Blue-light perovskite light-emitting device based on heptadecafluoroundecanoic acid modification and preparation method of blue-light perovskite light-emitting device

Abstract

The invention discloses a blue-light perovskite luminescent device based on heptadecafluoroundecanoic acid modification and a preparation method thereof, and the method comprises the steps: cleaning an ITO substrate, drying, stirring and dissolving according to a ratio to obtain a perovskite precursor solution, and adding a heptadecafluoroundecanoic acid solution into the precursor solution to obtain a doped solution; performing ultraviolet ozone treatment on the ITO substrate which is cleaned in advance, spin-coating a hole transport layer PEDOT: PSS on the ITO substrate, and performing annealing treatment; the preparation method comprises the following steps: preparing a hole transport layer, coating the surface of the hole transport layer with a doping solution in a glove box, annealing to form a luminescent layer, and sequentially depositing electron transport layers PO-T2T and TPBi and a top electrode LiF / Al on the perovskite film by using a high-vacuum thermal evaporation method to obtain the modified blue-light perovskite luminescent device. By doping heptadecafluoroundecanoic acid, the crystallization process of the perovskite can be improved, the phase distribution passivation defect of the perovskite is optimized, and limitation and poor device performance brought by a traditional preparation method are effectively relieved.

Description

Technical Field

[0001] The present invention relates to a light-emitting device, and in particular to a blue light perovskite light-emitting device based on heptadecafluoroundecanoic acid modification and a preparation method thereof. Background Art

[0002] Metal halide perovskites have special optical properties such as tunable luminescence, high color purity, and high photoluminescence quantum yield, making them strong candidates for next-generation light-emitting diodes. Although green, red, and blue perovskite light-emitting diodes (PeLEDs) have made remarkable breakthroughs and achieved external quantum efficiencies (EQEs) exceeding 20%, perovskites are easily corroded and decomposed by water and oxygen. Improving the stability of perovskite films is crucial for fabricating PeLEDs with excellent operational stability. Due to the presence of non-radiative recombination sites in perovskite films, the energy level mismatch between the perovskite layer and the transport layer becomes an obstacle for carrier collection and energy utilization. At the same time, defects in perovskite films can generate trap states within the band gap, trapping charge carriers and promoting the degradation of perovskites. In mixed halide perovskites, defects are also associated with the phase separation of halides, resulting in a rapid degradation of device performance under operating conditions. Therefore, the core approach to address this challenge involves synergistically reducing the number of crystal defects in perovskite films and improving carrier transport kinetics. Researchers have attempted to improve carrier transport, crystallinity, and passivation defects through strategies such as crystal regulation, additive engineering, and particle packing. Therefore, in order to further commercialize PeLEDs, it is urgent to solve the problems of PeLEDs stability. Summary of the invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide a blue light perovskite light-emitting device based on heptadecafluoroundecanoic acid modification and a preparation method thereof. The present invention passivates defects and reduces non-radiative recombination by adding heptadecafluoroundecanoic acid molecules to the perovskite precursor solution. At the same time, the phase distribution is optimized during the crystallization process, and its hydrophobicity is enhanced, thereby obtaining a highly efficient and stable perovskite light-emitting device, i.e., a diode, and improving the external quantum efficiency of the perovskite light-emitting diode and the stability of the device.

[0004] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions: A method for preparing a blue light emitting perovskite device modified with heptadecafluoroundecanoic acid, the method comprising the following steps: 1) Use detergent, high-purity water, ethanol and isopropanol to clean the conductive substrate ITO substrate in sequence; 2) Dry the cleaned conductive ITO substrate and store it in a drying cabinet; 3) Dissolve CsBr, PbBr2, PbCl2 and PEABr in DMSO solvent and stir at 30°C for 4 hours until all the powders are dissolved to obtain a perovskite precursor solution; 4) dissolving heptadecafluoroundecanoic acid powder in DMSO solvent to obtain heptadecafluoroundecanoic acid solution, and adding the heptadecafluoroundecanoic acid solution to the perovskite precursor solution to obtain a doping solution; 5) Spin-coat the hole transport layer PEDOT:PSS on the dried ITO conductive substrate in a fume hood and perform annealing; 6) Spin-coating the doping solution obtained in step 4) on the hole transport layer prepared in step 5), and performing annealing treatment to form a perovskite film; 7) By high vacuum thermal evaporation, the electron transport layer PO-T2T and TPBi and the electrode LiF / Al are sequentially deposited on the perovskite film prepared in step 6), and finally the blue light perovskite light-emitting device based on heptadecafluoroundecanoic acid modification with the structure of glass / ITO / PEDOT:PSS / (Cs / PEA)Pb(Cl / Br)3 / POT2T / TPBi / LiF / Al is obtained; wherein, The spin coating conditions of PEDOT:PSS were 6000 rpm / 60 s, and the annealing conditions were 140 °C / 15 min; The molar ratio of the perovskite precursor solution is CsBr∶PbBr2∶PbCl2∶PEABr=15∶6∶4∶5; The concentration of the heptadecafluoroundecanoic acid solution was 10 mg / mL, and 20 μL of heptadecafluoroundecanoic acid solution was added to each 1 mL of the precursor solution in the doping solution; The spin coating condition of the perovskite film is 4000 rpm / 60s, and the annealing condition is 70°C / 7 min; The thickness of the electron transport layer PO-T2T and TPBi was deposited by high vacuum thermal evaporation method with a thickness of 1 nm and 40 nm respectively, and the thickness of the electrode layer LiF and Al was 1 nm and 100 nm respectively.

[0005] A blue light perovskite light-emitting device based on heptadecafluoroundecanoic acid modification prepared by the above method.

[0006] By means of the above scheme, the present invention has at least the following advantages: The present invention discloses a blue light perovskite light emitting device based on heptadecafluoroundecanoic acid modification and a preparation method thereof. Heptadecafluoroundecanoic acid is added as an additive to a perovskite precursor solution. The method has the following advantages: 1) The molecule has a long-chain molecular structure in which the carboxylic acid group is connected to Pb 2+ The coordination is firmly anchored on the perovskite particles.

[0007] 2) The F ion at the other end can form an ionic bond with the halogen octahedron, thereby consolidating the stability of the octahedral framework.

[0008] 3) The -OH group can form hydrogen bonds with organic ligands and optimize the phase distribution of the perovskite crystallization process.

[0009] 4) The binding energy between F atoms and water molecules is higher, which hinders the entry of water molecules into perovskite and prevents its hydrolysis.

[0010] 5) In summary, the molecules enable the perovskite particles to be covered and the hydrolysis of the perovskite to be inhibited by passivating the hydrophobicity of the uncoordinated cations and F ions. While obtaining a high efficiency light-emitting diode of 22.88%, the perovskite film and device also show enhanced stability even under harsh hot and humid conditions.

[0011] The present invention provides a blue light perovskite light-emitting device modified with heptadecafluoroundecanoic acid and a preparation method thereof. The device has a simple manufacturing process and a convenient preparation flow. By doping with heptadecafluoroundecanoic acid, a perovskite film with high crystallinity, few defects and high hydrophobicity is prepared, thereby improving the luminous efficiency and stability of the perovskite light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a contact angle test diagram of the perovskite film of the present invention and a surface morphology diagram obtained by a scanning electron microscope (SEM); Figure 2 is a steady-state photoluminescence spectrum and a time-resolved photoluminescence decay curve of the perovskite film of the present invention; Figure 3 This is a performance diagram of the blue light perovskite light emitting diode device of the present invention. DETAILED DESCRIPTION

[0013] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Example

[0014] A blue light perovskite light emitting diode based on heptadecafluoroundecanoic acid modification, which is composed of a transparent conductive substrate, a hole transport layer, a blue light perovskite film, an electron transport layer, an electrode modification layer and an electrode arranged in sequence. Among them, the transparent conductive substrate is ITO transparent conductive glass. The blue light perovskite film is (Cs / PEA)Pb(Cl / Br)3, which is doped with heptadecafluoroundecanoic acid. The hole transport layer is PEDOT:PSS. The electron transport layer is PO-T2T and TPBi, with thicknesses of 1 nm and 40 nm respectively. The electrode modification layer is lithium fluoride, with a thickness of 1 nm. The metal cathode electrode is an aluminum electrode, with a thickness of 100 nm.

[0015] The preparation method is as follows: 1) Use detergent, high-purity water, ethanol and isopropanol to clean the conductive substrate ITO substrate in sequence; 2) Dry the cleaned conductive ITO substrate and store it in a drying cabinet; 3) CsBr (0.15 M), PbBr2 (0.06 M), PbCl2 (0.04 M) and PEABr (0.05 M) were dissolved in DMSO solvent according to the ratio, stirred at 30 °C for 4 hours, and the perovskite precursor solution was obtained after all the powders were dissolved; 4) Dissolve the heptadecafluoroundecanoic acid powder in DMSO solvent to obtain a heptadecafluoroundecanoic acid solution with a concentration of 10 mg / mL, take 20 microliters of the heptadecafluoroundecanoic acid solution and add it to the perovskite precursor solution to obtain a doping solution; 5) In a fume hood, spin-coat the hole transport layer PEDOT:PSS on the dried ITO conductive substrate at 6000 rpm / 60s, and anneal at 140℃ / 15min; 6) Spin-coating the doping solution prepared in step 4) on the hole transport layer prepared in step 5) at 4000 rpm / 60s, and annealing at 70°C / 7 min to form a perovskite film; 7) By high vacuum thermal evaporation, the electron transport layer PO-T2T (1 nm) and TPBi (40 nm) and the electrode LiF (1 nm) / Al (100 nm) are sequentially deposited on the perovskite film prepared in step 6), and finally an efficient and stable sky blue light perovskite light-emitting diode with a device structure of Glass / ITO / PEDOT:PSS / (Cs / PEA)Pb(Cl / Br)3 / POT2T / TPBi / LiF / Al is obtained.

[0016] For comparison, an undoped perovskite light-emitting diode was prepared, whose structure and preparation method were the same as those in Example 1, except that heptadecafluoroundecanoic acid was not added to the perovskite precursor solution, and the other preparation processes were the same as those in Example 1.

[0017] The properties of the different perovskite films prepared above were tested, such as Figure 1 a and Figure 1 b It can be clearly seen that the contact angle after doping with heptadecafluoroundecanoic acid increased from 27.8 degrees to 50.3 degrees, indicating that the doping of heptadecafluoroundecanoic acid increased the hydrophobicity of the perovskite film. Figure 1c and d are the SEM characterization results of the perovskite films of Comparative Example 1 and Example 1, respectively. It can be observed that there are many pores with different particle sizes and uneven grain distribution on the film of Comparative Example 1. In contrast, the modified film in Example 1 shows fewer pores, higher coverage and more uniform grain size. These improvements have a great positive impact on the optical properties of the perovskite film and the performance of the perovskite light-emitting diode device. Figure 2 a is the photoluminescence test of undoped perovskite film and perovskite film doped with heptadecafluoroundecanoic acid. It can be seen from the figure that the photoluminescence intensity is significantly improved after doping, indicating that heptadecafluoroundecanoic acid doping greatly reduces the defects in the perovskite film, effectively inhibits non-radiative recombination, and the photoluminescence peak position does not shift. Figure 2 b is the time-resolved photoluminescence decay curve of the undoped perovskite film and the perovskite film doped with heptadecafluoroundecanoic acid. As can be seen from the figure, the photoluminescence lifetime of the undoped perovskite film is short and the luminescence quenching phenomenon is serious. After doping with heptadecafluoroundecanoic acid, the photoluminescence lifetime is extended, showing a longer photoluminescence decay curve. This once again verifies the reduction of internal defects in the perovskite, which is completely consistent with the results of the photoluminescence test. Figure 3 In a, it can be observed that the device modified with heptadecafluoroundecanoic acid has an emission peak at 490 nm, and the full width at half maximum is narrow, which is 22 nm. At the same time, when the bias voltage increases from 3.2 V to 4.9 V, the device modified with heptadecafluoroundecanoic acid exhibits enhanced spectral stability, while the electroluminescence spectrum remains almost unchanged. Figure 3 b is the current density-voltage-brightness performance curve of the perovskite device. After the introduction of heptadecafluoroundecanoic acid into the perovskite precursor solution, the leakage current of the device is minimized due to the reduction of non-radiative defects and the improvement of film coverage. At the same time, the device modified with heptadecafluoroundecanoic acid exhibits a lower turn-on voltage. Figure 3 c is the value at a constant current density (1 mA cm -2 ) is used to further evaluate the stability of the device. In comparison, the working half-life of the device after heptadecafluoroundecanoic acid doping is twice that of comparative example 1. Figure 3 In d, a sky-blue perovskite light-emitting diode with an EQE of 22.88% was prepared.

[0018] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a blue light emitting perovskite light emitting device based on heptadecafluoroundecanoic acid modification, characterized in that: The method comprises the following steps: 1) Use detergent, high-purity water, ethanol and isopropanol to clean the conductive substrate ITO substrate in sequence; 2) Dry the cleaned conductive substrate ITO substrate and store it in a drying cabinet; 3) Dissolve CsBr, PbBr2, PbCl2 and PEABr in DMSO solvent and stir at 30°C for 4 hours until all the powders are dissolved to obtain a perovskite precursor solution; 4) dissolving heptadecafluoroundecanoic acid powder in DMSO solvent to obtain heptadecafluoroundecanoic acid solution, and adding the heptadecafluoroundecanoic acid solution to the perovskite precursor solution to obtain a doping solution; 5) Spin-coat the hole transport layer PEDOT:PSS on the dried ITO conductive substrate in a fume hood and perform annealing; 6) Spin-coating the doping solution obtained in step 4) on the hole transport layer prepared in step 5), and performing annealing treatment to form a perovskite film; 7) By high vacuum thermal evaporation, the electron transport layer PO-T2T and TPBi and the electrode LiF / Al are sequentially deposited on the perovskite film prepared in step 6), and finally the blue light perovskite light-emitting device based on heptadecafluoroundecanoic acid modification with the structure of glass / ITO / PEDOT:PSS / (Cs / PEA)Pb(Cl / Br)3 / POT2T / TPBi / LiF / Al is obtained; wherein, The spin coating conditions of PEDOT:PSS were 6000 rpm / 60 s, and the annealing conditions were 140 °C / 15 min; The molar ratio of the perovskite precursor solution is CsBr∶PbBr2∶PbCl2∶PEABr=15∶6∶4∶5; The concentration of the heptadecafluoroundecanoic acid solution was 10 mg / mL, and 20 μL of heptadecafluoroundecanoic acid solution was added to each 1 mL of the precursor solution in the doping solution; The spin coating condition of the perovskite film is 4000 rpm / 60s, and the annealing condition is 70°C / 7 min; The thickness of the electron transport layer PO-T2T and TPBi was deposited by high vacuum thermal evaporation method with a thickness of 1 nm and 40 nm respectively, and the thickness of the electrode layer LiF and Al was 1 nm and 100 nm respectively.

2. A blue light perovskite light-emitting device based on heptadecafluoroundecanoic acid modified by the method of claim 1.

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