Ultraviolet excitation white light fluorescent powder based on Cu-I cluster and preparation method thereof

Abstract

The invention discloses ultraviolet excitation white light fluorescent powder based on Cu-I clusters and a preparation method thereof, and belongs to the technical field of inorganic luminescent materials, raw materials for preparing the white light fluorescent powder are tetraphenoxy pyridine and cuprous iodide, the chemical general formula of the ultraviolet excitation white light fluorescent powder based on the Cu-I clusters is (C11H9NO) 4. (CuI) x, x is equal to 2-4, x is equal to 2-4, and x is equal to 2-4. The invention relates to a C44H36Cu4I4N4O4 fluorescent powder, which is composed of a yellow phase C44H36Cu2I2N4O4 and a blue phase C44H36Cu2I2N4O4. The excitation wavelength is 200-450 nm, the emission wavelength is 400-800 nm, and the fluorescence quantum yield is close to 100%. Compared with fluorescent powder prepared by a high-temperature solid-phase reaction method, the fluorescent powder prepared by adopting a wet chemical method is simpler in preparation process, shorter in production period, lower in production cost, higher in repeatability and suitable for large-scale production and illumination display application.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic luminescent materials, in particular to an ultraviolet-excited white-light phosphor based on Cu-I clusters and a preparation method thereof. Background Art

[0002] In the field of modern lighting and display technology, efficient, stable and economical white light phosphors are one of the core materials. They not only meet the needs of high-quality lighting and display technology, but also have great significance for energy conservation. According to statistics, about 20% of the world's electricity consumption comes from lighting. Traditional white light phosphors mostly rely on rare earth elements or quantum dots. Although these materials have good optical properties, they also face problems such as high cost, limited resources and environmental pollution. For example, although lead halide perovskite quantum dots show excellent spectral purity and high luminous intensity, the toxicity of lead and the instability of the perovskite structure hinder their actual commercialization. For another example, rare earth-based phosphors are generally prepared by high-temperature solid-phase reaction, which is a high-energy consumption production method and is not conducive to the green energy conservation advocated by the country. Therefore, with the development of technology and the improvement of environmental protection requirements, the development of new low-cost and environmentally friendly white light phosphors has become an urgent need in the industry.

[0003] Copper-based metal halides do not contain rare earths and have many advantages such as low cost and solution processing. With their excellent luminous efficiency and high defect tolerance, they have gradually become a suitable type of phosphor material and are widely used in many fields such as solar collectors, X-ray scintillators, white light-emitting diodes, anti-counterfeiting encryption, etc. Among the many copper-based metal halides, Cu-I clusters can produce wavelength-tunable emission spectra under specific ultraviolet light excitation due to their unique electronic structure and excellent luminescence properties, providing new possibilities for the development of new phosphors. Cu-I clusters have high quantum efficiency and broadband luminescence characteristics, can effectively convert ultraviolet light into high-quality white light, and the preparation process is simple and low-cost, which is more in line with the requirements of green chemistry. Therefore, white light phosphors based on Cu-I clusters are expected to replace traditional rare earth-based phosphors in fields such as LED lighting and high-definition display screens, providing a more economical and environmentally friendly white light solution. Summary of the invention

[0004] The present invention provides a novel ultraviolet-excited white light phosphor based on Cu-I clusters and a preparation method thereof, which meet the demand of modern lighting and display technology for high-performance white light phosphors.

[0005] Technical solution: The present invention uses tetraphenoxypyridine (4-Phenoxypyridine, C 11 H 9NO) and CuI as raw materials, saturated KI solution and ethanol as solvents, and a simple solution method reaction to prepare a Cu-I cluster-based ultraviolet-excited white-light phosphor. The chemical formula of the Cu-I cluster-based ultraviolet-excited white-light phosphor is (C 11 H 9 NO) 4 ·(CuI) x , where x = 2-4, from the yellow phase C 44 H 36 Cu 4 I 4 N 4 O 4 And blue phase C 44 H 36 Cu 2 I 2 N 4 O 4 When the value of x is between 2 and 4, the product phosphor is a mixed phase, and the luminescence is a superposition of blue and yellow, thereby achieving white light emission.

[0006] The excitation wavelength range of the white light phosphor is 200-450 nm, and the emission wavelength range covers 400-800 nm.

[0007] (1) White light phosphor when x = 3.17: the excitation wavelength range is 200-400nm, the optimal excitation peaks are 275nm and 390nm, and the emission wavelength range covers 400-750nm; under the excitation of 275-364nm ultraviolet light, the phosphor emits warm white light, under the excitation of 365-374nm ultraviolet light, the phosphor emits white light, under the excitation of 375-379nm ultraviolet light, the phosphor emits cold white light, and under the excitation of 380-400nm ultraviolet light, the phosphor emits blue light; under the excitation of 365nm, the color temperature is 8857K, the color rendering index is 64, the color coordinates are (0.26, 0.35), and the fluorescence quantum yield is close to 100%.

[0008] (2) White light phosphor when x = 3.28: the excitation wavelength range is 200-400nm, the optimal excitation peaks are 275 and 365nm, and the emission wavelength range covers 400-800nm; under 385nm excitation, the color temperature is 9447K, the color rendering index is 63, the color coordinates are (0.25, 0.35), and the fluorescence quantum yield is close to 100%; under 385-390nm ultraviolet light excitation, the phosphor displays white light.

[0009] (3) White light phosphor when x = 3.08: the excitation wavelength range is 200-450nm, the optimal excitation peaks are 275nm and 390nm, and the emission wavelength range covers 400-800nm; under 360nm excitation, the color temperature is 10250K, the color rendering index is 64, the color coordinates are (0.25, 0.34), and the fluorescence quantum yield is close to 100%; under 360-364nm ultraviolet light excitation, the phosphor emits white light.

[0010] The method for preparing the ultraviolet-excited white light phosphor based on Cu-I clusters comprises the following steps:

[0011] Step 1: Prepare a saturated potassium iodide (KI) solution at room temperature for subsequent reaction steps.

[0012] Step 2: Measure an appropriate amount of saturated KI solution and place it in sample bottle A, add an appropriate amount of CuI, stir and mix evenly to obtain solution A.

[0013] Step 3: Measure an appropriate amount of ethanol solution and put it into another sample bottle B, add an appropriate amount of tetraphenoxypyridine, stir and mix evenly to obtain a mixed solution B.

[0014] Step 4: Use a rubber-tipped dropper to take mixed solution B and drip it drop by drop into mixed solution A. Stir for 5 minutes until the reaction is complete.

[0015] Step 5: After the reaction in step 4 is completed, the mixed solution is placed in a centrifuge tube for centrifugation, the liquid is filtered, the product is collected, and it is dried in an oven at 60° C. for 6 hours. The powder is ground to obtain a UV-excited white light phosphor based on Cu-I clusters.

[0016] Furthermore, the molar ratio of CuI in the mixed solution A to tetraphenoxypyridine in the mixed solution B is 1:(1-2).

[0017] Beneficial effects: The method of the present invention optimizes the synthesis conditions and the structure of the Cu-I clusters, so that the prepared white light phosphor material has the advantages of emission peak width, adjustable excitation / emission wavelength, high luminous efficiency, etc. The present invention adopts a wet chemical method to prepare white light phosphors. Compared with phosphors prepared by a high-temperature solid-phase reaction method, the preparation process is simpler, the production cycle is shorter, the production cost is lower, and the repeatability is higher, which is suitable for large-scale production and lighting display applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is (C 11 H 9 NO) 4 ·(CuI) x (x=2) Excitation and emission spectra of the phosphor, where a is the excitation spectrum and b is the emission spectrum.

[0019] Figure 2 The present invention is (C 11 H 9 NO) 4 ·(CuI) x (x=4) Excitation and emission spectra of the phosphor, where a is the excitation spectrum and b is the emission spectrum.

[0020] Figure 3 The present invention is (C 11 H 9 NO) 4 ·(CuI) x (x=3.17) Excitation and emission spectra of the phosphor, where a is the excitation spectrum and b is the emission spectrum.

[0021] Figure 4 The present invention is (C 11 H 9 NO) 4 ·(CuI) x (x=3.17) The emission spectra of the phosphor corresponding to different excitation wavelengths.

[0022] Figure 5 The present invention is (C 11 H 9 NO) 4 ·(CuI) x (x=3.17) The excitation spectra of the phosphors correspond to different emission wavelengths.

[0023] Figure 6 The present invention is (C 11 H 9 NO) 4 ·(CuI) x (x=3.17) PLQY spectrum corresponding to the phosphor.

[0024] Figure 7 The present invention is (C 11 H 9 NO) 4 ·(CuI) x (x=3.28) Excitation and emission spectra of the phosphor, where a is the excitation spectrum and b is the emission spectrum.

[0025] Figure 8 The present invention is (C 11 H 9 NO) 4 ·(CuI) x (x=3.08) Excitation and emission spectra of the phosphor, where a is the excitation spectrum and b is the emission spectrum. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the embodiments.

[0027] Example 1: Preparation method of blue phase Cu-I cluster phosphor

[0028] This embodiment is a method for preparing a blue phase Cu-I cluster phosphor, comprising the following steps:

[0029] Step 1: Prepare a saturated KI solution at room temperature for subsequent steps.

[0030] Step 2: weigh 0.19 g (1 mmol) CuI, measure 2 mL of saturated KI solution and place it in sample bottle A, stir and mix evenly.

[0031] Step 3, weigh 0.34 g (2 mmol) of tetraphenoxypyridine, measure 4 mL of ethanol solution (99.7%) and put it into another sample bottle B, stir and mix evenly.

[0032] Step 4: Use a rubber-tipped dropper to take the mixed solution B of tetraphenoxypyridine ethanol, and drop it dropwise into the mixed solution A of CuI-KI. Stir for 5 minutes to complete the reaction.

[0033] Step 5: After the reaction in step 4 is completed, the mixed solution is placed in a centrifuge tube and centrifuged, the liquid is filtered, the product is collected, and dried in an oven at 60° C. for 6 hours.

[0034] Step six, grinding the powder to obtain a Cu-I cluster-based ultraviolet-excited phosphor.

[0035] After the above steps, C 44 H 36 Cu 2 I 2 N 4 O 4 (i.e. C 11 H 9 NO) 4 ·(CuI) x , x=2) blue light phosphor. Figure 1The figure shows the fluorescence spectrum of the ultraviolet-excited blue light phosphor based on the Cu-I cluster prepared in this embodiment, wherein a is the excitation spectrum, which is the excitation wavelength measured at an emission wavelength of 470 nm; b is the emission spectrum, which is the emission wavelength measured at an excitation wavelength of 365 nm. In the excitation spectrum, there is an excitation peak centered at about 275, 325 and 365 nm. When the excitation wavelength and the monitoring wavelength are changed, there is no position shift in the emission peak and the excitation peak, indicating that its fluorescence comes from a single luminescence center, which is caused by the charge transfer from metal to ligand (MLCT) and the charge transfer from halide to ligand (HLCT). The ultraviolet-excited phosphor of the Cu-I cluster has high luminescence intensity, a PLQY (photoluminescence quantum yield) of nearly 100%, and a spectrum half-peak width of about 82 nm. It has potential applications in emitting blue light and can be used in conjunction with commercial yellow phosphors or the yellow phase (C 44 H 36 Cu 4 I 4 N 4 O 4 ) combination to achieve color adjustable.

[0036] Example 2: Preparation method of yellow phase Cu-I cluster phosphor

[0037] This embodiment is a method for preparing a yellow phase Cu-I cluster phosphor, comprising the following steps:

[0038] Step 1: Prepare a saturated KI solution at room temperature for subsequent steps.

[0039] Step 2: weigh 0.19 g (1 mmol) CuI, measure 2 mL of saturated KI solution and place it in sample bottle A, stir and mix evenly.

[0040] Step 3, weigh 0.171 g (1 mmol) of tetraphenoxypyridine, measure 2 mL of ethanol solution and put it into another sample bottle B, stir and mix evenly.

[0041] Step 4: Use a rubber-tipped dropper to take the mixed solution B of tetraphenoxypyridine ethanol, and drop it dropwise into the mixed solution A of CuI-KI. Stir for 5 minutes to complete the reaction.

[0042] Step 5: After the reaction in step 4 is completed, the mixed solution is placed in a centrifuge tube and centrifuged, the liquid is filtered, the product is collected, and dried in an oven at 60° C. for 6 hours.

[0043] Step six, grinding the powder to obtain a Cu-I cluster-based ultraviolet-excited phosphor.

[0044] After the above steps, C 44 H 36 Cu 4 I 4 N4 O 4 (i.e. C 11 H 9 NO) 4 ·(CuI) x , x=2) yellow light phosphor. Figure 2 The figure shows the fluorescence spectrum of the ultraviolet-excited yellow phosphor based on the Cu-I cluster prepared in this embodiment, where a is the excitation spectrum, which is the excitation wavelength measured at a monitoring wavelength of 555 nm; b is the emission spectrum, which is the emission wavelength measured at an excitation wavelength of 365 nm. In the excitation spectrum, there is an excitation peak centered at about 275, 325 and 365 nm. When the excitation wavelength and the monitoring wavelength are changed, there is no position shift in the emission peak and the excitation peak, indicating that its fluorescence comes from a single luminescence center, caused by the charge transfer (CC) of the cluster center, and the CC excited state is a hybrid orbit of iodine-copper charge transfer (XMCT) and metal center "d-to-s" (MC). The CC excited state usually leads to low-energy emission, which can be observed in the case of metal center interaction. The ultraviolet-excited yellow phosphor of the Cu-I cluster has high luminescence intensity, a PLQY of nearly 100%, and a spectral half-peak width of about 94 nm. It has potential applications in emitting yellow light and can be used in conjunction with commercial blue LED chips or the blue phase (C 44 H 36 Cu 2 I 2 N 4 O 4 ) combination to achieve color adjustable.

[0045] Example 3: Preparation method of ultraviolet excited white light phosphor based on Cu-I clusters

[0046] The C prepared in this example 11 H 9 NO) 4 ·(CuI) x White light phosphor, wherein x=3.17, the specific preparation steps are as follows:

[0047] Step 1: Prepare a saturated KI solution at room temperature for subsequent steps.

[0048] Step 2: weigh 0.19 g (1 mmol) CuI, measure 2 mL of saturated KI solution and place it in sample bottle A, stir and mix evenly.

[0049] Step 3, weigh 0.216 g (1.26 mmol) of tetraphenoxypyridine, measure 4 mL of ethanol solution and put it into another sample bottle B, stir and mix evenly.

[0050] Step 4: Use a rubber-tipped dropper to take the mixed solution B of tetraphenoxypyridine ethanol, and drop it dropwise into the mixed solution A of CuI-KI. Stir for 5 minutes to complete the reaction.

[0051] Step 5: After the reaction in step 4 is completed, the mixed solution is placed in a centrifuge tube and centrifuged, the liquid is filtered, the product is collected, and dried in an oven at 60° C. for 6 hours.

[0052] Step six, grinding the powder to obtain a Cu-I cluster-based ultraviolet-excited white light phosphor.

[0053] After the above steps, the ultraviolet excitation (C 11 H 9 NO) 4 ·(CuI) x White light phosphor, wherein x=3.17. Figure 3 The fluorescence spectrum of the ultraviolet-excited white light phosphor based on the Cu-I cluster prepared in this embodiment is shown. a is the excitation spectrum, which is the excitation wavelength measured at a monitoring wavelength of 470nm; b is the emission spectrum, which is the emission wavelength measured at an excitation wavelength of 365nm. In the excitation spectrum, there is an excitation peak centered at about 275nm and 390nm. Under the excitation wavelength of 365nm, the half-peak width of the spectrum is about 147nm, the color temperature is 8857K, the color rendering index is 64, and the color coordinates are (0.26, 0.35). Figure 4 As shown, the corresponding emission wavelengths are measured by excitation with 390nm, 365nm and 275nm excitation peaks, which emit broadband blue light, broadband warm white light and broadband white light respectively. Figure 5 As shown, the excitation wavelengths corresponding to different emission wavelengths are inconsistent. Specifically, the excitation peaks corresponding to the emission peaks from 470nm to 490nm are similar, and the excitation peaks corresponding to the emission peaks from 530nm to 610nm are similar. It can be seen that the white light phosphor is a mixed phase, and the light emission comes from two luminescence centers. Figure 6 The PLQY of the white light phosphor is shown to be nearly 100%.

[0054] The above shows that the white light phosphor is a mixed phase of a single matrix, with the emission center emitting blue light at 470nm and the emission center emitting yellow light at 555nm. The corresponding chemical formula is: The chemical formula of the yellow light phase is C 44 H 36 Cu 4 I 4 N 4 O 4 , the chemical formula of the blue phase is C 44 H 36 Cu 2 I 2 N 4 O 4. The blue light phase is mainly caused by MLCT and HLCT charge transfer; the yellow light phase is mainly caused by CC charge transfer. The blue light phase and the yellow light phase have similar composition content and work together in the white light emission process. The white light powder can be used in conjunction with an adhesive and placed on a commercial 365nm UV LED chip to obtain bright white light emission when excited. Using a commercial 275nm UV LED chip, it can emit warm white light, and using a commercial 390nm UV LED chip, it can emit blue light. Not only does it achieve the adjustment from white light to warm white light, but it also achieves color tunability of multi-color LEDs.

[0055] Example 4: Preparation of UV-excited warm white light phosphor based on Cu-I clusters

[0056] The C prepared in this example 11 H 9 NO) 4 ·(CuI) x Warm white phosphor, where x=3.28, is prepared as follows:

[0057] In step 1, a saturated KI solution was prepared in advance at room temperature for use in subsequent steps.

[0058] Step 2: weigh 0.19 g (1 mmol) CuI, measure 2 mL of saturated KI solution and place it in sample bottle A, stir and mix evenly.

[0059] Step 3, weigh 0.209 g (1.22 mmol) of tetraphenoxypyridine, measure 4 mL of ethanol solution and put it into another sample bottle B, stir and mix evenly.

[0060] Step 4: Use a rubber-tipped dropper to take the mixed solution B of tetraphenoxypyridine ethanol, and drop it dropwise into the mixed solution A of CuI-KI. Stir for 5 minutes to complete the reaction.

[0061] Step 5: After the reaction in step 4 is completed, the mixed solution is placed in a centrifuge tube and centrifuged, the liquid is filtered, the product is collected, and dried in an oven at 60° C. for 6 hours.

[0062] Step six, grinding the powder to obtain a Cu-I cluster-based ultraviolet-excited white light phosphor.

[0063] After the above steps, the ultraviolet excited warm white light C 11 H 9 NO) 4 ·(CuI) x Phosphor, wherein x=3.28. Figure 7The figure shows the fluorescence spectrum of the warm white light phosphor based on the Cu-I cluster prepared in this embodiment, where a is the excitation spectrum, which is the excitation wavelength measured at an emission wavelength of 540nm; b is the emission spectrum, which is the emission wavelength measured at an excitation wavelength of 365nm. In the excitation spectrum, there are excitation peaks centered at around 275 and 365nm. Under different emission wavelength monitoring, its excitation wavelength is inconsistent, indicating that its luminescence comes from different luminescence centers. The warm white light phosphor is a mixed phase of a single matrix, with the emission center emitting blue light at 470nm and the emission center emitting yellow light at 555nm. The blue light phase is mainly caused by MLCT and HLCT charge transfer; the yellow light phase is mainly caused by CC charge transfer. The yellow light phase has more components in the powder and plays a major role in the emission process. The PLQY of the ultraviolet-excited warm white light phosphor of the Cu-I cluster is nearly 100%, and the spectral half-peak width is about 156nm, which has potential applications in warm white light lighting and display. The excitation wavelength range is 200-400nm, the best excitation peaks are 275 and 365nm, and the emission wavelength range covers 400-800nm. Under 385nm excitation, the color temperature is 9447K, the color rendering index is 63, and the color coordinates are (0.25, 0.35). Under (385-390)nm ultraviolet light excitation, the phosphor displays white light.

[0064] Example 5: Preparation of UV-excited cold white light phosphor based on Cu-I clusters

[0065] The C prepared in this example 11 H 9 NO) 4 ·(CuI) x The cold white light phosphor, wherein x=3.08, is prepared by the following steps:

[0066] In step 1, a saturated KI solution was prepared in advance at room temperature for use in subsequent steps.

[0067] Step 2: weigh 0.19 g (1 mmol) CuI, measure 2 mL of saturated KI solution and place it in sample bottle A, stir and mix evenly.

[0068] Step 3, weigh 0.222 g (1.3 mmol) of tetraphenoxypyridine, measure 4 mL of ethanol solution and put it into another sample bottle B, stir and mix evenly.

[0069] Step 4: Use a rubber-tipped dropper to take the mixed solution B of tetraphenoxypyridine ethanol, and drop it dropwise into the mixed solution A of CuI-KI. Stir for 5 minutes to complete the reaction.

[0070] Step 5: After the reaction in step 4 is completed, the mixed solution is placed in a centrifuge tube and centrifuged, the liquid is filtered, the product is collected, and dried in an oven at 60° C. for 6 hours.

[0071] Step six, grinding the powder to obtain a Cu-I cluster-based ultraviolet-excited white light phosphor.

[0072] After the above steps, the ultraviolet excited cold white light (C 11 H 9 NO) 4 ·(CuI) x Phosphor, wherein x=3.08. Figure 8 The figure shows the fluorescence spectrum of the cold white light phosphor based on the Cu-I cluster prepared in this embodiment, (a) is the excitation spectrum, which is the excitation wavelength measured at a monitoring wavelength of 470nm; (b) is the emission spectrum, which is the emission wavelength measured at an excitation wavelength of 365nm. In the excitation spectrum, there are excitation peaks centered at around 275 and 390nm. Under different emission wavelength monitoring, its excitation wavelength is inconsistent, indicating that its excitation center comes from different excitation centers. The cold white light phosphor is a mixed phase of a single matrix, with the emission center emitting blue light at 470nm and the emission center emitting yellow light at 555nm. The blue light phase is mainly caused by MLCT and HLCT charge transfer; the yellow light phase is mainly caused by CC charge transfer. The blue light phase is the most abundant component in the powder and plays a major role in the emission process. The PLQY of the ultraviolet-excited cold white light phosphor of the Cu-I cluster is nearly 100%, and the spectral half-peak width is about 139nm, which has potential applications in cold white light lighting and display. The excitation wavelength range is 200-450nm, the optimal excitation peaks are 275nm and 390nm, and the emission wavelength range covers 400-800nm; under 360nm excitation, the color temperature is 10250K, the color rendering index is 64, and the color coordinates are (0.25, 0.34). Under 360-364nm ultraviolet light excitation, the phosphor displays white light.

[0073] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes may be made to the form and details without departing from the spirit and scope of the present invention.

Claims

1. A UV-excited white light phosphor based on Cu-I clusters, characterized in that: The chemical formula of the ultraviolet excited white light phosphor is (C 11 H9NO)4·(CuI) x , where x = 2-4, from the yellow phase C 44 H 36 Cu4I4N4O4 and blue phase C 44 H 36 Cu2I2N4O4 composition.

2. The ultraviolet excited white light phosphor based on Cu-I clusters according to claim 1, characterized in that: The excitation wavelength range of the ultraviolet excited white light phosphor is 200-450nm; the emission wavelength range covers 400-800nm.

3. The method for preparing the ultraviolet excited white light phosphor based on Cu-I clusters according to claim 1, characterized in that: The preparation process includes the following steps: Step 1: prepare a saturated KI solution at room temperature; Step 2: Add CuI to the saturated KI solution, stir and mix evenly to obtain a mixed solution A; Step 3, adding tetraphenoxypyridine to the ethanol solution, stirring and mixing evenly to obtain a mixed solution B; Step 4: Use a rubber-tipped dropper to take mixed solution B, drop it into mixed solution A drop by drop, and stir for a while; Step 5: After the reaction in step 4 is completed, the mixed solution is centrifuged, filtered, and the product is collected. After drying and grinding, a Cu-I cluster-based ultraviolet-excited white light phosphor is obtained.

4. The preparation method according to claim 3, characterized in that: In step 4, the molar ratio of CuI in the mixed solution A to tetraphenoxypyridine in the mixed solution B is 1:(1-2).

5. The preparation method according to claim 3, characterized in that: In step 4, the drying condition is: drying in an oven at 60° C. for 6 hours.

6. The preparation method according to claim 3, characterized in that: In step 4, the stirring time is 5 minutes.

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