Composite film and preparation method thereof, photoelectric device and display device

Abstract

The invention discloses a composite film and a preparation method thereof, a photoelectric device and a display device, and relates to the technical field of display. The composite thin film comprises M layers of first thin films and N layers of second thin films which are sequentially and alternately stacked, M and N are independently integers larger than or equal to 1, materials of the first thin films comprise first nano-particles and positively charged peptide chains, and materials of the second thin films comprise second nano-particles and negatively charged peptide chains. According to the composite film provided by the invention, electrostatic interaction exists between the positively charged peptide chain and the negatively charged peptide chain, and a framework with toughness can be formed, so that the bending resistance of the composite film is improved.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a composite film and a preparation method thereof, an optoelectronic device, and a display device. Background Art

[0002] At present, flexible optoelectronic devices have shown broad application prospects due to their good flexibility, flexibility and bendability, and have improved the convenience and intelligence of life. Quantum dots have the advantages of adjustable spectrum, high luminous intensity, high color purity, long fluorescence lifetime, and light source that can excite multi-color fluorescence, and are widely used in optoelectronic devices. However, due to the properties of quantum dot nanoparticles, the bending process of flexible optoelectronic devices is often accompanied by the displacement of nanoparticles in the light-emitting layer, which causes the film layer to crack or even break, causing changes in the charge transfer of optoelectronic devices, resulting in a decrease in the performance of optoelectronic devices, shortening the service life of optoelectronic devices, and affecting the development of flexible optoelectronic devices.

[0003] At present, the service life of optoelectronic devices is short and needs further improvement. Summary of the invention

[0004] In view of this, the present application provides a composite film and a preparation method thereof, an optoelectronic device, and a display device.

[0005] An embodiment of the present application is implemented as follows: a composite film comprises M layers of a first film and N layers of a second film which are alternately stacked in sequence, wherein the M and the N are each independently an integer greater than or equal to 1, the material of the first film comprises first nanoparticles and positively charged peptide chains, and the material of the second film comprises second nanoparticles and negatively charged peptide chains.

[0006] Accordingly, the present invention also provides a method for preparing a composite film, comprising:

[0007] providing a substrate;

[0008] Providing a first mixed material and a second mixed material, wherein the first mixed material comprises first nanoparticles and positively charged peptide chains, and the second mixed material comprises second nanoparticles and negatively charged peptide chains;

[0009] The first mixed material and the second mixed material are alternately arranged on the substrate in sequence, the first mixed material forms a first thin film, the first thin film has M layers, the second mixed material forms a second thin film, the second thin film has N layers, the M and the N are each independently an integer greater than or equal to 1, to obtain a composite thin film.

[0010] Correspondingly, an embodiment of the present application also provides a photoelectric device, comprising a first electrode, a light-emitting layer, and a second electrode stacked in sequence, the light-emitting layer comprising a composite thin film, the composite thin film comprising M layers of a first thin film and N layers of a second thin film stacked alternately in sequence, the M and the N are each independently an integer greater than or equal to 1, the material of the first thin film comprises first nanoparticles and positively charged peptide chains, and the material of the second thin film comprises second nanoparticles and negatively charged peptide chains.

[0011] Correspondingly, an embodiment of the present application further provides a display device, which includes the above-mentioned optoelectronic device.

[0012] In the composite film provided by the present application, there is an electrostatic interaction between the positively charged peptide chains and the negatively charged peptide chains, which can form a tough skeleton, thereby improving the bending resistance of the composite film. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 is a schematic diagram of the structure of the composite film provided in the embodiment of the present application;

[0015] Figure 2 is a schematic structural diagram of another composite film provided in an embodiment of the present application;

[0016] Figure 3 is a flow chart of the preparation of the composite film provided in the embodiment of the present application;

[0017] Figure 4 It is a schematic diagram of the structure of the optoelectronic device provided in the embodiment of the present application.

[0018] Reference numerals:

[0019] A first film a-11, a second film a-12, a first film b-13, a second film b-14;

[0020] A first electrode 20; a first carrier functional layer 30; a second carrier functional layer 40; and a second electrode 50. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application. In addition, it should be understood that the specific implementation methods described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0022] In this application, unless otherwise stated, directional words such as "upper" and "lower" generally refer to the upper and lower parts of the device in actual use or working state, specifically the drawing direction in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of this application, the term "including" means "including but not limited to". The terms first, second, third, etc. are used only as labels and do not impose numerical requirements or establish an order.

[0023] In this application, "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0024] In the present application, "at least one" means one or more, and "plurality" means two or more. "One or several", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple, respectively.

[0025] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0026] Definition and explanation of terms:

[0027] The present application involves amino acids. For ease of understanding, the three-letter abbreviations and symbols of amino acids are explained below: Glycine (Gly, Gly), Alanine (Ala, A), Valine (Val, V), Leucine (Leu, L), Isoleucine (Ile, I), Proline (Pro, P), Phenylalanine (Phe, F), Tyrosine (Tyr, Y), Tryptophan (Trp, W), Serine (Se, L), rine, Ser, S), threonine (Thr, T), cysteine ​​(Cystine, Cys, C), methionine (Methionine, Met, M), asparagine (Asparagine, Asn, N), glutamine (Glutarnine, Gln, Q), aspartic acid (Aspartic acid, Asp, D), glutamic acid (Glu, E), lysine (Lys, K), arginine (Arginine, Arg, R), histidine (Histidine, His, H). For example, GRGDS-NH 2 A peptide chain is a peptide chain formed by the sequential condensation of a glycine, an arginine, a glycine, an aspartic acid, and a serine, and the -OH in the terminal group -COOH is replaced by an amino group -NH 2 Replaced, its structural formula is as follows:

[0028]

[0029] The technical solution of this application is as follows:

[0030] First, see Figure 1 An embodiment of the present application provides a composite film, comprising M layers of a first film and N layers of a second film alternately stacked in sequence, wherein the M and the N are each independently an integer greater than or equal to 1, the material of the first film comprises first nanoparticles and positively charged peptide chains, and the material of the second film comprises second nanoparticles and negatively charged peptide chains.

[0031] It should be noted that the peptide chain described in the present application also includes the terminal group -NH 2 Compounds substituted with carboxyl -COOH, or with amino -NH 2 Substituted compounds.

[0032] The composite film provided by the present application comprises a peptide chain containing an amino group and a carboxyl group, which can passivate defects on the surface of the nanoparticles and promote the beneficial properties of the film; an electrostatic effect exists between the positively charged peptide chain and the negatively charged peptide chain, which promotes the orderly arrangement and close fit of the first nanoparticles and the second nanoparticles; and the positively charged peptide chain and the negatively charged peptide chain can form a tough skeleton, thereby improving the bending resistance of the composite film and thus extending its service life.

[0033] It should be noted that amino acids include positively charged amino acids (also called basic amino acids) and negatively charged amino acids (also called acidic amino acids). Positively charged amino acids refer to amino acids with a net positive charge. This is because in its chemical molecule, in addition to the amino group in the amino acid terminal group, its side chain also contains positively charged groups, such as amino group (-NH 2 ), imino group (-NH-), positively charged amino acids such as histidine (Ⅰ), lysine (Ⅱ), and arginine (Ⅲ) are shown below:

[0034]

[0035] Correspondingly, negatively charged amino acids refer to amino acids with a net negative charge. This is because in its chemical molecule, in addition to the carboxyl group in the terminal group of the amino acid, its side chain also contains negatively charged groups, such as hydroxyl (-OH) and carboxyl (-COOH). The structural formula of negatively charged amino acids such as aspartic acid (IV) and glutamic acid (V) is shown below:

[0036]

[0037] When amino acids are in a physiological pH environment (usually 7.4), their carboxyl groups will lose protons and become negatively charged, while the amino groups will gain protons and become positively charged. Therefore, in a neutral environment, amino acids carry a certain amount of positive and negative charges, and the total charge is zero. However, taking negatively charged amino acids as an example, there are carboxyl groups on both the side chains and the main chains. Therefore, at physiological pH, even if the amino groups gain protons and become positively charged, the carboxyl groups on the side chains will also be negatively charged, making the entire amino acid molecule carry a net negative charge. Correspondingly, positively charged amino acids will carry a net positive charge at physiological pH.

[0038] Accordingly, the peptide chain is formed by the condensation of amino acids. When the peptide chain is in a physiological pH environment (usually 7.4), its carboxyl group will lose protons and become negatively charged, and the amino group will gain protons and become positively charged. Therefore, in a neutral environment, the peptide chain carries a certain amount of positive and negative charges, and the total charge is zero. However, when the amino acids in the peptide chain include positively charged amino acids and / or negatively charged amino acids, its charge situation needs to consider the positively charged amino acids and the negatively charged amino acids. For example, the sequence is GRGDS-NH 2The peptide chain contains one positively charged amino acid (arginine) and one negatively charged amino acid (aspartic acid), but has an amino group -NH 2 It replaces the original terminal carboxyl group -COOH, so that in this peptide chain, the number of amino groups is 3 and the number of carboxyl groups is 1. The amino group can obtain more protons, making the peptide chain positively charged.

[0039] In some embodiments, the amino acids in the positively charged peptide chain include one or more of lysine, arginine, histidine, glycine, aspartic acid, serine, proline, leucine, alanine, valine, and tryptophan.

[0040] In some embodiments, the positively charged peptide chain includes a KR peptide chain, an RH peptide chain, a KH peptide chain, a GRGDS-NH 2 One or more of peptide chain, HPLGK peptide chain, KGAVRHKPWK peptide chain.

[0041] For example, the KR peptide chain is a peptide chain formed by dehydration condensation of a lysine and an arginine. In some embodiments, the KR peptide chain has the following structural formula:

[0042]

[0043] In some embodiments, the amino acids in the negatively charged peptide chain include one or more of aspartic acid, glutamic acid, glycine, alanine, proline, leucine, valine, glutamine, phenylalanine, isoleucine, tryptophan, and serine.

[0044] In some embodiments, the negatively charged peptide chain includes one or more of a DE peptide chain, a DG peptide chain, an EA peptide chain, a DPLAV peptide chain, an EQFGA peptide chain, and a DGALIWSAED peptide chain.

[0045] The DE peptide chain is a peptide chain formed by dehydration condensation of an aspartic acid and a glutamic acid. In some embodiments, the DE peptide chain has the following structural formula:

[0046]

[0047] It can be understood that the positively charged peptide chain and the negatively charged peptide chain are not limited to the specific peptide chains listed above, and amino acids can be freely combined according to positive and negative charges to obtain positively charged peptide chains and negatively charged peptide chains.

[0048] It should be noted that the above-mentioned peptide chains can be synthesized and customized according to needs. The condensation reaction of amino acids belongs to the existing technology, and the synthesis method of each peptide chain will not be described in detail here.

[0049] In some embodiments, the positively charged peptide chain comprises a first positively charged group.

[0050] In some embodiments, the negatively charged peptide chain comprises a first negatively charged group.

[0051] Specifically, in some embodiments, the first positively charged group includes -NH 2 , -NH- or more.

[0052] In some embodiments, the first negatively charged group includes one or more of -OH, -COOH.

[0053] In some embodiments, the positively charged peptide chain also includes a second negatively charged group, which is the same as or different from the first negatively charged group, and in the positively charged peptide chain, the number of the first positively charged groups is greater than the number of the second negatively charged groups.

[0054] In some embodiments, the negatively charged peptide chain also includes a second positively charged group, which is the same as or different from the first positively charged group, and in the negatively charged peptide chain, the number of the first negatively charged groups is greater than the number of the second positively charged groups.

[0055] In some embodiments, the number of amino acids in the positively charged peptide chain and / or the negatively charged peptide chain is independently 2 to 10, for example, it can be a compound formed by condensation of 3, 4, 5, 6, 7, 8, or 9 amino acids. In other words, the positively charged peptide chain includes a positively charged oligopeptide, and the negatively charged peptide chain includes a negatively charged oligopeptide. In the present application, within the range of the number of amino acids, the length of the positively charged peptide chain and the negatively charged peptide chain is appropriate, which will not affect the steric hindrance of the nanoparticles and can ensure the performance of the beneficial properties of the film.

[0056] In some embodiments, the first nanoparticles and the positively charged peptide chains in each layer of the M-layer first film are the same or different.

[0057] In some embodiments, the second nanoparticles and negatively charged peptide chains in each layer of the N-layer second film are the same or different.

[0058] In some embodiments, the first nanoparticle and the second nanoparticle are the same or different.

[0059] In some embodiments, the sum of the values ​​of M and N is greater than or equal to 2 and less than or equal to 10, that is, 2≤M+N≤10, for example, M+N can be 3, 4, 5, 6, 7, 8, 9, etc. Within the range of the number of layers, the bending resistance of the composite film can be effectively improved, and its beneficial properties, such as luminescence performance, can be ensured not to be affected.

[0060] It should be noted that, in some embodiments, the M layers of the first film and the N layers of the second film are alternately stacked, and M may be equal to N, for example, forming a first film / second film structure; in other embodiments, M may be one layer larger than N, for example, forming a first film / second film / first film structure; in other embodiments, N may be one layer larger than M, for example, forming a second film / first film / second film structure. It can be understood that when M+N=2, that is, one layer of the first film a11 and one layer of the second film a12 are alternately arranged, and when M+N=10, that is, 5 layers of the first film and 5 layers of the second film are alternately arranged.

[0061] In some embodiments, see Figure 2 The composite film includes a first film a11, a second film a12, a first film b13, and a second film b14 which are stacked in sequence.

[0062] In some embodiments, the mass ratio of the first nanoparticle to the positively charged peptide chain is 100:(1-10), for example, it can be 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, etc.

[0063] In some embodiments, the mass ratio of the second nanoparticle to the negatively charged peptide chain is 100:(1-10), for example, it can be 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, etc.

[0064] In some embodiments, in the composite film, the molar ratio of the first nanoparticles to the second nanoparticles is (1-4): (1-4), for example, 1:2, 1:3, 2:1, 3:1, etc. Within the above range, it is beneficial to promote the electrostatic interaction between the positively charged peptide chains and the negatively charged peptide chains, so that the first nanoparticles and the second nanoparticles are arranged in an orderly manner and fit closely.

[0065] It can be understood that within the range of the mass ratio of nanoparticles to peptide chains, the beneficial properties of the film can be ensured and the bending tolerance of the film can be improved.

[0066] In some embodiments, the average particle sizes of the materials of the first nanoparticles and the second nanoparticles are respectively 5 nm to 10 nm, for example, 6 nm, 7 nm, 8 nm, 9 nm, etc.

[0067] In some embodiments, the materials of the first nanoparticles and the second nanoparticles are independently selected from quantum dots.

[0068] Furthermore, the quantum dots include one or more of single structure quantum dots, core-shell structure quantum dots and perovskite semiconductor materials.

[0069] The material of the single-structure quantum dots, the core material of the core-shell structure quantum dots and the shell material of the core-shell structure quantum dots can be respectively selected from but not limited to one or more of the group II-VI compounds, group IV-VI compounds, group III-V compounds and group I-III-VI compounds, and the shell layer of the core-shell structure quantum dots includes one or more layers. The II-VI group compounds include one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe and HgZnSTe. The IV-VI group compounds include one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe. The III-V group compounds include one or more of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs and InAlPSb. The I-III-VI group compounds include CuInS 2 、CuInSe 2 and AgInS 2 One or more of the .

[0070] As an example, the core-shell structured quantum dots include one or more of CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS and InP / ZnSe / ZnS.

[0071] The perovskite semiconductor material includes a doped or undoped inorganic perovskite semiconductor, or an organic-inorganic hybrid perovskite semiconductor. The inorganic perovskite semiconductor has a general structural formula of AMX 3 , where A is Cs + ion, M is a divalent metal cation selected from Pb 2+ Sn 2+ , Cu 2+ 、Ni 2+ 、Cd 2+ Cr 2+ , Mn 2+ 、Co 2+ , Fe 2+ ,Ge 2+ , Yb 2+ 、Eu 2+ One or more of, X is a halogen anion selected from Cl - Br - , I- one or more. The general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX 3 , wherein B is an organic amine cation selected from CH 3 (CH 2 ) n-2 NH 3 + or [NH 3 (CH 2 ) n NH 3 ] 2+ , where n≥2, M is a divalent metal cation selected from Pb 2+ Sn 2+ , Cu 2+ 、Ni 2+ 、Cd 2+ Cr 2+ , Mn 2+ 、Co 2+ , Fe 2+ ,Ge 2+ , Yb 2 + 、Eu 2+ One or more of the following, X is a halogen anion selected from Cl-, Br- , I-one or more.

[0072] In some embodiments, the thickness of each layer in the M layers of the first thin film and the N layers of the second thin film is independently 5 nm to 20 nm, for example, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, etc.

[0073] The thickness of the first film and the thickness of the second film may be the same or different.

[0074] In some embodiments, the thickness of the composite film is 10 nm to 50 nm, for example, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, etc.

[0075] Second, see Figure 3 The present invention also provides a method for preparing a composite film, comprising:

[0076] S11, providing a substrate;

[0077] S12, providing a first mixed material and a second mixed material, wherein the first mixed material includes first nanoparticles and positively charged peptide chains, and the second mixed material includes second nanoparticles and negatively charged peptide chains;

[0078] S13. Alternately arrange the first mixed material and the second mixed material on the substrate in sequence, the first mixed material forms a first thin film having M layers, the second mixed material forms a second thin film having N layers, and the M and N are each independently an integer greater than or equal to 1, to obtain a composite thin film.

[0079] It can be understood that in some embodiments, a first film may be formed first, and then a second film and a first film may be alternately formed on the film; in other embodiments, a second film may be formed first, and then a first film and a second film may be alternately formed on the film.

[0080] It should be noted that when forming each layer of the M-layer first film, the first nanoparticles and the positively charged peptide chains in the first mixed material of each layer are the same or different, and the mass ratio of the first nanoparticles to the positively charged peptide chains is the same or different. Correspondingly, when forming each layer of the N-layer second film, the second nanoparticles and the negatively charged peptide chains in the second mixed material of each layer are the same or different, and the mass ratio of the second nanoparticles to the negatively charged peptide chains is the same or different.

[0081] In some embodiments, forming a layer of the first film includes: providing a first solution, the first solution including first nanoparticles, positively charged peptide chains and a first solvent, and disposing the first solution on the substrate or a layer of the second film to form the first film.

[0082] In some embodiments, forming a layer of the second film includes: providing a second solution, the second solution including second nanoparticles, negatively charged peptide chains and a second solvent, and placing the second solution on a layer of the first film or the substrate to form a second film.

[0083] Further, the first solvent and the second solvent each independently include one or more of chlorobenzene, ethanol, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethanol, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, pyrrole, butyric acid, and cresol.

[0084] In some embodiments, in the first solution, the mass concentration of the first nanoparticles is 10 mg / mL to 40 mg / mL, for example, 15 mg / mL, 20 mg / mL, 25 mg / mL, 30 mg / mL, 35 mg / mL, etc. Within the mass concentration range, the first nanoparticles are facilitated to be fully and uniformly dissolved.

[0085] In some embodiments, in the first solution, the mass ratio of the first nanoparticles to the positively charged peptide chains is 100:(1-10), for example, it can be 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, etc.

[0086] In some embodiments, in the second solution, the mass concentration of the second nanoparticles is 10 mg / mL to 40 mg / mL, for example, 15 mg / mL, 20 mg / mL, 25 mg / mL, 30 mg / mL, 35 mg / mL, etc.

[0087] In some embodiments, in the second solution, the mass ratio of the second nanoparticles to the negatively charged peptide chains is 100:(1-10), for example, it can be 100:2, 100:3, 100:4, 100:5, 100:6, 100:7, 100:8, 100:9, etc.

[0088] In some embodiments, after disposing the first solution on the substrate or a layer of the second film, a first annealing step is further included.

[0089] Further, the temperature of the first annealing is 70°C to 80°C, for example, 72°C, 72°C, 72°C, 72°C, etc.; the time is 10min to 60min, for example, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, etc. Thus, within the range of the first annealing, it is beneficial to remove the first solvent and promote the formation of the first thin film.

[0090] In some embodiments, after disposing the second solution on a layer of the first film or the substrate, a second annealing step is further included.

[0091] Furthermore, the temperature of the second annealing is 70°C to 80°C, such as 72°C, 72°C, 72°C, 72°C, etc., and the time is 10min to 60min, such as 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min. Thus, within the range of the second annealing, it is beneficial to remove the second solvent and promote the formation of the second thin film.

[0092] In some embodiments, the substrate includes a first electrode.

[0093] In some other embodiments, the substrate includes a first electrode and a first carrier functional layer which are stacked.

[0094] Third, see Figure 4 The embodiment of the present application also provides a photoelectric device, comprising a first electrode 20, a light-emitting layer, and a second electrode 50 stacked in sequence, wherein the light-emitting layer comprises a composite film, and the composite film comprises M layers of a first film and N layers of a second film stacked alternately in sequence, wherein M and N are each independently an integer greater than or equal to 1, and the material of the first film comprises first nanoparticles and positively charged peptide chains, and the material of the second film comprises second nanoparticles and negatively charged peptide chains.

[0095] In some embodiments, both ends of the composite film are first films.

[0096] In some embodiments, both ends of the composite film are second films.

[0097] In some embodiments, two ends of the composite film are respectively a first film and a second film, the first film is close to the first electrode 20 , and the second film is close to the second electrode 50 .

[0098] In some embodiments, two ends of the composite film are respectively a first film and a second film, the second film is close to the first electrode 20 , and the first film is close to the second electrode 50 .

[0099] In some embodiments, the optoelectronic device comprises a light emitting diode.

[0100] In some embodiments, the optoelectronic device is a flexible optoelectronic device.

[0101] In some embodiments, the photoelectric device also includes one or more of a first carrier functional layer 30 and a second carrier functional layer 40, wherein the first carrier functional layer 30 is arranged between the first electrode 20 and the light-emitting layer, and the second carrier functional layer 40 is arranged between the light-emitting layer and the second electrode 50.

[0102] In some embodiments, the first carrier functional layer 30 is a hole functional layer, and the second carrier functional layer 40 is an electron functional layer. Accordingly, the first electrode 20 is an anode, and the second electrode 50 is a cathode.

[0103] In some other embodiments, the second carrier functional layer 40 is a hole functional layer, and the first carrier functional layer 30 is an electron functional layer. Accordingly, the second electrode 50 is an anode, and the first electrode 20 is a cathode.

[0104] Furthermore, the hole functional layer includes one or more of a hole injection layer and a hole transport layer.

[0105] The electronic functional layer includes one or more of an electron injection layer and an electron transport layer.

[0106] In some embodiments, the first electrode 20 and the second electrode 50 each independently include one or more of a metal, a carbon material, and a metal oxide; the metal includes one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb, and Mg; the carbon material includes one or more of graphite, carbon nanotubes, graphene, and carbon fiber; the metal oxide includes a metal oxide electrode or a composite electrode in which a metal is arranged between doped or undoped transparent metal oxides, and the material of the metal oxide electrode includes ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO 3 and one or more of AMO, the composite electrode includes AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO 2 / Ag / TiO 2 and TiO 2 / Al / TiO 2One or more of the above. Wherein, “ / ” indicates a stacked structure, for example, AZO / Ag / AZO indicates a composite electrode including an AZO layer, an Ag layer and an AZO layer stacked in sequence.

[0107] In some embodiments, the material of the hole functional layer includes 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4"-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N, N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tri(N-carbazolyl)-triphenylamine, 4,4',4'-tri(carbazolyl-9-yl)triphenylamine, trichloroisocyanuric acid, terbium-doped phosphate-based green luminescent materials, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, 4,4',4'-tri(N- 3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine), poly[bis(4-phenyl)(4-butylphenyl)amine], polyaniline, polypyrrole, poly(p-phenylenevinylene), poly(phenylenevinylene), poly[2-methoxy-5-(2-ethylhexyl) [(2-methoxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene], copper phthalocyanine, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT, PEDOT:PSS and its derivatives, PEDOT:PSS doped with s-MoO 3 The invention relates to one or more of derivatives of poly(N-vinylcarbazole) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-di(naphthalene-1-yl)-N,N'-diphenylbenzidine, spiro NPB, nano-polycrystalline diamond, microcrystalline cellulose and tetracyanoquinodimethane, doped graphene, undoped graphene, second doped metal oxide particles, second undoped metal oxide particles, metal sulfide, metal selenide and metal nitride, wherein the metal oxide in the second doped metal oxide particles and the metal oxide in the second undoped metal oxide particles each independently include MoO 3 , WO 3 、NiO、CrO 3 , CuO, Cu 2O.V 2 O 5 The doping element in the second doped metal oxide particles includes one or more of Mo, W, Ni, Cr, Cu, and V, and the metal sulfide includes CuS, MoS 3 , WS 3 One or more of the metal selenides, wherein the metal selenides include MoSe 3 ,WSe 3 One or more of the above, wherein the metal nitride comprises P-type gallium nitride.

[0108] In some embodiments, the material of the electronic functional layer includes one or more of first doped metal oxide particles, first undoped metal oxide particles, IIB-VIA semiconductor materials, IIIA-VA semiconductor materials, and IB-IIIA-VIA semiconductor materials, and the material of the first undoped metal oxide particles includes ZnO, TiO 2 SnO 2 、ZrO 2 、 2 O 5 One or more of the following, the metal oxide in the first doped metal oxide particles includes ZnO, TiO 2 SnO 2 、ZrO 2 、 2 O 5 、Al 2 O 3 The doping elements in the first doped metal oxide particles include one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga. The IIB-VIA semiconductor materials include one or more of ZnS, ZnSe, and CdS. The IIIA-VA semiconductor materials include one or more of InP and GaP. The IB-IIIA-VIA semiconductor materials include one or more of CuInS and CuGaS.

[0109] In a fourth aspect, an embodiment of the present application further provides a display device, which includes the above-mentioned optoelectronic device.

[0110] The display device can be any electronic product with a display function, including but not limited to smart phones, tablet computers, laptops, digital cameras, digital video cameras, smart wearable devices, smart weighing electronic scales, car displays, televisions or e-book readers, among which smart wearable devices can be, for example, smart bracelets, smart watches, virtual reality (VR) helmets, etc.

[0111] The present application is described in detail below through specific embodiments. The following embodiments are only partial embodiments of the present application and are not limitations of the present application.

[0112] Film Example 1

[0113] This embodiment provides a composite film, and the preparation method is as follows:

[0114] providing a substrate;

[0115] Prepare CdZnSe quantum dot solution and add GRGDS-NH 2 peptide chain (manufacturer Solarbio, CAS: 143648-02-6), to obtain a first solution, the mass concentration of CdZnSe in the first solution is 10 mg / mL, GRGDS-NH 2 The mass concentration of the peptide chain is 0.5 mg / mL; the first solution is spin-coated on the hole transport layer at a spin-coating speed of 2000 rpm for 30 seconds to form a first thin film;

[0116] A quantum dot solution of CdZnSe was prepared, and a DPLAV peptide chain (customized peptide chain from WuXi AppTec) was added to obtain a second solution, in which the mass concentration of CdZnSe in the second solution was 10 mg / mL, and the mass concentration of the DPLAV peptide chain was 0.5 mg / mL; the second solution was spin-coated on the first film at a speed of 2000 rpm for 30 seconds to form a second film, thereby obtaining a composite film.

[0117] Film Example 2

[0118] This embodiment is basically the same as the embodiment 1, except that after forming the second film, the embodiment further includes:

[0119] Prepare CdZnSe quantum dot solution and add GRGDS-NH 2 peptide chain (manufacturer Solarbio, CAS: 143648-02-6), to obtain a third solution, the mass concentration of CdZnSe in the third solution is 10 mg / mL, GRGDS-NH 2 The mass concentration of the peptide chain is 0.5 mg / mL; the third solution is spin-coated on the second film at a spin-coating speed of 2000 rpm for 30 seconds to form a first film b;

[0120] A quantum dot solution of CdZnSe was prepared, and a DPLAV peptide chain (customized peptide chain produced by WuXi AppTec) was added to obtain a fourth solution, in which the mass concentration of CdZnSe was 10 mg / mL, and the mass concentration of DPLAV peptide chain was 0.5 mg / mL; the fourth solution was spin coated on the first film b at a speed of 2000 rpm for 30 s to form a second film b. The first film, the second film, the first film b and the second film b constituted a light-emitting layer.

[0121] Film Example 3

[0122] This embodiment is basically the same as the embodiment 2, except that after forming the second film b, the embodiment further includes:

[0123] Prepare CdZnSe quantum dot solution and add GRGDS-NH 2 peptide chain (manufacturer Solarbio, CAS: 143648-02-6), to obtain the fifth solution, the mass concentration of CdZnSe in the fifth solution is 10 mg / mL, GRGDS-NH 2 The mass concentration of the peptide chain is 0.5 mg / mL; the fifth solution is spin-coated on the second film b at a speed of 2000 rpm for 30 seconds to form a first film c. The first film, the second film, the first film b, the second film b and the first film c constitute a light-emitting layer.

[0124] Film Example 4

[0125] This embodiment is substantially the same as Embodiment 1, except that, in this embodiment, the second thin film is first formed on the hole transport layer, and then the first thin film is formed on the second thin film.

[0126] Film Example 5

[0127] This embodiment is basically the same as embodiment 1, except that in this embodiment, GRGDS-NH 2 The peptide chain (manufacturer Solarbio, CAS: 143648-02-6) was replaced with the HPLGK peptide chain (manufacturer WuXi AppTec custom peptide chain).

[0128] Film Example 6

[0129] This embodiment is basically the same as embodiment 1, except that in this embodiment, GRGDS-NH 2 The peptide chain (manufacturer Solarbio, CAS: 143648-02-6) was replaced with the KR peptide chain (manufacturer WuXi AppTec custom peptide chain).

[0130] Film Example 7

[0131] This embodiment is basically the same as embodiment 1, except that in this embodiment, GRGDS-NH 2 The peptide chain (manufacturer Solarbio, CAS: 143648-02-6) was replaced with the KGAVRHKPWK peptide chain (manufacturer WuXi AppTec custom peptide chain).

[0132] Film Example 8

[0133] This example is basically the same as Example 1, except that in this example, the DPLAV peptide chain (customized peptide chain by manufacturer WuXi AppTec) is replaced with an EQFGA peptide chain (customized peptide chain by manufacturer WuXi AppTec).

[0134] Film Example 9

[0135] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the DPLAV peptide chain (customized peptide chain by manufacturer WuXi AppTec) is replaced with the DG peptide chain (customized peptide chain by manufacturer WuXi AppTec).

[0136] Film Example 10

[0137] This example is basically the same as Example 1, except that in this example, the DPLAV peptide chain (customized peptide chain by manufacturer WuXi AppTec) is replaced with the DGALIWSAED peptide chain (customized peptide chain by manufacturer WuXi AppTec).

[0138] Film Example 11

[0139] This embodiment is substantially the same as Embodiment 1, except that in this embodiment, CdZnSe in the first solution is replaced by ZnSe / ZnS.

[0140] Film Example 12

[0141] This embodiment is substantially the same as Embodiment 1, except that in this embodiment, CdZnSe in the second solution is replaced by ZnSeTe / ZnS.

[0142] Film Example 13

[0143] This embodiment is basically the same as embodiment 1, except that the GRGDS-NH 2 The mass concentration of the peptide chain was 0.1 mg / mL.

[0144] Film Example 14

[0145] This embodiment is basically the same as embodiment 1, except that the GRGDS-NH 2 The mass concentration of the peptide chain was 1 mg / mL.

[0146] Film Example 15

[0147] This embodiment is substantially the same as embodiment 1, except that the mass concentration of the DPLAV peptide chain in the second solution in this embodiment is 0.1 mg / mL.

[0148] Film Example 16

[0149] This embodiment is substantially the same as embodiment 1, except that the mass concentration of the DPLAV peptide chain in the second solution in this embodiment is 1 mg / mL.

[0150] Film Example 17

[0151] This embodiment is basically the same as embodiment 1, except that the GRGDS-NH 2 The mass concentration of the peptide chain was 0.01 mg / mL, and the mass concentration of the DPLAV peptide chain in the second solution was 2 mg / mL.

[0152] Film Example 18

[0153] This embodiment is basically the same as embodiment 1, except that the GRGDS-NH 2 The mass concentration of the peptide chain is 2 mg / mL, and the mass concentration of the DPLAV peptide chain in the second solution is 2 mg / mL.

[0154] Film Comparative Example 1

[0155] This comparative example is basically the same as Example 1, except that the first thin film and the second thin film are not prepared in this comparative example. The thin film preparation method includes: preparing a quantum dot solution of CdZnSe, and spin coating it on the hole transport layer at a spin coating speed of 2000 rpm for 30 seconds to form a thin film.

[0156] Film Comparative Example 2

[0157] This comparative example is basically the same as Example 1, except that the first film and the second film are not prepared in this comparative example. The method for preparing the film includes: preparing a CdZnSe quantum dot solution, adding NH 2 -(CH 2 ) 2 -COOH amino acid to obtain an amino acid-modified quantum dot solution, which is spin-coated on the hole transport layer at a spin coating speed of 2000 rpm for 30 s to form a thin film.

[0158] Film Comparative Example 3

[0159] This comparative example is substantially the same as Example 1, except that the second film is not formed in this comparative example, and only the first film is contained.

[0160] Device Example 1

[0161] This embodiment provides a flexible optoelectronic device, and the preparation method is as follows:

[0162] Provide ITO glass, wipe the ITO surface with a cotton swab dipped in a small amount of soapy water to remove impurities visible to the naked eye, then use deionized water, acetone, ethanol, and isopropanol for ultrasonic cleaning for 15 minutes, then blow dry with nitrogen, and irradiate with UV for 15 minutes to form an ITO anode;

[0163] PEDOT:PSS was spin-coated on the ITO anode at a speed of 5000 rpm for 30 s, followed by heating at 150 °C for 15 min to form a hole injection layer;

[0164] TFB was dissolved in chlorobenzene at a concentration of 8 mg / mL and spin-coated on the hole injection layer at a speed of 3000 rpm for 30 seconds, followed by UV irradiation for 10 minutes and heating at 200°C for 10 minutes to form a hole transport layer.

[0165] A composite thin film is formed on the hole transport layer according to the method of Example 1 to obtain a light-emitting layer;

[0166] ZnO was spin-coated on the light-emitting layer at a speed of 3000 rpm for 30 seconds, and then heated at 80°C for 30 minutes to form an electron transport layer;

[0167] On the electron transport layer, Ag is deposited by thermal evaporation with a vacuum degree not higher than 3x10 -4 Pa, speed 1 Å / s, time 1000s, thickness 100nm, forming cathode;

[0168] Packaging to obtain flexible optoelectronic devices.

[0169] Device Examples 2 to 18

[0170] Device Examples 2 to 18 are substantially the same as Example 1, with the only difference being that the light-emitting layers of Device Examples 2 to 18 are prepared by referring to the preparation method of the composite thin film of Examples 2 to 18.

[0171] Device Comparison Examples 1 to 3

[0172] Device Comparative Examples 1 to 3 are substantially the same as Example 1, except that the light-emitting layers of the devices of Comparative Examples 1 to 3 are prepared by referring to the thin film preparation method of Comparative Examples 1 to 3.

[0173] The maximum brightness and measured lifespan T95 of the flexible optoelectronic devices of device embodiments 1 to 18 and device comparison examples 1 to 3 were tested respectively. The results are shown in Table 1. The maximum brightness was tested using a brightness meter, and the test method for the measured lifespan T95 was:

[0174] The time required for the device to reduce its brightness to a certain percentage of the maximum brightness under constant current or voltage driving. The time for the brightness to drop to 95% of the maximum brightness is defined as T95, and this life is the measured life. In order to shorten the test cycle, the device life test is usually carried out at high brightness by accelerating device aging. The specific calculation formula is as follows:

[0175]

[0176] Among them, T95L is the lifespan at low brightness, T95H is the measured lifespan at high brightness, LH is the device accelerated to the maximum brightness, LL is 1000nit, and A is the acceleration factor. This experiment measured the lifespan of several groups of blue QLED devices at rated brightness and obtained an A value of 1.7.

[0177] Table 1

[0178]

[0179]

[0180] From Table 1, we can see that:

[0181] It can be seen from device embodiments 1 to 4 and device comparative example 1 that, compared with the conventional optoelectronic device of device comparative example 1, applying the peptide chain containing positive charge and the peptide chain containing negative charge to the light-emitting layer of the optoelectronic device can significantly improve the maximum brightness and the measured life span T95 of the optoelectronic device; increasing the number of layers of the film in the composite film, and exchanging the preparation order of the positively charged film and the negatively charged film have no significant effect on the performance of the optoelectronic device;

[0182] It can be seen from device example 1, device examples 5 to 12 and device comparative examples 1 to 3 that replacing the positively charged peptide chain or the negatively charged peptide chain has no significant effect on the performance of the optoelectronic device; device comparative examples 2 and device comparative examples 3 respectively incorporate amino acids and only positively charged peptide chains into quantum dots, and the performance of the optoelectronic devices thereof is improved compared with device comparative example 1, but is still inferior to the optoelectronic devices of device example 1 and device examples 5 to 12;

[0183] It can be seen from device example 1, device examples 13 to 16 and device comparison example 1 that the ratio of quantum dots and positively charged peptide chains or negatively charged peptide chains has a greater impact on the optoelectronic device. Within the range provided in this application, the maximum brightness of the optoelectronic device and the measured device life T95 can be significantly improved.

[0184] The lifespans of the flexible optoelectronic devices of device embodiments 1 to 18 and device comparison examples 1 to 3 after being bent 20,000 times, 50,000 times and 150,000 times were tested respectively, and the percentage of life loss was calculated. The results are shown in Table 2.

[0185] Table 2

[0186]

[0187]

[0188] From Table 2, we can see that:

[0189] It can be seen from device embodiments 1 to 4 and device comparative example 1 that, compared with the conventional optoelectronic device of device comparative example 1, applying the peptide chain containing positive charge and the peptide chain containing negative charge to the light-emitting layer of the optoelectronic device can significantly improve the bending resistance of the optoelectronic device; exchanging the preparation order of the positively charged film and the negatively charged film has no significant effect on the performance of the optoelectronic device, but increasing the number of layers of the positively charged film and the negatively charged film can significantly reduce the life loss after bending, because the positively charged peptide chain and the negatively charged peptide chain can form a tough skeleton, thereby improving the bending resistance of the optoelectronic device;

[0190] It can be seen from device example 1, device examples 5 to 12, and device comparison examples 1 to device comparison 3 that replacing the positively charged peptide chain or the negatively charged peptide chain, or replacing the material of the quantum dot, has no significant effect on the life loss of the optoelectronic device after being bent 20,000 times, 50,000 times, and 150,000 times. After being bent 150,000 times, the life loss is 13.1% or less; after being bent 150,000 times, the life of the device comparison example 1 is seriously reduced, with a loss of 73.1%. By incorporating amino acids or only positively charged peptide chains into the quantum dots, the bending resistance of the optoelectronic device is improved compared with that of the device comparison example 1. After the optoelectronic device of the device comparison example 2 is bent 150,000 times, the life loss is 63.1%, and after the optoelectronic device of the device comparison example 3 is bent 150,000 times, the life loss is 60.2%, and the life loss is significantly higher than that of the optoelectronic devices of device examples 1 and device examples 5 to 12;

[0191] By comparing the devices of device embodiment 1, device embodiments 13 to 18 and device comparison example 1, it can be seen that the ratio of quantum dots and positively charged peptide chains or negatively charged peptide chains has a certain influence on the bending resistance of the optoelectronic device. Within the range provided in the present application, after the optoelectronic device is bent 20,000 times, 50,000 times and 150,000 times, its life loss decreases slowly and its bending resistance is significantly improved.

[0192] The composite film and its preparation method, optoelectronic device, and display device provided in the embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A composite film, characterized in that: It comprises M layers of first thin films and N layers of second thin films which are alternately stacked in sequence, wherein M and N are independently integers greater than or equal to 1, the material of the first thin film comprises first nanoparticles and positively charged peptide chains, and the material of the second thin film comprises second nanoparticles and negatively charged peptide chains.

2. The composite film according to claim 1, characterized in that The positively charged peptide chain and the negatively charged peptide chain independently include one or more of an amino acid dehydration condensate, a compound in which the terminal group -NH2 of the amino acid dehydration condensate is substituted by a carboxyl group, and a compound in which the -OH in the terminal group -COOH of the amino acid dehydration condensate is substituted by an amino group; and / or The number of amino acids in the positively charged peptide chain and / or the negatively charged peptide chain is independently 2 to 10; and / or The first nanoparticles and the positively charged peptide chains in each layer of the M layers of the first thin film are the same or different; and / or The second nanoparticles and negatively charged peptide chains in each layer of the N layers of the second thin film are the same or different; and / or The first nanoparticles and the second nanoparticles are the same or different.

3. The composite film according to claim 1, characterized in that The positively charged peptide chain comprises a first positively charged group; and / or The negatively charged peptide chain includes a first negatively charged group.

4. The composite film according to claim 3, characterized in that The first positively charged group includes one or more of -NH2, -NH-; and / or The first negatively charged group includes one or more of -OH and -COOH; and / or The positively charged peptide chain further comprises a second negatively charged group, the second negatively charged group is the same as or different from the first negatively charged group, and in the positively charged peptide chain, the number of the first positively charged groups is greater than the number of the second negatively charged groups; and / or The negatively charged peptide chain also includes a second positively charged group, which is the same as or different from the first positively charged group, and in the negatively charged peptide chain, the number of the first negatively charged groups is greater than the number of the second positively charged groups.

5. The composite film according to any one of claims 1 to 4, characterized in that: The amino acids in the positively charged peptide chain include one or more of lysine, arginine, histidine, glycine, aspartic acid, serine, proline, leucine, alanine, valine, and tryptophan; and / or The amino acids in the negatively charged peptide chain include one or more of aspartic acid, glutamic acid, glycine, alanine, proline, leucine, valine, glutamine, phenylalanine, isoleucine, tryptophan and serine.

6. The composite film according to claim 5, characterized in that The positively charged peptide chain includes one or more of a KR peptide chain, a RH peptide chain, a KH peptide chain, a GRGDS-NH2 peptide chain, a HPLGK peptide chain, and a KGAVRHKPWK peptide chain; and / or The negatively charged peptide chain includes one or more of a DE peptide chain, a DG peptide chain, an EA peptide chain, a DPLAV peptide chain, an EQFGA peptide chain, and a DGALIWSAED peptide chain; and / or The first nanoparticle and the second nanoparticle each independently include quantum dots, and the quantum dots include one or more of single-structure quantum dots, core-shell structure quantum dots and perovskite semiconductor materials. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots and the shell materials of the core-shell structure quantum dots are independently selected from one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds and I-III-VI group compounds. The shell layer of the core-shell structure quantum dots includes one or more layers. The II-VI group compounds include one or more of ZnO, ZnS, ZnSe, ZnTe, ZnSeS, ZnSeTe and ZnSTe. The IV-VI group compounds include one or more of SnS, SnSe, SnTe, SnSeS, SnSeTe and SnSTe. The III-V group compounds include GaN, GaP, GaAs, GaSb, AlP, AlAs, AlSb, InN, I The compound of Group I-III-VI comprises one or more of CuInS2, CuInSe2 and AgInS2; the perovskite semiconductor material comprises a doped or undoped inorganic perovskite semiconductor or an organic-inorganic hybrid perovskite semiconductor; the inorganic perovskite semiconductor has a general structural formula of AMX3, wherein A is Cs + ions, M is a divalent metal cation, including Sn 2+ , Cu 2+ 、Ni 2+ Cr 2+ , Mn 2+ 、Co 2+ , Fe 2+ ,Ge 2+ , Yb 2+ 、Eu 2+ One or more of, X is a halogen anion, including Cl - Br - ,I - One or more of; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMY3, wherein B is an organic amine cation, including CH3(CH2) n-2 NH3 + or [NH3(CH2) n NH3] 2+ , where n≥2, M is a divalent metal cation, including Sn 2+ , Cu 2+ 、Ni 2+ Cr 2+ , Mn 2+ 、Co 2+ , Fe 2+ ,Ge 2+ , Yb 2+ 、Eu 2+ One or more of, Y is a halogen anion, including Cl - Br - ,I - One or more of .

7. The composite film according to claim 1, characterized in that The sum of the values of M and N is greater than or equal to 2 and less than or equal to 10; and / or The average particle size of the materials of the first nanoparticles and the second nanoparticles is independently 5 nm to 10 nm; and / or The thickness of each of the M layers of the first thin film and the N layers of the second thin film is independently 5 nm to 20 nm; and / or The thickness of the composite film is 10nm to 50nm; and / or The mass ratio of the first nanoparticle to the positively charged peptide chain is 100:(1-10); and / or The mass ratio of the second nanoparticle to the negatively charged peptide chain is 100:(1-10); and / or In the composite film, the molar ratio of the first nanoparticles to the second nanoparticles is (1-4): (1-4).

8. A method for preparing a composite film, characterized in that: include: providing a substrate; Providing a first mixed material and a second mixed material, wherein the first mixed material comprises first nanoparticles and positively charged peptide chains, and the second mixed material comprises second nanoparticles and negatively charged peptide chains; The first mixed material and the second mixed material are alternately arranged on the substrate in sequence, the first mixed material forms a first thin film, the first thin film has M layers, the second mixed material forms a second thin film, the second thin film has N layers, the M and the N are each independently an integer greater than or equal to 1, to obtain a composite thin film.

9. The preparation method according to claim 8, characterized in that: The positively charged peptide chain and the negatively charged peptide chain independently include one or more of an amino acid dehydration condensate, a compound in which the terminal group -NH2 of the amino acid dehydration condensate is substituted by a carboxyl group, and a compound in which the -OH in the terminal group -COOH of the amino acid dehydration condensate is substituted by an amino group; and / or The number of amino acids in the positively charged peptide chain and / or the negatively charged peptide chain is independently 2 to 10; and / or The first nanoparticles and the positively charged peptide chains in each layer of the M layers of the first thin film are the same or different; and / or The second nanoparticles and negatively charged peptide chains in each layer of the N layers of the second thin film are the same or different; and / or The first nanoparticles and the second nanoparticles are the same or different.

10. The preparation method according to claim 9, characterized in that: The positively charged peptide chain comprises a first positively charged group and a second negatively charged group, and in the positively charged peptide chain, the number of the first positively charged groups is greater than the number of the second negatively charged groups; and / or The negatively charged peptide chain comprises a first negatively charged group and a second positively charged group, and in the negatively charged peptide chain, the number of the first negatively charged groups is greater than the number of the second positively charged groups; and / or The amino acids in the positively charged peptide chain include one or more of lysine, arginine, histidine, glycine, aspartic acid, serine, proline, leucine, alanine, valine, and tryptophan; and / or The amino acids in the negatively charged peptide chain include one or more of aspartic acid, glutamic acid, glycine, alanine, proline, leucine, valine, glutamine, phenylalanine, isoleucine, tryptophan, and serine; and / or The positively charged peptide chain includes one or more of a KR peptide chain, a RH peptide chain, a KH peptide chain, a GRGDS-NH2 peptide chain, a HPLGK peptide chain, and a KGAVRHKPWK peptide chain; and / or The negatively charged peptide chain includes one or more of a DE peptide chain, a DG peptide chain, an EA peptide chain, a DPLAV peptide chain, an EQFGA peptide chain, and a DGALIWSAED peptide chain.

11. The preparation method according to claim 8, characterized in that: The sum of the values of M and N is greater than or equal to 2 and less than or equal to 10; and / or The average particle size of the materials of the first nanoparticles and the second nanoparticles is independently 5 nm to 10 nm; and / or The thickness of each of the M layers of the first thin film and the N layers of the second thin film is independently 5 nm to 20 nm; and / or The thickness of the composite film is 10nm to 50nm; and / or The mass ratio of the first nanoparticle to the positively charged peptide chain is 100:(1-10); and / or The mass ratio of the second nanoparticle to the negatively charged peptide chain is 100:(1-10); and / or In the composite film, the molar ratio of the first nanoparticles to the second nanoparticles is (1-4): (1-4).

12. The preparation method according to claim 8, characterized in that: The first mixed material forms a first film comprising: providing a first solution, wherein the first solution comprises first nanoparticles, positively charged peptide chains and a first solvent, and disposing the first solution on the substrate or a layer of the second film to form the first film; and / or The second mixed material forms a second film, including: providing a second solution, wherein the second solution includes second nanoparticles, negatively charged peptide chains, and a second solvent, and placing the second solution on a layer of the first film or the substrate to form a second film.

13. The preparation method according to claim 12, characterized in that: In the first solution, the mass concentration of the first nanoparticles is 10 mg / mL to 40 mg / mL; and / or In the first solution, the mass ratio of the first nanoparticle to the positively charged oligopeptide chain is 100:(1-10); and / or In the second solution, the mass concentration of the second nanoparticles is 10 mg / mL to 40 mg / mL; and / or In the second solution, the mass ratio of the second nanoparticles to the negatively charged oligopeptide peptide chain is 100:(1-10); and / or The first solvent and the second solvent each independently include one or more of chlorobenzene, ethanol, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethanol, methanol, ethanol, propanol, butanol, ethylene glycol, isopropanol, glycerol, dimethyl sulfoxide, acetone, acetophenone, tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, pyrrole, butyric acid, and cresol.

14. The preparation method according to claim 13, characterized in that: After the first solution is disposed on the substrate or a layer of the second film, the first annealing step further comprises: the temperature of the first annealing step is 70° C. to 80° C.; the time is 10 min to 60 min; and / or After the second solution is disposed on a layer of the first film or the substrate, the method further includes a second annealing process; the temperature of the second annealing process is 70° C. to 80° C.; and the time is 10 min to 60 min.

15. A photoelectric device, characterized in that: The invention comprises a first electrode, a light-emitting layer and a second electrode which are stacked in sequence, wherein the light-emitting layer comprises a composite thin film, and the composite thin film comprises M layers of a first thin film and N layers of a second thin film which are alternately stacked in sequence, wherein M and N are each independently an integer greater than or equal to 1, and the material of the first thin film comprises first nanoparticles and positively charged peptide chains, and the material of the second thin film comprises second nanoparticles and negatively charged peptide chains.

16. The optoelectronic device according to claim 15, characterized in that Both ends of the composite film are first films; or Both ends of the composite film are second films; or The two ends of the composite film are respectively a first film and a second film, the first film is close to the first electrode, and the second film is close to the second electrode; or The two ends of the composite film are respectively a first film and a second film, the second film is close to the first electrode, and the first film is close to the second electrode.

17. The optoelectronic device according to claim 15, characterized in that The positively charged peptide chain and the negatively charged peptide chain independently include one or more of an amino acid dehydration condensate, a compound in which the terminal group -NH2 of the amino acid dehydration condensate is substituted by a carboxyl group, and a compound in which the -OH in the terminal group -COOH of the amino acid dehydration condensate is substituted by an amino group; and / or The number of amino acids in the positively charged peptide chain and / or the negatively charged peptide chain is independently 2 to 10; and / or The first nanoparticles and the positively charged peptide chains in each layer of the M layers of the first thin film are the same or different; and / or The second nanoparticles and negatively charged peptide chains in each layer of the N layers of the second thin film are the same or different; and / or The first nanoparticles and the second nanoparticles are the same or different.

18. The optoelectronic device according to claim 17, characterized in that The positively charged peptide chain comprises a first positively charged group and a second negatively charged group, and in the positively charged peptide chain, the number of the first positively charged groups is greater than the number of the second negatively charged groups; and / or The negatively charged peptide chain comprises a first negatively charged group and a second positively charged group, and in the negatively charged peptide chain, the number of the first negatively charged groups is greater than the number of the second positively charged groups; and / or The amino acids in the positively charged peptide chain include one or more of lysine, arginine, histidine, glycine, aspartic acid, serine, proline, leucine, alanine, valine, and tryptophan; and / or The amino acids in the negatively charged peptide chain include one or more of aspartic acid, glutamic acid, glycine, alanine, proline, leucine, valine, glutamine, phenylalanine, isoleucine, tryptophan, and serine; and / or The positively charged peptide chain includes one or more of a KR peptide chain, a RH peptide chain, a KH peptide chain, a GRGDS-NH2 peptide chain, a HPLGK peptide chain, and a KGAVRHKPWK peptide chain; and / or The negatively charged peptide chain includes one or more of a DE peptide chain, a DG peptide chain, an EA peptide chain, a DPLAV peptide chain, an EQFGA peptide chain, and a DGALIWSAED peptide chain; and / or The first nanoparticle and the second nanoparticle each independently include quantum dots, and the quantum dots include one or more of single-structure quantum dots, core-shell structure quantum dots and perovskite semiconductor materials. The materials of the single-structure quantum dots, the core materials of the core-shell structure quantum dots and the shell materials of the core-shell structure quantum dots are independently selected from one or more of II-VI group compounds, IV-VI group compounds, III-V group compounds and I-III-VI group compounds. The shell layer of the core-shell structure quantum dots includes one or more layers. The II-VI group compounds include one or more of ZnO, ZnS, ZnSe, ZnTe, ZnSeS, ZnSeTe and ZnSTe. The IV-VI group compounds include one or more of SnS, SnSe, SnTe, SnSeS, SnSeTe and SnSTe. The III-V group compounds include GaN, GaP, GaAs, GaSb, AlP, AlAs, AlSb, InN, I The compound of Group I-III-VI comprises one or more of CuInS2, CuInSe2 and AgInS2; the perovskite semiconductor material comprises a doped or undoped inorganic perovskite semiconductor or an organic-inorganic hybrid perovskite semiconductor; the inorganic perovskite semiconductor has a general structural formula of AMX3, wherein A is Cs + ions, M is a divalent metal cation, including Sn 2+ , Cu 2+ 、Ni 2+ Cr 2+ , Mn 2+ 、Co 2+ , Fe 2+ ,Ge 2+ , Yb 2+ 、Eu 2+ One or more of, X is a halogen anion, including Cl-, Br - , I- one or more; the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMY3, wherein B is an organic amine cation, including CH3(CH2) n-2 NH3 + or [NH3(CH2) n NH3] 2+ , where n≥2, M is a divalent metal cation, including Sn 2+ , Cu 2+ 、Ni 2+ Cr 2+ , Mn 2+ 、Co 2+ , Fe 2+ ,Ge 2+ , Yb 2+ 、Eu 2+ One or more of, Y is a halogen anion, including Cl-, Br - ,I - One or more of .

19. The optoelectronic device according to claim 15, characterized in that The optoelectronic device further includes one or more of a first carrier functional layer and a second carrier functional layer, wherein the first carrier functional layer is arranged between the first electrode and the light-emitting layer, and the second carrier functional layer is arranged between the light-emitting layer and the second electrode; The first carrier functional layer is a hole functional layer, and the second carrier functional layer is an electron functional layer; or, the second carrier functional layer is a hole functional layer, and the first carrier functional layer is an electron functional layer; and / or The first electrode and the second electrode independently include one or more of a metal, a carbon material and a metal oxide; the metal includes one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, Yb and Mg; the carbon material includes one or more of graphite, carbon nanotubes, graphene and carbon fiber; the metal oxide includes a metal oxide electrode or a composite electrode in which a metal is arranged between doped or undoped transparent metal oxides, the material of the metal oxide electrode includes one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, MoO3 and AMO, and the composite electrode includes one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2 and TiO2 / Al / TiO2; and / or The materials of the hole functional layer include 4,4'-N,N'-dicarbazolyl-biphenyl, N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4"-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tri(N-carbazolyl)-triphenylamine, 4,4',4'-tri(carbazol-9-yl)triphenylamine, trichloroisocyanuric acid, terbium-doped phosphate-based green luminescent materials, 2,3, 6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene, 4,4',4'-tri(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(4-butylphenyl-diphenylamine), poly[bis(4-phenyl)(4-butylphenyl)amine], polyaniline, polypyrrole, poly(p-phenylene vinylene), poly(phenylene vinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylene] [vinyl], copper phthalocyanine, aromatic tertiary amine, polynuclear aromatic tertiary amine, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraaryl benzidine, PEDOT, PEDOT:PSS and its derivatives, PEDOT:PSS derivatives doped with s-MoO3, poly(N-vinyl carbazole) and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, N,N'-di(naphthalene-1-yl)-N,N'-diphenyl benzidine, spiro NPB, nano-polycrystalline diamond, microcrystalline cellulose and tetracyanoquinodimethane, doped graphene, undoped graphene, second doped metal oxide particles, second non One or more of doped metal oxide particles, metal sulfides, metal selenides and metal nitrides, the metal oxide in the second doped metal oxide particles and the metal oxide in the second undoped metal oxide particles independently include one or more of MoO3, WO3, NiO, CrO3, CuO, Cu2O, V2O5, the doping element in the second doped metal oxide particles includes one or more of Mo, W, Ni, Cr, Cu, V, the metal sulfide includes one or more of CuS, MoS3, WS3, the metal selenide includes one or more of MoSe3, WSe3, the metal nitride includes P-type gallium nitride; and / or The material of the electronic functional layer includes one or more of a first doped metal oxide particle, a first undoped metal oxide particle, a IIB-VIA semiconductor material, a IIIA-VA semiconductor material and an IB-IIIA-VIA semiconductor material. The material of the first undoped metal oxide particle includes one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxide in the first doped metal oxide particle includes one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3. The doping element in the first doped metal oxide particle includes one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga. The IIB-VIA semiconductor material includes one or more of ZnS, ZnSe, and CdS. The IIIA-VA semiconductor material includes one or more of InP and GaP. The IB-IIIA-VIA semiconductor material includes one or more of CuInS and CuGaS.

20. A display device, characterized in that: Comprising the optoelectronic device according to any one of claims 15 to 19.

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