Quantum dot light emitting diode device, method of manufacturing the same, and quantum dot film

Abstract

The application provides a quantum dot light emitting diode device, a manufacturing method thereof and a quantum dot film. The quantum dot light emitting diode device comprises a first electrode, a second electrode and a quantum dot light emitting layer. The quantum dot light emitting layer is arranged between the first electrode and the second electrode. The quantum dot light emitting layer comprises first quantum dots and second quantum dots, and the absolute value of the difference between the photo-induced luminescence peak wavelength of the first quantum dots and the photo-induced luminescence peak wavelength of the second quantum dots is less than or equal to 10 nm. The light emitting device of the application can be manufactured by using two kinds of quantum dots with similar photoelectric properties, thereby reducing the process difficulty and improving the production efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of quantum dots, and in particular to a quantum dot light-emitting diode device, a manufacturing method thereof, and a quantum dot film. BACKGROUND

[0002] Colloidal quantum dot nanomaterials have unique optoelectronic properties such as near 100% fluorescence quantum efficiency, tunable optical wavelength, extremely narrow full width at half maximum, and solution processability, and thus have become one of the research hotspots of optoelectronic devices. In recent years, with the in-depth research on quantum dot light-emitting diodes (QLED), great progress has been made in the current efficiency and lifetime of the devices.

[0003] In order to obtain an ideal light-emitting wavelength and a relatively narrow size distribution, high-temperature thermal injection or ion layer alternate adsorption growth of shell method can be usually used to synthesize quantum dot materials. However, due to process limitations, different batches of quantum dot materials may have deviations in light-emitting wavelength and size distribution, and their optoelectronic properties may have certain differences. When using quantum dot materials synthesized in different batches, the preparation process conditions of the light-emitting diode device need to be adjusted according to the optoelectronic properties of different quantum dot materials, thereby increasing the process difficulty and reducing the production efficiency. SUMMARY

[0004] Therefore, the present application aims to provide a quantum dot light-emitting diode device, a manufacturing method thereof, and a quantum dot film, which can be manufactured using quantum dots with different optoelectronic properties.

[0005] The present application provides a quantum dot light-emitting diode device, which comprises:

[0006] a first electrode;

[0007] a second electrode; and

[0008] a quantum dot light-emitting layer disposed between the first electrode and the second electrode.

[0009] The quantum dot light-emitting layer comprises first quantum dots and second quantum dots, and the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dots and the photoluminescence peak wavelength of the second quantum dots is less than or equal to 10 nm.

[0010] In an embodiment, the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dots and the photoluminescence peak wavelength of the second quantum dots is less than or equal to 5 nm; and / or

[0011] the absolute value of the difference between the full width at half maximum of the photoluminescence peak of the first quantum dot and the full width at half maximum of the photoluminescence peak of the second quantum dot is less than or equal to 10 nm; or

[0012] the absolute value of the difference between the full width at half maximum of the photoluminescence peak of the first quantum dot and the full width at half maximum of the photoluminescence peak of the second quantum dot is less than or equal to 3 nm.

[0013] In an embodiment, the quantum dot light-emitting layer is composed of the first quantum dot and the second quantum dot, the photoluminescence peak wavelength of the second quantum dot is greater than the photoluminescence peak wavelength of the first quantum dot, the mass fraction of the second quantum dot is greater than 50 wt% and less than 100 wt%, and the mass fraction of the first quantum dot is greater than 0 wt% and less than 50 wt%.

[0014] In an embodiment, the full width at half maximum of the photoluminescence peak of the second quantum dot is less than the full width at half maximum of the photoluminescence peak of the first quantum dot.

[0015] In an embodiment, the quantum dot light-emitting layer comprises at least three quantum dots, the difference between the maximum value and the minimum value of the photoluminescence peak wavelength of the at least three quantum dots is less than or equal to 10 nm, and the mass fraction of the quantum dot corresponding to the median of the photoluminescence peak wavelength of the at least three quantum dots is greater than the average of the mass fractions.

[0016] In an embodiment, among the at least three quantum dots, the full width at half maximum of one or two of the quantum dots corresponding to the median of the photoluminescence peak wavelength of the at least three quantum dots is the narrowest.

[0017] The present application also provides a quantum dot film, comprising:

[0018] a first quantum dot and a second quantum dot, the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dot and the photoluminescence peak wavelength of the second quantum dot is less than or equal to 10 nm.

[0019] In an embodiment, the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dot and the photoluminescence peak wavelength of the second quantum dot is less than or equal to 5 nm; and / or the absolute value of the difference between the full width at half maximum of the photoluminescence peak of the first quantum dot and the full width at half maximum of the photoluminescence peak of the second quantum dot is less than or equal to 10 nm; or the absolute value of the difference between the full width at half maximum of the photoluminescence peak of the first quantum dot and the full width at half maximum of the photoluminescence peak of the second quantum dot is less than or equal to 3 nm.

[0020] In an embodiment, the quantum dot light emitting layer is composed of the first quantum dots and the second quantum dots, the photo-luminescence peak wavelength of the second quantum dots is greater than the photo-luminescence peak wavelength of the first quantum dots, and the mass fraction of the second quantum dots is greater than the mass fraction of the first quantum dots.

[0021] In an embodiment, the full width at half maximum of the photo-luminescence peak of the second quantum dots is less than the full width at half maximum of the photo-luminescence peak of the first quantum dots.

[0022] In an embodiment, the quantum dot film includes at least three quantum dots, the difference between the maximum and the minimum of the photo-luminescence peak wavelength of the at least three quantum dots is less than or equal to 10 nm, and the mass fraction of the quantum dots corresponding to the median of the photo-luminescence peak wavelength of the three or more quantum dots is greater than the average of the mass fractions.

[0023] In an embodiment, among the three or more quantum dots, one or two of the quantum dots corresponding to the median of the photo-luminescence peak wavelength of the three or more quantum dots have the narrowest full width at half maximum.

[0024] The present application also provides a method for manufacturing a quantum dot light emitting diode device, which includes the following steps:

[0025] forming a first electrode;

[0026] forming a quantum dot light emitting layer on the first electrode; and

[0027] forming a second electrode on the quantum dot light emitting layer;

[0028] wherein the forming of the quantum dot light emitting layer on the first electrode includes:

[0029] preparing a quantum dot solution including first quantum dots and second quantum dots, the absolute value of the difference between the photo-luminescence peak wavelength of the first quantum dots and the photo-luminescence peak wavelength of the second quantum dots being less than or equal to 10 nm; and

[0030] forming the quantum dot solution on the first electrode, and solidifying the quantum dot solution to form the quantum dot light emitting layer.

[0031] In an embodiment, the absolute value of the difference between the photo-luminescence peak wavelength of the first quantum dots and the photo-luminescence peak wavelength of the second quantum dots is less than or equal to 5 nm; and / or

[0032] the absolute value of the difference between the full width at half maximum of the photo-luminescence peak of the first quantum dots and the full width at half maximum of the photo-luminescence peak of the second quantum dots is less than or equal to 10 nm; or

[0033] An absolute value of a difference between a full width at half maximum of a photo-induced luminescence peak of the first quantum dot and a full width at half maximum of a photo-induced luminescence peak of the second quantum dot is less than or equal to 3 nm.

[0034] The present application provides a quantum dot light emitting diode device, a manufacturing method thereof, and a quantum dot film. The quantum dot light emitting diode device comprises a first electrode, a second electrode, and a quantum dot light emitting layer. The quantum dot light emitting layer is disposed between the first electrode and the second electrode. The quantum dot light emitting layer comprises first quantum dots and second quantum dots, and an absolute value of a difference between a photo-induced luminescence peak wavelength of the first quantum dots and a photo-induced luminescence peak wavelength of the second quantum dots is less than or equal to 10 nm. The light emitting device of the present application can be manufactured by using two kinds of quantum dots with similar photoelectric properties, thereby reducing the process difficulty and improving the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the present application, the drawings needed in the following implementation description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0036] Figure 1 A structure schematic diagram of the quantum dot light emitting diode device provided by the first embodiment of the present application.

[0037] Figure 2 A flow chart of the manufacturing method of the quantum dot light emitting diode device provided by the third embodiment of the present application.

[0038] Figure 3 A flow chart of the step of forming the quantum dot light emitting layer on the first electrode in the third embodiment of the present application. Figure 2 A flow chart of the step of forming the quantum dot light emitting layer on the first electrode in the third embodiment of the present application.

[0039] Figure 4 A flow chart of the step of forming the quantum dot light emitting layer on the first electrode provided by the fourth embodiment of the present application.

[0040] FIG. 5(a) is a photo-induced luminescence spectrum diagram of the first quantum dot of the embodiment 1 of the present application.

[0041] FIG. 5(b) is a photo-induced luminescence spectrum diagram of the second quantum dot of the embodiment 1 of the present application.

[0042] FIG. 5(c) is an electroluminescence spectrum diagram of the quantum dot light emitting layer formed by mixing the first quantum dot and the second quantum dot in a mass ratio of 2:3 in the embodiment 1 of the present application.

[0043] FIG. 5(d) is a graph of external quantum efficiency versus luminance of quantum dot light emitting diode devices formed with first quantum dots, second quantum dots, and a mixture of the first and second quantum dots, respectively, according to Example 1 of the present application. DETAILED DESCRIPTION

[0044] The technical solutions in the present application will be apparently and completely described below with reference to 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 the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without any creative work fall within the scope of protection of the present application.

[0045] The inventors found in the synthesis of quantum dot materials that the photoluminescence spectrum (PL), full width at half maximum (FWHM), and quantum yield (QY) of different batches of quantum dot materials obtained by using the same synthesis formula have certain differences. The reason is that the formation process of quantum dot nucleation-growth is very sensitive to the process conditions during synthesis, such as reaction temperature stability, thermal nucleation instantaneous state, and precursor distribution concentration at each stage in the reaction system, thus leading to certain differences in the emission wavelength and full width at half maximum of the quantum dot materials synthesized in different batches, although the basic properties are close.

[0046] To this end, the present application provides a quantum dot light emitting diode device manufactured by using quantum dots with different photoelectric properties as materials, a preparation method thereof, and a quantum dot film. The quantum dot light emitting diode device involved in the present application can be used in a quantum dot light emitting diode display device, a photodetector, or a photovoltaic device such as a solar cell.

[0047] The present application provides a quantum dot light emitting diode device. The quantum dot light emitting diode device includes a first electrode, a second electrode, and a quantum dot light emitting layer. The quantum dot light emitting layer is disposed between the first electrode and the second electrode. The quantum dot light emitting layer includes first quantum dots and second quantum dots, and the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dots and the photoluminescence peak wavelength of the second quantum dots is less than or equal to 10 nm. The light emitting device of the present application can be manufactured by using two kinds of quantum dots with similar photoelectric properties, thus reducing the process difficulty and improving the production efficiency.

[0048] Hereinafter, the quantum dot light emitting diode device of the present application will be described in detail with reference to the drawings.

[0049] Please refer to Figure 1 ,Figure 1 A schematic diagram of a quantum dot light emitting diode device according to a first embodiment of the present application is provided. The quantum dot light emitting diode device 100 comprises a first electrode 10, a hole injection layer 20, a hole transport layer 30, a quantum dot light emitting layer 40, an electron transport layer 50 and a second electrode 60 which are sequentially stacked.

[0050] The first electrode 10 can be an anode. The material of the anode can be selected from one or more of indium tin oxide, fluorine-doped tin oxide, indium zinc oxide, graphene, and nanocarbon tube.

[0051] The material of the hole injection layer 20 can be one or more of PEDOT:PSS, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide.

[0052] The material of the hole transport layer 30 can be one or more of PVK, Poly-TPD, CBP, TCTA, and TFB.

[0053] The quantum dot light emitting layer 40 comprises first quantum dots and second quantum dots. Both the first quantum dots and the second quantum dots are colloidal quantum dots. That is, the first quantum dots and the second quantum dots can be stored in solution. When forming the quantum dot light emitting layer, a first solution containing the first quantum dots and a second solution containing the second quantum dots can be mixed in a certain proportion. The solvent of the first solution and the solvent of the second solution can be the same solvent or similar solvents, for example, both polar solvents or both non-polar solvents. In an embodiment, the solvent of the first solution and the solvent of the second solution are the same solvent.

[0054] It should be noted that when the colloidal quantum dots are dispersed in solution without being made into a quantum dot film, their electroluminescence spectrum cannot be tested, and therefore, their optical properties are characterized by photoluminescence properties of the quantum dots. When the colloidal quantum dots are made into a quantum dot film, the photoluminescence efficiency is low and the electroluminescence efficiency is high, and therefore, the properties are characterized by electroluminescence properties of the quantum dots. It should be noted that under the existing quantum dot material process conditions, the particle sizes of red quantum dot materials, green quantum dot materials and blue quantum dot materials applied to quantum dot light emitting devices are 12 nm to 15 nm, 10 nm to 12 nm, and 8 nm to 10 nm, respectively. The quantum dot light emitting devices prepared by using these quantum dots as light emitting layer materials have a red shift of 0 nm to 5 nm in the electroluminescence peak compared to the photoluminescence peak.

[0055] The photoluminescence spectra of the first quantum dots and the second quantum dots are in the same visible light region. For example, the first quantum dots and the second quantum dots are both green quantum dots. In one embodiment, the first quantum dots and the second quantum dots can be quantum dots of different batches manufactured by using the same material and the same process. In another embodiment, the first quantum dots and the second quantum dots can also be quantum dots manufactured by using different materials and / or different processes. As long as the photoluminescence spectra of the first quantum dots and the second quantum dots are in the same visible light region and the photoluminescence peak wavelengths are close, it is acceptable. The photoluminescence peak wavelengths can be close when the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dots and the photoluminescence peak wavelength of the second quantum dots is less than or equal to 10 nm. When the difference between the photoluminescence peak wavelength of the first quantum dots and the photoluminescence peak wavelength of the second quantum dots is small enough, the electroluminescence peaks of the first quantum dots and the second quantum dots overlap after red shift to obtain an electroluminescence spectrum with higher color purity. Further, the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dots and the photoluminescence peak wavelength of the second quantum dots is less than or equal to 5 nm.

[0056] In order to make the electroluminescence peak of the quantum dot light-emitting layer have a narrow full width at half maximum, in one embodiment, the absolute value of the difference between the full width at half maximum of the photoluminescence peak of the first quantum dots and the full width at half maximum of the photoluminescence peak of the second quantum dots is less than or equal to 10 nm. Further, the absolute value of the difference between the full width at half maximum of the photoluminescence peak of the first quantum dots and the full width at half maximum of the photoluminescence peak of the second quantum dots is less than or equal to 3 nm.

[0057] Further, in the present application, unless otherwise specified, all the quantum dots contained in the first quantum dots are manufactured in the same process and have little difference in optoelectronic performance. All the quantum dots contained in the second quantum dots are also manufactured in the same process and have little difference in optoelectronic performance. For example, the optoelectronic performance, such as the electroluminescence external quantum efficiency (EQE), the time (in T 95 @1000nit) taken for the manual maximum brightness of 1000 nit to decay to 95% of the maximum brightness, of a plurality of electroluminescence devices prepared from the first quantum dots has a fluctuation of no more than 50% between the maximum brightness and the time taken for the manual maximum brightness of 1000 nit to decay to 95% of the maximum brightness. If the performance difference is too large, serious non-radiative recombination transition will occur after mixing to prepare quantum dot devices as light-emitting layer materials, resulting in a decrease in device performance and the inability to obtain stable optoelectronic performance. When the optoelectronic performance of the same type of quantum dots has little difference, it can be ensured that the electroluminescence fluorescence of the quantum dot solution after film formation has a large overlapping part, avoiding problems such as shoulder peaks or multiple peaks.

[0058] The quantum dot light-emitting layer can include a red quantum dot light-emitting layer, a green quantum dot light-emitting layer, and a blue quantum dot light-emitting layer. The quantum dots include at least one of single or composite structure quantum dots of Group IV, Group II-V, Group II-VI, Group III-VI, Group III-V, Group IV-VI, Group VI-VI, Group VIII-VI, Group I-III-VI, Group II-IV-VI, Group II-IV-V of the periodic table. The composite structure quantum dots include core-shell structure quantum dots, and the material of the core of the core-shell structure quantum dots includes at least one of CdSe, CdS, CdTe, CdSeTe, CdZnS, PbSe, ZnTe, CdSeS, PbS, PbTe, HgS, HgSe, HgTe, GaN, GaP, GaAs, InP, InAs, InZnP, InGaP, and InGaN; and the material of the shell of the core-shell structure quantum dots includes at least one of ZnSe, ZnS, and ZnSeS.

[0059] The first quantum dots and the second quantum dots have the same or similar dispersibility in the same solvent to avoid the problem of poor solubility caused by intermixing of different components, which interferes with the solution method processing of the quantum dot light-emitting diode device. The "solution method" referred to in the present application refers to a method of forming a quantum dot light-emitting layer by using colloidal quantum dots dispersed in a solution, which can be, but is not limited to, one or more of spin coating, dip coating, printing, inkjet, spray coating, roll coating, doctor blade coating, casting, electrolytic deposition, slot die coating, and stripe coating. More specifically, the first quantum dots have a first organic ligand on the surface. The second quantum dots have a second organic ligand on the surface. The first organic ligand and the second organic ligand can be dissolved in the same solvent. In an embodiment, the first organic ligand and the second organic ligand are the same. The first organic ligand and the second organic ligand are each independently selected from one or more of oleic acid, oleylamine, alkyl acid having a carbon number of 4 to 20, trioctylphosphine, tributylphosphine, trioctyloxyphosphine, hexylphosphonic acid, oleylamine, ethylamine, triethylamine, propylamine, tripropylamine, butylamine, tributylamine, pentylamine, tripentylamine, n-hexylamine, trihexylamine, heptylamine, octylamine, trioctylamine, di-n-octylamine, decylamine, dodecylamine, tridodecylamine, tetradecylamine, hexadecylamine, octadecylamine, dioctadecylamine, and dodecanethiol.

[0060] When the first quantum dots and the second quantum dots are dispersed in the solvent, the distance between the quantum dot light-emitting cores of the first quantum dots and the second quantum dots is too large to produce energy resonance transfer. When the quantum dot solution is solidified into a film, the distance between the first quantum dots and the second quantum dots is shortened to a range in which energy resonance transfer can occur. Specifically, the energy resonance transfer phenomenon in the quantum dot film is manifested as a red shift of the electroluminescence peak position by transferring high-energy state donor (short-wavelength luminescence) energy to an adjacent low-energy state acceptor (long-wavelength luminescence). When the peak wavelength of photoluminescence of the first quantum dots and the peak wavelength of photoluminescence of the second quantum dots are close enough in the spectrum, for example, the absolute value of the difference between the peak wavelength of photoluminescence of the first quantum dots and the peak wavelength of photoluminescence of the second quantum dots is less than or equal to 10 nm, when the quantum dot solution is solidified into a film, the distance between the first quantum dots and the second quantum dots is shortened to a range in which energy resonance transfer can occur. Energy resonance transfer occurs between the first quantum dots and the second quantum dots, and high-energy state donor (quantum dots with shorter luminescence wavelength) energy is transferred to an adjacent low-energy state acceptor (quantum dots with longer luminescence wavelength). The quantum dots with shorter luminescence wavelength release energy and undergo red shift, and the quantum dots with longer luminescence wavelength receive energy and undergo blue shift. That is, after energy resonance transfer occurs between the two types of quantum dots, the luminescence peaks approach each other and overlap, the fluorescence at the same wavelength position is enhanced, and an electroluminescence spectrum with higher color purity is obtained.

[0061] Experiments show that by adjusting the mass fraction and full width at half maximum of the first quantum dots and the second quantum dots, the emission fluorescence at the peak wavelength can be significantly enhanced, and the full width at half maximum of the quantum dot electroluminescence peak shows a narrowing trend, thereby exhibiting better monochromaticity; at the same time, the photoelectric performance of the device is dominated by the part where the fluorescence is most enhanced, and the overall photoelectric performance approaches the best component among the first quantum dots and the second quantum dots.

[0062] For example, in the present embodiment, the quantum dot light-emitting layer is composed of first quantum dots and second quantum dots. The peak wavelength of photoluminescence λ(b) of the second quantum dots is greater than the peak wavelength of photoluminescence λ(a) of the first quantum dots. Experiments show that by making the mass fraction of the second quantum dots greater than the mass fraction of the first quantum dots, the emission fluorescence at the peak wavelength can be significantly enhanced, and the full width at half maximum of the quantum dot electroluminescence peak shows a narrowing trend, and better photoelectric performance is obtained. Specifically, the mass fraction of the second quantum dots is greater than 50wt% and less than 100wt%, and the mass fraction of the first quantum dots is greater than 0wt% and less than 50wt%.

[0063] If the mass fraction of the second quantum dots is less than the mass fraction of the first quantum dots, the red shift of the first quantum dots is small due to the energy loss, the degree of overlap of the electroluminescence peaks of the second quantum dots and the first quantum dots is low, and the obvious fluorescence enhancement and narrowing of the full width at half maximum cannot be obtained. Moreover, due to the energy loss, the degree of blue shift of the electroluminescence peak of the second quantum dots is less than the degree of red shift of the electroluminescence peak of the first quantum dots, and the electroluminescence peak wavelength of the quantum dot light-emitting layer is closer to the electroluminescence peak wavelength of the second quantum dots. Since the light-emitting intensity is proportional to the component content, the content of the second quantum dots is greater than the content of the first quantum dots, which can maximize the light-emitting intensity in the electroluminescence peak overlap region, and the light-emitting intensity in other regions converges towards the overlap region, thereby narrowing the full width at half maximum. Further, the full width at half maximum FWHM(b) of the photoluminescence peak of the second quantum dots can be narrower than the full width at half maximum FWHM(a) of the photoluminescence peak of the first quantum dots. That is, by narrowing the full width at half maximum of the component closer to the electroluminescence peak wavelength of the quantum dot light-emitting layer, the full width at half maximum of the electroluminescence peak of the quantum dot light-emitting layer can be narrowed.

[0064] The material of the electron transport layer 50 is one or more of n-type ZnO, TiO2, SnO, Ta2O3, AlZnO, ZnSnO, InSnO, Alq3, Ca, Ba, CsF, LiF, and CsCO3.

[0065] The second electrode 60 can be a cathode. The cathode is selected from one or more of Al, Ca, Ba, and Ag.

[0066] The second embodiment of the present application is substantially the same as the first embodiment, except that the quantum dot light-emitting layer includes at least three quantum dots, and the difference between the maximum and minimum values of the photoluminescence peak wavelengths of the at least three quantum dots is less than or equal to 10 nm. Thus, the present application can manufacture a quantum dot light-emitting layer using at least three quantum dots with similar photoelectric properties, thereby reducing the process difficulty and improving the production efficiency.

[0067] In the present embodiment, the properties of the at least three kinds of quantum dots are the same as the first quantum dots and the second quantum dots in the first embodiment. Specifically, the at least three kinds of quantum dots are all colloidal quantum dots. The photoluminescence spectra of the at least three kinds of quantum dots are in the same visible light region, and the photoluminescence peak wavelengths are close. The photoluminescence spectra of the at least three kinds of quantum dots being in the same visible light region and the photoluminescence peak wavelengths being close specifically means that the difference between the maximum value and the minimum value of the photoluminescence peak wavelengths of the at least three kinds of quantum dots is less than or equal to 10 nm. Further, the difference between the maximum value and the minimum value of the photoluminescence peak wavelengths of the at least three kinds of quantum dots is less than or equal to 5 nm. The difference between the maximum value and the minimum value of the full width at half maximum of the photoluminescence peaks of the at least three kinds of quantum dots is less than or equal to 10 nm. Further, the difference between the maximum value and the minimum value of the full width at half maximum of the photoluminescence peaks of the at least three kinds of quantum dots is less than or equal to 3 nm. All the quantum dots contained in each kind of quantum dot are manufactured in the same process, and the photoelectric properties are not significantly different. The dispersibilities of the at least three kinds of quantum dots in the same solvent are the same or similar. Here, no further description is given.

[0068] Experiments prove that the mass fraction of the quantum dots with the photoluminescence peak wavelength equal to and / or close to the median value of the photoluminescence peak wavelengths of the at least three kinds of quantum dots being greater than the average of the mass fractions of each kind of quantum dot not only can significantly enhance the emission of the peak wavelength, but also can narrow the full width at half maximum of the electroluminescence peaks of the quantum dots and obtain better photoelectric properties. Specifically, the mass fraction of the quantum dots can be normally distributed along the wavelength from short to long.

[0069] The electroluminescence peak wavelength of the quantum dot light-emitting layer will theoretically be closer to the median value of the wavelengths of the at least three kinds of quantum dots. The mass fraction of the quantum dots with the photoluminescence peak wavelength equal to and / or close to the median value of the photoluminescence peak wavelengths of the at least three kinds of quantum dots can be greater than the average of the mass fractions of each kind of quantum dot. Since the luminescence intensity is proportional to the component content, the luminescence intensity in the overlapping region of the electroluminescence peaks is the largest, and the luminescence intensity in other regions converges toward the overlapping region, thereby narrowing the full width at half maximum. Further, the full width at half maximum of one or two of the quantum dots with the photoluminescence peak wavelength equal to and / or close to the median value of the photoluminescence peak wavelengths of the at least three kinds of quantum dots can be the narrowest. That is, by narrowing the full width at half maximum of one or two of the components closer to the electroluminescence peak wavelength of the quantum dot light-emitting layer, the full width at half maximum of the electroluminescence peaks of the quantum dot light-emitting layer is narrowed. Further, the full width at half maximum of the electroluminescence peaks of the quantum dots can be normally distributed along the wavelength from short to long.

[0070] In particular, when the quantum dot light-emitting layer includes four quantum dots, the photo-luminescence peak wavelengths of the quantum dots are numbered as λ(a), λ(b), λ(c), and λ(d) in order of increasing wavelength, and the full width at half maximum of each quantum dot is FWHM(a), FWHM(b), FWHM(c), and FWHM(d), respectively. The photo-luminescence peak wavelengths λ(b) and λ(c) are the median values of the electroluminescence peak wavelengths of at least three quantum dots. The average mass fraction of each quantum dot is 25 wt%. In order to maximize the light-emitting intensity in the overlapping region of the electroluminescence peaks and narrow the full width at half maximum, the mass fraction of the quantum dots with photo-luminescence peak wavelengths λ(b) and λ(c) is greater than 25 wt% and less than 100 wt%. In a more specific embodiment, the mass fraction of the quantum dots with photo-luminescence peak wavelengths λ(b) and / or λ(c) is the largest among the mass fractions of all the quantum dots. The full width at half maximum of the electroluminescence peak of the quantum dots with photo-luminescence peak wavelengths λ(b) and / or λ(c) is the narrowest. Further, the mass fraction of the quantum dots and the full width at half maximum of the electroluminescence peak can be distributed normally with respect to the wavelength from short to long. For example, the mass fractions of the quantum dots with photo-luminescence peak wavelengths λ(a), λ(b), λ(c), and λ(d) can be 2:3:3:2.

[0071] When the quantum dot light-emitting layer includes five quantum dots, the photo-luminescence peak wavelengths of the quantum dots are numbered as λ(a), λ(b), λ(c), λ(d), and λ(e) in order of increasing wavelength, and the full width at half maximum of each quantum dot is FWHM(a), FWHM(b), FWHM(c), FWHM(d), and FWHM(e), respectively. The photo-luminescence peak wavelength λ(c) is the median value of the electroluminescence peak wavelengths of at least three quantum dots. The average mass fraction of each quantum dot is 20 wt%. In order to maximize the light-emitting intensity in the overlapping region of the electroluminescence peaks and narrow the full width at half maximum, the mass fraction of the quantum dots with photo-luminescence peak wavelength λ(c) is greater than 20 wt% and less than 100 wt%. In an embodiment, the mass fraction of the quantum dots with photo-luminescence peak wavelength λ(c) is the largest among the mass fractions of all the quantum dots. The full width at half maximum of the electroluminescence peak of the quantum dots with photo-luminescence peak wavelength λ(c) is the narrowest. Further, the mass fraction of the quantum dots and the full width at half maximum of the electroluminescence peak can be distributed normally with respect to the wavelength from short to long.

[0072] Reference is made to Figure 2 and Figure 3 , Figure 2 A flow chart of a method for manufacturing a quantum dot light-emitting diode device according to a third embodiment of the present application is shown in FIG. 3. Figure 3 Reference is made to Figure 2A flow chart of the step of forming a quantum dot light emitting layer on the first electrode. The method of manufacturing a quantum dot light emitting diode device of the present application comprises the following steps:

[0073] 1: forming a first electrode;

[0074] 2: forming a quantum dot light emitting layer on the first electrode; and

[0075] 3: forming a second electrode on the quantum dot light emitting layer.

[0076] Wherein, the step 2: forming a quantum dot light emitting layer on the first electrode comprises:

[0077] The step 21: providing a quantum dot solution, the quantum dot solution comprising a first quantum dot and a second quantum dot, an absolute value of a difference between a photoluminescence (PL) peak wavelength (WLP) of the first quantum dot and a photoluminescence peak wavelength of the second quantum dot being less than or equal to 10 nm.

[0078] The solvent of the present application can be, but is not limited to, one or more of n-octane, iso-octane, toluene, benzene, chlorobenzene, xylene, chloroform, acetone, cyclohexane, n-hexane, n-pentane, iso-pentane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, hexamethylphosphoramide, n-butyl ether, anisole, phenetol, phenylacetone, aniline, diphenyl ether, etc. In the step 21, the materials, optical properties, and other characteristics of the first quantum dot and the second quantum dot can refer to the first embodiment, which will not be repeated here.

[0079] The step 22: forming the quantum dot solution on the first electrode, and solidifying the quantum dot solution to form a quantum dot light emitting layer.

[0080] In the step 22, the reaction of the first quantum dot and the second quantum dot during the film forming process can refer to the first embodiment, which will not be repeated here.

[0081] Therefore, the present application can manufacture a quantum dot light emitting layer by using two quantum dots with similar photoelectric properties, thereby reducing the process difficulty and improving the production efficiency.

[0082] Please refer to 2 and Figure 4 , Figure 4 A flow chart of the step of forming a quantum dot light emitting layer on the first electrode provided by the fourth embodiment of the present application. The fourth embodiment of the present application is substantially the same as the third embodiment, and the only difference is that:

[0083] The step 2: forming a quantum dot light emitting layer on the first electrode comprises:

[0084] Step 221: providing a quantum dot solution, the quantum dot solution including at least three quantum dots, a difference between a maximum value and a minimum value of photoluminescence peak wavelengths of the at least three quantum dots being less than or equal to 10 nm. In step 221, the characteristics of the at least three quantum dots such as materials, optical properties, etc. can refer to the second embodiment, which will not be repeated here.

[0085] Step 222: forming the quantum dot solution on a first electrode, and solidifying the quantum dot solution to form a quantum dot light-emitting layer. In step 222, the reaction of the at least three quantum dots during the film forming process can refer to the first embodiment, which will not be repeated here.

[0086] The manufacturing method of the quantum dot light-emitting diode device of the present application can manufacture the quantum dot light-emitting layer by mixing two or more quantum dots with similar photoelectric properties together to prepare the quantum dot light-emitting layer of the organic light-emitting device, thereby avoiding adjusting the preparation process for quantum dots with different photoelectric properties, reducing the process difficulty, and improving the production efficiency. Moreover, by adjusting the composition ratio of different quantum dot materials in the quantum dot film, the intensity of the electroluminescence overlapping region of the multi-component quantum dot material is enhanced, and the electroluminescence spectrum with adjustable light-emitting peak position and narrowed half-peak full width can be obtained. The photoelectric performance of the light-emitting diode device prepared by using the mixed quantum dots can approach the photoelectric performance of the quantum dot electroluminescent device with the optimal performance in the quantum dot film, thereby improving the overall photoelectric performance of the mixed quantum dot component. In the following, the technical solutions of the present application will be described in detail in combination with specific embodiments.

[0087] Embodiment 1

[0088] Please refer to Figures 5(a) to 5(d)Figure 5(a) is a photoluminescence spectrum of the first quantum dots of Example 1 of the present application; Figure 5(b) is a photoluminescence spectrum of the second quantum dots of Example 1 of the present application; Figure 5(c) is an electroluminescence spectrum of a quantum dot light-emitting layer formed by mixing the first quantum dots and the second quantum dots of Example 1 of the present application in a mass ratio of 2:3; and Figure 5(d) is a graph of external quantum efficiency versus luminance of quantum dot light-emitting diode devices formed by the first quantum dots, the second quantum dots and the mixture of the first quantum dots and the second quantum dots, respectively, of Example 1 of the present application. A first solution containing the first quantum dots (denoted as QD1 in Table 1) and a second solution containing the second quantum dots (denoted as QD2 in Table 1) were prepared. The first quantum dots and the second quantum dots are both core-shell green quantum dots CdZnSe / CdZnS / ZnS, wherein CdZnSe is the core and CdZnS and ZnS are the shells. The first quantum dots and the second quantum dots can be obtained by using existing synthesis methods. The solvents of the first solution and the second solution are both n-octane. The electroluminescence peak wavelength of the first quantum dots is λ(a) = 527 nm, the full width at half maximum of the electroluminescence is FWHM(a) = 25 nm, and the particle size is 10 nm. The electroluminescence peak wavelength of the second quantum dots is λ(b) = 529 nm, the full width at half maximum of the electroluminescence is FWHM(b) = 22 nm, and the particle size is 12 nm. The organic coating ligands on the surfaces of the first quantum dots and the second quantum dots are both oleic acid.

[0089] The first solution and the second solution were mixed to obtain a quantum dot solution, wherein the mass ratio of the first quantum dots to the second quantum dots in the quantum dot solution was 2:3.

[0090] Quantum dot light-emitting diode devices were prepared using the first solution, the second solution and the quantum dot solution as the light-emitting layer, respectively. The structure of the quantum dot light-emitting diode and the selected functional layer materials are as follows: anode (ITO) / hole injection layer (PEDOT:PSS) / hole transport layer (TFB) / organic light-emitting layer (QDs) / electron transport layer (ZnO) / cathode (Al). The photoelectric performance and the lifetime of the quantum dot light-emitting diode devices were tested. The lifetime of the device was tested by using a 128-channel lifetime test system customized by Guangzhou New Horizon Company. The system architecture is a constant voltage and constant current source driving QLED, testing the change of voltage or current; a photodiode detector and a test system, testing the change of luminance (photo current) of QLED; a luminance meter testing and calibrating the luminance (photo current) of QLED. The test results are shown in Table 1. Table 1 is the test data of the light-emitting diode devices prepared in the examples and the comparative examples provided by the present application.

[0091] Example 2

[0092] A third solution containing third quantum dots (denoted as QD3 in Table 1), a fourth solution containing fourth quantum dots (denoted as QD4 in Table 1), a fifth solution containing fifth quantum dots (denoted as QD5 in Table 1), and a sixth solution containing sixth quantum dots (denoted as QD6 in Table 1) were prepared. The third quantum dots, the fourth quantum dots, the fifth quantum dots, and the sixth quantum dots are all core-shell red quantum dots CdZnSe / ZnSe / ZnS, in which CdZnSe is the core and ZnSe and ZnS are the shells. The solvents of the third solution, the fourth solution, the fifth solution, and the sixth solution are all n-octane. The electroluminescence peak wavelength of the third quantum dots is λ(a) = 626 nm, the full width at half maximum of the electroluminescence is FWHM(a) = 23 nm, and the particle size is 13 nm; the electroluminescence peak wavelength of the fourth quantum dots is λ(b) = 627.5 nm, the full width at half maximum of the electroluminescence is FWHM(b) = 24 nm, and the particle size is 12 nm; the electroluminescence peak wavelength of the fifth quantum dots is λ(c) = 628 nm, the full width at half maximum of the electroluminescence is FWHM(b) = 24 nm, and the particle size is 13.4 nm; the electroluminescence peak wavelength of the sixth quantum dots is λ(d) = 629 nm, the full width at half maximum of the electroluminescence is FWHM(d) = 24 nm, and the particle size is 14 nm; and the organic coating ligand on the surface of the third quantum dots, the fourth quantum dots, the fifth quantum dots, and the sixth quantum dots is octanethiol.

[0093] The third solution to the sixth solution were mixed to obtain a quantum dot solution, in which the mass ratio of the third quantum dots, the fourth quantum dots, the fifth quantum dots, and the sixth quantum dots in the quantum dot solution is 2:3:3:2.

[0094] A quantum dot light-emitting diode was prepared using the third solution, the fourth solution, the fifth solution, the sixth solution, and the quantum dot solution as the light-emitting layer. The structure of the quantum dot light-emitting diode and the selected functional layer materials are as follows: anode (ITO) / hole injection layer (PEDOT:PSS) / hole transport layer (TFB) / organic light-emitting layer (QDs) / electron transport layer (ZnO) / cathode (Al); and the photoelectric performance and the lifetime of the quantum dot light-emitting diode device were tested, and the test system and method were the same as in Embodiment 1. The test results are shown in Table 1.

[0095] Comparative Example 1

[0096] The quantum dot light-emitting diode device of Comparative Example 1 is substantially the same as that of Embodiment 1, except that the mass ratio of the first quantum dots and the second quantum dots in the quantum dot solution is 3:2.

[0097] The photoelectric performance and the lifetime of the quantum dot light-emitting diode device were tested, and the test system and method were the same as in Embodiment 1. The test results are shown in Table 1.

[0098] Comparative Example 2

[0099] The quantum dot light emitting diode device of Comparative Example 2 is substantially the same as that of Example 2, except that the mass ratio of the first quantum dots, the second quantum dots, the third quantum dots, and the fourth quantum dots in the quantum dot solution is 1:1:1:1.

[0100] The photoelectric performance and lifetime of the quantum dot light emitting diode device were tested, and the test system and method were the same as those of Example 1. The test results are shown in Table 1.

[0101] Table 1

[0102]

[0103] As can be seen from Table 1, in Example 1, the photoluminescence peak values of the first quantum dots and the second quantum dots are λ(a) = 527 nm and λ(b) = 529 nm, respectively, and the full width at half maximum is 25 nm and 22 nm, respectively. The particle sizes of the quantum dots are 10 nm and 12 nm, respectively. The electroluminescence peak values of the quantum dot light emitting diode devices prepared by using the first quantum dots and the second quantum dots as the light emitting layer material are 531 nm and 532.5 nm, respectively, the EQEs are 14.8% and 17.8%, respectively, and the lifetime test T 95 @1000nit are 3900 h and 4400 h, respectively.

[0104] The electroluminescence peak value of the quantum dot light emitting diode device prepared by mixing the first quantum dots and the second quantum dots in a mass ratio of 2:3 as the quantum dot light emitting layer material is 532 nm, the full width at half maximum is 21.5 nm, the EQE is 17%, and the lifetime test T 95 @1000nit = 4300 h. The photoluminescence peak values of the first quantum dots and the second quantum dots differ by 2 nm, and the full width at half maximum of the second quantum dots with a longer photoluminescence peak wavelength is narrower. After mixing in a mass ratio of 2:3, the electroluminescence peak of the prepared electroluminescence device is red-shifted compared to the photoluminescence peak, and the light intensity is the largest at the overlapping part of 532 nm, showing a single peak shape. The electroluminescence peak wavelength of the quantum dot light emitting layer is between the electroluminescence peak wavelengths of the devices in which the first quantum dots and the second quantum dots are used as the quantum dot light emitting layer material alone, and the full width at half maximum of the electroluminescence peak is only 21.5 nm, which is narrower than the full width at half maximum of the electroluminescence peaks of the devices in which the first quantum dots and the second quantum dots are used as the quantum dot light emitting layer material alone. In addition, the EQE and T 95 @1000nit are close to the optimal data of the first quantum dots and the second quantum dots.

[0105] In Example 2, the photoluminescence peak values of the first quantum dots, the second quantum dots, the third quantum dots and the fourth quantum dots are λ(a)=626nm, λ(b)=627.5nm, λ(c)=628nm, λ(d)=629nm, respectively, the full width at half maximum are 23nm, 24nm, 22nm, 25nm, respectively, the particle size distribution range of the quantum dots is 13±1.5nm, the quantum dot light-emitting diode devices prepared by taking the first quantum dots, the second quantum dots, the third quantum dots and the fourth quantum dots as the light-emitting layer material, the electroluminescence peak values are 629nm, 630nm, 631.5nm and 632nm, respectively, the EQEs are 18%, 16%, 19% and 14%, respectively, the T 95 @1000nit are 1550h, 2080h, 2160h and 2510h, respectively. The electroluminescence peak value of the quantum dot light-emitting diode device prepared by mixing the first quantum dots, the second quantum dots, the third quantum dots and the fourth quantum dots in a mass ratio of 2:3:3:2 as the quantum dot light-emitting layer material is 630.5nm, the full width at half maximum is 22nm, the EQE is 17.8%, and the T 95 @1000nit=2300h.

[0106] The electroluminescence peak value of the quantum dot light-emitting layer is close to the median of the electroluminescence peak values of the devices in which the first quantum dots, the second quantum dots, the third quantum dots and the fourth quantum dots are used alone as the quantum dot light-emitting layer material, and the full width at half maximum of the electroluminescence peak is only 22nm, which is narrower than the full width at half maximum of the electroluminescence peak of the device in which the first quantum dots are used alone as the quantum dot light-emitting layer material and the full width at half maximum of the electroluminescence peak of the device in which the second quantum dots are used alone as the quantum dot light-emitting layer material. In addition, the EQEs and T 95 @1000nit are all close to the optimal data of the first quantum dots and the second quantum dots.

[0107] Comparing Example 1 with Comparative Example 1 again, when the content of the second quantum dots is high, the light-emitting intensity in the overlapping region of the electroluminescence peaks is the largest due to the positive correlation between the light-emitting intensity and the component content, and the light-emitting intensity in other regions converges towards the overlapping region, thereby narrowing the full width at half maximum. Further, the full width at half maximum of the electroluminescence peak is narrower. In addition, the EQEs(%) and T 95 @1000nit are all better.

[0108] Comparing Example 2 and Comparative Example 2, when the quantum dot light-emitting layer is composed of at least three kinds of quantum dots, the electroluminescence peak of the quantum dot light-emitting layer is closer to the median value of the wavelengths of the at least three kinds of quantum dots. When the content of the third quantum dot and the fourth quantum dot is high, the light-emitting intensity in the overlapping region of the electroluminescence peaks is the highest due to the positive correlation between the light-emitting intensity and the content of the components, and the light-emitting intensity in other regions converges towards the overlapping region, thereby narrowing the full width at half maximum. Further, the full width at half maximum of the electroluminescence peak of Example 2 is narrower due to the normal distribution of the mass fraction of the quantum dots along the length of the wavelengths. Moreover, the EQE (%) and T 95 @1000 nit are all better.

[0109] In addition, the present application also provides a quantum dot film, which comprises first quantum dots and second quantum dots, and the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dots and the photoluminescence peak wavelength of the second quantum dots is less than or equal to 10 nm.

[0110] The first quantum dots and the second quantum dots are both colloidal quantum dots. That is, the first quantum dots and the second quantum dots can be stored in solution. When forming the quantum dot film, a first solution containing the first quantum dots and a second solution containing the second quantum dots can be mixed in a certain proportion. The solvent of the first solution and the solvent of the second solution can be the same solvent or similar solvents, for example, both polar solvents or both non-polar solvents. In an embodiment, the solvent of the first solution and the solvent of the second solution are the same solvent.

[0111] The photoluminescence spectra of the first quantum dots and the second quantum dots are in the same visible light region. For example, the first quantum dots and the second quantum dots are both green quantum dots. In an embodiment, the first quantum dots and the second quantum dots can be quantum dots of different batches manufactured using the same material and the same process. In another embodiment, the first quantum dots and the second quantum dots can also be quantum dots manufactured using different materials and / or different processes. As long as the photoluminescence spectra of the first quantum dots and the second quantum dots are in the same visible light region and the photoluminescence peak wavelengths are close, it is acceptable. The photoluminescence peak wavelengths can be close when the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dots and the photoluminescence peak wavelength of the second quantum dots is less than or equal to 10 nm. When the difference between the photoluminescence peak wavelength of the first quantum dots and the photoluminescence peak wavelength of the second quantum dots is small enough, after the quantum dot composition is cured to form the quantum dot light-emitting layer, the photoluminescence peaks of the first quantum dots and the second quantum dots overlap after red shift to obtain an electroluminescence spectrum with higher color purity. Further, the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dots and the photoluminescence peak wavelength of the second quantum dots is less than or equal to 5 nm.

[0112] To ensure that the electroluminescence peak of the quantum dot film has a narrow full width at half maximum (FWHM), in one embodiment, the absolute value of the difference between the FWHM of the photoluminescence peak of the first quantum dot and the FWHM of the photoluminescence peak of the second quantum dot is less than or equal to 10 nm. Further, the absolute value of the difference between the FWHM of the photoluminescence peak of the first quantum dot and the FWHM of the photoluminescence peak of the second quantum dot is less than or equal to 3 nm.

[0113] Furthermore, in this application, unless otherwise specified, all quantum dots contained in the first quantum dot are manufactured in the same process, and their photoelectric properties are not significantly different. Similarly, all quantum dots contained in the second quantum dot are also manufactured in the same process, and their photoelectric properties are not significantly different. For example, the photoelectric properties of multiple electroluminescent devices fabricated from the first quantum dot, such as the external quantum efficiency (EQE) and the time required for the manual maximum brightness of 1000 nits to decay to 95% (in T...), are similar. 95 The variation in performance between quantum dot components (represented by @1000nit) should not exceed 50%. If the performance difference is too large, the resulting mixture, used as the luminescent layer material, will cause severe nonradiative recombination transitions in quantum dot devices, leading to a decline in device performance and an inability to obtain stable photoelectric properties. When the photoelectric properties of the same type of quantum dots are not significantly different, it ensures that the electroluminescence fluorescence in the quantum dot composition has a large overlap, avoiding problems such as shoulder peaks or multiple peaks.

[0114] Quantum dots include at least one single or composite structure quantum dot from Group IV, II-V, II-VI, III-VI, III-V, IV-VI, VI-VI, VIII-VI, I-III-VI, II-IV-VI, and II-IV-V of the periodic table. Composite structure quantum dots include core-shell structure quantum dots. The core material constituting the core of the core-shell structure quantum dot includes at least one of CdSe, CdS, CdTe, CdSeTe, CdZnS, PbSe, ZnTe, CdSeS, PbS, PbTe, HgS, HgSe, HgTe, GaN, GaP, GaAs, InP, InAs, InZnP, InGaP, and InGaN; the shell material constituting the core-shell structure quantum dot includes at least one of ZnSe, ZnS, and ZnSeS.

[0115] The dispersibility of the first quantum dots and the second quantum dots in the same solvent is the same or similar to avoid the problem of poor solubility caused by intermixing of different components. More specifically, the surface of the first quantum dots has a first organic ligand. The surface of the second quantum dots has a second organic ligand. The first organic ligand and the second organic ligand can be dissolved in the same solvent. In an embodiment, the first organic ligand and the second organic ligand are the same. The first organic ligand and the second organic ligand are each independently selected from one or more of oleic acid, oleylamine, alkyl acid with a carbon number of 4 to 20, trioctylphosphine, tributylphosphine, trioctyloxyphosphine, hexylphosphonic acid, oleylamine, ethylamine, triethylamine, propylamine, tripropylamine, butylamine, tributylamine, pentylamine, tripentylamine, n-hexylamine, trihexylamine, heptylamine, octylamine, trioctylamine, di-n-octylamine, decylamine, dodecylamine, tridodecylamine, tetradecylamine, hexadecylamine, octadecylamine, dioctadecylamine, and dodecanethiol.

[0116] When the first quantum dots and the second quantum dots are dispersed in the solvent, the distance between the quantum dot light-emitting cores of the first quantum dots and the second quantum dots is too large to produce energy resonance transfer. When formed into a quantum dot film, the distance between the first quantum dots and the second quantum dots is shortened to a range in which energy resonance transfer can occur. Specifically, the energy resonance transfer phenomenon in the quantum dot film is manifested as a red shift of the electroluminescence peak position by transferring the energy of a high-energy state donor (short-wavelength light emission) to an adjacent low-energy state acceptor (long-wavelength light emission). When the photo-luminescence peak wavelength of the first quantum dots and the photo-luminescence peak wavelength of the second quantum dots are close enough in the spectrum, for example, the absolute value of the difference between the photo-luminescence peak wavelength of the first quantum dots and the photo-luminescence peak wavelength of the second quantum dots is less than or equal to 10 nm,

[0117] When formed into a quantum dot film, the distance between the first quantum dots and the second quantum dots is shortened to a range in which energy resonance transfer can occur. Energy resonance transfer occurs between the first quantum dots and the second quantum dots, transferring the energy of a high-energy state donor (quantum dots with shorter light-emitting wavelengths) to an adjacent low-energy state acceptor (quantum dots with longer light-emitting wavelengths). The quantum dots with shorter light-emitting wavelengths release energy and undergo red shift, and the quantum dots with longer light-emitting wavelengths receive energy and undergo blue shift. That is, after energy resonance occurs between the two types of quantum dots, the light-emitting peaks of the two types of quantum dots are close to each other and superimposed, obtaining fluorescence enhancement at the same wavelength position and an electroluminescence spectrum with higher color purity.

[0118] Experiments show that by adjusting the mass fraction and full width at half maximum of the first quantum dots and the second quantum dots, the emission fluorescence of the peak wavelength can be significantly enhanced, and the full width at half maximum of the electroluminescence peak of the quantum dot light-emitting layer formed by solidification of the quantum dot film shows a narrowing trend, thereby showing better monochromaticity; at the same time, the optoelectronic performance of the device manufactured using the quantum dot film is dominated by the part where the fluorescence is most enhanced, and the overall optoelectronic performance shows that it is close to the best component of the first quantum dots and the second quantum dots.

[0119] For example, in the present embodiment, the quantum dot light-emitting layer is composed of first quantum dots and second quantum dots. The photo-induced luminescence peak wavelength λ(b) of the second quantum dots is greater than the photo-induced luminescence peak wavelength λ(a) of the first quantum dots. Experiments show that by making the mass fraction of the second quantum dots greater than the mass fraction of the first quantum dots, the emission fluorescence of the peak wavelength can be significantly enhanced, the full width at half maximum of the quantum dot electroluminescence peak can be narrowed, and better optoelectronic performance can be obtained. Specifically, the mass fraction of the second quantum dots is greater than 50wt% and less than 100wt%, and the mass fraction of the first quantum dots is greater than 0wt% and less than 50wt%.

[0120] Due to energy loss in the process of energy transfer resonance, if the mass fraction of the second quantum dots is less than the mass fraction of the first quantum dots, due to energy loss, the red shift of the first quantum dots is small, the overlap degree of the electroluminescence peaks of the second quantum dots and the first quantum dots is low, and obvious fluorescence enhancement and full width at half maximum narrowing cannot be obtained. And due to energy loss, the blue shift degree of the electroluminescence peak of the second quantum dots is smaller than the red shift degree of the electroluminescence peak of the first quantum dots, and the electroluminescence peak wavelength of the quantum dot light-emitting layer is closer to the electroluminescence peak wavelength of the second quantum dots. Since the luminous intensity is proportional to the component content, the content of the second quantum dots is greater than the content of the first quantum dots, which can maximize the luminous intensity in the overlapping region of the electroluminescence peak, and the luminous intensity in other regions converges towards the overlapping region, thereby narrowing the full width at half maximum. Further, the full width at half maximum FWHM(b) of the photo-induced luminescence peak of the second quantum dots can be narrower than the full width at half maximum FWHM(a) of the photo-induced luminescence peak of the first quantum dots. That is, by making the full width at half maximum of the component closer to the electroluminescence peak wavelength of the quantum dot light-emitting layer narrow, the full width at half maximum of the electroluminescence peak of the quantum dot light-emitting layer can be narrowed.

[0121] Another embodiment of the present application provides a quantum dot film which is substantially the same as the above-mentioned embodiments, except that:

[0122] The quantum dot film includes at least three quantum dots, and the difference between the maximum and minimum of the photo-induced luminescence peak wavelengths of the at least three quantum dots is less than or equal to 10nm.

[0123] Thus, the present application can utilize at least three kinds of quantum dot films with similar photoelectric properties to manufacture quantum dot light-emitting layers, thereby reducing the process difficulty and improving the production efficiency. In the present embodiment, the properties of the at least three kinds of quantum dots are the same as those of the first quantum dots and the second quantum dots in the first embodiment. Specifically, the at least three kinds of quantum dots are all colloidal quantum dots. The photoluminescence spectra of the at least three kinds of quantum dots are in the same visible light region, and the photoluminescence peak wavelengths are close. Specifically, the difference between the maximum value and the minimum value of the photoluminescence peak wavelengths of the at least three kinds of quantum dots is less than or equal to 10 nm. Further, the difference between the maximum value and the minimum value of the photoluminescence peak wavelengths of the at least three kinds of quantum dots is less than or equal to 5 nm. The difference between the maximum value and the minimum value of the full width at half maximum of the photoluminescence peaks of the at least three kinds of quantum dots is less than or equal to 10 nm. Further, the difference between the maximum value and the minimum value of the full width at half maximum of the photoluminescence peaks of the at least three kinds of quantum dots is less than or equal to 3 nm. All the quantum dots contained in each kind of quantum dot are manufactured in the same process, and the photoelectric properties are similar. The dispersibilities of the at least three kinds of quantum dots in the same solvent are the same or similar. Details are not described herein.

[0124] Experiments prove that the mass fraction of the quantum dots with the photoluminescence peak wavelength equal to and / or close to the median value of the photoluminescence peak wavelengths of the at least three kinds of quantum dots is greater than the average of the mass fractions of each kind of quantum dot, which not only can significantly enhance the emission of the peak wavelength, but also can narrow the full width at half maximum of the electroluminescence peak of the quantum dots and obtain better photoelectric properties. Specifically, the mass fraction of the quantum dots can be normally distributed along the wavelength from short to long.

[0125] The electroluminescence peak wavelength of the quantum dot light-emitting layer will theoretically be closer to the median value of the wavelengths of the at least three kinds of quantum dots. The mass fraction of the quantum dots with the photoluminescence peak wavelength equal to and / or close to the median value of the photoluminescence peak wavelengths of the at least three kinds of quantum dots is greater than the average of the mass fractions of each kind of quantum dot. Since the light-emitting intensity is proportional to the component content, the light-emitting intensity in the overlapping region of the electroluminescence peaks is the maximum, and the light-emitting intensity in other regions converges toward the overlapping region, thereby narrowing the full width at half maximum. Further, the full width at half maximum of one or two of the quantum dots with the photoluminescence peak wavelength equal to and / or close to the median value of the photoluminescence peak wavelengths of the at least three kinds of quantum dots can be the narrowest. That is, the full width at half maximum of one or two of the components closer to the electroluminescence peak wavelength of the quantum dot film is narrowed, thereby narrowing the full width at half maximum of the electroluminescence peak of the quantum dot film. Further, the full width at half maximum of the electroluminescence peak of the quantum dots can be normally distributed along the wavelength from short to long.

[0126] In particular, when the quantum dot film includes four quantum dots, the photoluminescence peak wavelengths of the quantum dots are numbered as λ(a), λ(b), λ(c), and λ(d) in order of increasing wavelength, and the full width at half maximum are FWHM(a), FWHM(b), FWHM(c), and FWHM(d), respectively. The photoluminescence peak wavelengths λ(b) and λ(c) are the median values of the electroluminescence peak wavelengths of at least three quantum dots. The average of the mass fractions of the quantum dots is 25 wt%. In order to maximize the luminescence intensity in the overlapping region of the electroluminescence peaks and narrow the full width at half maximum, the mass fractions of the quantum dots with the photoluminescence peak wavelengths λ(b) and λ(c) are greater than 25 wt% and less than 100 wt%. In a more specific embodiment, the mass fraction of the quantum dot with the photoluminescence peak wavelength λ(b) and / or λ(c) can be the largest among the mass fractions of all the quantum dots. The full width at half maximum of the electroluminescence peak of the quantum dot with the photoluminescence peak wavelength λ(b) and / or λ(c) can be the narrowest. Further, the mass fractions of the quantum dots and the full width at half maximum of the electroluminescence peak can be distributed normally with respect to the wavelength from short to long. For example, the mass fractions of the quantum dots with the photoluminescence peak wavelengths λ(a), λ(b), λ(c), and λ(d) can be 2:3:3:2.

[0127] When the quantum dot film includes five quantum dots, the photoluminescence peak wavelengths of the quantum dots are numbered as λ(a), λ(b), λ(c), λ(d), and λ(e) in order of increasing wavelength, and the full width at half maximum are FWHM(a), FWHM(b), FWHM(c), FWHM(d), and FWHM(e), respectively. The photoluminescence peak wavelength λ(c) is the median value of the electroluminescence peak wavelengths of at least three quantum dots. The average of the mass fractions of the quantum dots is 20 wt%. In order to maximize the luminescence intensity in the overlapping region of the electroluminescence peaks and narrow the full width at half maximum, the mass fraction of the quantum dot with the electroluminescence peak wavelength λ(c) is greater than 20% and less than 100%. In an embodiment, the mass fraction of the quantum dot with the electroluminescence peak wavelength λ(c) is the largest among the mass fractions of all the quantum dots. The full width at half maximum of the electroluminescence peak of the quantum dot with the electroluminescence peak wavelength λ(c) is the narrowest. Further, the mass fractions of the quantum dots and the full width at half maximum of the electroluminescence peak can be distributed normally with respect to the wavelength from short to long.

[0128] The application provides a quantum dot light emitting diode device, a manufacturing method thereof and a quantum dot film. The quantum dot light emitting diode device comprises a first electrode, a second electrode and a quantum dot light emitting layer. The quantum dot light emitting layer is arranged between the first electrode and the second electrode. The quantum dot light emitting layer comprises first quantum dots and second quantum dots, and the absolute value of the difference between the photo-induced luminescence peak wavelength of the first quantum dots and the photo-induced luminescence peak wavelength of the second quantum dots is less than or equal to 10 nm. The light emitting device and the quantum dot film of the application can be manufactured by using two quantum dots with similar photoelectric properties, thereby reducing the process difficulty and improving the production efficiency.

[0129] The manufacturing method of the quantum dot light emitting diode device of the application can manufacture the quantum dot light emitting layer by mixing two or more quantum dots with similar photoelectric properties together, thereby avoiding adjusting the preparation process of the quantum dots with different photoelectric properties respectively, reducing the process difficulty and improving the production efficiency. Moreover, by adjusting the composition ratio of different quantum dot materials in the quantum dot film, the intensity of the electroluminescence overlapping region of the multi-component quantum dot material is enhanced, the electroluminescence spectrum with adjustable luminescence peak position and narrowed full width at half maximum can be obtained. The photoelectric performance of the light emitting diode device prepared by using the mixed quantum dots can be close to the photoelectric performance of the quantum dot electroluminescent device with the optimal performance in the quantum dot film, thereby improving the overall photoelectric performance of the mixed quantum dot component.

[0130] The above provides a detailed description of the embodiments of the application, and the principles and embodiments of the application are described by using specific examples. The above description of the embodiments is only used to help understand the application. Meanwhile, according to the idea of the application, the specific embodiments and application range can be changed by those skilled in the art. In summary, the content of the specification should not be understood as a limitation of the application.

Claims

1. A quantum dot light-emitting diode device, characterized in that, include: First electrode; Second electrode; as well as A quantum dot light-emitting layer is disposed between the first electrode and the second electrode; The quantum dot luminescent layer is composed of a first quantum dot and a second quantum dot. The absolute value of the difference between the photoluminescence peak wavelength of the first quantum dot and the photoluminescence peak wavelength of the second quantum dot is less than or equal to 10 nm. The photoluminescence peak wavelength of the second quantum dot is greater than that of the first quantum dot. The mass fraction of the second quantum dot is greater than 50 wt% and less than 100 wt%, and the mass fraction of the first quantum dot is greater than 0 wt% and less than 50 wt%. Alternatively, the quantum dot luminescent layer comprises at least three types of quantum dots, wherein the difference between the maximum and minimum values ​​of the photoluminescence peak wavelengths of the at least three types of quantum dots is less than or equal to 10 nm, and the mass fraction of the quantum dot corresponding to the median of the photoluminescence peak wavelengths of the at least three types of quantum dots is greater than the average mass fraction of each type of quantum dot.

2. The quantum dot light-emitting diode device as described in claim 1, characterized in that, The absolute value of the difference between the photoluminescence peak wavelength of the first quantum dot and the photoluminescence peak wavelength of the second quantum dot is less than or equal to 5 nm; and / or The absolute value of the difference between the full width at half maximum (FWHM) of the photoluminescence peak of the first quantum dot and the full WHM of the photoluminescence peak of the second quantum dot is less than or equal to 10 nm; or The absolute value of the difference between the full width at half maximum (FWHM) of the photoluminescence peak of the first quantum dot and the full width at half maximum (FWHM) of the photoluminescence peak of the second quantum dot is less than or equal to 3 nm.

3. The quantum dot light-emitting diode device as described in claim 1, characterized in that, When the quantum dot luminescent layer is composed of the first quantum dot and the second quantum dot, the full width at half maximum (FWHM) of the photoluminescence peak of the second quantum dot is smaller than that of the photoluminescence peak of the first quantum dot.

4. The quantum dot light-emitting diode device as described in claim 1, characterized in that, When the quantum dot luminescent layer includes at least three types of quantum dots, among the at least three types of quantum dots, one or two of the quantum dots corresponding to the median photoluminescence peak wavelength of the at least three types of quantum dots have the narrowest full width at half maximum (FWHM).

5. The quantum dot light-emitting diode device according to claim 1, characterized in that, The quantum dot light-emitting diode device includes a first electrode, a hole injection layer, a hole transport layer, the quantum dot light-emitting layer, an electron transport layer, and a second electrode, which are stacked sequentially. The first electrode is the anode, and the second electrode is the cathode.

6. The quantum dot light-emitting diode device according to claim 5, characterized in that, The material of the first electrode is selected from one or more of indium tin oxide, fluorine-doped tin oxide, indium zinc oxide, graphene, and carbon nanotubes; The material of the hole injection layer is selected from one or more of PEDOT:PSS, nickel oxide, molybdenum oxide, tungsten oxide, vanadium oxide, molybdenum sulfide, tungsten sulfide, and copper oxide; The material of the hole transport layer is selected from one or more of PVK, Poly-TPD, CBP, TCTA, and TFB; The quantum dot luminescent layer comprises at least one single or composite structure quantum dot from Group IV, II-V, II-VI, III-VI, III-V, IV-VI, VI-VI, VIII-VI, I-III-VI, II-IV-VI, and II-IV-V of the periodic table; the composite structure quantum dot comprises a core-shell structure quantum dot, wherein the core material of the core-shell structure quantum dot comprises at least one of CdSe, CdS, CdTe, CdSeTe, CdZnS, PbSe, ZnTe, CdSeS, PbS, PbTe, HgS, HgSe, HgTe, GaN, GaP, GaAs, InP, InAs, InZnP, InGaP, and InGaN, and the shell material of the core-shell structure quantum dot comprises at least one of ZnSe, ZnS, and ZnSeS; The material of the electron transport layer is selected from one or more of the following: n-type ZnO, TiO2, SnO, Ta2O3, AlZnO, ZnSnO, InSnO, Alq3, Ca, Ba, CsF, LiF, and CsCO3. The cathode material is selected from one or more of Al, Ca, Ba, and Ag.

7. A quantum dot film, characterized in that, The quantum dot film is composed of a first quantum dot and a second quantum dot. The absolute value of the difference between the photoluminescence peak wavelength of the first quantum dot and the photoluminescence peak wavelength of the second quantum dot is less than or equal to 10 nm. The photoluminescence peak wavelength of the second quantum dot is greater than that of the first quantum dot, and the mass fraction of the second quantum dot is greater than that of the first quantum dot. Alternatively, the quantum dot film comprises at least three types of quantum dots, wherein the difference between the maximum and minimum values ​​of the photoluminescence peak wavelengths of the at least three types of quantum dots is less than or equal to 10 nm, and the mass fraction of the quantum dot corresponding to the median of the photoluminescence peak wavelengths of the at least three types of quantum dots is greater than the average mass fraction of each type of quantum dot.

8. The quantum dot film as described in claim 7, characterized in that, The absolute value of the difference between the peak wavelength of photoluminescence of the first quantum dot and the peak wavelength of photoluminescence of the second quantum dot is less than or equal to 5 nm; and / or the absolute value of the difference between the full width at half maximum (FWHM) of the photoluminescence peak of the first quantum dot and the full width at half maximum (FWHM) of the photoluminescence peak of the second quantum dot is less than or equal to 10 nm; or the absolute value of the difference between the full width at half maximum (FWHM) of the photoluminescence peak of the first quantum dot and the full width at half maximum (FWHM) of the photoluminescence peak of the second quantum dot is less than or equal to 3 nm.

9. The quantum dot film as described in claim 7, characterized in that, When the quantum dot film is composed of the first quantum dot and the second quantum dot, the full width at half maximum (FWHM) of the photoluminescence peak of the second quantum dot is smaller than that of the photoluminescence peak of the first quantum dot.

10. The quantum dot film as described in claim 9, characterized in that, When the quantum dot film comprises at least three types of quantum dots, among the at least three types of quantum dots, one or two of the quantum dots corresponding to the median photoluminescence peak wavelength of the at least three types of quantum dots have the narrowest full width at half maximum (FWHM).

11. A method for manufacturing a quantum dot light-emitting diode device, characterized in that, Includes the following steps: Form the first electrode; A quantum dot light-emitting layer is formed on the first electrode; as well as A second electrode is formed on the quantum dot light-emitting layer; Wherein, forming a quantum dot light-emitting layer on the first electrode includes: Prepare a quantum dot solution, the quantum dot solution comprising a first quantum dot and a second quantum dot, wherein the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dot and the photoluminescence peak wavelength of the second quantum dot is less than or equal to 10 nm; and The quantum dot solution is formed on the first electrode, and the quantum dot solution is solidified to form the quantum dot light-emitting layer; The quantum dot solution comprises a first quantum dot and a second quantum dot, wherein the absolute value of the difference between the photoluminescence peak wavelength of the first quantum dot and the photoluminescence peak wavelength of the second quantum dot is less than or equal to 10 nm; the photoluminescence peak wavelength of the second quantum dot is greater than the photoluminescence peak wavelength of the first quantum dot, and the mass fraction of the second quantum dot is greater than the mass fraction of the first quantum dot. Alternatively, the quantum dot solution comprises at least three types of quantum dots, wherein the difference between the maximum and minimum values ​​of the photoluminescence peak wavelengths of the at least three types of quantum dots is less than or equal to 10 nm, and the mass fraction of the quantum dot corresponding to the median of the photoluminescence peak wavelengths of the at least three types of quantum dots is greater than the average mass fraction of each type of quantum dot.

12. The method for manufacturing a quantum dot light-emitting diode device as described in claim 11, characterized in that, The absolute value of the difference between the photoluminescence peak wavelength of the first quantum dot and the photoluminescence peak wavelength of the second quantum dot is less than or equal to 5 nm; and / or The absolute value of the difference between the full width at half maximum (FWHM) of the photoluminescence peak of the first quantum dot and the full WHM of the photoluminescence peak of the second quantum dot is less than or equal to 10 nm; or The absolute value of the difference between the full width at half maximum (FWHM) of the photoluminescence peak of the first quantum dot and the full width at half maximum (FWHM) of the photoluminescence peak of the second quantum dot is less than or equal to 3 nm.

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