the basis of the polymer composite light-emitting film, the present invention further provides an intrinsic flexible polymer light-emitting diode, comprising a substrate, a sacrificial layer, an elastomer substrate, an intrinsic flexible anode electrode, an intrinsic flexible anode electrode modification layer, an intrinsic flexible hole transport layer, an intrinsic flexible light-emitting layer, an intrinsic flexible electron transport layer and an intrinsic flexible cathode electrode arranged in sequence;

[0033] The intrinsic flexible light-emitting layer is the polymer composite light-emitting film described in the present invention.

[0034] Wherein, the substrate is selected from any one of silicon wafer, glass, ceramic and quartz;

[0035] The sacrificial layer is selected from at least one of octadecyltrimethoxysilane, octadecyltrichlorosilane, octadecyltrichlorosilane and phenyltrichlorosilane, and is prepared by heating treatment under vacuum conditions or immersion treatment in a solution;

[0036] The elastomer substrate is prepared by a solution spin coating method from any one of polyurethane elastomer, polydimethylsiloxane, hydrogenated styrene-butadiene block copolymer and styrene-butadiene rubber;

[0037] The surface of the elastomer substrate is subjected to ultraviolet ozonation treatment;

[0038] The thickness of the elastomer substrate is 0.3 mm to 2 mm.

[0039] Wherein, the intrinsic flexible anode electrode and the intrinsic flexible cathode electrode are both AgNW electrodes, which are obtained by patterning AgNW ink on a substrate using an electrospray printing method;

[0040] The dispersion liquid of the AgNW ink is any one of water, ethanol and isopropanol solvents;

[0041] The AgNW has a length of 20 to 50 μm and a diameter of 20 to 50 nm;

[0042] The thickness of the intrinsic flexible anode electrode and the intrinsic flexible cathode electrode are both 30-100 nm;

[0043] The intrinsic flexible anode modification layer is prepared by an electrospray printing method, and the ink used is a mixed solution of PEDOT:PSS ink and DMSO, wherein the mass fraction of the DMSO can be 15%;

[0044] The conditions of the electrospray printing are as follows:

[0045] The applied voltage is 1 to 10 kV, the nozzle model is one of 21G, 23G, 24G, 25G, 26G, 27G, 30G, 32G and 34G, the distance between the nozzle and the substrate is 0.1 to 0.5 mm, the ink extrusion rate is 2 to 100 μL / min, the substrate movement rate is 1 to 300 mm / s, and the printing cycle is 1 to 10 times.

[0046] The intrinsic flexible hole transport layer is prepared by a solution spin coating method using a blend of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and any one of Triton-100, Triton-45 and sorbitol, with a ratio of 1:1 to 1:5.

[0047] The intrinsic flexible electron transport layer is prepared by a solution spin coating method using a blend of polyethoxyethyleneimine and any one of zinc acetate dihydrate, 4,7-diphenyl-1,10-phenanthroline and poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide, with a ratio of 1:1 to 1:5.

[0048] The present invention selects a universal elastomer dopant to prepare a polymer composite light-emitting film, and applies it to multicolor PLED / IFPLED, which has a simple preparation process, low cost, and is conducive to industrial application. The PLED / IFPLED prepared by the present invention has a low turn-on voltage and excellent stability, and has broad application prospects in the fields of drive display, virtual reality, enhanced display, brain-computer interface, artificial intelligence, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a schematic diagram of the structure of the PLED device provided by the present invention.

[0050] Figure 2 This is a schematic diagram of the structure of the IFPLED device provided by the present invention.

[0051] Figure 3 It is the molecular formula of polycaprolactone polyurethane PU / PCL.

[0052] Figure 4 These are the contact angles of three polyurethanes: PU / PCL, TPU (BASF 1185A) and TPU (Lubrizol SG-80A) with water and diiodomethane.

[0053] Figure 5 The tensile modulus of three polyurethanes: PU / PCL, TPU (BASF 1185A) and TPU (Lubrizol SG-80A).

[0054] Figure 6 AFM morphology images of SY-PPV blended with PU / PCL with mass fractions of 0wt% and 30wt% at different magnification ratios.

[0055] Figure 7 Optical microscope images of the yellow light material SY-PPV blended with PU / PCL in different proportions under different tensile strains.

[0056] Figure 8 Optical microscope images of red light material MDMO-PPV and PU / PCL blended in different proportions under different tensile strains.

[0057] Fig. 9 Optical microscope images of the green light material PFOPV blended with PU / PCL in different proportions under different tensile strains.

[0058] Fig.10 Optical microscope images of blue light material PFB blended with PU / PCL in different proportions under different tensile strains.

[0059] Fig.11 The brightness-current density-voltage curve of the PLED device prepared by blending the yellow light material SY-PPV and PU / PCL in different proportions as the light-emitting layer.

[0060] Fig.12 The brightness-current density-voltage curve of the PLED device prepared by blending the red light material MDMO-PPV and PU / PCL in different proportions as the light-emitting layer.

[0061] Fig.13 The brightness-current density-voltage curve of the PLED device prepared by blending the green light material PFOPV with PU / PCL in different proportions as the light-emitting layer.

[0062] Fig.14The brightness-current density-voltage curve of the PLED device prepared by blending the blue light material PFB and PU / PCL in different proportions as the light-emitting layer.

[0063] Fig.15 This is the brightness-current density-voltage curve of the IFPLED device prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0064] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0065] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0066] The elastomeric polymer dopant used in the following examples is polycaprolactone polyurethane PU / PCL, which is obtained by block copolymerization of polycaprolactone diol (PCL) and 4,4-diphenylmethane diisocyanate (MDI). n is about 80,000, and its molecular formula is Figure 3 shown.

[0067] The PLED based on the polymer composite light-emitting film provided by the present invention is a vertical structure, and its structure is as follows Figure 1 As shown, from bottom to top, it includes a substrate, an anode, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode; wherein the light-emitting layer is obtained by blending an elastomeric polymer with a light-emitting conjugated polymer and then by solution spin coating.

[0068] The IFPLED based on the polymer light-emitting composite film provided by the present invention is a vertical structure, and its structure is as follows Figure 2 As shown, from bottom to top, it includes an intrinsic flexible elastomeric substrate, an intrinsic flexible anode electrode, an intrinsic flexible anode electrode modification layer, an intrinsic flexible hole transport layer, an intrinsic flexible light-emitting layer, an intrinsic flexible electron transport layer, and an intrinsic flexible cathode electrode; wherein the light-emitting layer is obtained by blending an elastomeric polymer with a light-emitting conjugated polymer and then by solution spin coating, and the intrinsic flexible anode electrode, the intrinsic flexible anode electrode modification layer and the intrinsic flexible cathode electrode are prepared by electrospray printing technology.

[0069] In the following examples, the electrical properties of PLED and IFPLED were measured under nitrogen atmosphere and room temperature.

[0070] Example 1: Preparation of elastomeric polycaprolactone polyurethane PU / PCL polymer film

[0071] 1) Using a glass sheet as a substrate, ultrasonically treat with detergent, deionized water, acetone and isopropanol at a power of 50 W and a frequency of 30 kHz for 10 min in sequence, blow dry with a nitrogen gun, and then treat the cleaned glass sheet with oxygen plasma (power of 100 Hz) for 10 min. Then, place the clean glass sheet in a clean glass culture dish, add n-hexane and octadecyltrimethoxysilane in a volume ratio of 1000:1 with a pipette, and place the culture dish at room temperature and atmospheric atmosphere for 5 min, take out the glass sheet, and obtain a glass sheet with a self-assembled molecular layer.

[0072] 2) Weigh an appropriate amount of PU / PCL material and dissolve it in N,N-dimethylformamide (DMF) to prepare a 100 mg / ml solution.

[0073] 3) Place the glass sheet with the self-assembled molecular layer prepared in step 1) on a hot stage, slowly draw 0.5 ml of PU / PCL solution with a 1 mL syringe and evenly drop it on the glass sheet with the self-assembled molecular layer (2 cm × 2 cm), and then anneal at 80 ° C for 4 hours to obtain a PU / PCL elastomer film with a thickness of 1 mm. Contact angle test and tensile modulus test of pure elastomer material PU / PCL are performed as follows Figure 4 and 5 shown.

[0074] Comparative Example 1:

[0075] 1) According to the same method as in Example 1, the PU / PCL solution in step 2) and step 3) was replaced with other types of polyurethane (including SG-80A and 1185A), and a 200 mg / ml solution was prepared by drop coating to prepare an elastomeric film for tensile modulus testing. In addition, a flat film was prepared by spin coating for contact angle measurement.

[0076] Figure 4 The contact angles of three polyurethanes, PU / PCL, TPU (BASF 1185A) and TPU (Lubrizol SG-80A), with water and diiodomethane. As can be seen from the figure, PCL increases the hydrophobicity of the structure and reduces the polarity.

[0077] Figure 5 It is the tensile modulus test of three polyurethanes: PU / PCL, TPU (BASF 1185A) and TPU (Lubrizol SG-80A). As can be seen from the figure, under the same thickness, the tensile strain is in the range of 0-100%, and the tensile modulus of PU / PCL varies in the range of 0.1-3MPa, which is closer to the modulus of human skin.

[0078] Example 2: Preparation of a composite luminescent film based on a blend of a luminescent conjugated polymer and an elastomer

[0079] 1) Using a silicon wafer as a substrate, ultrasonically treat with detergent, deionized water, acetone and isopropanol at a power of 50 W and a frequency of 30 kHz for 10 min in sequence, blow dry with a nitrogen gun, and then treat the cleaned silicon wafer with oxygen plasma (power of 100 Hz) for 10 min, then place the clean silicon wafer in a clean glass culture dish, then place the clean silicon wafer and 1 μL of octadecyltrimethoxysilane in the same culture dish, and place the culture dish in a vacuum drying oven at a vacuum degree of 0.1 Pascal and 120° C. for 3 h, wait until the vacuum drying oven is cooled to room temperature, take out the culture dish, and obtain a silicon wafer with a self-assembled molecular layer.

[0080] 2) Using a glass sheet as a substrate, ultrasonically treat the glass sheet with detergent, deionized water, acetone and isopropanol at a power of 50 W and a frequency of 30 kHz for 10 min in sequence. After being blown dry with a nitrogen gun, the cleaned glass sheet is treated with oxygen plasma (power of 100 Hz) for 10 min. Then, the clean glass sheet is placed in a clean glass culture dish, and n-hexane and octadecyltrimethoxysilane in a volume ratio of 1000:1 are added with a pipette. The culture dish is placed at room temperature and atmospheric conditions for 5 min, and the glass sheet is taken out to obtain a glass sheet with a self-assembled molecular layer.

[0081] 3) Place the silicon wafer with the self-assembled molecular layer prepared in step 1) at the center of the rotor of the coating machine, use a 50 μL pipette to extract 40 μL of the mixed solution of the luminescent conjugated polymer and the elastomeric polymer (the luminescent conjugated polymer materials include yellow light material SY-PPV (4 mg / ml), red light material MDMO-PPV (4 mg / ml), green light material PFOPV (2 mg / ml) and blue light material PFB (4 mg / ml), the elastomeric material is PU / PCL, the blending ratios are 10wt%, 30wt% and 50wt% respectively, and the solvent is THF), then evenly drop 40 μL of the solution on the silicon wafer with the self-assembled molecular layer, start the coating machine, and keep it at a speed of 7000 rpm for 1 min. Finally, the substrate was removed and placed on a hot plate at 80°C for annealing for 10 minutes to obtain a polymer luminescent composite film. The film thickness of different luminescent materials was different: 60nm for the yellow light material SY-PPV, 50nm for the red light material MDMO-PPV, 40nm for the green light material PFOPV, and 30nm for the blue light material PFB.

[0082] 4) Use a 100 ml glass beaker to weigh the PDMS184 stock solution and the cross-linking agent in a mass ratio of 15:1, and then stir with a glass cup for 5 minutes to mix them evenly. Then place the beaker with the PDMS184 stock solution and the cross-linking agent in a vacuum drying oven at 0.1 Pascal vacuum and room temperature for 30 minutes. After the bubbles in the solution in the beaker are completely removed, take out the beaker to obtain the PDMS elastomer precursor solution.

[0083] 5) Place the glass sheet with the self-assembled molecular layer prepared in step 2) on a hot stage, slowly draw 0.5 ml of the PDMS elastomer precursor solution with a 1 mL syringe and evenly drop it on the glass sheet (2 cm × 4 cm) with the self-assembled molecular layer, and then anneal at 80°C for 4 hours to obtain a PDMS elastomer substrate with a thickness of 1 mm.

[0084] 6) Peel off the elastomeric substrate prepared in step 5) from the surface of the glass sheet, evenly bond it to the surface of the silicon wafer with the polymer light-emitting composite film prepared in step 4), and place it on a hot plate at 80°C and heat it for 10 minutes. The heating makes the elastomeric substrate and the polymer light-emitting composite film fit more closely. Use tweezers to clamp the elastomeric substrate and quickly peel it off. The polymer light-emitting composite film can be peeled off from the surface of the silicon wafer by utilizing the viscosity of PDMS. This method can be used to prepare a polymer light-emitting composite film on the surface of the elastomeric substrate.

[0085] Comparative Example 2: Preparation of polymer luminescent film without elastomer doping

[0086] According to the same preparation method as in Example 2, the mixed solution of the luminescent conjugated polymer and the elastomeric polymer used in step 3) was replaced with a pure luminescent conjugated polymer solution (the luminescent conjugated polymer material included yellow light material SY-PPV (4 mg / ml), red light material MDMO-PPV (4 mg / ml), green light material PFOPV (2 mg / ml) and blue light material PFB (4 mg / ml), and the conditions of other steps were the same, to prepare an elastomeric substrate with a pure luminescent conjugated polymer film.

[0087] By comparing the AFM images of Example 2 and Comparative Example 2 ( Figure 6 ), the polymer luminescent composite film undergoes microphase separation to form a porous network microscopic phase separation morphology.

[0088] Through optical microscopy ( Figure 7-10 ) were blended with PU / PCL in different proportions and under different tensile strains. It was found that with the increase of the PU / PCL blending ratio, the stretchability of the polymer luminescent composite film gradually improved.

[0089] Example 3: Preparation of PLED based on the polymer luminescent composite film of Example 2

[0090] 1) A glass sheet is used as a substrate, and a 120 nm thick ITO anode electrode is sputtered on the surface of the glass sheet by a sputtering process. Detergent, deionized water, acetone and isopropanol are used in sequence for ultrasonic treatment at a power of 50 W and a frequency of 30 kHz for 10 minutes. After being blown dry with a nitrogen gun, a clean glass sheet with an ITO electrode is obtained. The glass sheet is treated with oxygen plasma (power of 100 Hz, time of 10 minutes) to increase the work function of the ITO electrode, thereby obtaining a glass substrate with an ITO electrode with a higher work function.

[0091] 2) Place the glass sheet (2 cm × 2 cm) with ITO positive electrode prepared in step 1) at the center of the rotor of the coating machine, and set the parameters of the coating machine to a speed of 4000 rpm, a time of 60 s, and an acceleration of 500 m / s 2 , use a 1ml syringe to extract 0.5ml of PEDOT / PSS solution, and evenly drop 0.2ml of it on the glass substrate with ITO electrode, start the coating machine, and evenly coat the PEDOT / PSS film on the substrate surface. Finally, remove the substrate and place it on a hot plate at 100℃ for annealing for 30min to obtain a glass substrate with an anode electrode and a hole transport layer film, and the thickness of the hole transport layer film is 40nm.

[0092] 3) Place the glass substrate with the positive electrode and the hole transport layer prepared in step 2) at the center of the rotor of the glue machine, extract 100 μL of the mixed solution of the luminescent conjugated polymer and the elastomeric polymer used in step 3) of Example 1 with a 200 μL pipette, and then evenly drop 80 μL of it on the substrate, start the glue machine, and keep it at a speed of 7000 rpm for 1 minute. Finally, remove the substrate and place it on a hot stage at 80°C for 20 minutes to obtain a glass substrate with a positive electrode, a hole transport layer and a polymer composite thin film luminescent layer. The film thickness of different luminescent materials is different, the yellow light material SY-PPV is 60nm, the red light material MDMO-PPV is 50nm, the green light material PFOPV is 40nm and the blue light material PFB is 30nm.

[0093] 4) The glass substrate with the anode, hole transport layer and polymer composite thin film luminescent layer prepared in step 3) is placed in a vacuum coating machine, and a layer of small molecule TPBi is evaporated on the surface of the polymer luminescent composite thin film as an electron transport layer material. The pressure in the chamber of the vacuum coating machine is maintained at 1×10 -5 mbar or less, the evaporation rate is With a thickness of 50 nm, a glass substrate with an anode, a hole transport layer, a polymer composite thin film light-emitting layer and an electron transport layer can be obtained.

[0094] 5) The glass substrate with the positive electrode, the hole transport layer, the polymer composite thin film light-emitting layer and the electron transport layer prepared in step 4) is placed in a vacuum coating machine, and a layer of inorganic material LiF is evaporated on the surface of the electron transport layer film as an electron injection layer. The pressure in the chamber of the vacuum coating machine is maintained at 1×10 -5 mbar or less, the evaporation rate is With a thickness of 1.1 nm, a glass substrate with an anode, a hole transport layer, a polymer composite thin film light-emitting layer, an electron transport layer and an electron injection layer can be prepared.

[0095] 5) Place the mask with strip electrodes on the glass substrate with the anode electrode, hole transport layer, polymer composite thin film light-emitting layer, electron transport layer and electron injection layer prepared in step 5) and place it in a vacuum coating machine, evaporate a layer of patterned metal electrode material on the surface of the electron injection layer film as the cathode electrode, and maintain the pressure in the chamber of the vacuum coating machine at 1×10 -5 mbar or less, the evaporation rate is With a thickness of 100 nm, a PLED based on a polymer light-emitting composite thin film light-emitting layer can be prepared.

[0096] Figure 11-Figure 14 This is the brightness-current density curve of the PLED prepared in this example. It can be seen from the curve that as the mass fraction of the blended elastomer increases, the maximum brightness of the PLED increases first and then decreases, and the current density decreases, indicating that the device can achieve higher luminous brightness at a lower current density, improving the efficiency of the device. At the same time, the device also has a lower turn-on voltage. For the yellow light material SY-PPV, the turn-on voltage of the device is 2.7V, and the maximum brightness is 21072Cd / m 2 For the red light material MDMO-PPV, the device has a turn-on voltage of 3.6V and a maximum brightness of 1463Cd / m 2 For the green light material PFOPV, the device has a turn-on voltage of 2.8V and a maximum brightness of 7070Cd / m 2 For the blue light material PFB, the device has a turn-on voltage of 3.0V and a maximum brightness of 4387Cd / m 2 .

[0097] Example 4: Preparation of IFPLED based on the polymer luminescent composite film of Example 2

[0098] 1) Using a glass sheet as a substrate, ultrasonically treating the glass sheet with detergent, deionized water, acetone and isopropanol at a power of 50 W and a frequency of 30 kHz for 10 min in sequence, blowing it dry with a nitrogen gun, and then treating the cleaned glass sheet with ultraviolet ozone (power of 100 Hz) for 10 min, then placing the clean glass sheet in a clean glass culture dish, adding n-hexane and octadecyltrimethoxysilane in a volume ratio of 1000:1 with a pipette, and placing the culture dish at room temperature and atmospheric conditions for 5 min, taking out the glass sheet, and obtaining a glass sheet with a self-assembled molecular layer.

[0099] 2) Place a glass sheet with a self-assembled molecular layer on a hot stage, slowly draw 0.5 ml of TPU (Lubrizol SG-80A) DMF solution (concentration of 200 mg / mL) with a 1 mL syringe and evenly drop it on the glass sheet with the self-assembled molecular layer (including two specifications of 2 cm×2 cm and 5 cm×5 cm glass sheets), and then anneal at 100°C for 2 hours to obtain an elastomer substrate with a thickness of 1 mm.

[0100] 3) The elastomer substrate (2 cm × 2 cm) prepared in step 2) was placed on the sample stage of the electrospray printing instrument, and AgNW ink (wherein the specifications of AgNW are as follows: diameter 30 nm, length 20 μm) was extracted with a 2.5 ml glass syringe, and the ink extrusion rate was set to 10 μL / min, the moving rate of the sample stage was set to 50 mm / s, the printing cycle was set to 1, the voltage was between 5 kV and 7 kV, the nozzle model was 30G, and the distance between the nozzle and the substrate was 0.1 mm. AgNW ink was printed at room temperature to obtain a patterned intrinsically flexible AgNW thin film electrode with a thickness of about 50 nm.

[0101] 4) The elastomeric substrate with the intrinsic flexible AgNW thin film anode electrode prepared in step 3) is placed on the sample stage of the electrospray printing instrument, and a 1 ml glass syringe is used to extract the PEDOT:PSS and DMSO mixed ink. The ink extrusion rate is set to 10 μL / min, the movement rate of the sample stage is 50 mm / s, the printing cycle is 1, and PEDOT:PSS is printed on the intrinsic flexible AgNW thin film electrode. Thermal annealing is performed to obtain an intrinsic flexible anode modification layer with a thickness of about 3 μm.

[0102] 5) Place the elastomer substrate with the intrinsic flexible AgNW thin film anode electrode and its modified layer prepared in step 4) at the center of the rotor of the sizing machine, extract 100 μL of the mixed solution of PEDOT / PSS and Triton X-100 (the solvent is water, and the mass ratio of PEDOT / PSS and Triton X-100 is 1:2.5) with a 200 μL pipette, and then evenly drop 100 μL of the mixed solution of PEDOT / PSS and Triton X-100 on the elastomer substrate with the intrinsic flexible AgNW thin film electrode, start the sizing machine, and keep it at a speed of 2000 rpm for 1 minute. Finally, remove the substrate and place it on a hot plate at 100°C for annealing for 30 minutes. The thickness of the intrinsic flexible hole transport layer film is 70 nm.

[0103] 6) Place the elastomeric substrate with the intrinsic flexible AgNW film anode electrode and its modified layer and the intrinsic flexible hole transport layer film prepared in step 5) at the center of the rotor of the sizing machine, extract 100 μL of SY-PPV and PU / PCL blended tetrahydrofuran solution with a 200 μL pipette (wherein the mass ratio of the two polymers is 7:3, and the concentration of SY-PPV in the mixture solution is 10 mg / mL), and then evenly drop 70 μL of it on the substrate, start the sizing machine, and keep it at a speed of 2000 rpm for 1 min. Finally, remove the silicon wafer and place it on a hot plate at 80°C for 20 min to obtain an elastomeric substrate with an intrinsic flexible AgNW film anode electrode, an intrinsic flexible hole transport layer film and an intrinsic flexible light-emitting layer film, and the thickness of the intrinsic flexible light-emitting layer film is 70 nm.

[0104] 7) Place the elastomer substrate with the intrinsic flexible AgNW film anode electrode and its modified layer, the intrinsic flexible hole transport layer film and the intrinsic flexible light-emitting layer film prepared in step 6) at the center of the rotor of the coating machine, extract 150 μL of the mixed solution of PEIE and PFNBr (wherein the mass ratio of the two polymers is 1:1, the concentration of PEIE in the mixed solution is 5 mg / ml, and the solvent is methanol) with a 200 μL pipette, and then evenly drop 100 μL of it on the substrate, start the coating machine, and keep it at a speed of 2000 rpm for 1 minute. Finally, remove the silicon wafer and place it on a hot plate at 100°C for 5 minutes. The thickness of the intrinsic flexible electron transport layer film is 40 nm.

[0105] 8) Place the elastomeric substrate with the intrinsic flexible AgNW thin film anode electrode and its modified layer, intrinsic flexible hole transport layer thin film, intrinsic flexible luminescent layer thin film and intrinsic flexible electron transport layer thin film prepared in step 7) on the sample stage of the electrospray printing instrument, and print AgNW ink on the substrate to obtain a patterned intrinsic flexible AgNW thin film cathode electrode according to the operation method and process conditions of step 3), and the thickness of the thin film cathode electrode is about 50nm. The above steps can produce an IFPLED based on an intrinsic flexible luminescent composite thin film luminescent layer.

[0106] Figure 3 It is a schematic diagram of the structure of the IFPLED device provided by the present invention. Fig.15 Brightness-current density-voltage curve of the IFPLED device prepared in this embodiment and the large-area light-emitting array display diagram. The turn-on voltage of the device is 4V and the maximum brightness is 1621Cd / m 2 , with good uniformity in 4×6 large-area light-emitting display arrays.

[0107] The above experimental results show that the new elastomer dopant is universal, and the PLED and IFPLED based on polymer luminescent composite film have the characteristics of high brightness, low turn-on voltage and high efficiency, which provides a simple and effective strategy for realizing high-performance driving displays in the future.

Claims

1. A polymer composite luminescent film prepared from a blend of a luminescent conjugated polymer and an elastomer dopant; The elastomer doping agent is a polycaprolactone type polyurethane or a thermoplastic polyurethane obtained by block copolymerization of polycaprolactone diol and 4,4-diphenylmethane diisocyanate.

2. The polymer composite light-emitting film according to claim 1, Features: In the blend, the mass content of the elastomer dopant is 10 to 50%; The polymer composite light-emitting film is prepared by using the blend through a solution spin coating method; The thickness of the polymer composite luminescent film is 30-100 nm.

3. The polymer composite light-emitting film according to claim 1 or 2, Features: The luminescent conjugated polymer is poly[{2,5-bis(3',7'-dimethyloctyloxy)-1,4-phenylethynyl}-co-{3-(4'-(3",7"-dimethyloctyloxy)phenyl)-1,4-phenylethynyl}-co-{3-(3'-(3",7"-dimethyloctyloxy)phenyl)-1,4-phenylethynyl}], poly(9,9-di-n-octylfluorenyl-2,7-diyl), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylethynyl], poly[(9,9-di-n-octylfluorenyl-2,7-phenyleneethynyl)] At least one of poly[(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenediamine)-alt-(9,9-di-n-octylfluorenyl-2,7-diyl)], poly[(9,9-di-octylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)] and poly[2-methoxy-5-[(3,7-dimethyloctyloxy)-1,4-phenyl]-1,2-ethylenediyl].

4. Application of the polymer composite light-emitting film according to any one of claims 1 to 3 in a highly flexible display device, a stretchable display device and an intrinsically flexible display device; The polymer composite luminescent film serves as a luminescent layer.

5. A polymer light-emitting diode, comprising an ITO anode electrode, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode electrode arranged in sequence; The light-emitting layer is the polymer composite light-emitting film according to any one of claims 1 to 3.

6. The polymer light emitting diode according to claim 5, Features: The material of the hole transport layer is any one of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, poly(9-vinylcarbazole), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-n-butyl)phenyl)-diphenylamine)], 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline], N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine and 4,4',4"-tri(carbazole-9-yl)triphenylamine; Depositing the hole transport layer by solution deposition or vacuum evaporation deposition; The thickness of the hole transport layer is 30-60 nm.

7. The polymer light emitting diode according to claim 5 or 6, Features: The material of the electron transport layer is any one of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, 1,3,5-tris[(3-pyridyl)-3-phenyl]benzene, zinc oxide nanoparticles, polyethoxyethyleneimine, 4,6-bis(3,5-di(3-pyridyl)phenyl)-2-methylpyrimidine and 4,7-diphenyl-1,10-phenanthroline and poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide; The electron transport layer is prepared by solution spin coating or vacuum evaporation deposition; The thickness of the electron transport layer is 10 to 50 nm.

8. The polymer light emitting diode according to any one of claims 5 to 7, Features: The electron injection layer is made of lithium fluoride or 8-hydroxyquinoline lithium; Depositing the electron injection layer by vacuum evaporation deposition; The thickness of the electron injection layer is 1 to 2 nm; The cathode electrode is Al or Ag; The cathode electrode is prepared by vacuum evaporation method.

9. An intrinsically flexible polymer light-emitting diode, comprising a substrate, a sacrificial layer, an elastomeric substrate, an intrinsically flexible anode electrode, an intrinsically flexible anode electrode modification layer, an intrinsically flexible hole transport layer, an intrinsically flexible light-emitting layer, an intrinsically flexible electron transport layer and an intrinsically flexible cathode electrode arranged in sequence; The intrinsic flexible light-emitting layer is the polymer composite light-emitting film according to any one of claims 1 to 3.

10. The intrinsically flexible polymer light emitting diode according to claim 9, Features: The substrate is selected from any one of silicon wafer, glass, ceramic and quartz; The sacrificial layer is selected from at least one of octadecyltrimethoxysilane, octadecyltrichlorosilane, octadecyltrichlorosilane and phenyltrichlorosilane, and is prepared by heating treatment under vacuum conditions or immersion treatment in a solution; The elastomer substrate is prepared by a solution spin coating method from any one of polyurethane elastomer, polydimethylsiloxane, hydrogenated styrene-butadiene block copolymer and styrene-butadiene rubber; The surface of the elastomer substrate is subjected to ultraviolet ozonation treatment; The thickness of the elastomer substrate is 0.3 mm to 2 mm.

11. The intrinsically flexible polymer light-emitting diode according to claim 9 or 10, Features: The intrinsic flexible anode electrode and the intrinsic flexible cathode electrode are both AgNW electrodes, which are obtained by patterning AgNW ink on a substrate using an electrospray printing method; The dispersion liquid of the AgNW ink is any one of water, ethanol and isopropanol solvents; The AgNW has a length of 20 to 50 μm and a diameter of 20 to 50 nm; The thickness of the intrinsic flexible anode electrode and the intrinsic flexible cathode electrode are both 30-100 nm; The intrinsic flexible anode modification layer is prepared by an electrospray printing method, and the ink used is a mixed solution of PEDOT:PSS ink and DMSO; The conditions of the electrospray printing are as follows: The applied voltage is 1 to 10 kV, the nozzle model is one of 21G, 23G, 24G, 25G, 26G, 27G, 30G, 32G and 34G, the distance between the nozzle and the substrate is 0.1-0.5 mm, the ink extrusion rate is 0.1 to 100 μL / min, the substrate movement rate is 1 to 300 mm / s, and the printing cycle is 1 to 10 times.

12. The intrinsically flexible polymer light emitting diode according to any one of claims 9 to 11, Features: The intrinsic flexible hole transport layer is prepared by a solution spin coating method from a blend of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid and any one of Triton-100, Triton-45 and sorbitol, with a ratio of 1:1 to 1:5; The intrinsic flexible electron transport layer is prepared by a solution spin coating method using a blend of polyethoxyethyleneimine and any one of zinc acetate dihydrate, 4,7-diphenyl-1,10-phenanthroline and poly(9,9-bis(3'-(N,N-dimethyl)-N-ethylaminopropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)) dibromide, with a ratio of 1:1 to 1:5.

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