Application of pyrazolo-boron Ce (III) complex as photoluminescent material

Abstract

The invention belongs to the technical field of photoluminescent materials, and relates to application of a pyrazolo boron Ce (III) complex as a photoluminescent material. The application specifically comprises the following steps: dissolving the pyrazoloboron Ce (III) complex in a solvent containing a benzene ring and a chlorine element; adding a polymer into the obtained solution; the polymer is polystyrene, polymethyl methacrylate, polycarbonate and polyimide; and carrying out ink-jet printing on the obtained solution, or carrying out spin coating to form a film, or carrying out nano imprinting to obtain the photoluminescent material. The pyrazolo-boron Ce (III) complex is used as a luminescent material to prepare the luminescent film, and the whole preparation process does not affect the luminescent characteristic of the pyrazolo-boron Ce (III) complex.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoluminescent materials. More specifically, it relates to the application of pyrazolylborate Ce(III) complexes as photoluminescent materials, and particularly to a preparation method for fabricating pixelated transparent display devices by using electrohydrodynamic jet printing, an inkjet printing technique, with pyrazolylborate Ce(III) complexes. Background Art

[0002] The field of light-emitting displays has a market share in the trillions, but the raw materials are severely "strangled" by foreign countries. Promoting the localization of light-emitting materials is in line with the national strategic orientation. As a kind of light-emitting material, d-f transition rare-earth complexes have the following advantages: (1) d-f transition is a parity-allowed transition with a large molar extinction coefficient and a short excited-state lifetime. Among them, the d-f transition cerium-based rare-earth complexes are only dozens of nanoseconds; (2) The outer d orbitals are greatly affected by the coordination environment, so the emission color can be adjusted by regulating the coordination field; (3) The ligand has a large coating volume and protects the rare-earth ion luminescence center well, so it has excellent heat resistance, solvent resistance, and water and oxygen resistance; (4) They are rich in reserves and cheap in cost. In particular, the abundance of cerium in the earth's crust is 0.006%, slightly higher than that of copper at 0.005%. Therefore, developing the application of rare-earth complexes in the field of luminescence has important strategic significance.

[0003] The application of rare-earth complexes in the field of luminescence can be traced back to 1990 at the earliest. J. Kido et al. first applied Tb(III) complexes as luminescent materials to organic light-emitting diodes. Currently, great progress has been made in the field of luminescence based on d-f transition cerium-based rare-earth complexes. In the patent CN 114057780B, the inventors successfully applied d-f transition cerium-based rare-earth complexes (specifically, a series of pyrazolylborate Ce(III) complexes with d-f transitions) as electroluminescent materials in the preparation of the OLED field, but did not apply them as a kind of photoluminescent material in photoluminescent fields such as transparent displays, color conversion layers, and anti-counterfeiting. Summary of the Invention

[0004] The present invention provides the application of pyrazolylborate Ce(III) complexes as photoluminescent materials, broadening the application scenarios of pyrazolylborate Ce(III) complexes.

[0005] According to the purpose of the present invention, there is provided the application of pyrazolylborate Ce(III) complexes as photoluminescent materials,

[0006] Denote the structural formula as

[0007] The structural formula of the pyrazolylborate Ce(III) complex is:

[0008]

[0009] Among them, R1, R2, R3, and R4 are each independently selected from alkyl, aryl, phenyl, halogen, or halogen-substituted alkyl.

[0010] Preferably, the alkyl is selected from C1-C 18 alkyl.

[0011] Preferably, R1 is -CH3;

[0012] R2 is selected from C1-C 18 alkyl or halogen;

[0013] R3 is -CH3;

[0014] R4 is selected from C1-C 18 alkyl or aryl.

[0015] Preferably, the pyrazolylborate Ce(III) complex is at least one of CeTp3, Ce(Tp 4Me )3, Ce(Tp 4Br )3, Ce(PzTp)3, Ce( i PrTp)3, Ce( n BuTp)3, and Ce(PhTp)3;

[0016] The structure of CeTp3 is shown as follows:

[0017]

[0018] The structure of Ce(Tp 4Me )3 is shown as follows:

[0019]

[0020] The structure of Ce(Tp 4Br )3 is shown as follows:

[0021]

[0022] The structure of Ce(PzTp)3 is shown as follows:

[0023] The structure of Ce( i PrTp)3 is shown as follows:

[0024]

[0025] The structure of Ce( n BuTp)3 is shown as follows:

[0026]

[0027] The structure of the Ce(PhTp)3 is as follows:

[0028]

[0029] Preferably, the photoluminescent material is used to prepare a photoluminescent display device.

[0030] Preferably, the photoluminescent material is used as an anti-counterfeiting material or as a color conversion layer material.

[0031] Preferably, the application specifically includes the following steps:

[0032] (1) Dissolve the pyrazolylborate Ce(III) complex in a solvent containing a benzene ring and a chlorine element;

[0033] (2) Add the polymer to the solution obtained in step (1); the polymer is polystyrene, polymethyl methacrylate, polycarbonate or polyimide;

[0034] (3) Perform inkjet printing, spin coating or nanoimprinting on the solution obtained in step (2) to obtain a photoluminescent material.

[0035] Preferably, the solvent is o-dichlorobenzene or a mixture of o-dichlorobenzene and dichlorobenzene; preferably, in the mixture, the volume ratio of dichlorobenzene is less than or equal to 30%.

[0036] Preferably, in step (1), the concentration of the pyrazolylborate Ce(III) complex in the solvent is 1 mg / ml to 10 mg / ml;

[0037] In step (2), the concentration of the polymer in the solution is 30 mg / ml to 250 mg / ml.

[0038] Preferably, in step (3), the base voltage of the inkjet printing is 800 - 1200 V, the pulse voltage is 800 - 1500 V, the frequency is 20 - 50 Hz, the duty cycle is 50% - 90%, the delay time is 30 - 60 ms, and the substrate moving speed is 10 - 20 mm / min.

[0039] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following technical advantages are mainly possessed:

[0040] In the present invention, the pyrazolylborate Ce(III) complex is used as a luminescent material to prepare a luminescent thin film, and the entire preparation process does not affect the luminescent properties of the pyrazolylborate Ce(III) complex. Specifically, for Ce(T P 4Me)3 complex as an example, for Ce(T P 4Me )3, both the powder and the thin film exhibit a blue - light triple - peak emission. The peak shapes are similar, but the peak position of the thin film shifts slightly towards the long - wavelength direction. After deconvolution fitting, for Ce(T P 4Me )3, the emission peak of the powder is at 425 nm, and that of the thin film is at 439 nm, but the full width at half maximum (FWHM) hardly changes. Under the excitation of a 365 - nm light source, bright blue - light emission can be observed for both the Ce(T P 4Me )3 powder and the thin film. After calculation, the CIE color coordinates of the Ce(T P 4Me )3 powder and the thin film are close, being (0.15, 0.05) and (0.15, 0.08) respectively. The excitation spectra and absorption spectra of the Ce(T P 4Me )3 powder and the thin film are also similar. Between 250 - 400 nm, there are two excitation peaks with similar positions. Correspondingly, there are also two absorption peaks between 250 - 400 nm in the absorption spectrum. The fluorescence lifetimes of the Ce(T P 4Me )3 powder and the thin film are basically the same, being 36.7 ns and 39.0 ns respectively. The similar optical properties of the Ce(T P 4Me )3 powder and the thin film indicate that the preparation of the thin film does not destroy the structure of the Ce(T P 4Me )3 complex and does not affect its luminescence properties. Finally, the photoluminescence quantum yield of the thin film is 45%. Description of the Drawings

[0041] Figure 1 This is a comparison of the properties of the Ce(T P 4Me )3 complex powder and thin film of the present invention. (a) Emission spectra of the powder and the thin film under 340 - nm laser excitation; (b) Deconvolution fitting curve of the powder emission spectrum; (c) Deconvolution fitting curve of the thin film emission spectrum; (d) Fluorescence image of the powder under 365 - nm excitation; (e) Fluorescence image of the thin film under 365 - nm excitation; (f) Comparison chart of the CIE color coordinates of the powder and the thin film; (g) Comparison of the excitation spectra of the powder and the thin film (the emission peak position of the powder is 425 nm, and the emission peak of the thin film is 439 nm); (h) Comparison of the absorption spectra of the powder and the thin film; (i) Comparison of the fluorescence lifetimes of the powder and the thin film (excited by a 340 - nm laser, the emission peak position of the powder is 425 nm, and the emission peak of the thin film is 439 nm).

[0042] Figure 2 This is a comparison of the properties of the Ce(T P 4Me)3 Comparison of the transmittance of the thin film and the pure thin film.

[0043] Figure 3 For Ce(T P 4Me )3 The relationship between the viscosity and contact angle of the complex solution, and the height, diameter of the printed pixel points and the PS concentration.

[0044] Figure 4 For Ce(T P 4Me )3 Variation diagram of the size of the electrohydrodynamic jet printing pixel points of the complex solution with the increase of the PS concentration (from top to bottom, the PS concentrations are 30, 60, 90, 110, 140, 170, 200 mg / ml). (a1)-(g1) Fluorescence microscope images under 405 nm laser excitation; (a2)-(g2) Three-dimensional white light interferometer images; (a3)-(g3) Height profile curves derived from three-dimensional data.

[0045] Figure 5 For Ce(T P 4Me )3 Schematic diagram for regulating the process parameters of the electrohydrodynamic jet printing of the complex solution.

[0046] Figure 6 For Ce(T P 4Me )3 Electrohydrodynamic jet printing pattern of the complex solution. Detailed implementation manners

[0047] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] All the following solution preparation processes are completed under the conditions of isolating water and oxygen at 20-30 °C. First, Ce(T with d-f transition P 4Me)3 complex (solute A) is dissolved in o-dichlorobenzene or a mixed solvent (solvent A) composed of o-dichlorobenzene and dichlorobenzene to form a mixed solution (solution A). The volume ratio of dichlorobenzene in the mixed solvent ranges from less than or equal to 30. In solution A, the mass / volume ratio of solute A to solvent A ranges from 1 mg / ml to 10 mg / ml. Stir solution A with a magnetic pole for 2 to 3 hours at a rotation speed of 2000 to 3000 revolutions per minute to dissolve solute A. Then filter solution A through a 0.22-micron nylon filter head to obtain solution B. Add polystyrene polymer (abbreviated as PS, weight-average molecular weight Mw = 30000 to 80000) to solution B, with a mass fraction ranging from 30 mg / ml to 250 mg / ml. Add a magnetic stir bar and stir for 72 to 96 hours at a rotation speed of 2000 to 3000 revolutions per minute to fully dissolve the polymer and obtain solution C. Filter solution C through a 0.45-micron nylon plug to obtain solution D. Let solution D stand for more than 120 hours to eliminate bubbles and set it aside for later use.

[0049] The following inkjet printing content is completed in an air environment. Slowly add solution D along the tube wall into the needle of the electrohydrodynamic printing device. Set the base voltage to 800 to 1200 V, the pulse voltage to 800 to 1500 V, the frequency to 20 to 50 Hz, the duty cycle to 50% to 90%, the delay time to 30 to 60 ms, and the printing speed to 10 to 20 mm / s. The printing substrate is ordinary transparent glass. When the concentration of solution D is increased from 30 mg / ml to 200 mg / ml, the coffee ring effect can be well inhibited.

[0050] The following are specific examples

[0051] Example 1 Ce(T P 4Me )3 complex inkjet printing ink application

[0052] Using Ce(T P 4Me )3 complex as the luminescent material, o-dichlorobenzene as the solvent, and polystyrene as the additive, prepare Ce(T P 4Me )3 complex inkjet printing ink. First, dissolve Ce(T P 4Me )3 complex powder in o-dichlorobenzene to prepare a solution (solution A) with a concentration of 8 mg / ml. Stir with a magnetic stirrer for 2 hours at a rotation speed of 2000 revolutions per minute to dissolve Ce(T P 4Me)3 complex powder completely dissolves. Then, filter solution A with a 0.22-micron nylon filter tip to obtain solution B. Add polystyrene polymer (abbreviated as PS, weight-average molecular weight Mw = 45000) to solution B with a mass fraction of 200 mg / ml, add a magnetic stir bar and stir for 80 hours at a rotation speed of 3000 revolutions per minute to fully dissolve the polymer and obtain solution C. Filter solution C with a 0.45-micron nylon plug to obtain solution D. Let solution D stand for 120 hours to remove air bubbles and set aside. Ce(T P 4Me )3 complex inks prepared films have the same photoluminescence properties as the powder, proving that the ink preparation process does not affect the luminescence characteristics of Ce(T P 4Me )3 complex ( Figure 1 and Table 1), and the film has good transparency ( Figure 2 ).

[0053] Using ordinary glass as the substrate, the electrohydrodynamic printing process parameters are: the base voltage (V b ) is 1100V, the pulse voltage (V p ) is 850V, the frequency (f) is 20Hz, the duty cycle is 70%, the inkjet delay time (the time to print at the same position) is 50ms, and the printing speed is 10mm / s. Finally, a refined pattern with a well-suppressed coffee ring effect, a pixel diameter of 95μm, and uniform size and fluorescence can be obtained ( Figure 4 in g1 - g3 of Figure 6 ).

[0054] Example 2 Application of Ce(T P 4Me )3 complex inkjet printing ink

[0055] Figure 1 This is the performance comparison between the Ce(T P 4Me )3 complex powder and the film. (a) Emission spectra of the powder and the film under 340nm laser excitation; (b) Peak-fitting curve of the powder emission spectrum; (c) Peak-fitting curve of the film emission spectrum; (d) Fluorescence image of the powder under 365nm excitation; (e) Fluorescence image of the film under 365nm excitation; (f) CIE chromaticity coordinate comparison diagram of the powder and the film; (g) Excitation spectrum comparison of the powder and the film (the powder selects the emission peak position of 425nm, and the film selects the emission peak of 439nm); (h) Absorption spectrum comparison of the powder and the film; (i) Fluorescence lifetime comparison of the powder and the film (using 340nm laser excitation, the powder selects the emission peak position of 425nm, and the film selects the emission peak of 439nm)

[0056] Table 1: Ce(T P4Me )3 Comparison of Photoluminescence Properties between Powder and Film

[0057]

[0058]

[0059] Specifically, taking the Ce(T P 4Me )3 complex as an example, as Figure 1 and shown in Table 1, both the Ce(T P 4Me )3 powder and the film exhibit blue light triple-peak emission, with similar peak shapes. Only the peak position of the film shifts slightly towards the long-wavelength direction ( Figure 1 a) in P 4Me ). After peak fitting, the emission peak of the Ce(T Figure 1 b in Figure 1 and P 4Me )3 powder is 425 nm, and that of the film is 439 nm, but the full width at half maximum (FWHM) hardly changes ( Figure 1 d in Figure 1 and P 4Me c in Figure 1 ). Under the excitation of a 365 nm light source, bright blue light emission can be observed for both the Ce(T P 4Me )3 powder and the film ( Figure 1 g in Figure 1 and P 4Me e in Figure 1 ). After calculation, the CIE color coordinates of the Ce(T Figure 1 and Table 1 prove that the Ce(T P 4Me )3 powder and the film have similar optical properties, indicating that the film preparation does not damage the structure of the Ce(T P 4Me )3 complex and does not affect its luminescence properties, indicating that the prepared Ce(T P 4Me )3 complex inkjet printing ink inherits the Ce(T P4Me )3 The good optical properties of the complex result in a photoluminescence quantum yield (PLQY) of 45% for the final thin film.

[0060] Example 3

[0061] o - Dichlorobenzene and chlorobenzene were selected as the mixed solvents, and polystyrene was used as the polymer additive. The thin film prepared from the inkjet printing ink formulated with the Ce(T P 4Me )3 complex as the luminescent material has high transparency. As Figure 2 shown, the transmittance is > 95% in the wavelength range of 400 - 800 nm, and the school emblem of Huazhong University of Science and Technology can be clearly seen, demonstrating its potential for applications in the field of transparent photoluminescence.

[0062] Example 4

[0063] The polystyrene polymer has a protective effect on the luminescence center of the pyrazolylborate Ce(III) complex, making the thin film have good stability and being beneficial for long - term use. Specifically, after the Ce(T P 4Me )3 complex thin film is placed in an air environment for 300 hours, the photoluminescence fluorescence quantum yield (PLQY) only decreases from 45% to 43%, maintaining 96% of the PLQY performance;

[0064] Ce(T P 4Me )3 complex solution, as the concentration of the polystyrene polymer increases, the solution viscosity increases, the contact angle decreases, and combined with the regulation of the electrohydrodynamic jet printing process, the diameter of the printed pixel dots decreases, and the maximum height (H max ) and the minimum height (H min ) both decrease, and the ratio of the height difference to the minimum height also decreases (Δ H / H min ), indicating that the height is more uniform, and the ratio of the minimum height to the diameter (H min / diameter) increases (a in Figure 3 and b in Figure 3 ), and finally the coffee - ring effect is effectively suppressed, and fluorescently uniform pixel dots are obtained ( Figure 4 ).

[0065] Example 5

[0066] The Ce(T P 4Me )3 complex solution is used for electrohydrodynamic jet printing applications. By adjusting the process parameters ( Figure 5 ) in electrohydrodynamic jet printing, including the base voltage (V b ), the pulsed voltage (V p) Frequency (f), duty cycle, inkjet delay time (time for printing at the same position), and printing speed. Eventually, a pattern with a pixel diameter of 95 μm and uniform fluorescence can be obtained. Figure 6 )

[0067] Ce(T P 4Me )3 complex thin film has a PLQY of 45%. Using excitation light with a wavelength less than 400 nm, it can emit blue light with a central wavelength of 439 nm, a full width at half maximum of 72 nm, and CIE coordinates of (0.15, 0.08). It can be used in fields such as LCD color conversion layers - under ultraviolet backlight, it emits blue light.

[0068] Ce(T P 4Me )3 complex thin film is completely transparent in the visible light range of 400 - 800 nm, with a transmittance of over 95%. It has a blue light emission with a PLQY of 45% under ultraviolet excitation and excellent stability. After being placed in the air environment for 300 hours, the PLQY remains above 96%. It can be used in anti-counterfeiting and other fields - through the electrohydrodynamic inkjet printing process or lithography process described above, a fine and transparent pattern of Ce(T P 4Me )3 complex can be obtained on the material to be displayed. Under ultraviolet excitation, a bright blue pattern appears.

[0069] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Use of pyrazole boron Ce(III) complex as a photoluminescent material, characterized in that, Record the structural formula as The structural formula of the pyrazolylborate Ce(III) complex is as follows: Wherein, R1, R2, R3, and R4 are each independently selected from alkyl, aryl, phenyl, halogen, or halogen-substituted alkyl.

2. The use according to claim 1, characterized in that, The alkyl group is selected from C1-C 18 alkyl groups.

3. The use according to claim 2, characterized in that, R1 is -CH3; R2 is selected from C1-C 18 alkyl or halogen; R3 is -CH3; R4 is selected from C1-C 18 alkyl or aryl groups.

4. The use according to claim 1, characterized in that, The pyrazole boron Ce(III) complex is at least one of CeTp3, Ce(Tp 4Me )3, Ce(Tp 4Br )3, Ce(PzTp)3, Ce( i PrTp)3, Ce( n BuTp)3, and Ce(PhTp)3; The structure of the CeTp3 is shown as follows: The Ce(Tp 4Me )3 has the following structure: The structure of the Ce(Tp 4Br )3 is as follows: The structure of the Ce(PzTp)3 is as follows: The Ce( i PrTp)3 has the following structure: The Ce( n BuTp)3 has the following structure: The structure of the Ce(PhTp)3 is shown as follows:

5. The use according to claim 1, characterized in that, The photoluminescent material is used for preparing a photoluminescent display device.

6. The use according to claim 1, characterized in that, The photoluminescent material is used as an anti-counterfeiting material or as a color conversion layer material.

7. The use according to claim 1, characterized in that, The application specifically includes the following steps: (1) Dissolve the pyrazolylborate Ce(III) complex in a solvent containing a benzene ring and a chlorine element; (2) Add a polymer to the solution obtained in step (1); the polymer is polystyrene, polymethyl methacrylate, polycarbonate, or polyimide; (3) Perform inkjet printing, spin coating, or nanoimprinting on the solution obtained in step (2) to obtain a photoluminescent material.

8. The use according to claim 7, characterized in that, The solvent is o-dichlorobenzene or a mixture of o-dichlorobenzene and dichlorobenzene; preferably, in the mixture, the volume ratio of dichlorobenzene is less than or equal to 30%.

9. The use according to claim 7, characterized in that, In step (1), the concentration of the pyrazolylborate Ce(III) complex in the solvent is 1 mg / ml to 10 mg / ml; In step (2), the concentration of the polymer in the solution is 30 mg / ml to 250 mg / ml.

10. The application according to claim 7, characterized in that, In step (3), for the inkjet printing, the base voltage is 800 - 1200 V, the pulse voltage is 800 - 1500 V, the frequency is 20 - 50 Hz, the duty cycle is 50% - 90%, the delay time is 30 - 60 ms, and the substrate moving speed is 10 - 20 mm / min.

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