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

Abstract

The present invention discloses a method for preparing a PDMS in-situ wrinkled anti-reflection film and a white-light organic light-emitting diode. The method is based on the physical and chemical process between the volatilization of the organic solvent on the polymer surface and the condensation of water vapor on the PDMS polymer surface, and the compressive stress generated by spin coating causes the membrane surface layer to become unstable, thereby synergistically generating a wrinkled structure. Water molecules act as the master in the traditional method. When the water vapor evaporates and dries, the master is removed to obtain a wrinkled unit structure. This method is used to form a film in situ on the non-conductive side of a conductive substrate, acting as an anti-reflection film for a white-light organic light-emitting diode (OLED). The present invention utilizes the optical refraction and anti-total reflection of the wrinkled rough surface to make the emitted light of the white-light OLED softer and enhance the visible brightness. It is a simple and efficient method for in-situ anti-reflection. Compared with the prior art, the method for preparing the OLED wrinkled anti-reflection film provided by the present invention has the characteristics of simple process, low cost, adjustable size, etc., so that the light output of the white-light OLED using the PDMS wrinkled anti-reflection film is significantly enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-processing and light-emitting diode preparation, and in particular to a preparation method of a PDMS in-situ wrinkled antireflection film and a white light 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 device's external quantum efficiency being much lower than the internal quantum efficiency. Therefore, enhancing OLED light extraction can effectively improve the device's actual light extraction efficiency 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. In situ preparation of an antireflection film directly 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 antireflection film with a uniform and controllable random wrinkled structure at the micro-nano scale. The study found that the generation of wrinkles 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 cause the sample to become unstable and form a wrinkled structure.

[0004] Currently, the commonly used methods for preparing wrinkled films include tensile force, solvent-induced force, template printing, and laser direct writing. The tensile force method requires mechanical assistance, resulting in generally high stress and only producing wrinkles on a macroscopic scale. The wrinkles produced by the solvent-induced method are very sensitive to the diffusion behavior of the solvent and have high environmental requirements, making large-scale production difficult. The template printing method can produce a replica of a seal similar to the master, but it involves a relatively cumbersome process such as the master demoulding process and the need for advance master preparation. Although the laser direct writing method produces smaller and adjustable wrinkles, the equipment used is expensive, increasing the production cost, which has become 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 preparation method for a white light organic light-emitting diode. The corrugated anti-reflection film is formed in situ based on the breathing pattern method combined with the compressive stress generated by spin coating, and a white light OLED device is prepared on a substrate containing the anti-reflection film to improve 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 wrinkled antireflection film, comprising the following steps:

[0008] (1) After mixing the PDMS prepolymer and the cross-linking agent at a set mass ratio in a glass container, an organic solvent is added for dilution to obtain a PDMS mixed solution;

[0009] (2) Stirring the PDMS mixed solution for a first set time, vacuum degassing for 30 to 60 minutes, and setting aside;

[0010] (3) After heating deionized water to boiling, the generated steam is introduced into the spin coater to achieve dynamic equilibrium of the closed environment humidity and control the relative humidity;

[0011] (4) Maintaining the heating temperature, after the humidity stabilization time reaches the second set time, the cleaned conductive substrate is placed horizontally with the non-conductive side of the back side facing upward, and 100 to 200 microliters of the degassed PDMS mixed solution is uniformly dripped onto the non-conductive side of the back side of the conductive substrate, and allowed to stand for 60 to 120 seconds;

[0012] (5) Fix the conductive substrate with the degassed PDMS mixed solution on a spin coater, wait for the humidity in the sealed environment to stabilize again, and then spin coat at a speed of 2000-6000 rpm for at least 60 seconds;

[0013] (6) The conductive substrate after spin coating is placed horizontally, and annealed at 80-200° C. for 3-10 hours to solidify to obtain a PDMS wrinkled antireflection film.

[0014] Preferably, in step (1), the set mass ratio of the PDMS prepolymer and the cross-linking agent is 10:1.

[0015] Preferably, in step (1), the organic solvent used for dilution is any one of chloroform, dichloromethane, chlorobenzene and dichlorobenzene, or a mixture of any of them, and the amount of organic solvent used for the mixture of 3.3 g of PDMS prepolymer and crosslinking agent is 0.2 to 2.0 ml.

[0016] Preferably, in step (2), the first setting time is 3-5 minutes. Preferably, the refractive index of PDMS is close to that of glass, which is conducive to light emission.

[0017] Preferably, in step (3), the method for making the ambient humidity reach dynamic equilibrium is: using a hygrometer to monitor the ambient humidity so as to keep the ambient humidity within the range of 60 to 90%.

[0018] Preferably, in step (4), the second set time is at least 3 minutes.

[0019] Preferably, in step (6), 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.

[0020] A method for preparing a white organic light-emitting diode based on the PDMS corrugated antireflection film prepared by the present invention comprises the following steps:

[0021] a. Using an organic solvent to ultrasonically clean the conductive substrate containing the PDMS wrinkled antireflection film, dry it, and place the conductive side of the conductive substrate upwards, and perform UV-O3 treatment for 15 to 30 minutes;

[0022] b. Place the conductive substrate with the conductive side facing down in a vacuum evaporation chamber, and sequentially deposit a hole injection layer, a hole transport layer, a white light emitting layer, an electron transport layer, and an electron injection layer; replace the mask and evaporate a metal cathode on the electron injection layer to prepare a white light OLED.

[0023] Preferably, in step a, the prepared PDMS wrinkled antireflection film / conductive substrate is ultrasonically cleaned using lotion, acetone, deionized water and isopropyl alcohol.

[0024] Preferably, the material of the conductive substrate is at least one of ITO, FTO, AZO, IZO, PET / ITO, and PI / ITO.

[0025] Preferably, the small molecule materials of the hole injection layer include but are not limited to MoO3, 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)be nzidine(MeO-TPD), N,N'–diphenyl-N,N'-di-[4-(N,N-di-p-tolyl-amino)phenyl]benzidine(NTNPB), N4,N4'-(biphenyl-4,4'-diyl)bis(N 4,N4',N4'-triphenylbiphenyl-4,4'-diamine)(TPT1), dipyrazino[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-tetr acyano-quinodimethane(F4-TCNQ), 2,2'-(naphthalene-2,6-diylidene)dimalononitrile(TNAP); preferably, the hole injection layer has a thickness of 20 to 50 nm;

[0026] Preferably, the hole transport layer material is N,N'-bis(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine(NPB), N,N'-bis(3-methylphenyl)-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(naphthalen-1-yl)-N,N'-bis(phenyl)-2,7-diamino-9,9-dimethyl-fluorene(DMFL-NPB), 9,9-bis[4-(N,N-bis-naphthol)] at least one of: n-(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-tolylben zene-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;

[0027] Preferably, the white light emitting layer is formed by stacking three single layers of red, green and blue light, or stacking two single layers of blue and yellow light, or co-doping blue and yellow light emitting guests to form a variety of device structures;

[0028] Preferably, the luminescent guest material is a combination of a fluorescent, phosphorescent or thermally activated delayed fluorescent material that emits any one of red, green, blue and yellow light;

[0029] 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-phenyl)-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);

[0030] Preferably, the blue light host material is at least one of bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III)(Firpic), 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-dime thyl-9,10-dihydroacridine(DMAC-TRZ), 2,3,4,6-tetra(9H-carbazol-9-yl)-5-fluorobenzonitrile(4CZFCN);<00,00075><00,00076>Preferably, the red light host material is<00,00077><00,00078>(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](acet ylacetonate)iridium(III)(Ir(flq)2(acac))、platium(II)5,10,15,20-tetra phenyltetrabenzoporphyrin(Pt(TPBP))、bis(2-phenylpyridine)(3-(pyri dine-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')-bipyrid ine]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-(diphenyl lamino)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);

[0033] Preferably, the yellow light guest material is 5,6,11,12-Tetraphenylnaphthacene (rubrene), iridium (III) bis (4-phenylthieno [3,2-c] pyridinato-N, C20) acetylacetonate (PO-01), bis [5-methyl-7-fluoro-5H-benzo (c) (1,5) naphthyridin-6-one] iridium (picolinate), acetylacetonatobis (4- (4-tert-butylphenyl) -thieno [3,2-c] pyrid inato-C2,N)iridium(Ir(tptpy)2(acac)), 2,4,6-Tris(4-(10H-phenoxazin-10-yl)phenyl)-1,3,5-triazine(tri-PXZ-TRZ), bis(1,2-diphenyl-1H-benzo[ d] At least one of imidazole)(acetylacetonate)iridium(III)(Ir(pbi)2(acac)), iridium(III)bis[2-(2-naphthyl)pyridine](acetylacetonate)(Ir(npy)2acac).

[0034] The luminescent host materials are 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 single-layer light-emitting layer is 15 to 60 nm;

[0035] 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 electron transport layer has a film thickness of 40 to 60 nm;

[0036] 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); preferably, the electron injection layer has a film thickness of 1.0 to 10 nm;

[0037] The conductive cathode material is preferably at least one of Al, Ag, Au, IZO, Ca, magnesium-silver alloy and lithium-aluminum alloy; the thickness of the cathode is preferably 60 to 120 nm.

[0038] Preferably, the evaporation rate of each functional layer material is controlled at:

[0039] 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

[0040] 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.

[0041] Preferably, a method for preparing a PDMS in-situ wrinkled antireflection film and a white organic light-emitting diode comprises the following steps:

[0042] 1) Cleaning the conductive substrate and drying it with nitrogen;

[0043] 2) Mix the prepolymer, cross-linking agent and diluent in appropriate proportions, stir evenly, and degas under vacuum;

[0044] 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;

[0045] 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;

[0046] 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 white light emitting layer, an electron transport layer, and an electron injection layer;

[0047] 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.

[0048] The breathing pattern method uses water droplets condensed onto the surface of a polymer solution as a template in a relatively high humidity environment, with the self-assembly of the water droplets as the driving force to produce uniformly distributed, sized periodic structures. This preparation method has the advantages of low cost, no need for complex equipment, self-removal of the template without the need for demolding, a wide range of polymer options, and in-situ film formation. Therefore, the present invention combines the breathing pattern method with the compressive stress generated by spin coating to form a wrinkled anti-reflection film in situ. White light OLED devices are prepared on substrates containing this anti-reflection film, improving the external light extraction efficiency and the ultimate external quantum efficiency.

[0049] Compared with the prior art, the present invention has the following obvious outstanding substantial features and significant advantages:

[0050] 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.

[0051] 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;

[0052] 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;

[0053] 4. In-situ construction of a white light OLED device 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 white light OLED's output light becomes softer, improving display quality. Furthermore, because the polymer layer's refractive index is close to that of glass, the coupling effect that prevents all light from being emitted from the front is avoided, enhancing the visible brightness of the white light device. This is a simple and efficient method for in-situ anti-reflection.

[0054] 5. The method provided by the present invention is applicable to white light OLED devices with 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 with different areas, rigidity and flexibility, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] 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.

[0056] Figure 1 The present invention provides a flow chart of the method for preparing the PDMS corrugated antireflection film.

[0057] Figure 2This is a flow chart of the method for preparing a white organic light emitting diode provided by the present invention.

[0058] Figure 3 This is a schematic diagram of the structure of a white light OLED device containing a wrinkled anti-reflection film provided by the present invention.

[0059] Figure 4 This is a comparison diagram of the emission of white light OLED devices with and without the wrinkled anti-reflection film in Example 1 provided by the present invention.

[0060] Figure 5 1 is a comparison chart of the current efficiency, external quantum efficiency and electroluminescence spectrum of the corrugated antireflection film device in Example 1 of the present invention and the reference device.

[0061] Figure 6 1 is a comparison chart of the current efficiency, external quantum efficiency and electroluminescence spectrum of the corrugated antireflection film device in Example 2 of the present invention and the reference device. DETAILED DESCRIPTION

[0062] 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:

[0063] Example 1

[0064] In this embodiment,

[0065] See also Figure 1 and Figure 2 A method for preparing a PDMS in-situ wrinkled antireflection film and a white organic light-emitting diode comprises the following steps:

[0066] Step 100: Weigh 3.3 g of PDMS prepolymer and PDMS crosslinker in a 10:1 weight ratio (w / w) and add them to a clean, transparent reagent bottle. Then, take 0.5 mL, 1.0 mL, and 1.5 mL of chloroform, respectively, and mix them with the PDMS solution.

[0067] Step 101: Stir evenly, seal, and place the mixed solution in a moderate vacuum environment for degassing for 1 hour;

[0068] 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%;

[0069] 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;

[0070] 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;

[0071] 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;

[0072] Step 201: The substrate in step 200 is placed with the conductive side facing downward in a vacuum evaporation chamber and sequentially deposited with functional layers, including MoO3 (10 nm) / TCTA (50 nm) / mCP:Firpic (8 wt%, 4 nm) / mCP:rubrene (3 wt%, 7 nm) / mCP:Firpic (8 wt%, 5.5 nm) / TPBi (40 nm) / LiF (0.8 nm);

[0073] 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, white light OLED devices based on PDMS wrinkled anti-reflection film (such as Figure 3 ) Preparation is completed.

[0074] 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.

[0075] The luminous contrast of the white light OLED device with and without the wrinkled anti-reflection film in this embodiment is as follows: Figure 4 As shown in Figure 2, the brightness of the device with anti-reflection film is significantly enhanced. The turn-on voltage is reduced from 4.2V to 4.1V, and the brightness is increased from 4831cd / m 2 Increased to 6313cd / m 2 ; Maximum current efficiency (CE) of the corrugated antireflection film device and the reference device max ), external quantum efficiency (EQE max ) and electroluminescence spectrum (EL) see Figure 5 .Depend on Figure 5 It can be seen that the current efficiency and EQE of the white light OLED device containing the wrinkled antireflection film prepared in Example 1 are significantly enhanced, and the CE max Improved from 5.61cd / A to 7.38cd / A; EQE maxThe EL spectrum shape remains unchanged, with the color coordinates remaining at (0.21, 0.33). This indicates that the wrinkled anti-reflection film does not change the color of the white light device, but only enhances the transmittance of the white OLED light.

[0076] Example 2

[0077] This embodiment is basically the same as the first embodiment, except that:

[0078] In this embodiment, a method for preparing a PDMS in-situ wrinkled antireflection film and a white organic light-emitting diode includes the following steps:

[0079] Step 100: Weigh 3.3 g of PDMS prepolymer and PDMS crosslinker in a 10:1 weight ratio (w / w) and add them to a clean, transparent reagent bottle. Mix 1.0 mL of chloroform with the PDMS solution.

[0080] Steps 101 to 200: These steps are the same as those in the first embodiment;

[0081] 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 NPB: rubrene (2 wt%, 50 nm) / BCP (8 nm) / Alq3 (30 nm) / Liq (1 nm);

[0082] 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: Liq is Al is So far, white light OLED devices based on PDMS wrinkled anti-reflection film (such as Figure 3 ) Preparation is completed.

[0083] 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.

[0084] In this embodiment, the device was tested for light emission, and the current efficiency (CE), EQE and EL spectrum were shown in Fig. Figure 6 .Depend on Figure 6 It can be seen that the light extraction efficiency of the white light OLED device containing the corrugated antireflection film prepared in Example 2 is significantly enhanced. The maximum brightness is increased from 5582 cd / m 2 Increased to 8397cd / m 2The maximum current efficiency increased from 1.78cd / A in the device without an anti-reflection film to 2.07cd / A. The maximum EQE increased from 0.91% in the device without an anti-reflection film to 1.01%. As can be seen from the figure, the maximum brightness, maximum CE, and maximum EQE increased by 50.4%, 16.3%, and 11%, respectively. In addition, the EL spectrum shape remained unchanged, with the color coordinates maintained at (0.30, 0.28). The wrinkled anti-reflection film does not change the light color of this white light device, but only has a better anti-reflection effect on the light output of the white light OLED.

[0085] The above-mentioned embodiment of the present invention is a method for preparing a PDMS in-situ wrinkled anti-reflection film and a white organic light-emitting diode. The method for preparing a PDMS wrinkled anti-reflection film adopts a method for preparing a PDMS wrinkled anti-reflection film. Based on the physical and chemical process between the volatilization of the organic solvent on the polymer surface and the condensation of water vapor on the PDMS polymer surface, the compressive stress generated by spin coating causes the membrane surface layer 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, and at the same time, the morphology of the wrinkled unit structure is optimized. The wrinkle size can be controlled by using conditions such as humidity, spin coating speed, and the type and amount of solvent in the dilution solution. The above-mentioned embodiment of the present invention forms a film in situ on the non-conductive side of the conductive substrate, which serves as an anti-reflection film for a white organic light-emitting diode (OLED). In addition, a functional layer is vacuum evaporated on the conductive side of the substrate containing the wrinkled anti-reflection film to form a variety of white light OLED devices with different structures, which are composed of three single layers of red light, green light, and blue light, or two single layers of blue light and yellow light, or co-doped with blue light and yellow light emitting guests. PDMS's refractive index 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 white OLEDs, enhancing visual brightness. This method is a simple and efficient in-situ anti-reflection method. Compared to existing technologies, the method for preparing a wrinkled OLED anti-reflection film provided by the above-mentioned embodiments of the present invention offers advantages such as simplicity, low cost, and adjustable size. This significantly enhances light emission from white OLEDs using this wrinkled PDMS anti-reflection film.

[0086] 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 white organic light emitting diode, characterized in that: Here are the steps: (1) After mixing a PDMS prepolymer and a cross-linking agent at a predetermined mass ratio in a glass container, an organic solvent is added for dilution. The amount of organic solvent used for a 3.3 g mixture of the PDMS prepolymer and the cross-linking agent is 0.2 to 2.0 ml, to obtain a PDMS mixed solution; (2) Stirring the PDMS mixed solution for a first set time, vacuum degassing for 30 to 60 minutes, and setting aside; (3) After heating deionized water to boiling, the generated steam is introduced into the spin coater to achieve dynamic equilibrium of the closed environment humidity and control the relative humidity; (4) Maintaining the heating temperature, after the humidity stabilization time reaches the second set time, the cleaned conductive substrate is placed horizontally with the non-conductive side of the back side facing upward, and 100 to 200 microliters of the degassed PDMS mixed solution is uniformly dripped onto the non-conductive side of the back side of the conductive substrate, and allowed to stand for 60 to 120 seconds; (5) Fix the conductive substrate with the degassed PDMS mixed solution on a spin coater, wait for the humidity in the sealed environment to stabilize again, and then spin coat at a speed of 2000-6000 rpm for at least 60 seconds; (6) placing the spin-coated conductive substrate horizontally, annealing and heat-treating it at 80-200° C. for 3-10 hours, and curing it 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 1.0-5.0 μm, a wrinkle height of 0.5-3.0 μm, and a wrinkle gap of 0.5-1.5 μm; The PDMS wrinkled antireflection film and the conductive substrate are then cleaned with an organic solvent, and a white 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 a white organic light emitting diode according to claim 1, wherein: In the step (1), the set mass ratio of the PDMS prepolymer and the cross-linking agent is 10:

1.

3. The method for preparing a white organic light emitting diode according to claim 1, wherein: In the step (1), the organic solvent used for dilution is any one of chloroform, dichloromethane, chlorobenzene and dichlorobenzene, or a mixture of any two of them.

4. The method for preparing a white organic light emitting diode according to claim 1, wherein: In step (2), the first set time is 3 to 5 minutes.

5. The method for preparing a white organic light emitting diode according to claim 1, wherein: In the step (3), the method for making the ambient humidity reach a dynamic balance is: using a hygrometer to monitor the ambient humidity so as to keep the ambient humidity within the range of 60% to 90%.

6. The method for preparing a white organic light emitting diode according to claim 1, wherein: In step (4), the second set time is at least 3 minutes.

7. The method for preparing a white organic light emitting diode according to claim 1, using the PDMS corrugated antireflection film prepared in step (6), characterized in that: Here are the steps: The conductive substrate including the PDMS wrinkled antireflection film was ultrasonically cleaned with an organic solvent, dried, and the conductive side of the conductive substrate was placed upward, and then subjected to UV-O3 treatment for 15 to 30 minutes; The conductive substrate is then placed with the conductive side facing down in a vacuum evaporation chamber, and a hole injection layer, a hole transport layer, a white light emitting layer, an electron transport layer, and an electron injection layer are sequentially deposited. The mask is replaced, and a metal cathode is evaporated on the electron injection layer to prepare a white light organic light-emitting diode.

8. The method for preparing a white organic light emitting diode according to claim 7, wherein: The white light emitting layer is formed by stacking three single layers of red, green and blue light, or stacking two single layers of blue and yellow light, or co-doping blue and yellow light emitting objects to form a variety of device structures; The luminescent guest material is a combination of fluorescent, phosphorescent or thermally activated delayed fluorescent materials that emit any one of red, green, blue and yellow light; Green light guest materials are 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]anthracesne(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), At least one of 5-chloro-2,4,6-tris(3,6-di-tert-butyl-9H-carbazol-9-yl)isophthalonitrile(t3CzIPN) and 4,4"-di-10H-phenoxazin-10-yl[1,1':2',1"-terphenyl]-4',5'-dicarbonitrile(Px-VPN); The blue light guest material is bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl)iridium(III) (Firpic), 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), at least one of 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 material uses (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-(pyri dine-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-(diphenyl lamino)phenyl]-10,10-dioxide-9H-thioxanthen-9-one(TXO-TPA)、5,6-bis At least one of (4-(9,9-dimethylacridin-10(9H)-yl)phenyl)pyrazine-2,3-dicarbonitrile (Ac-CNP); The yellow light guest material is 5,6,11,12-Tetraphenylnaphthacene (rubrene), iridium(III)bis(4-phenylthieno[3,2-c]pyridinato-N,C20)acetylacetonate(PO-01)、 bis[5-methyl-7-fluoro-5H-benzo(c)(1,5)naphthyridin-6-one]iridium(picolinate)、 acetylacetonatobis(4-(4-tert-butylphenyl)-thieno[3,2-c]pyridinato-C2,N)iridium(Ir(tptpy)2(acac))、2,4,6-Tris(4-(10H-phenoxazin-10-yl) phenyl)-1,3,5-triazine(tri-PXZ-TRZ), bis(1,2-diphenyl-1H-benzo[d]imidazole)(acetylacetonate)iridium(III)(Ir(pbi)2(acac)), iridium(III) at least one of bis[2-(2-naphthyl)pyridine](acetylacetonate)(Ir(npy)2acac).

9. The method for preparing a white organic light emitting diode according to claim 7, wherein: The evaporation rate of each functional layer material is 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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