Preparation method of in-situ porous antireflection film and organic light emitting diode

Abstract

The application discloses a preparation method of an in-situ porous antireflection film and an organic light emitting diode, and is characterized in that: water droplets condensed on the surface of a polymer solution are used as templates, and a porous polymer film with uniform distribution and uniform pore size is prepared by using the self-assembly of the water droplets as driving force; the film is formed on the non-conductive side of a conductive substrate in-situ, and serves as an antireflection film of the organic light emitting diode. The application forms the antireflection film of the OLED in-situ by using the breath figure method, and the scale is uniform, so that the red, green and blue light OLED emitted light is softer, and the visual brightness is enhanced. By adjusting the static relative humidity, the solution drop coating amount, the solution concentration and the like, the porous size on the antireflection film and the periodic arrangement are simple and adjustable, the size range is more flexible and controllable. The preparation method of the OLED antireflection film provided by the application has the characteristics of in-situ film forming without transfer, simple process, low cost, rapidness, large-area processing and the like, and is suitable for different areas and rigid and flexible various monochromatic light or white light OLED devices.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanofabrication and light-emitting diode preparation, and particularly relates to a preparation method of an in-situ porous antireflection film and an organic light-emitting diode. BACKGROUND

[0002] An organic light-emitting diode (OLED) has great application potential in full-color flat panel display and solid-state lighting due to its self-luminous, wide viewing angle, rich color, low-voltage direct current driving and other advantages. Although the internal quantum efficiency of the OLED is almost close to 100%, the external quantum efficiency is much lower than the internal quantum efficiency due to the light loss caused by waveguide mode, substrate mode and plasmonic mode, so enhancing the light extraction of the OLED can effectively improve the actual light extraction efficiency of the device and improve the practical value. The methods for improving the light extraction of the OLED include external light extraction and internal light extraction. The external light extraction mainly includes introducing a diffraction grating, a light scattering medium, an anode surface pattern, a microlens, a scattering film, sandblasting and the like outside the device, and the above technologies mostly involve a complex manufacturing process such as multiple pattern transfers, or need expensive equipment, harsh reaction conditions, high cost or are not suitable for flexible substrates and the like.

[0003] It is found that a random micro-nano lens structure, a light scattering medium layer, a polymer porous scattering film, a random concave-convex corrugated structure, a textured mesh substrate and a random wrinkle structure have no obvious influence on the brightness distribution and spectral stability of the device, but can achieve good external light extraction. Directly preparing an antireflection film on the surface of the device in-situ is a relatively simple, low-cost and suitable method for large-area light extraction. Preparing a porous antireflection film with uniform size and controllable micro-nano scale is one of the important strategies to achieve this purpose.

[0004] The currently reported porous structures for enhancing the light extraction of the OLED include cellulose paper, aluminum oxide, inverse opal, copper wire mesh and silver film. The polymer porous scattering film is suitable for rigid and flexible substrates, and currently a transfer or attachment method is mostly used to combine the OLED, and there are few reports on the OLED polymer porous scattering film prepared by an in-situ method. Commonly used methods for preparing the polymer porous film include a colloidal crystal template method, a surfactant self-assembly method and a mold imprinting method. However, the above methods all need different types of master plates and subsequent demolding processes. The master plate manufacturing process is relatively complicated and the demolding process may damage the porous structure, so these porous film preparation methods have certain limitations, which becomes a technical problem to be solved urgently. SUMMARY

[0005] In order to solve the prior art problems, the purpose of the present application is to overcome the shortcomings of the prior art, and provide a porous in-situ antireflection film and a preparation method of an organic light emitting diode, based on the breath figure method to form a porous in-situ antireflection film, and based on the antireflection film to prepare various single-color OLED devices, thereby significantly improving the external light extraction efficiency and the final external quantum efficiency.

[0006] To achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0007] A porous in-situ antireflection film and a preparation method of an organic light emitting diode, comprising the following steps:

[0008] (1) A polymer with a certain molecular weight and a refractive index close to glass is mixed with an organic solvent at a set mass ratio, and stirred and dissolved; a saturated salt solution is prepared, and the static relative humidity is controlled to be 40-95% in a closed environment and at a fixed temperature;

[0009] (2) A clean conductive substrate is placed above the saturated salt solution, and after the relative humidity is stabilized, 50-80 uL of the polymer solution is uniformly dropped and coated on the non-conductive side surface of the substrate, and after the solvent is naturally volatilized, a porous film is obtained;

[0010] (3) The prepared porous film is annealed and dried at 50-80°C for 10-30 min to obtain a porous antireflection film;

[0011] (4) The porous antireflection film together with the conductive substrate is cleaned with a suitable organic solvent, and an organic light emitting diode of red, green, blue, etc. is vacuum evaporated on the conductive side surface of the substrate in-situ. Different kinds of saturated salt solutions are prepared in a closed environment and at a fixed temperature to obtain static relative humidity, and a hygrometer is used to monitor the humidity in real time. This porous antireflection film is formed in-situ on the conductive substrate without the need for transfer or adhesion steps; the porous antireflection film is applicable to various single-color or white light OLED devices and various device structures.

[0012] Preferably, in the step (1), the number average molecular weight of the polymer is 2x10 4 -5x10 5 , and the polymer is any one or mixture of any several of polystyrene (PS), polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polycarbonate (PC) and block copolymer.

[0013] Preferably, in the step (1), the organic solvent is one or several of dichloromethane, trichloromethane, toluene, tetrahydrofuran, carbon disulfide, etc.; and the mass ratio of the polymer solution is 0.5%-3.0%.

[0014] Preferably, in the step (1), the solute salt of the saturated salt solution is any one of potassium carbonate, magnesium nitrate, potassium iodide, sodium chloride, potassium chloride, potassium nitrate or a mixture of any two or more thereof, and the humidity is controllable in the range of 40-95%.

[0015] Preferably, in the step (2), the material of the conductive substrate is at least one of ITO, FTO, AZO, IZO, PET / ITO and PI / ITO.

[0016] Preferably, in the step (3), the prepared porous polymer antireflection film has a porous periodic structure adjustable in a wide range from nanometer to micrometer, with an average pore diameter in the range of 0.1-5.0 um, an average pore depth in the range of 0.01-3.0 um and an average porosity in the range of 20-50%.

[0017] Preferably, the preparation method of the in-situ porous antireflection film and the organic light-emitting diode comprises the following steps: firstly, ultrasonic cleaning of the conductive substrate containing the porous antireflection film, drying and UV-O3 treatment of the conductive side of the conductive substrate for 15-30 minutes; then, placing the substrate with the conductive side downward in a vacuum evaporation chamber, sequentially layering and evaporating a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer and an electron injection layer; replacing a mask plate and evaporating a metal cathode on the electron injection layer to prepare the organic light-emitting diode.

[0018] The small molecule material of the hole injection layer preferably includes, but is 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'–diphenyl-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), 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-tetracyano-quinodimethane (F4-TCNQ), 2,2'-(naphthalene-2,6-diylidene)dimalononitrile (TNAP); preferably the film thickness of the hole injection layer is 20 to 50 nm.

[0019] The hole transport layer material is preferably at least one of 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-napht haalen-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-ethyloxetan-3-yl)methoxy)hexyl)phenyl)-N4,N4'-diphenylbiphenyl-4,4'-diamine (OTPD), 4,4'-(diphenyllsilanediyl)bis(N,N-diphenylaniline) (TSBPA), 4,4'-(diphenylmethylene)bis(N,N-diphenylaniline) (TCBPA); preferably the film thickness of the hole transport layer is 40-60 nm.

[0020] Preferably, the light-emitting layer is a red, green or blue light-emitting layer, wherein the light-emitting guest material is any one of a green, blue and red light-emitting fluorescent, phosphorescent and thermally activated delayed fluorescence material;

[0021] Preferably, the green guest material employs 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[l,l':2',l"-terphenyl]-4',5'-dicarbonitrile (Px-VPN);

[0022] Preferably, the blue guest 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);

[0023] Preferably, the red guest material is (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), 5,6,1 1,12-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-5,1 1 -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,At least one of 3-dicarbonitrile (Ac-CNP).

[0024] 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)triphenylamine(TcTa), 4,4'-bis(carbazol-9-yl)biphenyl(CBP), bis[2-(diphenylphosphino)phenyl]ether At least one of the following: 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 luminescent layer is 15–60 nm.

[0025] The electron transport layer material is preferably at least one of 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-quinolinolate)-4-(phenylphenolato)aluminium (BAlq), 1,3-bis[2-(2,2'-bipyridine-6-yl)-1,3,4-oxadiazo-5-yl]benzene (Bpy-OXD), 4-(naphthalen-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 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), Cs2CO3; preferably the film thickness of the electron transport layer is 40-60 nm.

[0026] 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), magnesium fluoride (MgF2); preferably the film thickness of the electron injection layer is 1.0-10 nm.

[0027] The conductive cathode material is preferably at least one of Al, Ag, Au, IZO, Ca, magnesium silver alloy, and lithium aluminum alloy; preferably the thickness of the cathode is 60-120 nm.

[0028] Preferably, the evaporation rate of each functional layer material should be controlled as follows: the evaporation rate of the electron injection layer material is 0.1-0.5 A / s the evaporation rate of the cathode material is 0.1-0.5 A / s the evaporation rate of other organic materials is 0.1-0.5 A / s

[0029] The present application prepares OLED devices by evaporating organic functional layers on the conductive side of the conductive substrate in a vacuum environment on the basis of the preparation of the porous antireflection film on the non-conductive side of the conductive substrate. The light emitted from the OLED device is emitted to the air through the antireflection film, and the light is enhanced by the porous optical refraction and anti-total reflection.

[0030] Preferably, the preparation method of the in-situ porous antireflection film and the organic light-emitting diode comprises the following steps:

[0031] 1) cleaning the conductive substrate and drying it with nitrogen;

[0032] 2) preparing a mixed solution of a certain molecular weight polymer and an organic solvent with a proper mass ratio, and dissolving it by ultrasonic and magnetic stirring;

[0033] 3) preparing saturated salt solutions of different types to form a closed environment with a fixed humidity;

[0034] 4) in the high-humidity environment of step 3), drop the polymer solution prepared in step 2) on the non-conductive side surface of the conductive substrate treated in step 1), and naturally evaporate the solvent; annealing and drying to prepare the porous antireflection film;

[0035] 5) ultrasonic cleaning the porous antireflection film / conductive substrate obtained in step 4) with multiple solutions, and cleaning the antireflection film by UV-O3 treatment;

[0036] 6) placing the conductive side of the antireflection film / substrate treated in step 5) downward in a vacuum evaporation chamber, and sequentially layering the hole injection layer, the hole transport layer, the light-emitting layer, the electron transport layer, and the electron injection layer by vacuum evaporation;

[0037] 7) replacing the mask plate, and evaporating metal materials on the surface of the electron injection layer prepared in step 6) to form a cathode electrode layer, thereby preparing the organic light-emitting diode containing the porous antireflection film.

[0038] The breath figure method is a method for preparing a porous polymer film with uniform distribution and uniform pore size under a relatively high humidity environment, using water droplets condensed on the surface of the polymer solution as a template and using the self-assembly of water droplets as a driving force. This method for preparing a porous film has the advantages of low cost, no need for complex equipment, no need for demolding for template self-removal, wide selection range of polymers, and in-situ film formation. Therefore, the present application forms a porous antireflection film in-situ based on the breath figure method, and prepares various single-color OLED devices based on the antireflection film, thereby significantly improving the external light extraction efficiency and the final external quantum efficiency.

[0039] Compared with the prior art, the present application has the following obvious and essential characteristics and advantages:

[0040] 1. The present application is based on the self-assembly of water vapor on the surface of the polymer to form a porous honeycomb structure; the water vapor self-assembly acts as a master in the traditional method, and the master is removed after the water vapor is evaporated and dried, so the process is simpler; and the self-assembly force makes the porous unit structure optimal, and the microlens effect is significant.

[0041] 2. By adjusting the static relative humidity, the solution drop coating amount, the solution concentration, etc., the size of the porous structure on the antireflection film and the periodic arrangement are simple and adjustable, the size range is more flexible and controllable, and the production efficiency is greatly improved; the saturated salt solution is used to form a water vapor gas phase environment, which does not require expensive equipment and is simple and easy to obtain, and can be mass produced.

[0042] 3. Compared with the prior art, the preparation method of the porous antireflection film provided by the present application has the characteristics of in-situ film formation on the conductive substrate without transfer or attachment steps, simple process, low cost, fast, and large-area processing.

[0043] 4. The red, green or blue light OLED device is constructed in-situ on the conductive side of the substrate containing the porous antireflection film, which does not affect the internal structure, brightness distribution and spectral stability of the device, utilizes the optical refraction and anti-total reflection of the porous rough surface to make the red, green or blue light OLED emitted light more soft, and improves the display quality; at the same time, since the refractive index of the polymer layer is close to that of glass, the coupling effect is avoided to make the light unable to be emitted from the front, and the visible brightness of the red, green or blue light device is enhanced, which is a simple and efficient method for in-situ antireflection.

[0044] 5. The porous antireflection film provided by the present application is applicable to various monochromatic light or white light OLED devices and various device structures, has stable performance, significant light enhancement effect, and can also consider the batch production of different area, rigidity and flexible light emitting devices, and has wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0046] Figure 1 The preparation method flow chart of the porous antireflection film and the corresponding organic light emitting diode provided by the present application.

[0047] Figure 2A schematic diagram of an OLED device structure provided by the present application containing a porous anti-reflection film.

[0048] Figure 3 A scanning electron microscope (SEM) image of the porous anti-reflection film prepared in the embodiment of the present application based on 1.0 wt% PS under different relative humidity (65% to 95%) conditions.

[0049] Figure 4 A comparison chart of the luminance and current efficiency of the blue OLED improved by the porous anti-reflection film prepared in the preferred embodiment 1 of the present application under different concentrations of PS under 75% relative humidity.

[0050] Figure 5 A comparison chart of the luminance and current efficiency of the blue OLED improved by the porous anti-reflection film prepared in the preferred embodiment 2 of the present application under different concentrations of PS under 1.0 wt% PS under different relative humidity (65% to 95%) conditions. DETAILED DESCRIPTION

[0051] The above scheme is further described in conjunction with specific examples, and the preferred embodiments of the present application are described in detail as follows:

[0052] Embodiment 1

[0053] In this embodiment, referring to Figure 1 A method for preparing an in-situ porous anti-reflection film and an organic light-emitting diode, comprising the following steps:

[0054] Step 100: Clean the ITO / glass substrate and dry it with nitrogen for standby; weigh different amounts of polymer PS, add organic solvent chloroform, and magnetically stir to dissolve to obtain a 0.5 wt% to 3 wt% polymer solution with different mass ratios;

[0055] Step 101: Configure a saturated sodium chloride solution to form 75% relative humidity, and after reaching stability, add the PS solution in step 100 to the non-conductive side surface of the cleaned conductive substrate, stand for 60 s, and naturally volatilize the solvent; anneal and dry to prepare a porous anti-reflection film;

[0056] Step 102: After the porous film / ITO glass substrate in step 101 is cleaned with a detergent, acetone, deionized water, and isopropyl alcohol, and ultrasonically cleaned, it is treated with UV-O3 for 15-30 minutes;

[0057] Step 103: Place the substrate conductive side down in the vacuum evaporation chamber to evaporate each functional layer in turn, 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)

[0058] Step 104: Finally, replace the mask plate to evaporate the 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 x 2 mm is prepared. The evaporation rate is: organic matter LiF is AL is The blue light OLED device based on the PS porous antireflection film is thus prepared. Figure 2 The device structure is shown in Figure 2 .

[0059] The preparation process of the comparative device is basically the same as that of Example 1, the only difference being that the PS porous antireflection film is not used in the comparative device.

[0060] The SEM images of the porous antireflection film prepared under different relative humidity (65%-95%) based on 1.0 wt% PS are shown in Figure 3 , which shows that the pores are uniformly distributed, the pore edge structures are different, and the pore size and pore spacing change significantly with different humidity, indicating that the relative humidity has a great influence on the pore morphology and can adjust the pore size and spacing size. The pore size and depth of the porous film prepared under 85% humidity are 5.5 microns and 5.0 microns, respectively, and the depth-to-diameter ratio reaches a maximum. Figure 2 The voltage-current-brightness and current efficiency of the blue light OLED device without an antireflection film and with an antireflection film prepared by 75% relative humidity under different PS concentrations are shown in Figure 4 . It can be seen from Figure 4 that the light-emitting efficiency of the blue light OLED device with the porous antireflection film prepared in Example 1 is significantly enhanced. The brightness of the 1 wt% PS porous antireflection film device is increased from 1694 cd / m 2 of the comparative example to 2578 cd / m 2 , the current efficiency is increased from 20.34 cd / A of the comparative example to 28.88 cd / A (an increase of 42%), and the maximum EQE of the corresponding device is increased from 14.14% of the comparative example to 15.41%. The maximum brightness and current efficiency of the devices with the porous antireflection films prepared by the other three different PS concentrations are also increased to different degrees compared with the comparative device. It can be seen that the porous antireflection film has a significant antireflection effect on the light emission of the OLED device.

[0061] Example 2

[0062] This embodiment is basically the same as Embodiment 1, except that:

[0063] In this embodiment, a method for preparing an in-situ porous antireflection film and an organic light-emitting diode includes the following steps:

[0064] Step 100: Clean the ITO / glass substrate and dry it with nitrogen. Weigh a certain mass of polymer PS, add an appropriate amount of organic solvent chloroform, mix, and magnetically stir to dissolve to obtain a 1.0 wt% polymer PS solution.

[0065] Step 101: Prepare different saturated salt solutions to achieve relative humidity of 65%, 75%, 85%, and 95%. After stabilization, drop the PS solution from step 100 onto the non-conductive side surface of the cleaned conductive substrate. Let it stand for 60 seconds to allow the solvent to evaporate naturally. Anneal and dry to prepare a porous antireflective membrane.

[0066] Steps 102-104: These steps are the same as in Example 1;

[0067] The preparation process of the reference device is basically the same as that of Example 1, except that the reference device does not have a PS porous antireflection membrane.

[0068] In this embodiment, a blue OLED device was fabricated based on a porous antireflection film prepared under different relative humidity conditions (65%–95%) with 1.0 wt% PS. The luminescence performance of the device's porous film / ITO glass / MoO3 (5nm) / NPB (35nm) / mCP (5nm) / DMAC-DPS:DPEPO (10 wt%, 20nm) / DPEPO (10nm) / Bphen (40nm) / LiF (0.8nm) / Al was tested. The voltage-current-brightness and current efficiency of the blue OLED devices with and without the antireflection film and with the porous antireflection film prepared under different relative humidity conditions (65%–95%) are shown in [reference needed]. Figure 5 .Depend on Figure 5 It can be seen that the light extraction efficiency of the blue OLED device containing the porous antireflection film prepared in Example 2 is significantly enhanced. Specifically, the brightness of the porous antireflection film device prepared at 85% relative humidity is significantly improved compared to the reference example of 1694 cd / m². 2 Increased to 3480 cd / m 2 The current efficiency increased from 20.34 cd / A in the reference model to 31.05 cd / A (an improvement of 53%), and the maximum EQE of the corresponding device increased from 14.14% in the reference model to 16.56%. The brightness of the corresponding blue OLED devices prepared with porous antireflective films at 65%, 75%, and 95% humidity levels increased to 2210 cd / m², respectively. 2 2578cd / m 2and 1862 cd / m 2 In addition, the maximum current efficiency and EQE are also improved to different degrees. Therefore, the porous antireflection film in Example 2 has a significant antireflection effect on the light emission of the OLED device.

[0069] The above-mentioned preparation method of the in-situ porous antireflection film and the organic light-emitting diode adopts the preparation method of the porous antireflection film, uses water droplets condensed on the surface of a polymer solution as a template, and prepares a porous polymer film with uniform distribution and uniform pore size, driven by the self-assembly of water droplets. The film is formed in-situ on the non-conductive side of the conductive substrate and serves as an antireflection film for an organic light-emitting diode (OLED). The conductive side surface of the substrate containing the porous antireflection film is sequentially vacuum evaporated with a hole injection layer, a hole transport layer, a single-color light-emitting layer (red, green or blue), an electron transport layer, an electron injection layer and a cathode. The present application uses the breath figure method to form an OLED antireflection film in-situ, and the porous structure with micro-nano scale has a similar light refraction and anti-total reflection effect as a micro-lens, making the red, green and blue OLED light more soft and enhancing the visual brightness. By adjusting the static relative humidity, the solution drop coating amount, the solution concentration and the like, the porous size and periodic arrangement of the antireflection film are simple and adjustable, and the size range is more flexible and controllable. Compared with the prior art, the above-mentioned OLED antireflection film preparation method has the characteristics of in-situ film formation without transfer, simple process, low cost, fast, large-area processing and the like, and is suitable for different areas and rigid, flexible, single-color light or white light OLED devices.

[0070] The above describes the embodiments of the present application in combination with the drawings, but the present application is not limited to the above-mentioned embodiments, and can be changed in various ways according to the purpose of the present application. Any change, modification, replacement, combination or simplification made according to the spirit and principles of the technical solutions of the present application shall be an equivalent replacement, as long as it meets the purpose of the present application and does not deviate from the technical principles and inventive concept of the present application. It belongs to the protection scope of the present application.

Claims

1. A method for fabricating an organic light-emitting diode, characterized in that, Includes the following steps: (1) A polymer with a refractive index close to that of glass of a certain molecular weight is mixed with an organic solvent at a set mass ratio and stirred to dissolve; a saturated salt solution is prepared and the static relative humidity is controlled at 40-95% in a closed environment and at a fixed temperature. (2) Place a cleaned conductive substrate on top of a saturated salt solution. After the relative humidity stabilizes, take 50 μL to 80 μL of polymer solution and uniformly drop it onto the non-conductive side of the substrate. After the solvent evaporates naturally, a porous membrane is obtained. (3) The prepared porous membrane is annealed at 50-80℃ for 10-30 min and dried to obtain a porous anti-reflection membrane; the average pore size ranges from 0.1 to 5.0 μm, the average pore depth ranges from 0.01 to 3.0 μm, and the average porosity ranges from 20% to 50%. (4) The porous antireflective film, together with the conductive substrate, is cleaned with a suitable organic solvent, and red, green and blue organic light-emitting diodes are vacuum-deposited on the conductive side surface of the substrate in situ. In step (1), the polymer has a number-average molecular weight of 2 × 10⁻⁶. 4 ~5×10 5 The polymer is any one or a mixture of polystyrene (PS), polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), polycarbonate (PC), and block copolymers; the organic solvent is one or more of dichloromethane, trichloromethane, toluene, tetrahydrofuran, and carbon disulfide; the polymer solution mass ratio is 0.5% to 3.0%.

2. The method for fabricating an organic light-emitting diode according to claim 1, characterized in that, In step (1), the solute salt of the saturated salt solution is any one or a mixture of several of potassium carbonate, magnesium nitrate, potassium iodide, sodium chloride, potassium chloride, and potassium nitrate, and the humidity is controllable within the range of 40% to 95%.

3. The method for fabricating an organic light-emitting diode according to claim 1, characterized in that, In step (2), the conductive substrate is made of at least one of ITO, FTO, AZO, IZO, PET / ITO, and PI / ITO.

4. The method for fabricating an organic light-emitting diode according to claim 1, characterized in that, In step (3), the porous polymer antireflective membrane obtained has a porous periodic structure that is tunable over a wide range from nanometers to micrometers.

5. The method for fabricating an organic light-emitting diode according to claim 1, characterized in that, The steps are as follows: First, ultrasonically clean the conductive substrate containing the porous antireflection membrane, dry it, and then treat it with UV-O3 for 15 to 30 minutes with the conductive side of the conductive substrate facing upwards. Then, the substrate is placed with the conductive side facing down 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 mask is replaced, and a metal cathode is deposited on the electron injection layer to prepare an organic light-emitting diode.

6. The method for fabricating an organic light-emitting diode according to claim 1, characterized in that, The light-emitting layer is a red, green, or blue light-emitting layer, wherein the light-emitting object material is any one of the fluorescent, phosphorescent, and thermally activated delayed fluorescent materials that emit green, blue, and red light. The green light guest material uses 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), at least one of 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 material uses 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); 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](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 At least one of (4-(9,9-dimethylacridin-10(9H)-yl)phenyl)pyrazine-2,3-dicarbonitrile (Ac-CNP).

7. The method for fabricating an organic light-emitting diode according to claim 1, characterized in that, The evaporation rate of each functional layer material should be controlled within the range of: the evaporation rate of the electron injection layer material is... The evaporation rate of the cathode material is The evaporation rate of other organic matter is

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