CN115368778B - Quantum dot ink, preparation method and application - Google Patents

Quantum dot ink, preparation method and application Download PDF

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Publication number
CN115368778B
CN115368778B CN202210948025.9A CN202210948025A CN115368778B CN 115368778 B CN115368778 B CN 115368778B CN 202210948025 A CN202210948025 A CN 202210948025A CN 115368778 B CN115368778 B CN 115368778B
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solvent
quantum dot
ink
solute
dot ink
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CN115368778A (en
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郭标
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Beijing Xiaomi Mobile Software Co Ltd
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Beijing Xiaomi Mobile Software Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/30—Inkjet printing inks
    • C09D11/38—Inkjet printing inks characterised by non-macromolecular additives other than solvents, pigments or dyes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/30—Inkjet printing inks
    • C09D11/36—Inkjet printing inks based on non-aqueous solvents

Abstract

The application provides quantum dot ink, a preparation method and application, wherein the total content of all raw material components in the quantum dot ink is 100%, and the content of all raw material components is expressed as follows in percentage by mass: 48-90% of a first solvent; 9-50% of a second solvent; 0.5 to 4 percent of solute; the first solvent comprises n-tetradecane and the second solvent comprises 2-phenylbutene; the solute is configured to be soluble in the first solvent, the second solvent, or a mixed solvent of the first solvent and the second solvent. The quantum dot ink provided by the disclosure can form a marangoni flow from outside to inside through a double-solvent system construction without increasing the viscosity of the quantum dot ink, and is balanced with capillary flow from inside to outside of a coffee ring effect, so that the coffee ring is eliminated. In the process of using the quantum dot ink to carry out ink-jet printing, the viscosity of the quantum dot ink is lower, the ink-jet printing is facilitated, the formed quantum dot film has uniform film distribution, high-efficiency printing is realized, and the performance of a display device is improved.

Description

Quantum dot ink, preparation method and application
Technical Field
The disclosure relates to the technical field of display, in particular to quantum dot ink, a preparation method and application.
Background
The QLED (Quantum Dot Light Emitting Diodes, quantum dot light emitting diode) is formed by making the quantum dots into thin films, and putting the quantum dot thin layers into a display can reduce backlight brightness and color crosstalk of RGB color filters, so that better backlight utilization rate and prompt display color gamut space are obtained. In the process of forming a film by adopting ink-jet printing of quantum dot ink, a coffee ring effect often exists, namely the thickness of the edge of the film is larger than that of the center of the film, so that the thickness of the film is uneven, and the electrical property and the optical property of the quantum dot are affected.
At present, the problem of 'coffee ring' effect in the ink-jet printing process is usually solved by increasing the viscosity of the quantum dot ink, however, the problem that the 'coffee ring' cannot be completely eliminated by increasing the viscosity of the quantum dot ink, and the ink is not easy to be ejected from a nozzle due to the high viscosity of the quantum dot ink, so that the printing difficulty is increased.
Disclosure of Invention
In order to overcome the problems in the related art, the present disclosure provides a quantum dot ink, a preparation method and an application.
According to a first aspect of the present disclosure, there is provided a quantum dot ink comprising the following raw material components, the sum of the contents of the raw material components being 100%, the contents of the raw material components being expressed as mass percent:
48-90% of a first solvent;
9-50% of a second solvent;
0.5 to 4 percent of solute;
the first solvent comprises n-tetradecane and the second solvent comprises 2-phenylbutene;
the solute is configured to be soluble in the first solvent, the second solvent, or a mixed solvent of the first solvent and the second solvent.
In some embodiments of the present disclosure, the quantum dot ink comprises the following raw material components, the sum of the contents of the raw material components is 100%, and the contents of the raw material components are expressed as mass percent as follows:
60-70% of a first solvent;
30-40% of a second solvent;
2-3% of solute.
In some embodiments of the present disclosure, the ratio c1= (first solvent+second solvent)/solute by mass is 24.5-199.
In some embodiments of the present disclosure, the ratio c2=second solvent/solute by mass is 12 to 19.
In some embodiments of the present disclosure, the ratio c3=first solvent/solute by mass is 12 to 180.
In some embodiments of the present disclosure, the ratio c4=first solvent/second solvent by mass percent is 1 to 9.5.
In some embodiments of the disclosure, the solute includes quantum dots and ligands disposed on the quantum dot surface.
In some embodiments of the present disclosure, the ligand comprises one or more of octanethiol, dodecathiol, and octadecanethiol, undecylenic acid, tetradecanoic acid, oleic acid, stearic acid, oleylamine, n-octylamine, trioctylphosphine, and trioctylphosphine oxide.
In some embodiments of the present disclosure, the quantum dots include one or more of group IIB-VIA, group IIIA-VA, group IVA-VIA, group IB-IIIA-VIA, group IIB-IVA-VIA, group IIA-IVB-VA, group VIII-VIA single or composite structure quantum dots and perovskite quantum dots.
In some embodiments of the present disclosure, the quantum dots include one or more of CdS, cdSe, cdSeS, cdZnSeS, znS, inP and ZnSe.
According to a second aspect of the present disclosure, there is provided a method of preparing a quantum dot ink for preparing the quantum dot ink of the first aspect of the present disclosure, the method of preparing the quantum dot ink comprising the steps of:
adding a first solvent and a second solvent into a reactor, and mixing to obtain a mixed solvent;
and stirring the mixed solvent and the solute for a first preset time to obtain a mixed solution, and filtering the mixed solution through a filter membrane to obtain the quantum dot ink.
According to a third aspect of the present disclosure, there is provided an inkjet printing method using the quantum dot ink according to the first aspect of the present disclosure as an inkjet printing ink.
According to a fourth aspect of the present disclosure, there is provided a quantum dot film made from the quantum dot ink of the first aspect of the present disclosure by inkjet printing.
According to a fifth aspect of the present disclosure, there is provided a display device comprising a backlight and a quantum dot film according to the third aspect of the present disclosure.
The technical scheme provided by the embodiment of the disclosure can comprise the following beneficial effects: under the condition of not increasing the viscosity of the quantum dot ink, the quantum dot ink constructed by the double-solvent system forms a marangoni flow from outside to inside, and balances with a capillary flow of a coffee ring effect from inside to outside, so that the coffee ring is eliminated. In the process of using the quantum dot ink to carry out ink-jet printing, the viscosity of the quantum dot ink is lower, the ink-jet printing is facilitated, the formed quantum dot film has uniform film distribution, high-efficiency printing is realized, and the performance of a display device is improved.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description, serve to explain the principles of the application.
Fig. 1 is a flow chart illustrating a method of preparing quantum dot ink according to an exemplary embodiment.
Fig. 2 is a cross-sectional elevation scan of a quantum dot film obtained by inkjet printing of the quantum dot ink prepared in example 1.
Fig. 3 is a cross-sectional elevation scan of a quantum dot film produced by inkjet printing of the quantum dot ink prepared in example 6.
Fig. 4 is a cross-sectional elevation scan of a quantum dot film produced by ink-jet printing of a quantum dot ink prepared in accordance with a comparative example.
Detailed Description
Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the application. Rather, they are merely examples of apparatus and methods consistent with aspects of the application as detailed in the accompanying claims.
In the process of preparing the quantum dot film by quantum dot ink jet printing, the coffee ring effect is a main factor influencing the quality of the quantum dot film, and the coffee ring film with the edge thickness of the film being larger than the center thickness of the film can seriously influence the electrical property and the optical property of the quantum dot. The formation of the coffee ring mainly has two factors, on one hand, because the pinning effect of the three-phase contact line occurs after the ink drops of the quantum dot ink contact with the substrate, and the three-phase contact line is the edge of the ink drops, namely the boundary between the substrate and the ink drops and the gas when the quantum dot ink forms the ink drops on the surface of the substrate. Since the substrate cannot be a completely uniform surface, when the three-phase contact wire is on the substrate, deformation occurs due to the influence of the surface chemistry and the morphology non-uniformity, namely, the pinning effect of the three-phase contact wire. On the other hand, as the edges of the ink drops are fixed on the contact lines in the evaporation process of the ink drops, the diameters of the ink drops are unchanged, the contact angle is reduced, namely the contact surface of the ink drops with the substrate is unchanged, the volatilization speed of the solvent in the center of the ink drops is smaller than that of the solvent at the edges of the ink drops, and in order to supplement the volatilization of the solvent at the edges of the ink drops, capillary flow which is in the flow direction from the center of the ink drops to the edges of the ink drops is formed in the ink drops, and almost all the containers in the ink drops are conveyed to the edges of the ink drops and deposited, so that the quantum dot film is in a coffee ring shape with thick edges and thin middle. The pinning effect of the three-phase contact line is related to the substrate, so that the conditions are more and difficult to control, and the problem of influencing capillary flow is generally solved for solving the problem of coffee ring.
In the prior art, the problem of coffee ring effect in the process of ink-jet printing is usually solved by increasing the viscosity of the quantum dot ink, for example, by adding terpineol into the quantum dot ink, and not changing the surface tension while increasing the viscosity, so as to eliminate the coffee ring, or by adding a block copolymer with a molecular formula of sulfhydryl-polystyrene-A-R for adjusting the viscosity into the quantum dot ink. However, increasing the viscosity of the quantum dot ink suppresses capillary flow, but does not completely eliminate capillary flow, the coffee ring does not completely disappear, and the high viscosity of the quantum dot ink makes the ink difficult to eject from the nozzle, increasing the difficulty of printing.
In order to solve the technical problems, the disclosure provides a quantum dot ink, wherein the total content of raw material components in the quantum dot ink is 100%, and the content of the raw material components is expressed as follows in percentage by mass: 48-90% of a first solvent; 9-50% of a second solvent; 0.5 to 4 percent of solute; the first solvent comprises n-tetradecane and the second solvent comprises 2-phenylbutene; the solute is configured to be soluble in the first solvent, the second solvent, or a mixed solvent of the first solvent and the second solvent. The quantum dot ink provided by the disclosure can form a marangoni flow from outside to inside through a double-solvent system construction without increasing the viscosity of the quantum dot ink, and is balanced with capillary flow from inside to outside of a coffee ring effect, so that the coffee ring is eliminated. In the process of using the quantum dot ink to carry out ink-jet printing, the viscosity of the quantum dot ink is lower, the ink-jet printing is facilitated, the formed quantum dot film has uniform film distribution, high-efficiency printing is realized, and the performance of a display device is improved.
An exemplary embodiment of the present disclosure provides a quantum dot ink, which includes the following raw material components, the total content of the raw material components is 100%, and the content of the raw material components is expressed as follows by mass percent: 48-90% of a first solvent; 9-50% of a second solvent; 0.5 to 4 percent of solute; the first solvent comprises n-tetradecane and the second solvent comprises 2-phenylbutene; the solute is configured to be soluble in the first solvent, the second solvent, or a mixed solvent of the first solvent and the second solvent.
In this embodiment, the first solvent and the second solvent have good solubility for the solute, the first solvent is an organic solvent with a high boiling point and a low surface tension, and the second solvent has a lower boiling point and a higher surface tension than the first solvent, so that the second solvent with a low boiling point volatilizes faster and the first solvent with a high boiling point volatilizes slower in the drying process of the quantum dot ink. This phenomenon is more pronounced at the edges of the ink drop, such that the high boiling point first solvent at the edge of the ink drop increases and the low boiling point second solvent decreases. While the surface tension of the high boiling point first solvent at the edge of the drop is low, so that the surface tension at the edge of the drop is low, the surface tension at the center of the drop is high, and a surface tension gradient is generated between the edge of the drop and the center of the drop. Under the action of the surface tension gradient, the second solvent with high surface tension can generate tension on the first solvent with low surface tension around the second solvent, so that ink drops flow from the low surface tension to the high surface tension, and solutes are brought back to the center of the ink drops, namely, the marangoni flow opposite to the capillary flow of the coffee ring effect is formed, thereby eliminating the coffee ring effect, improving the uniformity of solute distribution, reducing the edge deposition intensity, and enabling the quantum dot film to have uniform film distribution.
The boiling point of the first solvent is more than or equal to 200 ℃, and the first solvent can be alkane organic matters including saturated alkane or unsaturated alkane, for example, one or more of n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane and isomers thereof (such as 1-methylundecane, 3-methyltetradecane and 3-methyltridecane), wherein straight chain or branched alkane with the carbon number between 11 and 15 meets the boiling point range, has lower surface tension and volatilizes more slowly in the drying process. Preferably, the present disclosure uses N-tetradecane as the first solvent, the N-tetradecane having a boiling point of 253.5 ℃ and a surface tension of 26.5N/m.
The boiling point of the second solvent is lower than that of the first solvent, the surface tension is higher than that of the first solvent, and the second solvent volatilizes faster in the drying process of the quantum dot ink. Illustratively, the second solvent may include one or more of chlorobenzene, cyclohexanone, o-xylene, 2-phenylbutene. Preferably, the present disclosure uses 2-phenylbutene as the second solvent, the 2-phenylbutene having a boiling point of 184.804 ℃ and a surface tension of 28.998N/m.
The solute is configured to be soluble in the first solvent, the second solvent or a mixed solvent formed by the first solvent and the second solvent, so that the solute can be uniformly dispersed in the solvent, the probability of nozzle blockage during ink-jet printing is reduced, and the quantum dot film obtained through ink-jet printing has uniform film distribution.
Illustratively, the solute includes quantum dots and ligands disposed on the quantum dot surface. Quantum dots (quantum dots) are nano-scale semiconductors, which emit light of a specific frequency by applying a certain electric field or light pressure to the quantum dots, the emission spectrum of which can be controlled by changing the size of the quantum dots, and the emission spectrum of which can cover the whole visible light region by changing the size and chemical composition of the quantum dots. The quantum dots can comprise red light quantum dots, green light quantum dots or blue light quantum dots, and the red light quantum dots, the green light quantum dots or the blue light quantum dots are respectively printed into films and are arranged on the display panel according to a certain rule, so that the display imaging of the display panel is realized.
Illustratively, the quantum dots may include single element or composite structured quantum dots of groups IIB-VIA, IIIA-VA, IVA-VIA, IB-IIIA-VIA, IIB-IVA-VIA, IIA-IVB-VA, VIII-VIA, or combinations including one or more of the perovskite quantum dots. Further, the quantum dots include CdS, cdSe, cdSeS, cdZnSeS, znS, inP and ZnSeOne or more of the materials may also include CsPbI 3 Si, ge, cdTe, pbS, pbSe, inAs, etc.
Because the quantum dots are inorganic compounds, the solubility in the organic solvent formed by the first solvent or the second solvent is not high, and the ligands are arranged on the surfaces of the quantum dots to form solutes, the solubility of the quantum dots in the organic solvent can be improved, the suitability of the quantum dots with different types and components and the first solvent and the second solvent with different content ratios is improved, the aggregation phenomenon of the quantum dots is inhibited, and the probability of nozzle blockage during ink-jet printing is reduced. Illustratively, the ligands include one or more of octanethiol, dodecanethiol, and octadecanethiol, undecylenic acid, tetradecanoic acid, oleic acid, stearic acid, oleylamine, n-octylamine, trioctylphosphine, and trioctylphosphine oxide.
The mass percent of the content of the first solvent and the second solvent in the quantum dot ink is mainly determined by the content of the solute. When the content of the solute is low, a small amount of the second solvent is adopted in the quantum dot ink, and the coffee ring effect can be eliminated by weak marangoni flow. When the solute content is high, a large amount of second solvent is adopted in the quantum dot ink, so that the marangoni flow is enhanced to eliminate the coffee ring effect.
The total content of the first solvent, the second solvent and the solute is 100%. Illustratively, the first solvent is present in the quantum dot ink in a mass percentage of 48 to 90%, preferably 60 to 70%. The mass percentage of the second solvent in the quantum dot ink is 9-50%, preferably 30-40%. The mass percentage of the solute in the quantum dot ink is 0.5-4%, preferably 2-3%. In the obtained quantum dot ink, the solute is stably dispersed in the first solvent and the second solvent, and the viscosity and the surface tension of the quantum dot ink can meet the requirement of ink-jet printing, so that the quantum dot ink has good stability in the ink-jet printing process, and the obtained quantum dot film has uniform film distribution.
In some possible embodiments, the ratio c1= (first solvent+second solvent)/solute by mass may be 24.5 to 199, or 30 to 50. The ratio c2=second solvent/solute by mass may be 12 to 19 or 12 to 14. The ratio c3=first solvent/solute by mass may be 12 to 180 or 20 to 35. The ratio c4=first solvent/second solvent by mass may be 1 to 9.5 or 1.5 to 2.5.
The method has the advantages that the strength of the marangoni flow in the quantum dot ink is influenced by reasonably controlling at least one ratio of the ratio of C1= (first solvent+second solvent)/solute, C2= second solvent/solute, C3= first solvent/solute and C4= first solvent/second solvent, so that the balance of the marangoni flow in the quantum dot ink and capillary flow in a coffee ring effect is formed, the coffee ring effect is eliminated, the solute distribution uniformity is improved, the edge deposition strength is reduced, and the quantum dot film has uniform film distribution. In an exemplary embodiment, as shown in fig. 1, the present disclosure provides a method for preparing a quantum dot ink, for preparing the quantum dot ink, including the steps of:
s1, adding a first solvent and a second solvent into a reactor, and mixing to obtain a mixed solvent;
s2, stirring the mixed solvent and the solute for a first preset time to obtain a mixed solution, and filtering the mixed solution through a filter membrane to obtain the quantum dot ink.
In step S1, a first solvent and a second solvent are added into a reactor according to the content of each raw material component in the predetermined quantum dot ink, wherein the first solvent comprises n-tetradecane, the second solvent comprises 2-phenylbutene, and the first solvent and the second solvent are uniformly mixed to obtain a mixed solvent.
In step S2, a solute is added to the mixed solvent, and the mixed solvent and the solute are stirred for a first predetermined time, which may be 30 minutes, so that the solute is uniformly dispersed in the mixed solvent to obtain a mixed solution. The mixed solution is filtered by a filter membrane, which can be a filter membrane with the aperture of 0.45 mu m, so that the quantum dot ink with uniformly dispersed solute and no agglomeration is obtained.
In one exemplary embodiment, the present disclosure provides an inkjet printing method, with the quantum dot ink described above as the inkjet printing ink.
Illustratively, the inkjet printing method may include continuous inkjet printing and drop-on-demand printing. Continuous inkjet printing refers to continuous accumulation of ink in a target area, and ink in a non-target area is recovered by a recovery system, and includes Hertz inkjet and Sweet inkjet.
Drop-on-demand printing refers to the fact that ink droplets are ejected as needed, only in target areas, and not in non-target areas. Drop-on-demand printing includes thermal bubble jet printing, electrostatic jet printing, and piezoelectric jet printing. In thermal foaming ink jet printing, quantum dot ink is placed in an ink box of an ink jet printer, a thin film resistor is used for heating a nozzle, ink drops in the nozzle are vaporized, a plurality of tiny bubbles are formed in an ink cavity, the vaporized ink drops are ejected onto a substrate from the nozzle under the action of pressure, the temperature of the vaporized ink drops suddenly drops, the bubbles are broken, and the ink drops become liquid, so that the ink jet printing is completed. In electrostatic ink jet printing, quantum dot ink is placed in an ink box of an ink jet printer, an electrostatic field is filled between a substrate and an ink device, a piezoelectric converter enables surface tension of a nozzle and ink in an ink path to be in an equilibrium state, when printing is started, the original equilibrium state is broken, and ink drops are ejected from the nozzle onto the substrate through the electrostatic field, so that the ink jet printing is completed. In piezoelectric ink jet printing, quantum dot ink is placed in an ink box of an ink jet printer, a plurality of tiny piezoelectric ceramics are arranged near a nozzle, the piezoelectric ceramics deform under the action of voltage change, ink stored in the ink pipe is extruded, and when the pressure reaches a preset value, the nozzle ejects ink drops onto a substrate. The pattern printed by the ink jet adopts a dot matrix pattern, so that the color and tone of the manufactured display panel are rich in change, and the display panel has good display effect. The printing substrate can be an Indium Tin Oxide (ITO) glass substrate coated with ZnO by spin coating, so that the printing substrate can well transfer charges. Other substrates having good electron transport properties may also be used as the printing substrate, and the present disclosure is not limited thereto.
In one exemplary embodiment, the present disclosure provides a quantum dot film made from the quantum dot ink described above by inkjet printing. Illustratively, the printed substrate after inkjet printing is placed in a vacuum drying oven for vacuum drying, and the dried quantum dot ink drops are the quantum dot film. The vacuum drying can reduce the drying time of the quantum dot ink, is favorable for the uniformity and the flatness of the quantum dot film, and improves the optical performance and the electrical performance of the display device.
In one example embodiment, the present disclosure also provides a display device including a backlight and the quantum dot film described above.
In this embodiment, the display device may be a liquid crystal display (Liquid Crystal Display, LCD), the backlight source may be a cold cathode fluorescent lamp (Cold Cathode Fluorescent Lamp, ccol), or a Light-Emitting Diode (LED). The red light quantum dots, the green light quantum dots and the blue light quantum dots are distributed on a printing substrate through ink jet printing according to a certain rule, the quantum dot film is packaged and then placed in a backlight source, the quantum dots in the quantum dot film are excited through light excitation of the backlight source, the red light filter unit is obtained by red light obtained by the red light quantum dots, the green light filter unit is obtained by green light emission of the green light quantum dots, the blue light filter unit is obtained by blue light emission of the blue light quantum dots, and the difference of light transmittance of the backlight source is generated through control of current and an electric field, so that display imaging of the quantum dot film is controlled.
The display device may also be a quantum dot Light Emitting Diode (Quantum Dot Light Emitting Diodes, QLED), which has a structure similar to an Organic Light-Emitting Diode (OLED), except that the Light Emitting layer is formed of a quantum dot thin film, holes generated by the anode and electrons generated by the cathode are moved by an electric field, injected into the hole transporting layer and the electron transporting layer, respectively, and migrate to the Light Emitting layer, and excitons are formed after the holes and electrons are converged in the Light Emitting layer formed of the quantum dot thin film, and the excitons recombine to excite the quantum dots to emit Light.
The quantum dot ink, the preparation method and the application provided by the disclosure are described in detail below with reference to specific examples, and the contents in the examples and comparative examples are mass percent.
Example 1
Adding n-tetradecane and 2-phenylbutene into a reactor, mixing to obtain a mixed solvent, adding a solute into the mixed solvent, stirring for 30 minutes at normal temperature to obtain a mixed solution, and filtering the mixed solution through a filter membrane with the thickness of 0.45 mu m to obtain the quantum dot ink. Wherein, the content of n-tetradecane is 90%, the content of 2-phenylbutene is 9.5%, the content of solute is 0.5%, c1=199, c2=19, c3=180, c4=9.47, the solute comprises red light CdSe quantum dots, and oleic acid and oleylamine ligand arranged on the surfaces of the red light CdSe quantum dots, so that the solute is uniformly dispersed in the mixed solvent and has good solubility in the mixed solvent. In this example, n-tetradecane is much more than 2-phenylbutene due to the low solute content, and weak marangoni flow can eliminate capillary flow in the coffee ring effect.
The quantum dot ink in the embodiment is adopted for piezoelectric type ink-jet printing, the stability of the ink-jet printing quantum dots is high, ink drops are smoothly ejected from the nozzles, and the quantum dot film is obtained by drying the ink drops on the printing substrate. Fig. 2 is a scanned cross-sectional height of a quantum dot film obtained by inkjet printing of the quantum dot ink prepared in example 1, and as can be seen from fig. 2, the quantum dot film has a thinner thickness due to a smaller solute content, but the cross-sectional height is uniform, so that the coffee ring effect is effectively suppressed, and a uniform printed film is obtained.
Example 2
Adding n-tetradecane and 2-phenylbutene into a reactor, mixing to obtain a mixed solvent, adding a solute into the mixed solvent, stirring for 30 minutes at normal temperature to obtain a mixed solution, and filtering the mixed solution through a filter membrane with the thickness of 0.45 mu m to obtain the quantum dot ink. Wherein, the content of n-tetradecane is 80%, the content of 2-phenylbutene is 19%, the content of solute is 1%, c1=99, c2=19, c3=80, c4=4.21, the solute comprises green light CdSe quantum dots, and oleic acid and oleylamine ligand arranged on the surfaces of the green light CdSe quantum dots, so that the solute is uniformly dispersed in the mixed solvent and has good solubility in the mixed solvent. In this example, the increased content of 2-phenylbutene resulted in increased marangoni flow as compared to example 1, to eliminate capillary flow in the coffee ring effect. The quantum dot ink in the embodiment is adopted for piezoelectric type ink-jet printing, the stability of the ink-jet printing quantum dots is high, ink drops are smoothly ejected from the nozzles, and the quantum dot film is obtained by drying the ink drops on the printing substrate.
Example 3
Adding n-tetradecane and 2-phenylbutene into a reactor, mixing to obtain a mixed solvent, adding a solute into the mixed solvent, stirring for 30 minutes at normal temperature to obtain a mixed solution, and filtering the mixed solution through a filter membrane with the thickness of 0.45 mu m to obtain the quantum dot ink. Wherein, the content of n-tetradecane is 69%, the content of 2-phenylbutene is 29%, the content of solute is 2%, c1=49, c2=14.5, c3=34.5, c4=2.38, the solute comprises blue light CdSe quantum dots, and oleic acid and oleylamine ligand arranged on the surfaces of the blue light CdSe quantum dots, so that the solute is uniformly dispersed in the mixed solvent and has good solubility in the mixed solvent. In this example, the increased content of 2-phenylbutene resulted in increased marangoni flow as compared to example 2, to eliminate capillary flow in the coffee ring effect. The quantum dot ink in the embodiment is adopted for piezoelectric type ink-jet printing, the stability of the ink-jet printing quantum dots is high, ink drops are smoothly ejected from the nozzles, and the quantum dot film is obtained by drying the ink drops on the printing substrate.
Example 4
Adding n-tetradecane and 2-phenylbutene into a reactor, mixing to obtain a mixed solvent, adding a solute into the mixed solvent, stirring for 30 minutes at normal temperature to obtain a mixed solution, and filtering the mixed solution through a filter membrane with the thickness of 0.45 mu m to obtain the quantum dot ink. Wherein the n-tetradecane content is 70%, the 2-phenylbutene content is 28%, the solute content is 2%, c1=49, c2=14, c3=35, c4=2.5, and the solute comprises green light CsPbI 3 Quantum dot and set up in green light CsPbI 3 Oleic acid and oil on quantum dot surfacesAmine ligands, which allow the solute to be uniformly dispersed in the mixed solvent and have good solubility in the mixed solvent. In this example, the increased content of 2-phenylbutene resulted in increased marangoni flow as compared to example 2, to eliminate capillary flow in the coffee ring effect. The quantum dot ink in the embodiment is adopted for piezoelectric type ink-jet printing, the stability of the ink-jet printing quantum dots is high, ink drops are smoothly ejected from the nozzles, and the quantum dot film is obtained by drying the ink drops on the printing substrate.
Example 5
Adding n-tetradecane and 2-phenylbutene into a reactor, mixing to obtain a mixed solvent, adding a solute into the mixed solvent, stirring for 30 minutes at normal temperature to obtain a mixed solution, and filtering the mixed solution through a filter membrane with the thickness of 0.45 mu m to obtain the quantum dot ink. Wherein, the content of n-tetradecane is 60%, the content of 2-phenylbutene is 37%, the content of solute is 3%, c1=32.33, c2=12.33, c3=20, c4=1.62, the solute comprises red light lnP quantum dots and octathiol ligand arranged on the surfaces of the red light lnP quantum dots, so that the solute is uniformly dispersed in the mixed solvent and has good solubility in the mixed solvent. In this example, the increased content of 2-phenylbutene resulted in increased marangoni flow as compared to example 4, to eliminate capillary flow in the coffee ring effect. The quantum dot ink in the embodiment is adopted for piezoelectric type ink-jet printing, the stability of the ink-jet printing quantum dots is high, ink drops are smoothly ejected from the nozzles, and the quantum dot film is obtained by drying the ink drops on the printing substrate.
Example 6
Adding n-tetradecane and 2-phenylbutene into a reactor, mixing to obtain a mixed solvent, adding a solute into the mixed solvent, stirring for 30 minutes at normal temperature to obtain a mixed solution, and filtering the mixed solution through a filter membrane with the thickness of 0.45 mu m to obtain the quantum dot ink. Wherein, the content of n-tetradecane is 48%, the content of 2-phenylbutene is 48%, the content of solute is 4%, c1=24, c2=12, c3=12, c4=1, the solute comprises green light lnP quantum dots and octanethiol ligand arranged on the surfaces of the green light lnP quantum dots, so that the solute is uniformly dispersed in the mixed solvent and has good solubility in the mixed solvent. In this example, the increased content of 2-phenylbutene resulted in increased marangoni flow as compared to example 5, to eliminate capillary flow in the coffee ring effect.
The quantum dot ink in the embodiment is adopted for piezoelectric type ink-jet printing, the stability of the ink-jet printing quantum dots is high, ink drops are smoothly ejected from the nozzles, and the quantum dot film is obtained by drying the ink drops on the printing substrate. Fig. 3 is a scanned cross-sectional height image of a quantum dot film obtained by inkjet printing of the quantum dot ink prepared in example 6, and as can be seen from fig. 3, the thickness of the quantum dot film is thicker due to the higher solute content, but the cross-sectional height is uniform, so that the coffee ring effect is effectively inhibited, and a uniform printed film is obtained.
In order to more clearly explain the technical scheme of the disclosure, examples 7-12 of the quantum dot ink are also listed in the disclosure, wherein the formulations of examples 7-12 are shown in table 1.
Table 1 formulations of quantum dot inks of examples 7-12
The preparation methods and the inkjet printing methods of examples 7 to 12 are the same as those of examples 1 to 6, and are not described here.
Comparative example
Adding n-tetradecane and solute into a reactor, stirring for 30 minutes at normal temperature to obtain a mixed solution, and filtering the mixed solution through a filter membrane with the thickness of 0.45 mu m to obtain the quantum dot ink. The content of n-tetradecane is 98%, the content of solute is 2%, and the solute comprises red light lnP quantum dots and octanethiol ligand arranged on the surfaces of the red light lnP quantum dots, so that the solute is uniformly dispersed in the mixed solvent and has good solubility in the mixed solvent.
Fig. 4 is a scanned cross-sectional height of a quantum dot film obtained by ink-jet printing of the quantum dot ink prepared in comparative example, and as can be seen from fig. 4, there is significant edge deposition on the edge of the quantum dot film, and the quantum dot film has a coffee ring shape with an edge thickness greater than the center thickness, and has poor uniformity.
As can be seen from the above examples and comparative examples, the quantum dot ink provided by the present disclosure forms a marangoni flow from the outside to the inside through a two-solvent system without increasing the viscosity of the quantum dot ink, and balances with a capillary flow from the inside to the outside of the coffee ring effect, thereby eliminating the coffee ring. In the ink-jet printing process of the quantum dot ink, the viscosity of the quantum dot ink is low, the ink-jet printing is facilitated, and the formed quantum dot film has uniform film distribution.
Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the application being indicated by the following claims.
It is to be understood that the application is not limited to the precise arrangements and instrumentalities shown in the drawings, which have been described above, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims (13)

1. The quantum dot ink is characterized by comprising the following raw material components, wherein the total content of the raw material components is 100%, and the content of the raw material components is expressed as follows in percentage by mass:
48-90% of a first solvent;
9-50% of a second solvent;
0.5 to 4 percent of solute;
the first solvent comprises n-tetradecane and the second solvent comprises 2-phenylbutene;
the boiling point of the first solvent is higher than the boiling point of the second solvent, and the surface tension of the first solvent is lower than the surface tension of the second solvent;
the solute is configured to be soluble in the first solvent, the second solvent, or a mixed solvent of the first solvent and the second solvent;
the ratio c1= (first solvent+second solvent)/solute by mass is 24.5-199.
2. The quantum dot ink according to claim 1, wherein the quantum dot ink comprises the following raw material components, the sum of the contents of the raw material components is 100%, and the contents of the raw material components are expressed as mass percent:
60-70% of a first solvent;
30-40% of a second solvent;
2-3% of solute.
3. The quantum dot ink of claim 1, wherein the ratio c2=second solvent/solute by mass is 12-19.
4. The quantum dot ink of claim 1, wherein the ratio c3=first solvent/solute by mass is 12-180.
5. The quantum dot ink of claim 1, wherein the ratio c4=first solvent/second solvent by mass is 1 to 9.5.
6. The quantum dot ink of claim 1, wherein the solute comprises quantum dots and ligands, the ligands being disposed on the surface of the quantum dots.
7. The quantum dot ink of claim 6, wherein the ligand comprises one or more of octanethiol, dodecathiol, and octadecanethiol, undecylenic acid, tetradecanoic acid, oleic acid, stearic acid, oleylamine, n-octylamine, trioctylphosphine, and trioctylphosphine oxide.
8. The quantum dot ink of claim 7, wherein the quantum dot comprises one or more of group IIB-VIA, group IIIA-VA, group IVA-VIA, group IB-IIIA-VIA, group IIB-IVA-VIA, group IIA-IVB-VA, group VIII-VIA single or composite structure quantum dots, and perovskite quantum dots.
9. The quantum dot ink of claim 8, wherein the quantum dot comprises one or more of CdS, cdSe, cdSeS, cdZnSeS, znS, inP and ZnSe.
10. A method for preparing a quantum dot ink, wherein the method for preparing a quantum dot ink according to any one of claims 1 to 9 comprises the steps of:
adding a first solvent and a second solvent into a reactor, and mixing to obtain a mixed solvent;
and stirring the mixed solvent and the solute for a first preset time to obtain a mixed solution, and filtering the mixed solution through a filter membrane to obtain the quantum dot ink.
11. An inkjet printing method characterized in that the quantum dot ink according to any one of claims 1 to 9 is used as an inkjet printing ink.
12. A quantum dot film, characterized in that it is made from the quantum dot ink according to any one of claims 1 to 9 by inkjet printing.
13. A display device comprising a backlight and the quantum dot film of claim 12.
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Citations (2)

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CN109321038A (en) * 2018-10-10 2019-02-12 福州大学 A kind of quantum dot ink based on inkjet printing
CN109337444A (en) * 2018-09-11 2019-02-15 苏州星烁纳米科技有限公司 Quantum dot ink, quantum stippling film and display device

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Publication number Priority date Publication date Assignee Title
CN109337444A (en) * 2018-09-11 2019-02-15 苏州星烁纳米科技有限公司 Quantum dot ink, quantum stippling film and display device
CN109321038A (en) * 2018-10-10 2019-02-12 福州大学 A kind of quantum dot ink based on inkjet printing

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