A method for preparing a PDMS in-situ wrinkled antireflection film and a monochromatic organic light-emitting diode

Abstract

The present invention discloses a method for preparing a PDMS in-situ wrinkled anti-reflection film and a monochromatic organic light-emitting diode. The method is based on the physical and chemical process of self-assembly of the breathing pattern of water vapor on the surface of the PDMS polymer, combined with the compressive stress generated by spin coating, which causes the skin layer of the PDMS film to become unstable and synergistically produces a wrinkled structure. Water molecules act as the master in the traditional method. When the water vapor evaporates and dries, the master is removed by itself to obtain a wrinkled unit structure. The wrinkle size is regulated by conditions such as humidity, spin coating speed, and the type and amount of solvent in the dilution solution. A functional layer is vacuum evaporated on the conductive side of the substrate containing the wrinkled anti-reflection film to construct a red, green or blue light OLED device. The method of the present invention is a simple and efficient method for in-situ anti-reflection. Compared with the existing technology, the method for preparing the OLED wrinkled anti-reflection film provided by the present invention has the characteristics of simple process, low cost, and adjustable size, thereby significantly enhancing the light output of the red, green or blue light OLED using the PDMS wrinkled anti-reflection film.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-processing and light-emitting diode preparation, in particular to a preparation method of a PDMS in-situ wrinkled anti-reflection film and a monochromatic organic light-emitting diode. Background Art

[0002] Organic light-emitting diodes (OLEDs) have shown great application potential in full-color flat-panel displays and solid-state lighting due to their advantages such as autonomous luminescence, wide viewing angle, rich colors, and low-voltage DC drive. Although the internal quantum efficiency of OLEDs is almost 100%, due to light extraction losses caused by waveguide modes, substrate modes, and plasmon modes, approximately 80% of the photons emitted by the organic light-emitting layer are confined inside the device, and only about 20% of the photons are transmitted to the outside, resulting in the external quantum efficiency being much lower than the internal quantum efficiency. Therefore, enhancing the light extraction of OLEDs can effectively improve the actual light extraction efficiency of the device and improve its practical value. Methods for improving OLED light extraction include external light extraction and internal light extraction. Among them, external light extraction mainly includes introducing diffraction gratings, light scattering media, anode surface patterns, microlenses, scattering films, sandblasting, multi-layer stepped films, etc. outside the device. Most of the above technologies involve complex processes such as multiple pattern transfers, or require expensive equipment, harsh reaction conditions, high costs, or are not suitable for flexible substrates.

[0003] The study found that random micro-nano lens structures, light-scattering medium layers, polymer porous scattering films, random concave-convex corrugated structures, textured mesh substrates, and random wrinkled structures have no significant effect on the brightness distribution and spectral stability of the device, but can achieve good external light extraction. Directly preparing a layer of anti-reflection film in situ on the device surface is a relatively simple, low-cost method suitable for large-area light extraction. The key to achieving this goal is to prepare an anti-reflection film with a uniform and controllable random wrinkled structure at the micro-nano scale. The study found that the generation of the wrinkled structure on the film surface must be based on a base layer and an epidermis layer with different elastic moduli. On this basis, it is necessary to obtain a double-layer film sample with different physical properties, and then introduce stress to make the sample unstable to form a wrinkled structure.

[0004] Currently, the commonly used methods for preparing wrinkled membranes include tensile force method, solvent-induced method, template printing method, and laser direct writing method. Among them, the tensile force method requires mechanical assistance, the stress is generally large, and only macroscopic wrinkles can be obtained; the wrinkles prepared by the solvent-induced method are very sensitive to the diffusion behavior of the solvent and have high environmental requirements, making it difficult to prepare on a large scale; the template printing method can obtain wrinkle replicas similar to the master, but there are relatively cumbersome processes such as the master needing to be demolded and prepared in advance; although the laser direct writing method can obtain smaller and adjustable wrinkles, the equipment used is expensive, which increases the preparation cost, becoming a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In order to solve the problems of the prior art, the purpose of the present invention is to overcome the shortcomings of the existing technology and provide a PDMS in-situ corrugated anti-reflection film and a method for preparing a monochromatic organic light-emitting diode. The corrugated anti-reflection film is formed in situ based on the physical and chemical process of the breathing diagram method combined with the compressive stress generated by spin coating. Based on this anti-reflection film, a variety of monochromatic OLED devices are prepared, which significantly improves the external light extraction efficiency and the final external quantum efficiency.

[0006] In order to achieve the above invention purpose, the present invention adopts the following technical solutions:

[0007] A method for preparing a PDMS in-situ wrinkled antireflection film and a monochromatic organic light emitting diode comprises the following steps:

[0008] (1) mixing a PDMS prepolymer and a curing agent in a set mass ratio, and adding an organic solvent to dilute the mixture to obtain a PDMS mixed solution; vacuum degassing the mixed solution for 30 to 60 minutes and setting aside; and adjusting the relative humidity of the atmosphere inside the spin coater to 60 to 90% using deionized water;

[0009] (2) After the humidity inside the spin coater is stable, the cleaned conductive substrate is placed horizontally with the non-conductive side of the reverse side facing upwards, and 100 to 200 microliters of the degassed PDMS mixed solution is uniformly dripped onto the surface and allowed to stand for 60 to 120 seconds; the conductive substrate is fixed on the spin coater and spin-coated at a speed of 2000 to 6000 rpm for at least 60 seconds; annealing is performed at 80 to 200°C for 3 to 10 hours to obtain a PDMS wrinkled anti-reflection film; the present invention heats deionized water to boiling, and then introduces the generated steam into the spin coater so that the humidity in the closed environment reaches a dynamic equilibrium, controls the relative humidity, and maintains the heating temperature constant to prepare a PDMS wrinkled anti-reflection film; the wrinkled anti-reflection film is formed in situ on the conductive substrate without the need for a transfer or adhesion step;

[0010] (3) The PDMS wrinkled antireflection film and the conductive substrate are cleaned with an organic solvent, and a vacuum evaporated red, green or blue organic light emitting diode is formed in situ on the conductive side surface of the conductive substrate.

[0011] Preferably, in step (1), the mass ratio of the prepolymer to the curing agent is 10: 1. The refractive index of the PDMS corrugated antireflection film is close to that of glass, which is conducive to light emission.

[0012] Preferably, in step (1), the organic solvent is any one of chloroform, dichloromethane, chlorobenzene, and dichlorobenzene, or a mixture thereof; the mixture of PDMS prepolymer and PDMS crosslinker is diluted with the organic solvent at a ratio of 0.2 to 2.0 ml of the organic solvent to 3.3 g of the mixture. The PDMS corrugated antireflection film has a refractive index close to that of glass, which facilitates light emission.

[0013] Preferably, in step (2), the environmental humidity is brought into dynamic equilibrium by monitoring the environmental humidity using a hygrometer to maintain the environmental humidity at any humidity within the range of 60 to 90%.

[0014] Preferably, in step (2), the material of the conductive substrate is at least one of ITO, FTO, AZO, IZO, PET / ITO, and PI / ITO.

[0015] Preferably, in step (2), the prepared PDMS wrinkled antireflection film has a wrinkle structure ranging from nanometers to micrometers, with a wrinkle width of 1.0 to 5.0 um, a wrinkle height of 0.5 to 3.0 um, and a wrinkle gap of 0.5 to 1.5 um.

[0016] Preferably, in the step (3), when preparing a monochromatic organic light emitting diode, the conductive substrate containing the wrinkled antireflection film is firstly ultrasonically cleaned with an organic solvent, dried, and then treated with UV-O3 for 15 to 30 minutes with the conductive side of the substrate facing upwards;

[0017] The conductive side of the substrate is then placed downward in a vacuum evaporation chamber, and a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer are sequentially deposited. The light-emitting layer is a red, green, or blue light-emitting layer. The mask is replaced, and a metal cathode is evaporated on the electron injection layer to prepare a red, green, or blue organic light-emitting diode.

[0018] Preferably, in step (3), the material of the conductive substrate is at least one of ITO, FTO, AZO, IZO, PET / ITO, and PI / ITO.

[0019] Preferably, in step (3), the preferred small molecule materials for the hole injection layer include but are not limited to 4,4',4"-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine(m-MTDATA), 4,4',4"-tris(N-(naphthaalene-2-yl)-N-phenyl-amino)triphenylamine(2T-NATA), copper(II)phthalocyanine(CuPC), titanium(IV)oxide Phthalocyanine(TiOPC), pyrazino[2,3-f][1,10]phenanthroline-2,3–dicarbonitrile(PPDN), N,N,N',N'-tetrakis(4-methoxyphenyl)benzidine(MeO-TPD), N,N'–diph enyl-N,N'-di-[4-(N,N-di-p-tolyl-amino)phenyl]benzidine(NTNPB), N4,N4'-(biphenyl-4,4'-diyl)bis(N4,N4',N4'-triphenylbiphenyl-4,4'-diamine)(TPT1), dipyr azino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN), diquinoxalino[2,3-a:2',3'-c]phenazine (HATNA), 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4-TCNQ), 2,2'-(naphthalene-2,6-diylidene)dimalononitrile (TNAP); preferably, the hole injection layer has a film thickness of 20 to 50 nm.

[0020] The hole transport layer material is preferably N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine(NPB), N,N'-bis(3-methylpheny l)-N,N'-bis(phenyl)-benzidine(TPD)、4,4',4"-tris(carbazol-9-yl)triphenylamine(TcTa)、N,N'-bis(3 -methylphenyl)-N,N'-bis(phenyl)-2,7-diamino-9,9-spirobifluorene(Spiro-TPD)、N,N'-bis(naphthale n-1-yl)-N,N'-bis(phenyl)-2,7-diamino-9,9-dimethyl-fluorene(DMFL-NPB), 9,9-bis[4-(N,N-bis-napht at least one of: N,N-di-(1,2-diphenyl-2-yl-amino)phenyl]-9Hfluorene (NPAPF), di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane (TAPC), N1,N4-diphenyl-N1,N4-di-m-tolylbenzene-1,4-diamine (TTP), N4,N4'-bis(4-(6-((3-ethyl oxetan-3-yl)methoxy)hexyl)phenyl)-N4,N4'-diphenylbiphenyl-4,4'-diamine (OTPD), 4,4'-(diphenyllsilanediyl)bis(N,N-diphenylaniline) (TSBPA), and 4,4'-(diphenylmethylene)bis(N,N-diphenylaniline) (TCBPA); preferably, the hole transport layer has a film thickness of 40 to 60 nm;

[0021] Preferably, in step (3), the light-emitting layer is a red, green or blue light-emitting layer, wherein the light-emitting guest material is any one of fluorescent, phosphorescent and thermally activated delayed fluorescent materials that emit green, blue or red light;

[0022] Preferably, the green light-emitting host material is selected from at least one of fac-tris(2-phenylpyridine)iridium(III)(fac-Ir(ppy)3), bis(2-phenylpyridine)(acetylacetonate)iridium(III)(Ir(ppy)2(acac)), 9,10-bis[N,N-di-(p-tolyl)-amino]anthracene(TTPA), N 10 ,N 10 ,N 10 ',N 10 '-tetraphenyl-9,9'-bianthracene-10,10'-diamine(BA-TAD), 9,9',9”-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzene-1,2,3-triyl)tris(3,6-dimethyl-9H-carbazole)(TmCzTrz), (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile(4CzIPN), 2,5-bis(4-(10H-phenoxazin-10-yl)phenyl)-1,3,4-oxadiazole(2PXZ-OXD), 10,10'-(4,4'-sulfonylbis(4,1-phenylene))bis(10H-phenoxazine)(PXZ-DPS), 1,4-bis(9,9-dimethylacridan-10-yl-pphenyl)-2,5-bis(p-tolyl-methanoyl)benzene(AcPmBPX), bis(4-(9,9-dimethylacridin-10(9H)-yl)phenyl)methanone(DMAC-BP), 5-chloro-2,4,6-tris(3,6-di-tert-butyl-9H-carbazol-9-yl)isophthaloni trile(t3CzIPN), 4,4”-di-10H-phenoxazin-10-yl[1,1':2',1”-terphenyl]-4',5'-dicarbon itrile(Px-VPN);

[0023] Preferably, the blue light host material is at least one of 4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl(BCzVBi), perylene, 2,5,8,11-tetra-tert-butylperylene(TBPe), 4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl(DPAVBi), 4,4'-bis[4-(diphenylamino)styryl]biphenyl(BDAVBi), 1,4-bis(4-(9H-carbazol-9-yl)styryl)benzene(BCzSB), bis(2,4-difluorophenylpyridinato)(5-(pyridin-2-yl)-1H-tetrazolate)iridium(III)(FIrN4), fac-tris(1,3-diphenyl-benzimidazolin-2-ylidene-C,C2')iridium(III)(fac-Ir(dpbic)3), bis(4-(9H-3,9'-bicarbazol-9-yl)phenyl)methanone(CC2BP), 10,10'-(4,4'-sulfonylbis(4,1-phenylene))bis(9,9-dimethyl-9,10-dihydroacridine)(DMAC-DPS), 10,10'-(4,4'-(4-phenyl-4H-1,2,4-triazole-3,5-diyl)bis(4,1-phenylene))bis(10H-phenoxazine)(2PXZ-TAZ), 10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9,9-dimethyl-9,10-dihydroacridine(DMAC-TRZ), 2,3,4,6-tetra(9H-carbazol-9-yl)-5-fluorobenzonitrile(4CZFCN);

[0024] Preferably, the red light host material adopts (E)-2-(2-(4-(dimethylamino)styryl)-6-methyl-4H-pyran-4-ylidene)malononitrile (DCM), 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran (DCJTB), 5,6,11,12-tetraphenylnaphthacene (Rubrene), tetraphenyldibenzoperiflanthene (DBP), bis(2-benzo[b]thiophen-2-yl-pyridine)(acetylacetonate)iridium(III) (Ir(btp)2(acac)), bis[2-(9,9-dimethyl-9H-fluoren-2-yl)quinoline](acetylacetonate)iridium(III) (Ir(flq)2(acac)), platium(II)5,10,15,20-tetraphenyltetrabenzoporphyrin (Pt(TPBP)), bis(2-phenylpyridine)(3-(pyridine-2-yl)-2H-chromen-2-onate)iridium(III) (fac-Ir(ppy)2Pc), platium(II)octaethylporphine (PtOEP), tris(dibenzoylmethane)phenanthroline europium(III) (Eu(dbm)3(Phen)), tris[4,4'-di-tert-butyl-(2,2')-bipyridine]ruthenium(III) complex (Ru(dtb-bpy)3·2(PF6)), 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene (TBRb), 2-[4-(diphenylamino)phenyl]-10,10-dioxide-9H-thioxanthen-9-one (TXO-TPA), 5,6-bis(4-(9,9-dimethylacridin-10(9H)-yl)phenyl)pyrazine-2,At least one of 3-dicarbonitrile (Ac-CNP).

[0025] The luminescent host material is preferably 1,3-bis(carbazol-9-yl)benzene(mCP), 2,8-bis(diphenylphosphoryl)dibenzo[b,d]thiophene(PPT), 4,4',4"-tris(carbazol-9-yl)tripheny lamine(TcTa), 4,4'-bis(carbazol-9-yl)biphenyl(CBP), bis[2-(diphenylphosphino)phenyl]ether At least one of oxide (DPEPO), 2,6-di(9H-carbazol-9-yl)pyridine (PYD-2Cz), 2,4,6-tris(3-(9H-carbazol-9-yl)phenyl)-1,3,5-triazine (TCPZ), 4'-(9H-carbazol-9-yl)biphenyl-3,5-dicarbonitrile (BCzTPA), 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene (TmPyPB), and 10-(4-(4-(9H-carbazol-9-yl)phenylsulfonyl)phenyl)-9,9-dimethyl-9,10-dihydroacridine (CzAcSF); preferably, the thickness of the light-emitting layer is 15 to 60 nm.

[0026] The electron transport layer material is preferably 4,7-diphenyl-1,10-phenanthroline (Bphen), 2,2',2"-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), bathocuproine (BCP), tris-(8-hydroxyquinolinato)aluminum (Alq3), 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), bis(2-methyl-8-qu inolinolate)-4-(phenylphenolato)aluminium(BAlq), 1,3-bis[2-(2,2'-bipyridine-6-yl)-1,3,4-oxadiazo-5-yl]benzene(Bpy-OXD), 4-(naphthal en-1-yl)-3,5-diphenyl-4H-1,2,4-triazole(NTAZ), tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane(3TPYMB), phenyl-dipyrenylphosphine At least one of oxide (POPy2), 1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene (OXD-7), 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene (TmPyPB), and Cs2CO3; preferably, the film thickness of the electron transport layer is 40 to 60 nm.

[0027] The electron injection layer material is preferably at least one of lithium fluoride (LiF), 8-hydroxyquinolinolato-lithium (Liq), cesium fluoride (CsF), 8-hydroxyquinoline sodium salt (NaQ), and magnesium fluoride (MgF2); the electron injection layer preferably has a film thickness of 1.0 to 10 nm.

[0028] The conductive cathode material is preferably at least one of Al, Ag, Au, IZO, Ca, magnesium-silver alloy and lithium-aluminum alloy; the cathode thickness is 60 to 120 nm.

[0029] Preferably, in step (3), the evaporation rate of each functional layer material should be controlled to: the evaporation rate of the electron injection layer material is The evaporation rate of cathode material is The evaporation rate of other organic matter is

[0030] In the present invention, a corrugated anti-reflection film is prepared on the non-conductive side of the reverse side of a conductive substrate, and an organic functional layer is evaporated on the conductive side of the substrate under a vacuum environment to prepare an OLED device. The light emitted from the OLED device passes through the anti-reflection film and is emitted into the air. The optical refraction and anti-total reflection of the corrugations are used to enhance the light output.

[0031] Preferably, a method for preparing a PDMS in-situ wrinkled antireflection film and a monochromatic organic light emitting diode comprises the following steps:

[0032] 1) Cleaning the conductive substrate and drying it with nitrogen;

[0033] 2) Mix the prepolymer, cross-linking agent and diluent in appropriate proportions, stir evenly, and degas under vacuum;

[0034] 3) In a high humidity environment, the PDMS mixed solution prepared in step 2) is dripped onto the non-conductive side surface of the conductive substrate treated in step 1), spin-coated to form a film, and calcined and solidified to prepare a wrinkled antireflection film;

[0035] 4) The PDMS wrinkled antireflection film / conductive substrate obtained in step 3) was ultrasonically cleaned with various solutions and treated with UV-O3 for 15 to 30 minutes;

[0036] 5) placing the antireflection film / substrate treated in step 4) with the conductive side facing downward in a vacuum deposition chamber, and sequentially depositing a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer, wherein the light-emitting layer is a red, green, or blue light-emitting layer;

[0037] 6) The mask is replaced, and a metal material is evaporated on the surface of the electron injection layer prepared in step 5) to form a cathode electrode layer, thereby preparing an organic light emitting diode containing a wrinkled antireflection film.

[0038] The present invention utilizes the self-assembly principle of the breathing diagram method in combination with the stress introduced by spin coating to form a simple and effective method for forming a wrinkled anti-reflection film. The breathing diagram method is a method in which water droplets condensed onto the surface of a polymer solution are used as a template and the self-assembly of the water droplets is used as a driving force to prepare a periodic structure with uniform distribution and uniform size under a relatively high humidity environment. This preparation method has the advantages of low cost, no need for complex equipment, no need for demolding due to self-removal of the template, a wide range of polymer selection, and in-situ film formation. Therefore, the present invention combines the physicochemical process based on the breathing diagram method with the compressive stress generated by spin coating to form a wrinkled anti-reflection film in situ, and prepares a variety of monochrome OLED devices based on this anti-reflection film, significantly improving the external light extraction efficiency and the final external quantum efficiency.

[0039] Compared with the prior art, the present invention has the following obvious outstanding substantial features and significant advantages:

[0040] 1. Compared to traditional methods for preparing PDMS wrinkled antireflection films, this method utilizes the physical and chemical process between the volatilization of organic solvents and the condensation of water molecules on the polymer surface, combined with the compressive stress generated by spin coating, to destabilize the PDMS membrane's surface layer and form a wrinkled structure. Water vapor self-assembly acts as the master in traditional methods, and the master is removed after the water vapor evaporates and dries. The synergistic effect of water vapor condensation self-assembly and the compressive stress generated by spin coating results in an optimally morphological wrinkled unit structure.

[0041] 2. Compared with the existing technology, the preparation method of the PDMS wrinkled antireflection film provided by the present invention has the advantages of in-situ film formation on the conductive substrate without the need for transfer or adhesion steps, simple process, low cost, rapidity, and large-area processing capability;

[0042] 3. By regulating the humidity within a wide range of 60% to 90% by adjusting the water vapor flow rate, and controlling the spin coating speed and the type and amount of solvent used to dilute the PDMS solution, different fold heights and depths can be obtained, making the size easily adjustable and the size range more flexible;

[0043] 4. In-situ construction of red, green, or blue OLED devices on the conductive side of a substrate containing a PDMS wrinkled anti-reflection film does not affect the device's internal structure, brightness distribution, or spectral stability. By utilizing the optical refraction and anti-total reflection of the wrinkled rough surface, the output light of the red, green, or blue OLED is softened, improving display quality. Furthermore, because the refractive index of the polymer layer is close to that of glass, the coupling effect that prevents all light from being emitted from the front is avoided, thereby enhancing the visible brightness of the red, green, or blue device. This is a simple and efficient method for in-situ anti-reflection.

[0044] 5. The method provided by the present invention is applicable to a variety of monochrome OLED devices and different device structures. The anti-reflection film has stable performance and significant light-emitting enhancement effect. It can also take into account the mass production of light-emitting devices of different areas, rigidity and flexibility, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 The present invention provides a flow chart of the method for preparing the PDMS corrugated antireflection film.

[0047] Figure 2 This is a flow chart of the method for preparing an organic light emitting diode provided by the present invention.

[0048] Figure 3 This is a schematic diagram of the structure of an OLED device containing a wrinkled anti-reflection film provided by the present invention.

[0049] Figure 4 These are scanning electron microscope (SEM) images of PDMS wrinkled antireflection films of different thicknesses prepared at different coating rates in an embodiment of the present invention.

[0050] Figure 5 This is a comparison chart of the current efficiency and external quantum efficiency of the PDMS corrugated antireflection film device prepared by mixing 1.0 ml of chloroform solution at different rotation speeds under 75% humidity in the preferred embodiment 1 of the present invention and the device in the reference example.

[0051] Figure 6 This is the effect of the antireflection film prepared by mixing different amounts of chloroform-diluted PDMS solution in the preferred embodiment 1 of the present invention on the luminescence performance of the green light OLED device.

[0052] Figure 7 This is a comparison chart of the current efficiency and external quantum efficiency of the PDMS corrugated antireflection film device prepared at different rotation speeds in the preferred embodiment 2 of the present invention and the device in the reference example. DETAILED DESCRIPTION

[0053] The above solution is further described below with reference to specific implementation examples. The preferred embodiments of the present invention are described in detail as follows:

[0054] Example 1

[0055] In this embodiment,

[0056] See also Figure 1 and Figure 2 A method for preparing a PDMS in-situ wrinkled antireflection film and a monochromatic organic light emitting diode comprises the following steps:

[0057] Step 100: Weigh 3.3 g of PDMS prepolymer and PDMS crosslinker in a 10:1 mass ratio, add them to a clean transparent reagent bottle, and take 0.5 mL, 1.0 mL, and 1.5 mL of chloroform, respectively, to mix with the PDMS solution;

[0058] Step 101: Stir evenly, seal, and place the mixed solution in a moderate vacuum environment for degassing for 1 hour;

[0059] Step 102: After heating deionized water to boiling, the generated steam is introduced into the spin coater to allow the humidity in the closed environment to reach a dynamic equilibrium, and the relative humidity is controlled to be 75%;

[0060] Step 103: After the ITO glass substrate is ultrasonically cleaned with detergent, acetone, deionized water, and isopropyl alcohol, it is treated with UV-O3 for 15 to 30 minutes, and then 120 μL of the PDMS solution in step 101 is added dropwise to the non-conductive side surface of the substrate and allowed to stand for 60 seconds;

[0061] Step 104: placing the PDMS solution / substrate in a stable dynamic humidity environment, and spin coating at 2000, 4000, and 6000 rpm for 60 seconds to obtain wrinkled films of different thicknesses, and then annealing at 80-200° C. for 3-10 hours to obtain a PDMS wrinkled film;

[0062] Step 200: The dried PDMS wrinkled film / ITO glass substrate in step 104 is ultrasonically cleaned using detergent, acetone, deionized water, and isopropyl alcohol, and then treated with UV-O3 for 15 to 30 minutes;

[0063] Step 201: Place the substrate in step 200 with the conductive side facing downward in a vacuum deposition chamber and sequentially deposit functional layers, including MoO3 (5 nm) / NPB (35 nm) / 4CzIPN:CBP (5 wt%, 15 nm) / TPBi (40 nm) / LiF (0.8 nm);

[0064] Step 202: Finally, replace the mask to evaporate cathode metal Al to prepare an electrode cathode layer with a thickness of 80-100 nm. In this way, an OLED device with a light-emitting area of ​​not less than 2 mm×2 mm is prepared.

[0065] Control the evaporation rate to: organic matter LiF is AL is So far, green OLED devices based on PDMS wrinkled anti-reflection film (such as Figure 3 ) Preparation is completed.

[0066] The preparation process of the reference device is basically the same as that of Example 1, with the only difference being that there is no wrinkled antireflection film in the reference device.

[0067] SEM images of wrinkled antireflection films prepared at different spin coating rates ( Figure 4 ) shows that the fold unit structure is uniform and the morphology is similar, but the width of the fold unit varies with the rotation speed, indicating that the spin coating rate has no significant effect on the fold morphology, but the fold size is adjustable; Figure 3 The devices were tested for luminescence. The current efficiency and EQE of green devices without antireflection film and with different thickness antireflection films prepared under 1.0ml chloroform and 75% humidity were shown in Fig. Figure 5 .Depend on Figure 5 It can be seen that the light extraction efficiency of the green OLED device with the wrinkled antireflection film prepared in Example 1 is significantly enhanced. The current efficiency is increased from 45.21 cd / A in the reference example to 51.44 cd / A, 57.31 cd / A and 53.65 cd / A respectively. According to the test results, the maximum brightness of the device is increased from 6721 cd / m 2 increased to 7254cd / m 2 , 8874cd / m 2 and 7344cd / m 2 The maximum EQE of the device increased from 20.14% of the reference to 23.15%, 24.74% and 23.44% respectively. The effect of mixing 0.5ml, 1.0ml and 1.5ml of chloroform in PDMS solution on the performance of green OLED devices is shown in Figure 6 The highest EQEs are 10.52%, 24.68% and 18.34% respectively. It can be seen that 1.0ml of chloroform is conducive to obtaining a relatively better pleated structure and has a better anti-reflection effect on OLED light output.

[0068] Example 2

[0069] This embodiment is basically the same as the first embodiment, with the following special features:

[0070] In this embodiment, a method for preparing a PDMS in-situ wrinkled antireflection film and a monochromatic organic light emitting diode includes the following steps:

[0071] Step 100: Weigh 3.3 g of PDMS prepolymer and PDMS crosslinker in a 10:1 mass ratio, add them to a clean transparent reagent bottle, and mix 1.0 mL of chloroform with the PDMS solution;

[0072] Steps 101 to 200: These steps are the same as those in Example 1;

[0073] Step 201: The substrate from step 200 is placed with the conductive side facing downward in a vacuum deposition chamber and sequentially deposited with functional layers, including MoO3 (5 nm) / NPB (35 nm) / mCP (5 nm) / DMAC-DPS:DPEPO (10 wt%, 20 nm) / DPEPO (10 nm) / Bphen (40 nm) / LiF (0.8 nm).

[0074] Step 202: Finally, replace the mask to evaporate the cathode metal Al to prepare an electrode cathode layer with a thickness of 80 to 100 nm. In this way, an OLED device with a light-emitting area of ​​not less than 2 mm × 2 mm is prepared. The evaporation rate of organic matter is: LiF is AL is So far, blue OLED devices based on PDMS wrinkled anti-reflection film (such as Figure 3 ) Preparation is completed.

[0075] The preparation process of the reference device is basically the same as that of Example 1, with the only difference being that there is no wrinkled antireflection film in the reference device.

[0076] In this embodiment, the device is tested for light emission, and the current efficiency and EQE are shown in FIG. Figure 7 .Depend on Figure 7 As can be seen, the blue OLED device with a corrugated anti-reflection film, prepared in Example 2, exhibits significantly enhanced light extraction efficiency. Current efficiency increases from 23.98 cd / A for the device without an anti-reflection film to 25.47 cd / A, 29.67 cd / A, and 25.34 cd / A, respectively. EQE increases from 14.14% for the device without an anti-reflection film to 15.79%, 16.28%, and 14.98%, respectively. As can be seen from the figure, the maximum EQE increases by 11.7%, 15.1%, and 5.9%, respectively.

[0077] The above-mentioned embodiment of the preparation method of the PDMS in-situ wrinkled anti-reflection film and the monochromatic organic light-emitting diode adopts the preparation method of the PDMS wrinkled anti-reflection film, based on the physical and chemical process of self-assembly of the breathing diagram of water vapor on the surface of the PDMS polymer, combined with the compressive stress generated by spin coating to cause the epidermis of the PDMS film to become unstable and synergistically produce a wrinkled structure. Water molecules act as the master in the traditional method. When the water vapor evaporates and dries, the master is removed by itself, and the morphology of the wrinkled unit structure is optimized. The size of the wrinkles is regulated by conditions such as humidity, spin coating speed, and the type and amount of solvent of the dilution solution. In this way, a film is formed in situ on the non-conductive side of the conductive substrate to serve as an anti-reflection film for red, green or blue organic light-emitting diodes (OLEDs). A functional layer is vacuum evaporated on the conductive side of the substrate containing the wrinkled anti-reflection film to construct a red, green or blue OLED device. The refractive index of PDMS is close to that of glass, facilitating light emission. Furthermore, the optical refraction and anti-total reflection of the wrinkled, rough surface soften the light emitted by the red, green, or blue OLED, enhancing visual brightness. This method is a simple and efficient in-situ anti-reflection method. Compared to existing technologies, the method for preparing the OLED wrinkled anti-reflection film in the above embodiment offers advantages such as simplicity, low cost, and adjustable size. This significantly enhances light emission from the red, green, or blue OLEDs using this wrinkled PDMS anti-reflection film.

[0078] The above describes the embodiments of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principles of the technical solution of the present invention should be equivalent replacement methods. As long as they comply with the purpose of the invention and do not deviate from the technical principles and inventive concepts of the present invention, they belong to the scope of protection of the present invention.

Claims

1. A method for preparing a PDMS in-situ wrinkled antireflection film and a monochromatic organic light emitting diode, characterized in that: The steps include: (1) PDMS prepolymer and curing agent were mixed at a predetermined mass ratio, and 0.2 to 2.0 ml of organic solvent was added to 3.3 g of the mixture of PDMS prepolymer and PDMS crosslinker to obtain a PDMS mixed solution; the mixed solution was vacuum degassed for 30 to 60 minutes and set aside; the relative humidity of the atmosphere inside the spin coater was adjusted to 60 to 90% using deionized water; (2) After the humidity inside the spin coater stabilizes, the cleaned conductive substrate is placed horizontally with the non-conductive side facing upward, and 100 to 200 microliters of degassed PDMS mixed solution is uniformly dripped onto the surface and allowed to stand for 60 to 120 seconds; the conductive substrate is fixed on the spin coater and spin-coated at a speed of 2000 to 6000 rpm for at least 60 seconds; annealing is performed at 80 to 200°C for 3 to 10 hours to obtain a PDMS wrinkled anti-reflection film; the PDMS wrinkled anti-reflection film has a wrinkle structure ranging from nanometers to micrometers, with a wrinkle width of 1.0 to 5.0 μm, a wrinkle height of 0.5 to 3.0 μm, and a wrinkle gap of 0.5 to 1.5 μm; the wrinkle size is regulated by using humidity, spin coating speed, solvent type and dosage of the PDMS solution; (3) The PDMS wrinkled antireflection film and the conductive substrate are cleaned with an organic solvent, and a red, green or blue monochromatic organic light emitting diode is formed by in-situ vacuum evaporation on the conductive side surface of the conductive substrate.

2. The method for preparing the PDMS in-situ wrinkled antireflection film and the monochromatic organic light emitting diode according to claim 1, characterized in that: In the step (1), the mass ratio of the prepolymer to the curing agent is 10:

1.

3. The method for preparing the PDMS in-situ wrinkled antireflection film and monochromatic organic light emitting diode according to claim 1, characterized in that: In the step (1), the organic solvent is any one of chloroform, dichloromethane, chlorobenzene and dichlorobenzene, or a mixture of any two or more thereof, and is diluted with the organic solvent.

4. The method for preparing the PDMS in-situ wrinkled antireflection film and the monochromatic organic light emitting diode according to claim 1, characterized in that: In the step (2), the environmental humidity is made to reach a dynamic balance by using a hygrometer to monitor the environmental humidity so as to maintain the environmental humidity at any humidity within the range of 60% to 90%.

5. The method for preparing the PDMS in-situ wrinkled antireflection film and monochromatic organic light emitting diode according to claim 1, characterized in that: In the step (2), the material of the conductive substrate is at least one of ITO, FTO, AZO, IZO, PET / ITO, and PI / ITO.

6. The method for preparing the PDMS in-situ wrinkled antireflection film and monochromatic organic light emitting diode according to claim 1, characterized in that: In the step (3), when preparing a monochromatic organic light emitting diode, the conductive substrate containing the wrinkled antireflection film is firstly ultrasonically cleaned with an organic solvent, dried, and then treated with UV-O3 for 15 to 30 minutes with the conductive side of the substrate facing upward; The conductive side of the substrate is then placed downward in a vacuum evaporation chamber, and a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer are sequentially deposited. The light-emitting layer is a red, green, or blue light-emitting layer. The mask is replaced, and a metal cathode is evaporated on the electron injection layer to prepare a red, green, or blue organic light-emitting diode.

7. The method for preparing the PDMS in-situ wrinkled antireflection film and the monochromatic organic light emitting diode according to claim 6, characterized in that: In step (3), the light-emitting layer is a red, green or blue light-emitting layer, wherein the light-emitting guest material is any one of fluorescent, phosphorescent and thermally activated delayed fluorescent materials that emit green, blue or red light; The green light-emitting host materials include at least one of fac-tris(2-phenylpyridine)iridium(III) (fac-Ir(ppy)3), bis(2-phenylpyridine)(acetylacetonate)iridium(III) (Ir(ppy)2(acac)), 9,10-bis[N,N-di-(p-tolyl)-amino]anthracene (TTPA), N 10 ,N 10 ,N 10' ,N 10' -tetraphenyl-9,9'-bianthracene-10,10'-diamine(BA-TAD)、 9,9',9”-(5-(4,6-diphenyl-1,3,5-triazin-2-yl)benzene-1,2,3-triyl)tris(3,6-dimethyl-9H-carbazole) (TmCzTrz), (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN), 2,5-bis(4-(10H-phenoxazin-10-yl)phenyl)-1,3,4-oxadiazole (2PXZ-OXD), 10,10'-(4,4'-sulfonylbis(4,1-phenylene))bis(10H-phenoxazine) (PXZ-DPS), 1,4-bis(9,9-dimethylacridan-10-yl-pphenyl)-2,5-bis(p-tolyl-methanoyl)benzene (AcPmBPX), bis(4-(9,9-dimethylacridin-10(9H)-yl)phenyl)methanone (DMAC-BP), 5-chloro-2,4,6-tris(3,6-di-tert-butyl-9H-carbazol-9-yl)isophthalonitrile (t3CzIPN), 4,4”-di-10H-phenoxazin-10-yl[1,1':2',1”-terphenyl]-4',5'-dicarbonitrile (Px-VPN); The blue-light host materials include at least one of 4,4'-bis(9-ethyl-3-carbazovinylene)-1,1'-biphenyl (BCzVBi), perylene, 2,5,8,11-tetra-tert-butylperylene (TBPe), 4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi), 4,4'-bis[4-(diphenylamino)styryl]biphenyl (BDAVBi), 1,4-bis(4-(9H-carbazol-9-yl)styryl)benzene (BCzSB), bis(2,4-difluorophenylpyr idinato)(5-(pyridin-2-yl)-1H-tetrazolate)iridium(III) (FIrN4), fac-tris(1,3-diphenyl-benzimidazolin-2-ylidene-C,C2')iridium(III) (fac-Ir(dpbic)3), bis(4-(9H-3,9'-bicarbazol-9-yl)phenyl)methanone (CC2BP), 10,10'-(4,4'-sulfonylbis(4,1-phenylene))bis(9,9-dimethyl-9,10-dihydroacridine) (DMAC-DPS), 10,10'-(4,4'-(4-phenyl-4H-1,2,4-triazole-3,5-diyl)bis(4,1- phenylene))bis(10H-phenoxazine) (2PXZ-TAZ), 10-(4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl)-9,9-dimethyl-9,10-dihydroacridine (DMAC-TRZ), 2,3,4,6-tetra(9H-carbazol-9-yl)-5-fluorobenzonitrile (4CZFCN); The red-light host materials include (E)-2-(2-(4-(dimethylamino)styryl)-6-methyl -4H-pyran-4-ylidene)malononitrile (DCM), 4-(dicyanomethylene)-2-tert-butyl-6-(1, 1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran(DCJTB), 5,6,11,12-tetra phenylnaphthacene(Rubrene), tetraphenyldibenzoperiflanthene(DBP), bis(2-benzo[b]thiophen-2-yl-pyridine)(acetylacetonate)iridium(III)(Ir(btp)2(acac)), bis[2-(9,9-dimethyl-9H-fluoren-2-yl)quinoline](acetylacetonate)iridium(III)(Ir(flq)2(acac)), platium(II)5,10,15,20-tetraphenyltetrabenzoporphyrin(Pt(TPBP)), bis(2-phenylpyridine)(3-(pyridine-2-yl)-2H-chromen-2-onate)iridium(III)(fac-Ir(ppy)2Pc), platium(II)octaethylporphine(PtOEP), tris(dibenzoylmethane)phenanthrolineeuropium(III) (Eu(dbm)3(Phen)), tris[4,4'-di-tert-butyl-(2,2')-bipyridine]ruthenium(III)complex (Ru(dtb-bpy)3·2(PF6)), 2,8-di-tert-butyl-5,11-bis(4-tert-butylphenyl)-6,12-diphenyltetracene(TBRb), 2-[4-(diphenyllamino)phenyl]-10,10-dioxide-9H -thioxanthen-9-one(TXO-TPA), 5,6-bis(4-(9,9-dimethylacridin-10(9H)-yl)phenyl) pyrazine-2,3-dicarbonitrile(Ac-CNP) or at least one of them.

8. The method for preparing the PDMS in-situ wrinkled antireflection film and the monochromatic organic light emitting diode according to claim 6, characterized in that: In step (3), the evaporation rate of each functional layer material should be controlled as follows: the evaporation rate of the electron injection layer material is The evaporation rate of cathode material is The evaporation rate of other organic matter is

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