BTC-modified CsPbBr3 quantum dot and preparation method thereof

Abstract

The invention discloses a BTC modified CsPbBr3 quantum dot and a preparation method thereof, and belongs to the technical field of quantum dot materials. According to the preparation method disclosed by the invention, 4-bromothiophene-2-formaldehyde (BTC) with a thiophene group is introduced as a ligand and is used for guiding two-dimensional growth of the CsPbBr3 quantum dot. According to the CsPbBr3 quantum dot film, the stability of a CsPbBr3 quantum dot structure is improved through strong interaction between 4-bromothiophene-2-formaldehyde and a PbBr6 < 4-> octahedron, and delocalized pi-bonds contained in an aromatic structure of the 4-bromothiophene-2-formaldehyde can promote charge transfer, reduce a band tail state and inhibit an auger process of the CsPbBr3 quantum dot, so that the CsPbBr3 quantum dot film with high brightness and strong stability is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of quantum dot materials and relates to a BTC-modified CsPbBr3 quantum dot and a preparation method thereof. Background Art

[0002] Quantum dots have the advantages of high fluorescence quantum efficiency, luminescence wavelength covering the entire visible spectrum (400-700nm), and relatively narrow half-width (12-42nm). They are widely used in sensitized solar cells, photoluminescence, photocatalysis and other fields. In display technology, preparing CsPbBr3 quantum dots into films is the key form to realize their functional applications. However, CsPbBr3 quantum dot films currently face many problems in the preparation and use process.

[0003] CsPbBr3 can achieve pure blue emission, but due to its own instability, it will undergo significant fluorescence quenching, which will lead to extremely low fluorescence intensity of the film prepared by CsPbBr3 blue light quantum dots. In addition, the electroluminescence (EL) performance of CsPbBr3 is also facing the challenge of red shift. The existing technology uses a method of polymer-coated CsPbBr3 quantum dots to passivate the defects on the surface of quantum dots, thereby improving the emission stability of CsPbBr3 quantum dot solid films. However, this method increases the obstacles for carrier transfer between CsPbBr3 quantum dots. Based on this, researchers have improved the charge transfer capacity of CsPbBr3 by reducing the density of surface ligands. However, in solid-state films, this approach is often accompanied by a decrease in photoluminescence quantum yields (PLQYs), making it difficult to achieve the ideal performance level.

[0004] Therefore, it is necessary to explore an effective method to improve the stability and brightness of quantum dot films to meet various application requirements. Summary of the invention

[0005] The present invention aims to solve the problems and defects in the above-mentioned prior art. The present invention provides a BTC-modified CsPbBr3 quantum dot and a preparation method thereof, and introduces 4-bromothiophene-2-carboxaldehyde (BTC) to modify the CsPbBr3 quantum dot through a ligand-assisted synthesis strategy, and by regulating the doping amount of the aromatic ligand BTC, a CsPbBr3 quantum dot film with high brightness and strong stability is obtained.

[0006] In the first aspect, the present invention provides a method for preparing BTC-modified CsPbBr3 quantum dots, comprising: heating cesium carbonate, octadecene and oleic acid in a nitrogen environment to react, to obtain a Cs-OA precursor solution; heating lead bromide, 4-bromothiophene-2-carboxaldehyde and octadecene in a nitrogen environment to react, then sequentially adding oleylamine and oleic acid, heating to react, until the lead bromide is completely dissolved, to obtain a mixed solution; injecting the Cs-OA precursor solution into the mixed solution to react, and cooling in an ice-water bath after the reaction is completed, to obtain BTC-modified CsPbBr3 quantum dots.

[0007] Furthermore, in the preparation method provided by the present invention, the added amount of 4-bromothiophene-2-carboxaldehyde is 0.2 to 0.4 mol.

[0008] Specifically, in the preparation method provided by the present invention, the added amount of 4-bromothiophene-2-carboxaldehyde is 0.3 mol.

[0009] Furthermore, in the preparation method provided by the present invention, the mass of cesium carbonate used to prepare the Cs-OA precursor solution is 0.1 g, the volume of octadecene is 10 mL, and the volume of oleic acid is 0.8 mL.

[0010] Furthermore, in the preparation method provided by the present invention, the preparation of the Cs-OA precursor solution includes: heating to 100° C. in a nitrogen environment, mixing and reacting for 1 hour; heating to 120° C., mixing and reacting for 1 hour.

[0011] Furthermore, in the preparation method provided by the present invention, the mass of lead bromide used to prepare the mixed solution is 0.138 g, the volume of octadecene is 10 mL, the volume of oleylamine is 0.6 mL, and the volume of oleic acid is 1.2 mL.

[0012] Furthermore, in the preparation method provided by the present invention, the preparation of the mixed solution includes: heating to 100° C. in a nitrogen environment and reacting for 20 minutes; after adding oleylamine and oleic acid, heating to 120° C. and obtaining a mixed solution after lead bromide is completely dissolved.

[0013] Furthermore, in the preparation method provided by the present invention, the preparation of the BTC-modified CsPbBr3 quantum dots includes: the reaction temperature is 90°C, the reaction time is 10s, and the amount of Cs-OA precursor solution added is 1.6mL.

[0014] In a second aspect, the present invention provides a BTC-modified CsPbBr3 quantum dot prepared by the above-mentioned preparation method.

[0015] In a third aspect, the present invention provides the use of BTC-modified CsPbBr3 quantum dots in the preparation of a light-emitting layer of a light-emitting diode device.

[0016] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0017] After the BTC ligand with thiophene group is introduced into the synthesis of CsPbBr3 blue light quantum dots, the BTC molecule can provide stronger steric hindrance through its unique thiophene group to guide the two-dimensional growth. The aromatic framework of the BTC ligand can prevent the aggregation of CsPbBr3, thereby ensuring the structural stability of CsPbBr3. The delocalized π bond in the aromatic structure of the BTC ligand improves the charge transport performance of CsPbBr3. In addition, the bromine and carbonyl groups on the BTC ligand can effectively improve the bonding between BTC and PbBr6. 4- The affinity between the octahedra passivates surface defects and improves the structural stability of CsPbBr3, making the BTC-modified CsPbBr3 quantum dot film high in brightness and strong in stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the PL spectrum of CsPbBr3 quantum dot film modified by BTC. PL is the incident light of photoluminescence, and FWHM is the full width at half maximum; the PL spectra from top to bottom correspond to Example 3, Example 1 and Example 2 respectively.

[0019] Figure 2 The PL spectrum of the BTC-modified CsPbBr3 quantum dot film changes with time. Among them, pristine represents the initial state.

[0020] Figure 3 The time-resolved photoluminescence image of the CsPbBr3 quantum dot film modified with BTC. Among them, w / oBTC is the CsPbBr3 quantum dot film; w BTC is the CsPbBr3 quantum dot film modified with BTC. DETAILED DESCRIPTION

[0021] The technical scheme of the present invention is described below in conjunction with the embodiments, but the present invention is not limited to the following embodiments. The experimental methods and detection methods described in each embodiment are conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0022] Example 1

[0023] This embodiment provides a method for preparing a BTC-doped quantum dot film.

[0024] S1: Add 0.1g Cs2CO3, 10mL ODE (octadecene) and 0.8mL OA (oleic acid) into a 50mL three-necked flask, heat to 100°C under N2 environment, stir for 1h, then heat to 120°C, stir for 1h to obtain a clear Cs-OA precursor solution. The Cs-OA precursor solution needs to be heated to 90°C before use, otherwise the Cs-OA precursor solution will solidify at room temperature (<30°C).

[0025] S2: 0.138g PbBr2, 0.057g BTC (4-bromothiophene-2-carboxaldehyde, 0.3mol), and 10mL ODE were added to a 50mL three-necked flask, heated at 100°C for 20min with nitrogen, and then 0.6mL OAm (oleylamine) and 1.2mL OA were injected into the mixed solution, heated to 120°C until PbBr2 was completely dissolved, cooled to 90°C, and then 1.6mL Cs-OA precursor solution was quickly injected into the three-necked flask. After reacting for 10s, the three-necked flask was quickly cooled in an ice-water bath to obtain BTC-modified CsPbBr3 quantum dots.

[0026] S3: The BTC-modified CsPbBr3 quantum dots were prepared into a film by solution spin coating at a spin coating speed of 3500 rpm for 40 seconds.

[0027] Example 2

[0028] This embodiment provides a method for preparing a BTC-doped quantum dot film.

[0029] The preparation method of the BTC-modified CsPbBr3 quantum dot film in this embodiment is the same as that in Example 1, except that the amount of BTC added in this embodiment is 0.2 mol.

[0030] Example 3

[0031] This embodiment provides a method for preparing a BTC-doped quantum dot film.

[0032] The preparation method of the BTC-modified CsPbBr3 quantum dot film in this embodiment is the same as that in Example 1, except that the amount of BTC added in this embodiment is 0.4 mol.

[0033] Comparative Example 1

[0034] This embodiment provides a method for preparing a BTC-doped quantum dot film.

[0035] The preparation method of the BTC-modified CsPbBr3 quantum dot film in this embodiment is the same as that in Example 1, except that the amount of BTC added in this embodiment is 0.

[0036] Example 4

[0037] This example provides the PL spectrum of BTC-modified CsPbBr3 quantum dot film.

[0038] The PL (photoluminescence) spectra of the BTC-modified CsPbBr3 quantum dot films prepared in Examples 1 to 3 are as follows: Figure 1 As shown, the PL spectrum of the BTC-modified CsPbBr3 quantum dot film changes with time. Figure 2 shown.

[0039] Depend on Figure 1 It can be seen that the CsPbBr3 quantum dot film modified by BTC can be used as the light-emitting layer of the light-emitting diode, and with the increase of BTC doping concentration, the half-peak full width of the CsPbBr3 quantum dot film modified by BTC gradually increases. This is because the BTC molecule can provide stronger steric hindrance through its unique thiophene group to guide the two-dimensional growth. The aromatic framework of the BTC ligand can prevent the aggregation of CsPbBr3, thereby ensuring the structural stability of CsPbBr3. The delocalized π bond in the aromatic structure of the BTC ligand improves the charge transport performance of CsPbBr3. In addition, the bromine and carbonyl groups on the BTC ligand can effectively improve the bonding between BTC and PbBr6 4- The affinity between octahedra, passivation of surface defects, and improvement of CsPbBr3 structural stability. However, when more BTC is added, the half-peak full width increases significantly. When the BTC doping amount is 0.3 mol, the half-peak full width is narrower and has higher color purity. Therefore, the BTC doping amount of the optimal solution provided by the present invention is 0.3 mol.

[0040] Depend on Figure 2 It can be seen that when the BTC doping amount is 0.3 mol, the PL spectrum of the quantum dot film modified with BTC ligand does not change significantly within 2 hours, and its stability improvement effect is obvious.

[0041] Example 5

[0042] This example provides time-resolved photoluminescence images of CsPbBr3 quantum dot films.

[0043] The time-resolved photoluminescence of the BTC-modified CsPbBr3 quantum dot film prepared in Example 1 and the CsPbBr3 quantum dot film without BTC modification provided in Comparative Example 1 were compared. Figure 3 As shown. Figure 3 It can be seen that the TRPL curve decay of the CsPbBr3 quantum dot film modified with BTC (BTC doping amount is 0.3 mol) is significantly slower than the TRPL curve of the CsPbBr3 quantum dot film without BTC modification, indicating that the addition of BTC can improve the stability of the CsPbBr3 quantum dot film.

[0044] The embodiments described above are part of the embodiments of the present invention, but not all of them. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but only represents selected embodiments of the present invention. All other embodiments obtained without creative work and related deductions and substitutions made by ordinary technicians in the field under the conditions of the concept of the present invention belong to the scope of protection of the present invention.

Claims

1. A method for preparing BTC-modified CsPbBr3 quantum dots, characterized in that: include: Cesium carbonate, octadecene and oleic acid are heated to react in a nitrogen environment to obtain a Cs-OA precursor solution; lead bromide, 4-bromothiophene-2-carboxaldehyde and octadecene are heated to react in a nitrogen environment, and then oleylamine and oleic acid are added in sequence and heated to react until lead bromide is completely dissolved to obtain a mixed solution; the Cs-OA precursor solution is injected into the mixed solution to react, and after the reaction is completed, it is cooled in an ice water bath to obtain BTC-modified CsPbBr3 quantum dots.

2. The preparation method according to claim 1, characterized in that: The added amount of the 4-bromothiophene-2-carboxaldehyde is 0.2-0.4 mol.

3. The preparation method according to claim 2, characterized in that: The added amount of the 4-bromothiophene-2-carboxaldehyde is 0.3 mol.

4. The preparation method according to claim 1, characterized in that: The mass of cesium carbonate used to prepare the Cs-OA precursor solution was 0.1 g, the volume of octadecene was 10 mL, and the volume of oleic acid was 0.8 mL.

5. The preparation method according to claim 1, characterized in that: The preparation of the Cs-OA precursor solution includes: heating to 100° C. in a nitrogen environment, mixing and reacting for 1 hour; heating to 120° C., mixing and reacting for 1 hour.

6. The preparation method according to claim 1, characterized in that: The mass of lead bromide used to prepare the mixed solution is 0.138 g, the volume of octadecene is 10 mL, the volume of oleylamine is 0.6 mL, and the volume of oleic acid is 1.2 mL.

7. The preparation method according to claim 1, characterized in that: The preparation of the mixed solution comprises: heating to 100° C. in a nitrogen environment and reacting for 20 minutes; after adding oleylamine and oleic acid, heating to 120° C. and completely dissolving lead bromide to obtain a mixed solution.

8. The preparation method according to claim 1, characterized in that: The preparation of the BTC-modified CsPbBr3 quantum dots includes: a reaction temperature of 90°C, a reaction time of 10s, and an addition amount of 1.6mL of Cs-OA precursor solution.

9. A BTC-modified CsPbBr3 quantum dot prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the BTC-modified CsPbBr3 quantum dots as claimed in claim 9 in preparing a light-emitting layer of a light-emitting diode device.

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