High-efficiency high-brightness perovskite light-emitting diode and preparation method thereof

Abstract

The application discloses a kind of high efficiency high brightness perovskite light-emitting diode and preparation method thereof, the method includes the following steps: (1) on ITO conductive glass, hole transport layer is prepared;(2) on hole transport layer, perovskite light-emitting layer is prepared: perovskite precursor solution is spin-coated into film, dropwise adding anti-solvent in spin-coating process, perovskite light-emitting layer is obtained by annealing treatment;The perovskite precursor solution uses theanine as crystallization regulator;(3) on perovskite light-emitting layer, electron transport layer, electron injection layer and metal electrode are prepared in sequence, and high efficiency high brightness perovskite light-emitting diode is obtained.The application introduces theanine molecule as crystallization regulator in perovskite precursor solution, effectively controls the crystallization kinetics of three-dimensional perovskite, inhibits the rapid growth of crystal and the formation of defect, and the obtained perovskite thin film grain is small and the surface is dense and flat, the defect density is low, which significantly improves the external quantum efficiency and luminous brightness of perovskite light-emitting diode.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic device technology, and in particular to a high-efficiency, high-brightness perovskite light-emitting diode and its fabrication method. Background Technology

[0002] Metal halide perovskite light-emitting diodes (PeLEDs) are considered a next-generation candidate for high-efficiency, low-cost, and high-color-purity display technologies due to their excellent photoelectric properties, low-cost solution processing characteristics, and continuously tunable emission wavelengths. In recent years, PeLEDs have developed rapidly, achieving full spectral coverage from blue light to near-infrared light, with external quantum efficiencies exceeding 25%, demonstrating broad application prospects.

[0003] Currently, the material systems for achieving high-performance PeLEDs are mainly divided into two categories: quasi-two-dimensional perovskites and three-dimensional perovskites. Among them, quasi-two-dimensional perovskites exhibit significant advantages in luminous efficiency due to their quantum confinement effect and high exciton binding energy. However, these materials generally suffer from problems such as ion migration and phase separation, which severely restrict the operational stability of the devices. In contrast, three-dimensional perovskites have stronger structural rigidity and higher ion migration barriers, exhibiting superior intrinsic stability and higher luminous brightness, and are therefore considered the ideal material system for realizing high-performance PeLEDs. Nevertheless, three-dimensional perovskite films generally face the problem of excessively fast crystallization rates during solution preparation. This uncontrolled crystallization behavior easily leads to excessively large grain sizes and excessively high crystal defect densities, which in turn exacerbates exciton dissociation and nonradiative recombination, severely limiting further improvements in device luminous efficiency and stability. Summary of the Invention

[0004] To overcome the aforementioned shortcomings and deficiencies of the prior art, the present invention aims to provide a high-efficiency, high-brightness perovskite light-emitting diode and its preparation method. By introducing theanine molecules as crystallization regulators into the perovskite precursor solution, synergistic coordination and hydrogen bonding interactions are formed between the theanine molecules and the perovskite precursor, effectively regulating the crystallization kinetics of the three-dimensional perovskite, suppressing excessively rapid crystal growth and defect formation, and resulting in perovskite thin films with smaller grains, denser and smoother surfaces, and lower defect density, significantly improving the external quantum efficiency and luminous brightness of the perovskite light-emitting diode.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a method for fabricating a high-efficiency, high-brightness perovskite light-emitting diode, comprising the following steps:

[0007] (1) A hole transport layer is prepared on ITO conductive glass;

[0008] (2) Preparation of perovskite luminescent layer on hole transport layer: spin-coating perovskite precursor solution into film, adding antisolvent during spin-coating process, and obtaining perovskite luminescent layer after annealing treatment;

[0009] The perovskite precursor solution uses theanine as a crystallization regulator.

[0010] (3) An electron transport layer, an electron injection layer and a metal electrode are sequentially fabricated on the perovskite light-emitting layer to obtain a high-efficiency, high-brightness perovskite light-emitting diode.

[0011] In some embodiments of the present invention, the perovskite is formamidinium lead bromide perovskite.

[0012] In some embodiments of the present invention, the perovskite precursor solution is prepared by dissolving formamidine hydrobromide (FABr), lead bromide (PbBr2), and theanine in dimethyl sulfoxide (DMSO), wherein the concentration of PbBr2 in the perovskite precursor solution is 0.1 ~ 0.4 mol / L, the molar ratio of FABr to PbBr2 is 1:1 ~ 1.4:1, and the molar ratio of theanine to PbBr2 is 1:100 ~ 10:100.

[0013] In some embodiments of the present invention, the molar ratio of theanine to PbBr2 is 7.5:100 to 8.5:100.

[0014] In some embodiments of the present invention, after obtaining the perovskite luminescent layer in step (3), the following steps are also performed:

[0015] After the perovskite luminescent layer cools to room temperature, a PO-T2T ethyl acetate solution is spin-coated onto its surface, followed by annealing to obtain an interface-modified perovskite luminescent layer.

[0016] The present invention also provides a high-efficiency, high-brightness perovskite light-emitting diode, which is prepared by the aforementioned method for preparing a high-efficiency, high-brightness perovskite light-emitting diode.

[0017] The present invention also provides a perovskite precursor solution, which is prepared by dissolving formamidine hydrobromide (FABr), lead bromide (PbBr2) and theanine in dimethyl sulfoxide (DMSO), wherein the concentration of PbBr2 in the perovskite precursor solution is 0.1 ~ 0.4 mol / L, the molar ratio of FABr to PbBr2 is 1:1 ~ 1.4:1, and the molar ratio of theanine to PbBr2 is 5:100 ~ 10:100.

[0018] In some embodiments of the present invention, the molar ratio of theanine to PbBr2 is 7.5:100 to 8.5:100.

[0019] The present invention also provides a perovskite luminescent layer, which is prepared from the perovskite precursor solution.

[0020] The present invention also provides a perovskite light-emitting device, including the perovskite light-emitting layer.

[0021] Further, in step (1), the ITO conductive glass is ultrasonically cleaned with detergent and deionized water in sequence before use, dried with nitrogen and placed in an oven to dry, and finally treated with ultraviolet ozone.

[0022] Further, in step (1), the hole transport layer is prepared by solution spin coating, the hole transport layer solution concentration is 0.5 ~ 2 mg / mL, the spin coating speed is 2000 ~ 4000 rpm, the spin coating time is 20 ~ 60 s, the annealing temperature is 80 ~ 120 ℃, and the annealing time is 5 ~ 20 min.

[0023] Further, in step (2), the spin coating speed is 4000 ~ 6000 rpm, the time is 35 ~ 60 s, the annealing temperature is 60 ~ 100 ℃, and the time is 5 ~ 30 min. During the spin coating process, an anti-solvent is added dropwise, and the anti-solvent is one or more of ethyl acetate, chlorobenzene, or toluene.

[0024] Furthermore, in step (3), each functional layer is prepared by vacuum evaporation, with an electron transport layer thickness of 30~60 nm, an electron injection layer thickness of 0.5~2 nm, and a metal electrode thickness of 80~120 nm.

[0025] Furthermore, the concentration of the PO-T2T ethyl acetate solution is 0.2~0.3 mg / mL.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) The present invention introduces theanine molecules as crystallization regulators into the perovskite precursor solution, forming synergistic coordination and hydrogen bonding with the perovskite precursor, effectively regulating the crystallization dynamics of three-dimensional perovskite, inhibiting excessive crystal growth and defect formation, and obtaining perovskite thin film with smaller grains and dense, flat surface and low defect density.

[0028] (2) This invention significantly improves the crystal quality of three-dimensional perovskite films, reduces the bulk defect density, and inhibits defect-induced nonradiative recombination by regulating the theanine molecule. Furthermore, an interface modification layer is introduced on the surface of the perovskite layer to effectively passivate the defect states on the surface of the perovskite film and reduce the nonradiative recombination centers at the interface, thereby significantly improving the photoluminescence performance of the film. It has a good development prospect for application in light-emitting devices.

[0029] (3) The perovskite light-emitting diode prepared by the present invention has high external quantum efficiency and high luminous brightness. Attached Figure Description

[0030] Figure 1 The following are device performance diagrams of the perovskite light-emitting diode prepared in Example 1 of the present invention, wherein (a) is a current density-voltage-brightness curve, (b) is an external quantum efficiency-brightness curve, and (c) is a normalized electroluminescence spectrum.

[0031] Figure 2 The following are device performance diagrams of the perovskite light-emitting diode prepared in Example 2 of the present invention, wherein (a) is a current density-voltage-brightness curve, (b) is an external quantum efficiency-brightness curve, and (c) is a normalized electroluminescence spectrum.

[0032] Figure 3 The following are device performance diagrams of the perovskite light-emitting diode prepared in Example 3 of the present invention, wherein (a) is a current density-voltage-brightness curve, (b) is an external quantum efficiency-brightness curve, and (c) is a normalized electroluminescence spectrum.

[0033] Figure 4 The diagram shows the device performance of the perovskite light-emitting diode prepared in Comparative Example 1 of this invention, where (a) is the current density-voltage-brightness curve, (b) is the external quantum efficiency-brightness curve, and (c) is the normalized electroluminescence spectrum.

[0034] Figure 5 The following are device performance diagrams of the perovskite light-emitting diode prepared in Example 4 of the present invention, wherein (a) is a current density-voltage-brightness curve, (b) is an external quantum efficiency-brightness curve, and (c) is a normalized electroluminescence spectrum.

[0035] Figure 6 This is a scanning electron microscope image of the perovskite luminescent layer film prepared in Comparative Example 1 of the present invention.

[0036] Figure 7 This is a scanning electron microscope image of the perovskite luminescent layer film prepared in Example 1 of the present invention.

[0037] Figure 8 This is a scanning electron microscope image of the perovskite luminescent layer film prepared in Example 2 of the present invention.

[0038] Figure 9 This is a scanning electron microscope image of the perovskite luminescent layer film prepared in Example 3 of the present invention.

[0039] Figure 10 This is a scanning electron microscope image of the perovskite luminescent layer film prepared in Example 4 of the present invention.

[0040] Figure 11 The photoluminescence spectra of the perovskite luminescent layer film prepared in Example 1 and the perovskite luminescent layer film prepared in Comparative Example 1 are shown.

[0041] Figure 12 The photoluminescence spectra of the perovskite luminescent layer film prepared in Example 4 and the perovskite luminescent layer film prepared in Example 1 are shown. Detailed Implementation

[0042] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0043] In the following examples, the theanine used in this example has the molecular formula C7H. 14 N2O3, structural formula:

[0044] .

[0045] Example 1

[0046] The perovskite precursor solution in this embodiment is prepared as follows:

[0047] FABr and PbBr2 were dissolved in dimethyl sulfoxide (DMSO) at a molar ratio of 1.2:1, with a PbBr2 concentration of 0.2 mol / L. Theanine was added (theanine to PbBr2 molar ratio of 8:100). The solution was stirred overnight on a hot plate at 50 °C, cooled, and then filtered for later use.

[0048] The fabrication steps of the perovskite light-emitting diode in this embodiment are as follows:

[0049] 1) Clean the ITO conductive glass sequentially with detergent and deionized water using ultrasonic cleaning, dry it with nitrogen, place it in an oven to dry, and then treat it with ultraviolet ozone for 20 minutes.

[0050] 2) Preparation of hole transport layer: A 0.5 mg / mL 4PABCz ethanol solution was spin-coated onto a clean ITO conductive glass at a spin speed of 4000 rpm for 30 s, followed by annealing at 100 ℃ for 10 min to obtain the hole transport layer.

[0051] 3) Preparation of the perovskite luminescent layer: The precursor solution was spin-coated onto the 4PABCz layer prepared in step 2) at a spin speed of 5000 rpm for 45 s. At 26 s, 100 μL of ethyl acetate was rapidly added to the perovskite film as an antisolvent. The film was then annealed at 80 °C for 10 min to obtain the perovskite luminescent layer.

[0052] 4) The perovskite light-emitting layer prepared in step 3) is transferred to a vacuum evaporation chamber, and 40 nm CN-T2T, 1 nm LiF and 100 nm Al electrodes are deposited layer by layer to obtain a perovskite light-emitting diode.

[0053] The perovskite light-emitting diode prepared according to embodiments of the present invention comprises, in sequence, a transparent substrate, an anode, a hole transport layer, a perovskite light-emitting layer, an electron transport layer, an electron injection layer, and a metal electrode. The perovskite light-emitting layer contains theanine molecules as a crystallization regulator.

[0054] Example 2

[0055] The perovskite precursor solution in this embodiment is prepared as follows:

[0056] FABr and PbBr2 were dissolved in dimethyl sulfoxide (DMSO) at a molar ratio of 1.2:1, with a PbBr2 concentration of 0.2 mol / L. Theanine was added (theanine to PbBr2 molar ratio of 5:100). The solution was stirred overnight on a hot plate at 50 °C, cooled, and then filtered for later use.

[0057] The fabrication steps of the perovskite light-emitting diode in this embodiment are the same as those in Embodiment 1.

[0058] Example 3

[0059] The perovskite precursor solution in this embodiment is prepared as follows:

[0060] FABr and PbBr2 were dissolved in dimethyl sulfoxide (DMSO) at a molar ratio of 1.2:1, with a PbBr2 concentration of 0.2 mol / L. Theanine was added (theanine to PbBr2 molar ratio of 10:100). The solution was stirred overnight on a hot plate at 50 °C, cooled, and then filtered for later use.

[0061] The fabrication steps of the perovskite light-emitting diode in this embodiment are the same as those in Embodiment 1.

[0062] Example 4

[0063] The preparation of the perovskite precursor solution in this embodiment is the same as in Example 1; in step 3) of the perovskite light-emitting diode fabrication process, interface treatment was performed after the perovskite light-emitting layer was prepared. The interface modification material used was 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazole (PO-T2T). The specific preparation method is as follows:

[0064] 1) Clean the ITO conductive glass sequentially with detergent and deionized water using ultrasonic cleaning, dry it with nitrogen, place it in an oven to dry, and then treat it with ultraviolet ozone for 20 minutes.

[0065] 2) Preparation of hole transport layer: A 0.5 mg / mL 4PABCz ethanol solution was spin-coated onto a clean ITO conductive glass at a spin speed of 4000 rpm for 30 s, followed by annealing at 100 ℃ for 10 min to obtain the hole transport layer.

[0066] 3) Preparation of the perovskite luminescent layer: The precursor solution was spin-coated onto the 4PABCz layer prepared in step 2) at a spin speed of 5000 rpm for 45 s. At 26 s, 100 μL of ethyl acetate was rapidly added dropwise onto the perovskite film as an antisolvent. The film was then annealed at 80 ℃ for 10 min to obtain the perovskite luminescent layer. After the perovskite luminescent layer cooled to room temperature, a 0.25 mg / mL PO-T2T ethyl acetate solution was spin-coated onto its surface at a spin speed of 6000 rpm for 30 s. The film was then annealed at 80 ℃ for 1 min to obtain the interface-modified perovskite luminescent layer.

[0067] 4) The perovskite light-emitting layer prepared in step 3) is transferred to a vacuum evaporation chamber, and 40 nm CN-T2T, 1 nm LiF and 100 nm Al electrodes are deposited layer by layer to obtain a perovskite light-emitting diode.

[0068] Comparative Example 1

[0069] The precursor solution in this comparative example differs from the precursor solution in Example 1 in that theanine was not added. The specific preparation is as follows:

[0070] FABr and PbBr2 were dissolved in dimethyl sulfoxide (DMSO) at a molar ratio of 1.2:1, with the concentration of PbBr2 being 0.2 mol / L.

[0071] The fabrication steps of the perovskite light-emitting diode in this comparative example are the same as those in Example 1.

[0072] Comparative Example 2

[0073] The precursor solution preparation for this comparative example is the same as that for Comparative Example 1; the difference lies in step 3) of the perovskite light-emitting diode fabrication process, where an interface treatment was performed after the perovskite light-emitting layer was prepared. The interface modification material used was 2,4,6-tris[3-(diphenylphosphino)phenyl]-1,3,5-triazole (PO-T2T). The specific preparation method is as follows:

[0074] 1) Clean the ITO conductive glass sequentially with detergent and deionized water using ultrasonic cleaning, dry it with nitrogen, place it in an oven to dry, and then treat it with ultraviolet ozone for 20 minutes.

[0075] 2) Preparation of hole transport layer: A 0.5 mg / mL 4PABCz ethanol solution was spin-coated onto a clean ITO conductive glass at a spin speed of 4000 rpm for 30 s, followed by annealing at 100 ℃ for 10 min to obtain the hole transport layer.

[0076] 3) Preparation of the perovskite luminescent layer: The precursor solution was spin-coated onto the 4PABCz layer prepared in step 2) at a spin speed of 5000 rpm for 45 s. At 26 s, 100 μL of ethyl acetate was rapidly added dropwise onto the perovskite film as an antisolvent. The film was then annealed at 80 ℃ for 10 min to obtain the perovskite luminescent layer. After the perovskite luminescent layer cooled to room temperature, a 0.25 mg / mL PO-T2T ethyl acetate solution was spin-coated onto its surface at a spin speed of 6000 rpm for 30 s. The film was then annealed at 80 ℃ for 1 min to obtain the interface-modified perovskite luminescent layer.

[0077] 4) The perovskite light-emitting layer prepared in step 3) is transferred to a vacuum evaporation chamber, and 40 nm CN-T2T, 1 nm LiF and 100 nm Al electrodes are deposited layer by layer to obtain a perovskite light-emitting diode.

[0078] Test results:

[0079] 1. Device performance testing

[0080] Performance data of perovskite light-emitting diode devices in Examples 1-4, Comparative Examples 1 and 2 are shown in Table 1 and Figures 1-5 .

[0081] Comparing the device performance data of Examples 1-4 and Comparative Examples 1 and 2, it can be seen that the addition of theanine to the perovskite precursor solution has a significant impact on the performance of perovskite light-emitting diodes.

[0082] (1) Performance comparison of devices with and without theanine. By comparing Examples 1-3 with Comparative Example 1, it can be seen that the devices with theanine (Examples 1-3) are significantly better than Comparative Example 1 without theanine in terms of maximum brightness, maximum current efficiency, and maximum external quantum efficiency. The maximum EQE of the device in Comparative Example 1 is only 0.13%, and the maximum brightness is only 8698 candela / m²; while the EQE of Examples 1-3 all exceed 13%, and the maximum brightness all exceed 170000 candela / m², indicating that the introduction of theanine can significantly improve the luminous efficiency and luminous brightness of the device.

[0083] (2) Comparison of device performance with different amounts of theanine. In Example 2, the molar ratio of theanine to PbBr2 was 5:100, and the device exhibited the highest maximum brightness (355,428 candela / m²), but the maximum current efficiency (59.91 candela / ampere) and maximum external quantum efficiency (13.23%) were relatively low among the three. In Example 1, the theanine content was increased to 8:100. Although the maximum brightness decreased slightly (262,956 candela / m²), the maximum current efficiency (84.25 candela / ampere) and maximum external quantum efficiency (19.33%) were significantly improved, making it the best among the three. In Example 3, the theanine content was further increased to 10:100. The device performance decreased somewhat (maximum brightness was 174,501 candela / m², external quantum efficiency was 18.98%, and current efficiency was 82.73 candela / ampere), but it was still far superior to Comparative Example 1. The above results indicate that the amount of theanine added is not necessarily better the more it is added, but rather there is an optimal value. Too little addition makes it difficult to fully exert its crystallization regulation and defect passivation effects; too much addition easily leads to the aggregation of additive molecules, which is detrimental to charge carrier transport. When the addition amount is appropriate (8:100), an optimal balance can be achieved between crystallization regulation and charge transport.

[0084] Comparing the performance data of Examples 1 and 4, it can be seen that the performance of the perovskite light-emitting diode is further improved after introducing a PO-T2T interface modification layer on the surface of the perovskite light-emitting layer. The device prepared in Example 4 has a maximum EQE of 23.06% and a maximum luminance of 358,135 candela / m², both significantly better than Example 1 which only added theanine. However, comparing the performance data of Comparative Examples 1 and 2, it can be seen that introducing a PO-T2T interface modification layer on the surface of the perovskite light-emitting layer without theanine does not significantly improve the performance of the perovskite light-emitting diode, and is far lower than that of Examples 1 and 4. This indicates that the interface modification layer and the bulk phase regulation of theanine molecules have a synergistic effect, which can jointly improve the luminous efficiency and luminous brightness of the device.

[0085] Table 1 Performance data of perovskite light-emitting diode devices in Examples 1-4, Comparative Examples 1 and 2

[0086] Example 1 262956 84.25 19.33 537 Example 2 355428 59.91 13.23 538 Example 3 174501 82.73 18.98 537 Comparative Example 1 8698 0.59 0.13 538 Comparative Example 2 23894 1.76 0.39 538 Example 4 358135 94.9 23.06 537

[0087] 2. Microstructure testing of perovskite thin films:

[0088] Figures 6 to 9The images show scanning electron microscope (SEM) images of the perovskite luminescent layers prepared in Comparative Example 1 and Examples 1-3. As can be seen from the images, the film in Comparative Example 1 without theanine molecules has a rough surface, irregular grain shapes, uneven grain size distribution, and numerous pinholes. In contrast, after adding theanine in Example 1, the perovskite film surface is denser and smoother, the grain growth is more regular and the size is smaller, and the number of pinholes is significantly reduced. The film morphologies of Examples 2 and 3 are similar to those of Example 1, all exhibiting dense surface morphologies. These results indicate that theanine, as a crystallization regulator, can effectively inhibit irregular nucleation and growth of perovskite during rapid crystallization, thereby promoting the formation of high-quality, low-defect-density films.

[0089] Figure 10 The image shows a scanning electron microscope (SEM) image of the perovskite luminescent layer prepared in Example 4. As can be seen from the image, compared to the unmodified perovskite film (Example 1), the morphology of the perovskite film did not change significantly after the introduction of the PO-T2T interface modification layer; the surface remained dense and smooth, with a uniform grain size distribution. This indicates that the spin-coating process of the interface modification layer does not damage the structure of the underlying perovskite film, and this interface modification strategy has good compatibility.

[0090] 3. Photoluminescence properties

[0091] Figure 11 The figures show the photoluminescence spectra of the perovskite luminescent layers prepared in Example 1 and Comparative Example 1. As can be seen from the figures, the photoluminescence intensity of Comparative Example 1 is low, indicating severe nonradiative recombination. In contrast, the photoluminescence intensity of Example 1 is significantly enhanced, directly demonstrating that theanine can effectively passivate bulk defects and greatly suppress defect-induced nonradiative recombination.

[0092] Figure 12 The figures show the photoluminescence spectra of the perovskite light-emitting layers prepared in Examples 4 and 1. As can be seen from the figures, the photoluminescence intensity of Example 4 is significantly higher than that of Example 1, indicating that the PO-T2T interface modification layer can effectively passivate defect states on the perovskite film surface, reduce non-radiative recombination centers at the interface, and thus enhance radiative recombination. This result is consistent with the trend of improved device performance, further confirming the importance of the synergistic effect of interface modification and theanine molecule regulation in improving the performance of perovskite light-emitting diodes.

[0093] Those skilled in the art will readily understand that the above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a high-efficiency, high-brightness perovskite light-emitting diode, characterized in that, Includes the following steps: (1) A hole transport layer is prepared on ITO conductive glass; (2) Preparation of perovskite luminescent layer on hole transport layer: spin-coating perovskite precursor solution into film, adding antisolvent during spin-coating process, and obtaining perovskite luminescent layer after annealing treatment; The perovskite precursor solution uses theanine as a crystallization regulator. (3) An electron transport layer, an electron injection layer and a metal electrode are sequentially fabricated on the perovskite light-emitting layer to obtain a high-efficiency, high-brightness perovskite light-emitting diode.

2. The method for fabricating a high-efficiency, high-brightness perovskite light-emitting diode according to claim 1, characterized in that, The perovskite is formamidinium lead bromide perovskite.

3. The method for fabricating a high-efficiency, high-brightness perovskite light-emitting diode according to claim 2, characterized in that, The perovskite precursor solution is prepared by dissolving formamidine hydrobromide (FABr), lead bromide (PbBr2), and theanine in dimethyl sulfoxide (DMSO). The concentration of PbBr2 in the perovskite precursor solution is 0.1 ~ 0.4 mol / L, and the molar ratio of FABr to PbBr2 is 1:1 ~ 1.4:

1. The molar ratio of theanine to PbBr2 is 1:100 ~ 10:

100.

4. The method for fabricating a high-efficiency, high-brightness perovskite light-emitting diode according to claim 3, characterized in that, The molar ratio of theanine to PbBr2 is 7.5:100 to 8.5:

100.

5. The method for fabricating a high-efficiency, high-brightness perovskite light-emitting diode according to claim 1, characterized in that, In step (3), after obtaining the perovskite luminescent layer, the following steps are also performed: After the perovskite luminescent layer cools to room temperature, a PO-T2T ethyl acetate solution is spin-coated onto its surface, followed by annealing to obtain an interface-modified perovskite luminescent layer.

6. A high-efficiency, high-brightness perovskite light-emitting diode, characterized in that, It is prepared by the method for preparing a high-efficiency, high-brightness perovskite light-emitting diode according to any one of claims 1 to 5.

7. A perovskite precursor solution, characterized in that, It is prepared by dissolving formamidine hydrobromide (FABr), lead bromide (PbBr2) and theanine in dimethyl sulfoxide (DMSO), wherein the concentration of PbBr2 in the perovskite precursor solution is 0.1 ~ 0.4 mol / L, the molar ratio of FABr to PbBr2 is 1:1 ~ 1.4:1, and the molar ratio of theanine to PbBr2 is 5:100 ~ 10:

100.

8. The perovskite precursor solution according to claim 7, characterized in that, The molar ratio of theanine to PbBr2 is 7.5:100 to 8.5:

100.

9. A perovskite luminescent layer, characterized in that, It is prepared from the perovskite precursor solution according to claim 7 or 8.

10. A perovskite light-emitting device, characterized in that, Includes the perovskite luminescent layer as described in claim 9.

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