Preparation method of low-haze quantum dot light conversion adhesive film

Abstract

The invention provides a preparation method of a low-haze quantum dot light conversion adhesive film, which comprises the following steps: carrying out ligand exchange on the surface of a quantum dot by adopting a metal halide salt solution, and removing a long-chain organic ligand to form an inorganic ligand modified quantum dot solution; mixing the quantum dot solution with EVA (Ethylene Vinyl Acetate) particles, melting, extruding and granulating to prepare color master batch particles; uniformly mixing the color master batch particles, EVA particles, a cross-linking agent, an assistant cross-linking agent, a silane coupling agent, a light stabilizer, an antioxidant and other auxiliary components, and carrying out melt extrusion and tape casting to prepare the low-haze quantum dot light conversion adhesive film. The preparation method is simple in process, high in controllability and suitable for large-scale production, and the prepared adhesive film has high dispersity, low haze, high light transmittance and excellent light stability and can be widely applied to the fields of photovoltaic modules, displays, lighting equipment and the like.

Description

Technical Field

[0001] The invention relates to the technical field of nanomaterials, and in particular to a method for preparing a low-fog quantum dot light-converting adhesive film. Background Art

[0002] Quantum dots are nanoparticles with excellent optical properties and are widely used in display, luminescence, photocatalysis and other fields. The surface structure of quantum dots has an important influence on their stability and performance. Usually, in the preparation process of quantum dots, long-chain organic ligands (such as oleic acid, oleylamine, etc.) are introduced. These ligands help to improve the stability of quantum dots in solution, prevent the formation of surface dangling bonds, and achieve efficient luminescence of quantum dots. However, the non-polar properties of these long-chain organic ligands limit the dispersibility of quantum dots in polar materials (such as ethylene-vinyl acetate copolymer, EVA), causing quantum dots to easily agglomerate, thereby affecting their application performance in light conversion films.

[0003] In order to solve the problem of insufficient dispersibility of quantum dots in polar materials, the traditional technology usually adopts the method of ligand exchange, that is, using exogenous short-chain ligands (such as MPA, EDA, etc.) to replace the long-chain organic ligands on the surface of quantum dots. However, during the substitution process, due to the low solubility of the ligand in the traditional quantum dot antisolvent, the ligand exchange effect is poor, a large number of long-chain ligands remain on the surface of quantum dots, and the ligand exchange efficiency is not high; the removal process of organic ligands requires strict control of reaction conditions, and the slightest carelessness may cause quantum dots to agglomerate or performance degradation; the stability is insufficient after ligand exchange, and some inorganic ligands may desorb in polar solvents, resulting in a decrease in the long-term stability of quantum dots; the haze and optical properties of the film are not ideal. Although inorganic ligands can improve dispersibility, the existing methods have limited effects on reducing the haze of the film and improving the optical properties, and cannot meet the needs of actual applications.

[0004] Therefore, it is necessary to provide a preparation method for improving the stability of quantum dot film to solve the above problems. Summary of the invention

[0005] In view of the above-mentioned technical problems of poor dispersion and insufficient stability of quantum dots, a method for preparing a low-haze quantum dot light-converting adhesive film is provided. The present invention uses a metal halide salt (RX n ) as an inorganic ligand, dissolved in an organic solvent (such as dimethylformamide, DMF) to generate a metal cation inorganic ligand [R (solvent) n ] n+ When the metal salt solution and the quantum dot solution are mixed and stirred, the organic ligands on the surface of the quantum dots are replaced by inorganic ligands to form an inorganic ligand-quantum dot complex QD / [R(solvent) n ] n+ .

[0006] This inorganic ligand-quantum dot complex is added to the EVA film as a light conversion agent. The prepared EVA light conversion film has lower haze and higher stability, providing a better solution for the application of quantum dots in optical film materials.

[0007] The technical means adopted by the present invention are as follows:

[0008] A method for preparing a low-haze quantum dot light-converting adhesive film, characterized in that it comprises the following steps:

[0009] S1. Performing ligand exchange on the surface of quantum dots, dissolving a metal halide salt in an organic solvent, adding a quantum dot solution, stirring the reaction, centrifuging to remove the supernatant and washing, to obtain an inorganic ligand-modified quantum dot solution;

[0010] S2, mixing the quantum dot solution with EVA particles, melting, extruding, and granulating to obtain masterbatch particles containing quantum dots;

[0011] S3. After uniformly mixing the masterbatch particles, EVA particles and other components, the mixture is melt-extruded and tape-cast to obtain a low-fog quantum dot light-converting adhesive film.

[0012] Further, the quantum dots are one or more combinations of CdSe, CdS, CdZnSe, CdZnS, CdZnSeS, CdSe / ZnS, CdSe / CdZnS, CdZnS / ZnS, CdZnSeS / ZnS, CdZnSe / CdZnS, CdSe / ZnSe, ZnSe / ZnS, and CdSe / CdZnS / ZnS.

[0013] Furthermore, the metal halide salt is one of ZnCl2, ZnBr2, AlCl3, AlBr3, GaCl3, and GaBr3.

[0014] Furthermore, the organic solvent used to dissolve the metal halide is one of dimethyl sulfoxide, dimethylformamide and methylformamide.

[0015] Furthermore, the concentration of the metal halide solution is 0.02-0.2 g / ml, and the concentration of the quantum dot solution is 0.05-0.5 g / ml.

[0016] Furthermore, the weight ratio of the metal salt to the quantum dots is 1:6 to 1:20.

[0017] Furthermore, the content of quantum dot nanomaterials in the masterbatch particles is 3-25wt%, and the proportion in the quantum dot light-converting adhesive film is 0.6-2wt%.

[0018] Furthermore, the proportion of each component in the light-converting adhesive film is as follows:

[0019] Masterbatch particles 5-20wt%;

[0020] EVA particles 71-90wt%;

[0021] Crosslinking agent 0.5-3wt%;

[0022] Auxiliary cross-linking agent 0.4-2wt%;

[0023] Silane coupling agent 0.1-2wt%;

[0024] Light stabilizer 0.05-1wt%;

[0025] Antioxidant 0.05-1wt%.

[0026] Further, the cross-linking agent is one or a combination of tert-butyl peroxy-2-ethylhexyl carbonate, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and tert-amyl peroxy-2-ethylhexyl carbonate; the auxiliary cross-linking agent is one or a combination of triallyl isocyanurate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, triallyl cyanurate, ethoxymethylpropane triacrylate, and propoxy trimethylolpropane triacrylate.

[0027] Furthermore, the silane coupling agent is one or a combination of γ-(methacryloyloxy)propyltrimethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltriethoxysilane, and γ-glycidyloxypropyltrimethoxysilane.

[0028] Further, the light stabilizer is one or a combination of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinylethanol) succinate, and bis(1,2,2,6,6-pentamethylpiperidinol) sebacate; the antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, The invention can be selected from the group consisting of pentaerythritol [tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tris[2.4-di-tert-butylphenyl] phosphite, bis(2.4-di-tert-butylphenyl) pentaerythritol diphosphite, tris(nonylphenyl) phosphite, and triphenyl phosphite, or a combination of the two or more thereof.

[0029] Furthermore, in the melt extrusion of step S3, the temperature of the feed section, extrusion section and discharge section of the extruder is 70-120°C, preferably 80-100°C; the temperature in the tape casting process is 120-150°C, and the thickness of the film is 0.2-0.5mm.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. The present invention uses ligand exchange technology to replace the long-chain organic ligands on the surface of quantum dots with inorganic ligands generated in metal halide solutions. This ligand exchange effectively enhances the polarity of quantum dots, enabling them to be evenly dispersed in polar materials, avoiding the problem of quantum dot agglomeration, and improving the transparency and optical uniformity of the film.

[0032] 2. The present invention uses inorganic ligands to stabilize the surface of quantum dots, thereby enhancing the chemical stability of quantum dots in the EVA matrix. The inorganic ligands are firmly bound to the surface of quantum dots through strong coordination, which significantly reduces the risk of thermal degradation of quantum dots during melt extrusion and high-temperature tape casting, thereby ensuring the long-term stability and optical properties of quantum dots.

[0033] 3. The present invention optimizes the ratio of quantum dot masterbatch particles and EVA particles and strictly controls the reaction conditions during ligand exchange and mixing, so that the quantum dots can be evenly distributed in the film. The high dispersion of the quantum dots effectively reduces the haze of the film and improves its light transmittance, providing better visual and optical properties for the practical application of the light-converting film.

[0034] 4. The present invention further improves the mechanical properties, chemical stability and durability of the film by adding multiple auxiliary ingredients such as cross-linking agents, co-cross-linking agents, silane coupling agents, light stabilizers and antioxidants; by adding light stabilizers and antioxidants, the stability of the film in high temperature, high humidity and strong light environments is improved, yellowing and light decay are avoided, thereby significantly extending the service life of the film.

[0035] In summary, the present invention provides a method for preparing a quantum dot light-converting adhesive film with low haze and high stability through a technical route that combines ligand exchange, melt extrusion and cast molding. The method has the advantages of simple process, strong controllability, and suitability for large-scale production. The prepared adhesive film has high dispersibility, low haze, high light transmittance and excellent light stability, and can be widely used in photovoltaic modules, displays, lighting equipment and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0037] Figure 1 It is a transmittance curve diagram of Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The present invention provides a method for preparing a low-haze quantum dot light-converting adhesive film, comprising the following steps:

[0040] S1. Perform ligand exchange on the surface of quantum dots, dissolve metal halide in an organic solvent, add quantum dot solution, stir for reaction, centrifuge to remove supernatant and wash to obtain inorganic ligand modified quantum dot solution; the quantum dots are CdSe, CdS, CdZnSe, CdZnS, CdZnSeS, CdSe / ZnS, CdSe / CdZnS, CdZnS / ZnS, CdZnSeS / ZnS, CdZnSe / CdZnS, CdSe / ZnSe, ZnSe / ZnS, One or more combinations of CdSe / CdZnS / ZnS; the metal halide is one of ZnCl2, ZnBr2, AlCl3, AlBr3, GaCl3, GaBr3; the organic solvent used to dissolve the metal halide is one of dimethyl sulfoxide, dimethylformamide, dimethyl sulfoxide, methylformamide; the concentration of the metal halide solution is 0.02-0.2g / ml, the concentration of the quantum dot solution is 0.05-0.5g / ml, and the weight ratio of the metal halide to the quantum dots is 1:6 to 1:20.

[0041] S2. The quantum dot solution is mixed with EVA particles, and the mixture is melted, extruded and granulated to obtain masterbatch particles containing quantum dots; the content of quantum dot nanomaterials in the masterbatch particles is 3-25wt%, and the proportion in the quantum dot light-converting adhesive film is 0.6-2wt%.

[0042] S3, after the masterbatch particles are uniformly mixed with the EVA particles and other components, they are melt extruded and tape-cast to obtain a low haze quantum dot light-converting film. In step S3, in the melt extrusion, the temperature of the feed section, the extrusion section and the discharge section of the extruder is 70-120°C, preferably 80-100°C; in the tape-casting process, the temperature is 120-150°C, and the film thickness is 0.2-0.5mm.

[0043] The proportions of the components in the light-converting film are as follows:

[0044] Masterbatch particles 5-20wt%; EVA particles 71-90wt%; crosslinking agent 0.5-3wt%; auxiliary crosslinking agent 0.4-2wt%; silane coupling agent 0.1-2wt%; light stabilizer 0.05-1wt%; antioxidant 0.05-1wt%.

[0045] Wherein, the cross-linking agent is one or a combination of tert-butyl peroxy-2-ethylhexyl carbonate, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and tert-amyl peroxy-2-ethylhexyl carbonate; the auxiliary cross-linking agent is one or a combination of triallyl isocyanurate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, triallyl cyanurate, ethoxymethylpropane triacrylate, and propoxy trimethylolpropane triacrylate.

[0046] The silane coupling agent is one or a combination of γ-(methacryloyloxy)propyltrimethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltriethoxysilane, and γ-glycidyloxypropyltrimethoxysilane.

[0047] The light stabilizer is one or a combination of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinylethanol) succinate, and bis(1,2,2,6,6-pentamethylpiperidinol) sebacate; the antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tetra[β-(3,5-di-tert-butyl-1-piperidinylethanol) succinate, and bis(1,2,2,6,6-pentamethylpiperidinol) sebacate. The invention can be selected from the group consisting of pentaerythritol [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tris[2.4-di-tert-butylphenyl] phosphite, bis(2.4-di-tert-butylphenyl) pentaerythritol diphosphite, tris(nonylphenyl) phosphite, and triphenyl phosphite, or a combination of the two or more thereof.

[0048] Example 1

[0049] The present invention provides a method for preparing a low-haze quantum dot light-converting adhesive film, and the specific steps are as follows:

[0050] 286.3g ZnCl2 was dissolved in 2000ml dimethylformamide (DMF) by ultrasonic dissolution, and the ZnCl2 / DMF solution was added to 150ml CdZnS / ZnS hexane solution (concentration of 0.3g / ml), and stirred vigorously for 24h. Then, the quantum dot solution was centrifuged, the supernatant was removed, and toluene / DMF was used for centrifugal washing three times, and the precipitate was dissolved in 150ml DMF solution to obtain CdZnS / ZnS-DMF quantum dot solution (concentration of 0.3g / ml).

[0051] Take 100 ml of CdZnS / ZnS-DMF quantum dot solution (concentration of 0.3 g / ml) and 200 g of EVA particles, mix them evenly, and add them into a twin-screw extruder granulator. The temperatures of the feed section, extrusion section and discharge section of the granulator are set to 110°C, 115°C and 120°C, respectively. After melting, extrusion, wire drawing and pelletizing, masterbatch particles with a particle size of 2 mm are finally obtained.

[0052] Take 100g (10%) masterbatch particles, 889g (88.9%) EVA particles, 5g (0.5%) crosslinking agent tert-butyl peroxy-2-ethylhexyl carbonate, 4g (0.4%) co-crosslinking agent trimethylolpropane triacrylate, 1g (0.1%) silane coupling agent vinyl tris (β-methoxyethoxy) silane, 0.5g (0.05%) antioxidant 2,2'-methylenebis (4-methyl-6-tert-butyl peroxy) ... After being evenly mixed with 0.5g (0.05%) of light stabilizer bis(1,2,2,6,6-pentamethylpiperidinol) sebacate, the mixture was poured into an extruder, and the temperatures of the feed section, extrusion section and discharge section of the extruder were set to 110°C, 115°C and 120°C respectively. After melt extrusion and heating to 140°C, the molten raw material was injected into a mold and subjected to cast molding to finally obtain a light-converting film with a film thickness of 0.4mm.

[0053] Example 2

[0054] The present invention provides a method for preparing a low-haze quantum dot light-converting adhesive film, and the specific steps are as follows:

[0055] Take 373.2gAlCl3 and dissolve it in 2800ml methylformamide (MFA) and dissolve it by ultrasound. Add the AlCl3 / MFA solution to 200mlCdZnSeS / ZnS hexane solution (concentration is 0.3g / ml) and stir vigorously for 24h. Then, centrifuge the quantum dot solution, remove the supernatant, use toluene / MFA, centrifuge and wash three times, and dissolve the precipitate in 200mlMFA solution to obtain CdZnSeS / ZnS-MFA quantum dot solution (concentration is 0.3g / ml).

[0056] Take 100 ml of CdZnSeS / ZnS-MFA quantum dot solution (concentration of 0.3 g / ml) and 200 g of EVA particles, mix them evenly, and add them into a twin-screw extruder granulator. The temperatures of the feed section, extrusion section and discharge section of the granulator are set to 110°C, 115°C and 120°C, respectively. After melting, extrusion, wire drawing and pelletizing, masterbatch particles with a particle size of 2 mm are finally obtained.

[0057] Take 200g (20%) of masterbatch particles, 710g (71%) of EVA particles, 30g (3%) of crosslinking agent peroxy-2-ethylhexyl carbonate tert-amyl ester, 20g (2%) of auxiliary crosslinking agent triallyl tricyanate, 20g (2%) of silane coupling agent vinyl triethoxysilane, 10g (1%) of antioxidant 2,2'-thiobis [3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 10g (1%) of light stabilizer sebacate bis (1,2,2,6,6-pentamethylpiperidinol) ester and mix them evenly, then pour them into an extruder, and the temperatures of the feed section, extrusion section and discharge section of the extruder are set to 80°C, 85°C and 90°C respectively. After melt extrusion and heating to 120°C, the molten raw material is injected into a mold, and after cast molding, a light-converting film with a film thickness of 0.2 mm is finally obtained.

[0058] Example 3

[0059] The present invention provides a method for preparing a low-haze quantum dot light-converting adhesive film, and the specific steps are as follows:

[0060] Take 266.7gAlBr3 and dissolve it in 3200ml dimethyl sulfoxide (DMSO) and dissolve it by ultrasonic. Add AlBr3 / DMSO solution to 300mlCdZnSeS / CdZnS hexane solution (concentration is 0.1g / ml) and stir vigorously for 24h. Then, centrifuge the quantum dot solution, remove the supernatant, use toluene / DMSO, centrifuge and wash three times, and dissolve the precipitate in 300mlDMSO solution to obtain CdZnSeS / ZnS-DMSO quantum dot solution (concentration is 0.1g / ml).

[0061] Take 300 ml of CdZnSeS / ZnS-DMSO quantum dot solution (concentration of 0.1 g / ml) and 270 g of EVA particles, mix them evenly, and add them into a twin-screw extruder granulator. The temperatures of the feed section, extrusion section and discharge section of the granulator are set to 110°C, 115°C and 120°C, respectively. After melting, extrusion, wire drawing and pelletizing, masterbatch particles with a particle size of 2 mm are finally obtained.

[0062] Take 150g (15%) masterbatch particles, 821g (82.1%) EVA particles, 10g (1%) crosslinking agent 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 7g (0.7%) co-crosslinking agent triallyl isocyanurate, 3g (0.3%) silane coupling agent γ-(methacryloyloxy)propyltrimethoxysilane, 4g (0.4%) antioxidant β-(3,5-di-tert-butyl-4- After being evenly mixed with 10-hydroxyphenyl)propionic acid octadecyl ester and 5g (0.5%) of light stabilizer bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, the mixture was poured into an extruder. The temperatures of the feed section, extrusion section and discharge section of the extruder were set to 70°C, 75°C and 80°C respectively. After melt extrusion and heating to 120°C, the molten raw material was injected into a mold and subjected to cast molding to finally obtain a light-converting film with a film thickness of 0.5 mm.

[0063] Example 4

[0064] The present invention provides a method for preparing a low-haze quantum dot light-converting adhesive film, and the specific steps are as follows:

[0065] Take 244.3gGaCl3 and dissolve it in 2500ml dimethylformamide (DMF) and dissolve it by ultrasonic. Add the GaCl3 / DMF solution to 400mlCdZnSeS hexane solution (concentration is 0.1g / ml) and stir vigorously for 24h. Then, centrifuge the quantum dot solution, remove the supernatant, use toluene / DMF, centrifuge and wash three times, and dissolve the precipitate in 400mlDMF solution to obtain CdZnSeS-DMF quantum dot solution (concentration is 0.1g / ml).

[0066] Take 400 ml CdZnSeS-DMF quantum dot solution (concentration of 0.1 g / ml) and 160 g EVA particles, mix them evenly, and add them into a twin-screw extruder granulator. The temperatures of the feed section, extrusion section and discharge section of the granulator are set to 110°C, 115°C and 120°C respectively. After melting, extrusion, wire drawing and pelletizing, masterbatch particles with a particle size of 2 mm are finally obtained.

[0067] Take 50g (5%) masterbatch particles, 900g (90%) EVA particles, 25g (2.5%) crosslinking agent 2,5-dimethyl-2,5-bis (tert-butylperoxy) hexane, 11g (1.1%) co-crosslinking agent trimethylolpropane trimethacrylate, 7g (0.7%) silane coupling agent vinyl trimethoxysilane, 2g (0.2%) antioxidant tetrakis [β- (3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] Pentaerythritol ester and 3g (0.3%) of light stabilizer poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinylethanol) succinate were mixed evenly and poured into an extruder. The temperatures of the feed section, extrusion section and discharge section of the extruder were set to 110°C, 115°C and 120°C respectively. After melt extrusion, the temperature was raised to 140°C, and the molten raw material was injected into a mold. After cast molding, a light-converting film with a film thickness of 0.3 mm was finally obtained.

[0068] Comparative Example 1

[0069] This comparative example refers to Example 1, and the difference from Example 1 is that the metal salt solution is not used to perform ligand exchange on the quantum dot solution. Specifically:

[0070] Take 100 ml of CdZnS / ZnS hexane quantum dot solution (concentration of 0.3 g / ml) and 200 g of EVA particles, mix them evenly, and add them into a twin-screw extruder granulator. The temperatures of the feed section, extrusion section and discharge section of the granulator are set to 110°C, 115°C and 120°C, respectively. After melting, extrusion, wire drawing and pelletizing, masterbatch particles with a particle size of 2 mm are finally obtained.

[0071] Take 100g (10%) masterbatch particles, 889g (88.9%) EVA particles, 5g (0.5%) crosslinking agent tert-butyl peroxy-2-ethylhexyl carbonate, 4g (0.4%) co-crosslinking agent trimethylolpropane triacrylate, 1g (0.1%) silane coupling agent vinyl tris (β-methoxyethoxy) silane, 0.5g (0.05%) antioxidant 2,2'-methylenebis (4-methyl-6-tert-butyl peroxy) ... After being evenly mixed with 0.5g (0.05%) of light stabilizer bis(1,2,2,6,6-pentamethylpiperidinol) sebacate, the mixture was poured into an extruder, and the temperatures of the feed section, extrusion section and discharge section of the extruder were set to 110°C, 115°C and 120°C respectively. After melt extrusion and heating to 140°C, the molten raw material was injected into a mold and subjected to cast molding to finally obtain a light-converting film with a film thickness of 0.4mm.

[0072] Test Example 1

[0073] Take a 50mm×50mm light-transmitting film, and measure the haze and transmittance of the film according to the spectrophotometer method of GB-T / 2410-2008. The wavelength range of the spectrophotometer is set to 350-1000nm.

[0074] The quantum dot adhesive films prepared in Example 1 and Comparative Example 1 were tested as light conversion adhesive films, and the transmittance curves were as follows: Figure 1 As shown in Table 1, according to the test results:

[0075] Table 1 Quantum dot film performance test comparison table

[0076]

[0077] It can be seen from the above results that, compared with the light-converting adhesive film made of quantum dots without ligand exchange, the light-converting adhesive film made of quantum dots with ligand exchange of the present invention has a certain degree of improvement in visible light transmittance and a decrease in haze.

[0078] Test Example 2

[0079] The photovoltaic glass is stacked in the order of photovoltaic glass, upper light-converting adhesive film, solar cell, lower light-converting adhesive film and lower photovoltaic glass from bottom to top, and then placed in a vacuum laminator. After evacuation for 10 minutes, the temperature is raised to 120°C and laminated at a pressure of 25 MPa to obtain a photovoltaic module.

[0080] The quantum dot adhesive films prepared in Example 1 and Comparative Example 1 were respectively used as light conversion adhesive films (including an upper light conversion adhesive film and a lower light conversion adhesive film), and laminated according to the above method to obtain photovoltaic modules. The initial power generation and DH1000h power of the photovoltaic modules were respectively measured, and the attenuation rates were calculated and compared to obtain the test data shown in Table 2:

[0081] Table 2 Comparison of performance tests of photovoltaic modules prepared by quantum dot adhesive films

[0082] Initial power (W) Initial gain DH1000h power (W) Decay rate Example 1 448.2 +0.11％ 440.2 -1.79％ Comparative Example 1 443.5 — 435.8 -1.72％

[0083] From the above results, it can be seen that compared with the light-converting adhesive film made of quantum dots without ligand exchange, the initial power of the light-converting adhesive film made of quantum dots with ligand exchange of the present invention is improved to a certain extent, while the stability is not affected. The light-converting adhesive film obtained after the quantum dots are ligand exchanged has a reduced haze, and the visible light converted and emitted by the film after absorbing ultraviolet light can be more absorbed and utilized by the photovoltaic module, so the initial power is improved. The exchanged inorganic ligands are firmly fixed on the surface of the quantum dots, playing a protective role, so the stability is not affected.

[0084] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, a person of ordinary skill in the art should understand that any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a low haze quantum dot light conversion adhesive film, characterized in that: The following steps are involved: S1. Performing ligand exchange on the surface of quantum dots, dissolving a metal halide salt in an organic solvent, adding a quantum dot solution, stirring the reaction, centrifuging to remove the supernatant and washing, to obtain an inorganic ligand-modified quantum dot solution; S2, mixing the quantum dot solution with EVA particles, melting, extruding, and granulating to obtain masterbatch particles containing quantum dots; S3. After uniformly mixing the masterbatch particles, EVA particles and other components, the mixture is melt-extruded and tape-cast to obtain a low-fog quantum dot light-converting adhesive film.

2. The method for preparing the low haze quantum dot light conversion adhesive film according to claim 1, characterized in that: The quantum dots are one or more combinations of CdSe, CdS, CdZnSe, CdZnS, CdZnSeS, CdSe / ZnS, CdSe / CdZnS, CdZnS / ZnS, CdZnSeS / ZnS, CdZnSe / CdZnS, CdSe / ZnSe, ZnSe / ZnS, and CdSe / CdZnS / ZnS.

3. The method for preparing the low haze quantum dot light conversion adhesive film according to claim 1, characterized in that: The metal halide salt is one of ZnCl2, ZnBr2, AlCl3, AlBr3, GaCl3, and GaBr3.

4. The method for preparing the low haze quantum dot light conversion adhesive film according to claim 3, characterized in that: The organic solvent used to dissolve the metal halide is one of dimethyl sulfoxide, dimethylformamide and methylformamide.

5. The method for preparing the low haze quantum dot light conversion adhesive film according to claim 1, characterized in that: The concentration of the metal halide solution is 0.02-0.2 g / ml, the concentration of the quantum dot solution is 0.05-0.5 g / ml, and the weight ratio of the metal salt to the quantum dots is 1:6-1:

20.

6. The method for preparing the low haze quantum dot light conversion adhesive film according to claim 1, characterized in that: The content of quantum dot nanomaterial in the masterbatch particles is 3-25wt%, and the proportion in the quantum dot light-converting adhesive film is 0.6-2wt%.

7. The method for preparing the low haze quantum dot light conversion adhesive film according to claim 1, characterized in that: The proportions of the components in the light-converting film are as follows: Masterbatch particles 5-20wt%; EVA particles 71-90wt%; Crosslinking agent 0.5-3wt%; Auxiliary cross-linking agent 0.4-2wt%; Silane coupling agent 0.1-2wt%; Light stabilizer 0.05-1wt%; Antioxidant 0.05-1wt%.

8. The method for preparing the low haze quantum dot light conversion adhesive film according to claim 7, characterized in that: The cross-linking agent is one or a combination of tert-butyl peroxy-2-ethylhexyl carbonate, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, and tert-amyl peroxy-2-ethylhexyl carbonate; the auxiliary cross-linking agent is one or a combination of triallyl isocyanurate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, triallyl cyanurate, ethoxymethylpropane triacrylate, and propoxy trimethylolpropane triacrylate.

9. The method for preparing the low haze quantum dot light conversion adhesive film according to claim 1, characterized in that: The silane coupling agent is one or a combination of γ-(methacryloyloxy)propyltrimethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, vinyltriethoxysilane, and γ-glycidyloxypropyltrimethoxysilane; the light stabilizer is one or a combination of bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate, polysuccinic acid (4-hydroxy-2,2,6,6-tetramethyl-1-piperidinethanol) ester, and bis(1,2,2,6,6-pentamethylpiperidinol) sebacate; The antioxidant is one or a combination of β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-thiobis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], tris[2.4-di-tert-butylphenyl] phosphite, bis(2.4-di-tert-butylphenyl) pentaerythritol diphosphite, tris(nonylphenyl) phosphite, and triphenyl phosphite.

10. The method for preparing the low haze quantum dot light conversion adhesive film according to claim 1, characterized in that: In the melt extrusion of step S3, the temperature of the feed section, extrusion section and discharge section of the extruder is 70-120°C, preferably 80-100°C; the temperature in the tape casting process is 120-150°C, and the thickness of the film is 0.2-0.5mm.

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