A preparation route for dual-component multi-core-shell perovskite quantum dots for LED color conversion technology

Abstract

The present invention belongs to the field of optoelectronic materials technology and specifically discloses a preparation route for dual-component multi-core-shell perovskite quantum dots for LED color conversion technology, comprising the following steps: S1: coating the surface of perovskite quantum dots with a higher band gap than the outer shell with a layer of amorphous SiO2 or preparing a molecular sieve containing perovskite quantum dots with a higher band gap than the outer shell to obtain a precursor 1; S2: using the precursor 1 obtained in step S1 as part of a precursor to synthesize dual-component multi-core-shell perovskite quantum dots. The present invention utilizes perovskite quantum dots with a higher band gap than the outer shell as part of a precursor to synthesize perovskite quantum dots with a lower band gap than the inner core, thereby synthesizing a composite nanostructure in which two different components of perovskite quantum dots coexist. In the present invention, the inner core transfers energy to the outer shell, and the perovskite quantum dots in the outer shell exhibit the excitation characteristics of the inner core quantum dots, thereby adjusting the optimal excitation wavelength of the outer shell quantum dots.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic materials, and in particular relates to a preparation route of double-component multi-core-shell perovskite quantum dots for LED color conversion technology. Background Art

[0002] Perovskite quantum dots (PQDs) are gradually replacing traditional rare earth phosphors due to their numerous advantages in luminescence efficiency, color purity, brightness, and wavelength tunability. They hold great potential for application in mini- and micro-LED displays, and the use of PQDs in color conversion layers has garnered widespread attention from both academia and industry. Currently, the primary drawback of PQDs lies in their poor stability, particularly for red-emitting PQDs, which exhibit significantly lower stability and brightness than their green counterparts. When used as color conversion materials, PQDs are typically excited by blue LEDs. However, red PQDs, as semiconductor materials, have a smaller band gap than green PQDs. When excited by blue or near-ultraviolet light, the photon energy of the excitation light significantly exceeds the red band gap, generating a large number of high-energy hot carriers and activating potential shallow-level defects. During the subsequent hot carrier relaxation process, a large number of carriers are trapped by the shallow-level defects into non-radiative recombination channels, resulting in reduced luminescence efficiency. Experiments show that red perovskite quantum dots can only exhibit the brightest luminescence and the highest quantum yield when excited by green light.

[0003] Currently, researchers are primarily using perovskite quantum dots (QDs) to improve their stability and luminescence efficiency. However, optimizing perovskite QDs presents several challenges: Ion doping typically results in a blue-shifted spectrum, and for red QDs, adjusting the halogen ratio is infeasible to offset the blue-shift. While existing methods can improve QD stability and luminescence efficiency, they largely fail to optimize the energy level structure of red QDs, preventing them from achieving peak luminescence under blue light excitation and rendering them incompatible with current LED display technology.

[0004] Therefore, it is very necessary to develop a new technology to meet the needs of LED color conversion. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the existing technology and provide a preparation route for dual-component multi-core-shell perovskite quantum dots for LED color conversion technology. By using perovskite quantum dots with a higher band gap than the outer shell as part of the precursor to synthesize perovskite quantum dots with a lower band gap than the inner core, a composite nanostructure in which two different components of perovskite quantum dots coexist is synthesized.

[0006] To achieve the above objectives, one of the technical solutions of the present invention is: a preparation route for dual-component multi-core-shell perovskite quantum dots for LED color conversion technology, comprising the following steps:

[0007] S1: coating a layer of amorphous SiO2 on the surface of perovskite quantum dots having a band gap higher than that of the shell layer or preparing a molecular sieve containing perovskite quantum dots having a band gap higher than that of the shell layer to obtain precursor 1;

[0008] S2: Using the precursor 1 prepared in step S1 as part of the precursor to synthesize two-component multiple core-shell structure perovskite quantum dots.

[0009] Preferably, the molecular sieves used in the preparation of the molecular sieve containing perovskite quantum dots having a band gap higher than that of the outer shell in step S1 include but are not limited to MCM-41 molecular sieve, SAB-15 molecular sieve, and nano-Si molecular sieve.

[0010] Preferably, when the precursor 1 in step S2 is a perovskite quantum dot with a band gap higher than that of the shell layer and a layer of amorphous SiO2 is coated on the surface, the perovskite quantum dot with a band gap higher than that of the shell layer is prepared by a high-temperature hot injection method, a low-temperature hot injection method or an anti-solvent method.

[0011] Preferably, in step S2, when the precursor 1 is a perovskite quantum dot having a band gap higher than that of the outer shell layer and a layer of amorphous SiO2 is coated on the surface, the two-component multiple core-shell structure perovskite quantum dots are synthesized by liquid phase reaction.

[0012] Preferably, when the precursor 1 in step S2 is a molecular sieve containing perovskite quantum dots having a band gap higher than that of the outer shell, the dual-component multiple core-shell structure perovskite quantum dots are synthesized by solid phase calcination.

[0013] In order to achieve the above objectives, the second technical solution of the present invention is: a dual-component multi-core-shell structure perovskite quantum dot for LED color conversion technology.

[0014] In order to achieve the above objectives, the third technical solution of the present invention is: an application of dual-component multiple core-shell structure perovskite quantum dots for LED color conversion technology.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The dual-component multiple core-shell structure of the present invention can utilize the energy transfer mechanism to enhance the luminescence efficiency of the outer shell perovskite quantum dots without causing the luminescence wavelength to shift;

[0017] 2. In the present invention, the core transfers energy to the shell, and the perovskite quantum dots of the shell exhibit the excitation characteristics of the core quantum dots, which can adjust the optimal excitation wavelength of the shell quantum dots. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the dual-component multiple core-shell structure perovskite quantum dots of the present invention;

[0019] Figure 2 This is a transmission electron microscopy image of the dual-component multiple core-shell structure perovskite quantum dots prepared in Example 1 of the present invention;

[0020] Figure 3 This is a graph showing the peak intensity change of the excitation spectrum of the dual-component multiple core-shell structure perovskite quantum dots prepared in Example 1 of the present invention as the content of the CsPbBr3 additive increases;

[0021] Figure 4 This is a graph showing changes in the luminescence intensity and wavelength of the dual-component multi-core-shell perovskite quantum dots prepared in Example 1 of the present invention under blue light excitation as the content of the CsPbBr3 additive increases;

[0022] Figure 5 Schematic diagram of the Micro-LED color conversion layer structure prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is described in more detail below with reference to the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0024] A preparation route for dual-component multi-core-shell perovskite quantum dots for LED color conversion technology includes the following steps:

[0025] S1: coating a layer of amorphous SiO2 on the surface of perovskite quantum dots having a band gap higher than that of the shell layer or preparing a molecular sieve containing perovskite quantum dots having a band gap higher than that of the shell layer to obtain precursor 1;

[0026] S2: Using the precursor 1 prepared in step S1 as part of the precursor to synthesize two-component multiple core-shell structure perovskite quantum dots.

[0027] The molecular sieves used in the preparation of the molecular sieve containing perovskite quantum dots with a band gap higher than that of the outer shell in step S1 include but are not limited to MCM-41 molecular sieve, SAB-15 molecular sieve, and nano-Si molecular sieve.

[0028] In step S2, when the precursor 1 is a perovskite quantum dot with a band gap higher than that of the shell layer and a layer of amorphous SiO2 is coated on the surface, the perovskite quantum dot with a band gap higher than that of the shell layer is prepared by a high-temperature hot injection method, a low-temperature hot injection method or an anti-solvent method.

[0029] In step S2, when the precursor 1 is a perovskite quantum dot with a band gap higher than that of the outer shell layer and a layer of amorphous SiO2 is coated on the surface, the two-component multiple core-shell structure perovskite quantum dots are synthesized by liquid phase reaction.

[0030] When the precursor 1 in step S2 is a molecular sieve containing perovskite quantum dots with a band gap higher than that of the outer shell, the dual-component multiple core-shell structure perovskite quantum dots are synthesized by high-temperature solid-phase sintering.

[0031] A dual-component multi-core-shell perovskite quantum dot for LED color conversion technology.

[0032] An application of dual-component multi-core-shell perovskite quantum dots for LED color conversion technology.

[0033] Example 1

[0034] A dual-component multi-core-shell perovskite quantum dot CsPbBr3@CsPbI3 is prepared by an improved high-temperature hot injection method. The specific steps are as follows:

[0035] 1. Coating a layer of amorphous SiO2 on the surface of CsPbBr3 perovskite quantum dots prepared by traditional high-temperature hot injection method:

[0036] (1) 0.4073 g of Cs2CO3 was dissolved in a mixed solvent of 20 mL of octadecene and 1.25 mL of oleylamine at 120 °C in an argon atmosphere as a Cs precursor;

[0037] (2) 0.1102 g of PbBr2 was dissolved in a mixed solvent of 20 mL of octadecene, 2 mL of oleylamine, and 2 mL of oleic acid at 180 °C in an argon atmosphere as a Br precursor;

[0038] (3) In an argon environment at 180°C, 1.6 mL of the LCS precursor was added to the vigorously stirred Br precursor. After reacting for 5 seconds, the mixture was quickly cooled in ice water. Subsequently, 0.2 mL of APTES (3-aminopropyltriethoxysilane) was added dropwise and stirred in air for 30 minutes to hydrolyze SiO2 on the perovskite surface. The SiO2 formed in this step prevents ion migration between Br and I.

[0039] (4) The above solution was centrifuged at 11000 rpm / min for 5 min, the supernatant was discarded, 1 mL of n-hexane was added for dispersion, and the solution was centrifuged at 1100 rpm / min for 5 min again. Then 10 mL of n-hexane was added for dispersion, and the solution was centrifuged at 4000 rpm / min for 5 min. The supernatant was CsPbBr3@SiO2.

[0040] 2. Use CsPbBr3@SiO2 as part of the precursor to synthesize red two-component multiple core-shell structure perovskite quantum dots CsPbBr3@CsPbI3:

[0041] (1) 0.1382 g of PbI2 was dissolved in a mixed solvent of 20 mL of octadecene, 2 mL of oleylamine, and 2 mL of oleic acid at 180 °C in an argon atmosphere as an I precursor;

[0042] (2) In an argon environment at 180°C, 1.6 mL of LCS precursor and 0.3 mL of LCSPbBr3@SiO2 were added to the vigorously stirred I precursor. After reacting for 5 seconds, the mixture was quickly placed in ice water for cooling. Subsequently, 0.2 mL of APTES was added dropwise and stirred in air for 30 minutes to hydrolyze SiO2 on the perovskite surface. The SiO2 formed in this step serves to protect the perovskite quantum dots from damage by the external environment in the outermost layer.

[0043] (3) The above solution was centrifuged at 11000 rpm / min for 5 min, the supernatant was discarded, 1 mL of n-hexane was added for dispersion, and the mixture was centrifuged again at 11000 rpm / min for 5 min. Then 10 mL of n-hexane was added for dispersion, and the mixture was centrifuged at 3000 rpm / min for 5 min. The supernatant was CsPbBr3@CsPbI3. The final centrifugal speed in this step was 3000 rpm in order to obtain CsPbBr3@CsPbI3 with a larger size than CsPbBr3@SiO2.

[0044] The diameter of CsPbBr3@SiO2 prepared in this embodiment is about 10 nm, and the diameter of CsPbBr3@CsPbI3 is about 20 nm.

[0045] The obtained dual-component multi-core-shell structure perovskite quantum dots were tested and the results were Figure 2 Transmission electron microscopy images of dual-component multiple core-shell structure perovskite quantum dots, Figure 3 The peak intensity change diagram of the excitation spectrum of the two-component multiple core-shell structure perovskite quantum dots as the content of CsPbBr3 additives increases, Figure 4 The luminescence intensity and wavelength of the dual-component multi-core-shell perovskite quantum dots under blue light excitation change with the increase of CsPbBr3 additive content. Figure 2 It can be seen that the two-component multiple core-shell structure perovskite quantum dots have a smaller core covered by a shell, and an amorphous SiO2 coating layer on the outermost layer. The core size is about 10nm in diameter, and the overall size is about 20nm in diameter. Figure 3(R1, R2, R3, and R4 are the sample numbers with increasing CsPbBr3 content as an additive) It can be seen that the excitation spectrum of the two-component multiple core-shell structure perovskite quantum dots gradually shifts to the blue light region as the CsPbBr3 additive content increases. Figure 4 (R1, R2, R3, and R4 are the sample numbers with gradually increasing CsPbBr3 content as an additive) It can be seen that under blue light excitation, the luminescence intensity of the two-component multiple core-shell structure perovskite quantum dots can be increased to 3.5 times that of ordinary red perovskite quantum dots, and there is no obvious shift in the luminescence wavelength.

[0046] Example 2

[0047] A dual-component multi-core-shell perovskite quantum dot CsPbBr3@CsPbI3 was prepared by an improved low-temperature hot injection method. The specific steps are as follows:

[0048] 1. A layer of amorphous SiO2 is coated on the surface of CsPbBr3 perovskite quantum dots prepared by low-temperature hot injection method:

[0049] (1) 0.0652 g of Cs2CO3 was dissolved in a mixed solvent of 10 mL of n-octane and 0.5 mL of oleylamine at 120 °C as a Cs precursor;

[0050] (2) 0.2202 g of PbBr2 was dissolved in a mixed solvent of 10 mL of octadecene, 0.5 mL of oleylamine, 1 mL of oleic acid, and 0.2 mL of APTES at 120 °C as a Br precursor;

[0051] (3) At 120°C, pour the Cs precursor into the vigorously stirred Br precursor, react for 2 minutes, then change to 90°C and continue the reaction for 20 minutes, and finally cool naturally to room temperature;

[0052] (4) The above solution was centrifuged at 11000 rpm / min for 5 min, the supernatant was discarded, 1 mL of n-octane was added for dispersion, and the mixture was centrifuged again at 11000 rpm / min for 5 min. Then, 10 mL of n-octane was added for dispersion, and the mixture was centrifuged at 4000 rpm / min for 5 min. The supernatant was CsPbBr3@SiO2. The SiO2 formed by the addition of APTES in this step prevented the ion migration between Br and I.

[0053] 2. Use CsPbBr3@SiO2 as part of the precursor to synthesize red two-component multiple core-shell structure perovskite quantum dots CsPbBr3@CsPbI3:

[0054] (1) 0.2766 g of PbI2 was dissolved in a mixed solvent of 10 mL of octadecene, 0.5 mL of oleylamine, 1 mL of oleic acid, and 0.2 mL of APTES at 120 °C as an I precursor;

[0055] (2) At 120°C, the Cs precursor and 0.3 mL CsPbBr3@SiO2 were simultaneously poured into the vigorously stirred I precursor. After reacting for 2 minutes, the temperature was changed to 90°C and the reaction was continued for 20 minutes. Finally, the reaction was naturally cooled to room temperature.

[0056] (3) The above solution was centrifuged at 11,000 rpm / min for 5 minutes, the supernatant was discarded, 1 mL of n-octane was added for dispersion, and the mixture was centrifuged again at 11,000 rpm / min for 5 minutes. Then, 10 mL of n-octane was added for dispersion, and the mixture was centrifuged at 3,000 rpm / min for 5 minutes. The supernatant was CsPbBr3@CsPbI3. The SiO2 formed by the addition of APTES in this step serves to protect the perovskite quantum dots from damage by the external environment. The final centrifugal speed in this step was 3,000 rpm / min to obtain CsPbBr3@CsPbI3 with a larger size than CsPbBr3@SiO2.

[0057] Example 3

[0058] A two-component perovskite quantum dot CsPbBr3-CsPbI3-SiO2 is prepared by an improved high-temperature solid-phase method. The specific steps are as follows:

[0059] 1. Prepare molecular sieves containing CsPbBr3 (including but not limited to MCM-41 molecular sieve, SAB-15 molecular sieve, nano-Si molecular sieve, etc., here MCM-41 molecular sieve is used as an example):

[0060] (1) 0.3670g PbBr2, 0.2128g CsBr, and 1.3476g MCM-41 molecular sieve were mixed uniformly in 20mL water by ultrasonication for 15min. The mixture was placed in a quartz crucible and heated to 600℃ at 10℃ / min in a tube furnace with argon gas. The mixture was kept at this temperature for 30min and then cooled naturally to room temperature. The calcination temperature in this step was 600℃, which partially closed the pores of the MCM-41 molecular sieve and encapsulated the CsPbBr3.

[0061] (2) The calcined powder was placed in 5 mL of DMF (N,N-dimethylformamide) and ultrasonically dispersed for 5 minutes, followed by centrifugation at 5000 rpm / min for 5 minutes, the supernatant was removed, and the above steps were repeated twice. This step is to remove impurities on the surface of the molecular sieve and in the unclosed pores; 5 mL of alcohol was added to the above precipitate, ultrasonically dispersed for 5 minutes, followed by centrifugation at 5000 rpm / min for 5 minutes, and the supernatant was removed; 5 mL of water was added to the above precipitate, ultrasonically dispersed for 5 minutes, followed by centrifugation at 5000 rpm / min for 5 minutes, and the supernatant was removed; the final precipitate was dried at 80 ° C to obtain the molecular sieve CsPbBr3-MCM-41 containing CsPbBr3, which can exhibit green luminescence under blue light excitation;

[0062] 2. Preparation of dual-component perovskite quantum dots CsPbBr3-CsPbI3-SiO2 using CsPbBr3-MCM-41:

[0063] (1) 0.4610 g of PbI2, 0.2598 g of CsI, and 0.6738 g of CsPbBr3-MCM-41 were mixed uniformly in 20 mL of water by ultrasonication for 15 min. The mixture was placed in a quartz crucible and heated to 750 °C at 10 °C / min in a tube furnace while introducing argon. The mixture was kept warm for 30 min and then naturally cooled to room temperature. The calcination temperature in this step was 750 °C. The remaining pores of the MCM-41 molecular sieve were completely closed, encapsulating the CsPbI3.

[0064] (2) The calcined powder was placed in 5 mL of DMF (N,N-dimethylformamide) and ultrasonically dispersed for 5 minutes, followed by centrifugation at 5000 rpm / min for 5 minutes, the supernatant was removed, and the above steps were repeated twice. This step is to remove impurities on the surface of the molecular sieve; 5 mL of alcohol was added to the obtained precipitate, ultrasonically dispersed for 5 minutes, followed by centrifugation at 5000 rpm / min for 5 minutes, and the supernatant was removed; 5 mL of water was added to the above precipitate, ultrasonically dispersed for 5 minutes, followed by centrifugation at 5000 rpm / min for 5 minutes, and the supernatant was removed; the precipitate was finally dried at 80 ° C to obtain the dual-component perovskite quantum dots CsPbBr3-CsPbI3-SiO2, which only exhibited red luminescence under blue light excitation.

[0065] Example 4

[0066] A dual-component multi-core-shell structure perovskite quantum dot CsPbBr3@CsPbI3 is applied to the Micro-LED color conversion layer. In this embodiment, a Cr-coated microporous glass is used as a carrier. The dual-component multi-core-shell structure perovskite quantum dot solution prepared in Example 1 is spin-coated on the Cr-coated microporous glass. The spin-coating parameters are preferably 2000 rpm for 1 min to obtain a Micro-LED color conversion layer with the following structure: Figure 5 shown.

Claims

1. A method for preparing dual-component multi-core-shell perovskite quantum dots for LED color conversion technology, characterized in that: The steps include: S1: coating a layer of amorphous SiO2 on the surface of perovskite quantum dots having a band gap higher than that of the shell layer or preparing a molecular sieve containing perovskite quantum dots having a band gap higher than that of the shell layer to obtain precursor 1; S2: Using the precursor 1 prepared in step S1 as part of the precursor to synthesize two-component multiple core-shell structure perovskite quantum dots.

2. The method for preparing a dual-component multi-core-shell perovskite quantum dot according to claim 1, wherein: The molecular sieves used in the preparation of the molecular sieve containing perovskite quantum dots with a band gap higher than that of the outer shell in step S1 include MCM-41 molecular sieve, SAB-15 molecular sieve, and nano-Si molecular sieve.

3. The method for preparing a dual-component multi-core-shell perovskite quantum dot according to claim 1, wherein: In step S2, when the precursor 1 is a perovskite quantum dot with a band gap higher than that of the shell layer and a layer of amorphous SiO2 is coated on the surface, the perovskite quantum dot with a band gap higher than that of the shell layer is prepared by a high-temperature hot injection method, a low-temperature hot injection method or an anti-solvent method.

4. The method for preparing a dual-component multi-core-shell perovskite quantum dot according to claim 1, wherein: In step S2, when the precursor 1 is a perovskite quantum dot with a band gap higher than that of the outer shell layer and a layer of amorphous SiO2 is coated on the surface, the two-component multiple core-shell structure perovskite quantum dots are synthesized by liquid phase reaction.

5. The method for preparing a dual-component multi-core-shell perovskite quantum dot according to claim 1, wherein: When the precursor 1 in step S2 is a molecular sieve containing perovskite quantum dots with a band gap higher than that of the outer shell, the dual-component multiple core-shell structure perovskite quantum dots are synthesized by high-temperature solid-phase sintering.

6. A dual-component multiple core-shell structure perovskite quantum dot prepared by the method for preparing dual-component multiple core-shell structure perovskite quantum dot according to any one of claims 1 to 5.

7. An application of the dual-component multi-core-shell perovskite quantum dots as claimed in claim 6 in a Micro-LED color conversion layer.

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