Method for improving the fluorescence efficiency of perovskite fiber film and perovskite fiber film with high fluorescence efficiency obtained by the method

Abstract

The present invention discloses a method for improving the fluorescence efficiency of a perovskite fiber film, the method comprising the following steps: subjecting a perovskite polymer fiber film to multiple cold and hot alternating treatments. The perovskite fiber film prepared by the method has high fluorescence efficiency. The present invention also discloses a perovskite fiber film with high fluorescence efficiency prepared by the method.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of organic photoelectric materials, and more specifically, to a method for improving the fluorescence efficiency of a perovskite fiber film and a perovskite fiber film with high fluorescence efficiency obtained by the method. Background Art

[0002] Perovskite quantum dots (PQD) have broad application prospects in the fields of solar cells, X-ray imaging, light-emitting diodes (LEDs), lasers, photodetectors and backlight displays due to their excellent optoelectronic properties (J. Mater. Chem. C 2016, 4, 11-27). Converting high-quality quantum dots into thin films is the key to achieving high-performance solid-state optical applications. However, its stability and the significant reduction in the quantum efficiency of quantum dots after film formation have become the biggest challenges hindering its application. One of the reasons is that the aggregation of perovskite quantum dots during film formation leads to an increase in trap states and a loss of surface capping agents, resulting in a decrease in optical properties. Another reason is that there are also some problems with the stability of perovskite quantum dots themselves. When perovskite quantum dots are exposed to the external environment for a long time, factors such as humidity, light, temperature, and oxygen will induce the degradation of perovskite quantum dots and cause severe irreversible quenching of photoluminescence.

[0003] Mixing perovskite precursors with polymers and spinning them into fiber membranes is a good way to convert them into solid membranes and improve their stability. For example, some technologies use electrospinning technology to in-situ synthesize perovskite nanocrystal composite fibers to improve the stability of perovskite quantum dots. However, so far, the reported efficiency of perovskite fibers prepared by spinning is generally low. Summary of the invention

[0004] Based on the above problems, the purpose of the present invention is to provide a method for improving the fluorescence efficiency of a perovskite fiber film and a perovskite fiber film with high fluorescence efficiency obtained by the method. The perovskite fiber film prepared by the method has high fluorescence efficiency.

[0005] In one aspect, the present invention provides a method for improving the fluorescence efficiency of a perovskite fiber film, comprising the following steps:

[0006] The perovskite polymer fiber membrane is subjected to multiple alternating hot and cold treatments.

[0007] The present invention found that the main reason why the fluorescence efficiency of perovskite fibers prepared by spinning is generally low is that the perovskite is usually not fully crystallized due to the very fast spinning process, so the efficiency is not high. However, due to the limitations of the polymer itself, it is not suitable to use the traditional high-temperature annealing method to improve the fluorescence efficiency. The fluorescence efficiency of perovskite composite fibers can be improved by repeated alternating hot and cold treatments.

[0008] Furthermore, the method of alternating hot and cold treatment is: firstly heat treatment at a temperature of 140 to 200°C, and then cold treatment at -180 to 30°C, and the time of the heat treatment is 10 to 30 seconds.

[0009] Furthermore, the total time of each hot and cold alternating treatment is 30s to 2min.

[0010] Furthermore, the number of times of the hot-cold alternating treatment is 10 to 30 times.

[0011] By controlling the conditions of the above-mentioned alternating hot and cold treatments, the obtained perovskite fiber film can be better improved to have a high fluorescence efficiency.

[0012] Furthermore, the molecular formula of the perovskite in the perovskite fiber film is ABX 3 (A:MA + , Cs + ; B:Pb 2+ , X:Br - , Cl - , I - ).

[0013] Furthermore, the preparation of the perovskite polymer fiber membrane comprises the following steps:

[0014] The perovskite polymer fiber membrane is obtained by electrostatic spinning using a polymer spinning solution containing a perovskite precursor.

[0015] Furthermore, in the polymer spinning solution, the concentration of the perovskite precursor is 0.01-0.2 mol / L.

[0016] Furthermore, the perovskite precursor is selected from MABr, MACl, MAI, CsI, CsBr, CsCl, PbI 2 、PbCl 2 、PbBr 2 and at least one of its doping molecules.

[0017] Furthermore, in the polymer spinning solution, the polymer is selected from one or more of PMMA, PU, ​​PVDF, PVDF-HFP, PAN, PS, PCL or PVP.

[0018] Furthermore, in the polymer spinning solution, the concentration of the polymer is determined according to the type of the polymer, and generally ranges from 5 to 30 wt%.

[0019] Furthermore, in the polymer spinning solution, the solvent is an organic solvent, selected from one or more of a mixed solution of DMF, DMSO, DMAc and acetone.

[0020] Furthermore, the conditions for the electrospinning are: an injection speed of 0.4 to 1.2 mL / h, a spinning voltage of 13 to 20 kV, and a receiving distance of 10 to 15 cm.

[0021] In another aspect, the present invention provides a perovskite fiber film with high fluorescence efficiency, which is prepared by the method as described above.

[0022] The beneficial effects of the present invention are as follows:

[0023] In the method provided by the present invention, a natural physical barrier is provided by the outer layer polymer, so that the quantum dots block water and oxygen and improve stability; the method can produce one-dimensional fibers or large-area films in a short time, and has the advantage of a natural flexible structure; the method improves the fluorescence efficiency of the perovskite composite fiber by repeatedly alternating hot and cold treatments; in addition, the method can effectively reduce the limitation of the polymer's inability to withstand high temperatures and improve the crystallinity of the perovskite quantum dots.

[0024] The perovskite film obtained by the method of the present invention has good thermal stability and water stability and greatly improved fluorescence performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0026] Figure 1 The scanning electron microscope images of the perovskite fibers before and after treatment in Example 1 are shown. DETAILED DESCRIPTION

[0027] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0028] Example 1

[0029] A method for improving the fluorescence efficiency of a perovskite fiber film comprises the following steps:

[0030] 1) Weigh 0.6 mmol PbI 2 , 0.54mmol CsBr, 0.06mmol CsI were dissolved in 10mL DMF, and after the precursor was dissolved, 1.288g PMMA was added to prepare a spinning solution with a concentration of 12%. Then the above precursor solution was loaded into a syringe, the injection speed was 0.7mL / h, the spinning voltage was adjusted to 16.9kV, the receiving distance was 15cm, and electrospinning was performed on an aluminum foil substrate for 20min to obtain the perovskite polymer fiber precursor.

[0031] 2) The fiber was placed on a high temperature hot plate at 160°C for 20 seconds and then placed on ice for 30 seconds, and the treatment was repeated 14 times to obtain a perovskite polymer fiber membrane. The fluorescence quantum efficiency of the treated fiber was 19.07%.

[0032] Comparative Example 1

[0033] A method for preparing a perovskite fiber film comprises the following steps:

[0034] 1) Weigh 0.6 mmol PbI 2 , 0.54mmol CsBr, 0.06mmol CsI were dissolved in 10mL DMF, and after the precursor was dissolved, 1.288g PMMA was added to prepare a spinning solution with a concentration of 12%. Then, the above precursor solution was loaded into a syringe, the injection speed was corrected to 0.7mL / h, the spinning voltage was adjusted to 16kV, the receiving distance was 20cm, and electrospinning was performed on an aluminum foil substrate for 20min to obtain the perovskite polymer fiber precursor. Through the quantum efficiency test, the fluorescence quantum efficiency of the precursor was 2.14%.

[0035] Figure 1 Example 1 ( Figure 1 middle right) and comparative example 1 ( Figure 1 SEM image of the fiber film obtained (left in the middle). Figure 1 It can be seen that the morphology of the fiber after the hot-cold alternating treatment in step 2) in Example 1 is almost unchanged from the morphology of the fiber obtained without the hot-cold alternating treatment in Comparative Example 1, but the luminescence performance is significantly improved.

[0036] Example 2

[0037] A method for improving the fluorescence efficiency of a perovskite fiber film comprises the following steps:

[0038] 1) Weigh 0.8 mmol PbI 2 , 0.72mmol CsBr, 0.08mmol CsI were dissolved in 10mL DMF, and after the precursor was dissolved, 1.288g PMMA was added to prepare a spinning solution with a concentration of 12%. Then the precursor solution was loaded into a syringe, the injection speed was corrected to 0.6mL / h, the spinning voltage was adjusted to 16.9kV, the receiving distance was 15cm, and electrospinning was performed on an aluminum foil substrate for 20min to obtain the perovskite polymer fiber precursor.

[0039] 2) The fiber was placed on a high temperature hot plate at 150°C for 30 seconds and then placed on ice for 1 minute, and the treatment was repeated 20 times to obtain a perovskite polymer fiber membrane. The fluorescence quantum efficiency of the treated fiber was 18.85%.

[0040] Example 3

[0041] A method for improving the fluorescence efficiency of a perovskite fiber film comprises the following steps:

[0042] 1) Weigh 0.4 mmol PbI 2 , 0.36mmol CsBr, 0.04mmol CsI were dissolved in 10mL DMF, and after the precursor was dissolved, 1.667g PVDF was added to prepare a spinning solution with a concentration of 15%. Then the above precursor solution was loaded into a syringe, the injection speed was corrected to 0.6mL / h, the spinning voltage was adjusted to 16.9kV, the receiving distance was 15cm, and electrospinning was performed on an aluminum foil substrate for 20min to obtain the perovskite polymer fiber precursor.

[0043] 2) The fiber was placed on a high temperature hot plate at 200°C for 15 seconds and then placed on ice for 70 seconds, and the treatment was repeated 15 times to obtain a perovskite polymer fiber membrane. The fluorescence quantum efficiency of the treated fiber was 19%.

[0044] Example 4

[0045] A method for improving the fluorescence efficiency of a perovskite fiber film comprises the following steps:

[0046] 1) Weigh 0.6 mmol PbI 2 , 0.6mmol CsI was dissolved in 10mL DMF, and after the precursor was dissolved, 1.288g PMMA was added to prepare a spinning solution with a concentration of 12%. Then the precursor solution was loaded into a syringe, the injection speed was corrected to 0.7mL / h, the spinning voltage was adjusted to 16.9kV, the receiving distance was 15cm, and electrospinning was performed on an aluminum foil substrate for 20min to obtain the perovskite polymer fiber precursor.

[0047] 2) The fiber was placed on a high temperature hot plate at 200°C for 10 seconds and then placed on ice for 30 seconds, and the treatment was repeated 16 times to obtain a perovskite polymer fiber membrane. The fluorescence quantum efficiency of the treated fiber was 18.9%.

[0048] Comparative Example 2

[0049] A method for improving the fluorescence efficiency of a perovskite fiber film comprises the following steps:

[0050] 1) Weigh 0.6 mmol PbI 2, 0.54mmol CsBr, 0.06mmol CsI were dissolved in 10mL DMF, and after the precursor was dissolved, 1.288g PMMA was added to prepare a spinning solution with a concentration of 12%. Then the above precursor solution was loaded into a syringe, the injection speed was corrected to 0.7mL / h, the spinning voltage was adjusted to 16.9kV, the receiving distance was 15cm, and electrospinning was performed on an aluminum foil substrate for 20min to obtain the perovskite polymer fiber precursor.

[0051] 2) The fiber was placed in a high temperature heat treatment of 120°C for 20 seconds, and then cooled naturally at room temperature for 30 seconds, and the treatment was repeated 14 times to obtain a perovskite polymer fiber membrane. The fluorescence quantum efficiency of the treated fiber was 1.42%.

[0052] Comparative Example 3

[0053] A method for improving the fluorescence efficiency of a perovskite fiber film comprises the following steps:

[0054] 1) Weigh 0.6 mmol PbI 2 , 0.54mmol CsBr, 0.06mmol CsI were dissolved in 10mL DMF, and after the precursor was dissolved, 1.288g PMMA was added to prepare a spinning solution with a concentration of 12%. Then the above precursor solution was loaded into a syringe, the injection speed was corrected to 0.7mL / h, the spinning voltage was adjusted to 16.9kV, the receiving distance was 15cm, and electrospinning was performed on an aluminum foil substrate for 20min to obtain the perovskite polymer fiber precursor.

[0055] 2) The fiber was placed in a high temperature heat treatment of 160°C for 20 seconds, and then cooled naturally at room temperature for 30 seconds, and the treatment was repeated twice to obtain a perovskite polymer fiber membrane. The fluorescence quantum efficiency of the treated fiber was 3.95%.

[0056] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for improving the fluorescence efficiency of a perovskite fiber film prepared by spinning, characterized in that: The steps include: The perovskite polymer fiber membrane prepared by spinning is subjected to multiple alternating hot and cold treatments; The method of alternating hot and cold treatment is: firstly heat treatment at a temperature of 140 to 200°C, and then cold treatment at -180 to 30°C; The heat treatment time is 10 to 30 seconds; The total time of each hot-cold alternating treatment is 30 seconds to 2 minutes, and the number of hot-cold alternating treatments is 10 to 30 times.

2. The method according to claim 1, characterized in that The preparation of the perovskite polymer fiber membrane comprises the following steps: Electrostatic spinning is performed using a polymer spinning solution containing a perovskite precursor to obtain the perovskite polymer fiber membrane.

3. The method according to claim 2, characterized in that In the polymer spinning solution, the concentration of the perovskite precursor is 0.01 to 0.2 mol / L; The perovskite precursor is selected from at least one of MABr, MACl, MAI, CsI, CsBr, CsCl, PbI2, PbCl2, PbBr2 and doping molecules thereof.

4. The method according to claim 2, characterized in that: In the polymer spinning solution, the polymer is selected from one or more of PMMA, PU, ​​PVDF, PVDF-HFP, PAN, PS, PCL or PVP.

5. The method according to claim 2, characterized in that: In the polymer spinning solution, the solvent is an organic solvent, which is one or more selected from a mixed solution of DMF, DMSO, DMAc and acetone.

6. The method according to claim 2, characterized in that The conditions for the electrospinning are: an injection speed of 0.4 to 1.2 mL / h, a spinning voltage of 13 to 20 kV, and a receiving distance of 10 to 15 cm.

7. A perovskite fiber film with high fluorescence efficiency, characterized in that: Prepared according to the method according to any one of claims 1 to 6.

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