Perovskite light emitting diode containing a modification layer and evaporation preparation method thereof

Abstract

The application discloses a perovskite light-emitting diode containing a modification layer and a vapor deposition preparation method thereof. The diode is one of the following two: the first kind is: from top to bottom, a metal cathode, an electron transport layer, a perovskite light-emitting layer, an interface modification layer, a hole transport layer and ITO conductive glass; or the second kind is: from top to bottom, a metal cathode, an electron transport layer, a perovskite light-emitting layer, an interface modification / hole transport mixed layer and ITO conductive glass; the interface modification layer is an amino acid compound (CH2) n CHNH2COOH). The application adds an interface layer between the hole transport layer and the perovskite layer of the perovskite light-emitting diode, plays a role in improving the interface barrier, passivates the interface defects, improves the carrier transport efficiency, enhances the electroluminescence and photoluminescence efficiency, and further improves the device brightness, current efficiency and other performances.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of light-emitting diodes, in particular to a preparation method of a perovskite light-emitting diode capable of improving performance. BACKGROUND

[0002] As the light-emitting layer of an LED, the lead halide perovskite has the following advantages: (1) the light-emitting peak position can be adjusted in the visible light or even near-infrared light range through component design; (2) it has high defect tolerance, and can obtain high fluorescence yield, light-emitting purity and super-wide light-emitting color gamut; (3) it has bipolar charge transport capacity, and the carrier mobility is high, so that the device can obtain high brightness; (4) the preparation cost of the perovskite LED is low, and the raw materials, equipment and preparation method all meet the low-cost requirements. The molecular formula of the all-inorganic perovskite material is CsPbX3, wherein Cs is cesium, Pb is lead, and X is one of iodine (I), chlorine (Cl) and bromine (Br). This inorganic perovskite has the characteristics of good thermal stability and high color purity, however, in the low-cost solution-based process, the perovskite thin film with electron traps and hole traps and rough surface is not conducive to PELED, and the thin film prepared by the multi-source thermal evaporation preparation process is good in uniformity in terms of fluorescence peak position, half peak width and thin film morphology.

[0003] At present, the PeLED has made breakthrough development in red light, green light and even blue light performance, but there is still a lot of room for improvement in light-emitting efficiency and stability. Since the perovskite material will form large crystal grains in the film forming process, thereby reducing the coverage rate of the light-emitting layer, the main method for improving the efficiency at present is to control and passivate the morphology of the perovskite layer, thereby enhancing the light-emitting performance of the device. Therefore, the multi-source thermal evaporation preparation process and interface engineering play an important role in improving the performance of the light-emitting device. SUMMARY

[0004] The purpose of the present application is to solve the technical problem of poor perovskite light-emitting layer morphology quality, many defects in the thin film and poor performance of the light-emitting diode in the preparation of the perovskite light-emitting diode in the prior art, and to provide a method for improving the performance of the perovskite light-emitting diode. The method is to make a modification layer of an amino acid compound material between the hole transport layer and the evaporated perovskite light-emitting layer. The carboxyl and amino groups in the amino acid can play a great role because of the coulomb interaction between molecules, so that the positive and negative ions and the functional groups in the amino acid can be combined, such as -COOH and the excess Pb 2+ ions in the perovskite light-emitting layer, and -NH2 and Br -The ions form interaction, thereby passivating the anion and cation defects of the surface, thereby inhibiting the non-radiative recombination defects of the perovskite film, improving the fluorescence quantum efficiency of the light-emitting layer, and further improving the performance of the device.

[0005] The technical scheme of the present application is:

[0006] The perovskite light-emitting diode containing the modification layer is one of the following two:

[0007] The first one is: from top to bottom, metal cathode, electron transport layer, perovskite light-emitting layer, interface modification layer, hole transport layer, anode and substrate;

[0008] Or, the second one is: from top to bottom, metal cathode, electron transport layer, perovskite light-emitting layer, interface modification / hole transport mixed layer, anode and substrate;

[0009] In the first one, the perovskite light-emitting layer is a composite phase of APbBr3 and A4PbBr6; the molar ratio of the two is 1:0.1-0.25;

[0010] Wherein, the composition of A is Cs, Na and Rb, the molar ratio of Cs:Na:Rb is 9-6:2:1; the thickness is 30-100nm;

[0011] The interface modification layer is an amino acid compound;

[0012] The amino acid compound is one or two of 4-aminobutyric acid, glycine and 5-aminopentanoic acid;

[0013] In the second one, the hole transport / interface modification mixed layer is a mixture of hole transport material and amino acid compound, the volume ratio of the two is 11-9:1; the thickness is 30-60nm;

[0014] The substrate is glass;

[0015] The anode is ITO, and the thickness is 20-500nm;

[0016] The metal cathode is Al or Ag, and the thickness is 70-120nm;

[0017] The electron transport layer is substance C and substance D; the thickness is 10-50nm;

[0018] The material C is 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl) benzene (TPBI) or 4,7-diphenyl-1,10-phenanthroline (Bphen); the material D is one or more of LiF, CsF, Cs2CO3, Liq;

[0019] The material of the hole transport layer is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), NiOx nanoparticles, polyvinylcarbazole (PVK), or poly(bis(4-phenyl)(4-butylphenyl)amine) (Poly-TPD), and the thickness is 25-50 nm.

[0020] The preparation method of the perovskite light-emitting diode containing a modification layer is one of the following two methods:

[0021] Method one,

[0022] (1) preparing a hole transport layer on a substrate with an anode coating;

[0023] (2) preparing an interface modification layer on the hole transport layer;

[0024] (3) evaporating and growing a perovskite light-emitting layer on the interface modification layer;

[0025] (4) sequentially evaporating an electron transport layer and a cathode layer above the perovskite light-emitting layer;

[0026] Alternatively, method two

[0027] (1) preparing a hole transport / interface modification mixed layer on a substrate with an anode coating;

[0028] (2) preparing a perovskite light-emitting layer on the hole transport / interface modification mixed layer;

[0029] (3) sequentially evaporating an electron transport layer and a cathode layer above the perovskite light-emitting layer.

[0030] Specific preparation steps;

[0031] In the method one, the hole transport layer is prepared as follows:

[0032] A hole transport layer solution is added dropwise on a pretreated substrate with an anode coating, and then spin-coated and annealed to obtain the hole transport layer.

[0033] When the material of the hole transport layer is NiO, the concentration of the NiO solution is 10-20 mg / ml.

[0034] The spin-coating speed is 2000-6000 revolutions per minute, and the spin-coating time is 20-40 seconds; the annealing temperature is 110-150°C, and the annealing time is 10-30 minutes.

[0035] Preparation of the interface modification layer:

[0036] The amino acid compound solution is spin-coated on the hole transport layer by a spin coater to form the interface modification layer after annealing at 80-110℃;

[0037] 10-100 mg of the amino acid compound is added to 1 ml of deionized water; the rotation speed of the spin coater is 5000-8000 rpm, and the spin coating time is 20-40 s; 0.05-0.20 ml of the amino acid compound solution is spin-coated per 4 cm2.

[0038] Preparation of the perovskite light-emitting layer:

[0039] PbBr2 and substance M are respectively placed in the evaporation chamber, and the substrate covered with the hole transport layer and the interface modification layer is placed in the evaporation chamber, evaporation is started when the vacuum degree reaches 5x10 -4 Pa, and the perovskite light-emitting layer is obtained after annealing at 90-120℃ for 20-40 min after the evaporation is completed and the substrate is placed in the vacuum chamber for 1-2 h; the thickness of the perovskite light-emitting layer is 30-100 nm; the substance M is CsBr or BBr, and B=Na and Rb;

[0040] CsBr: PbBr2: BBr = 5-6: 4: 1, and B=Na and Rb, and the molar ratio of the two is 1:1.

[0041] The evaporation rate of CsBr is 0.8-1.5 angstrom per second, the evaporation rate of PbBr2 is 0.5-1 angstrom per second, and the evaporation rate of BBr is 0.8-1.5 angstrom per second,

[0042] In the method two, the preparation method of the hole transport layer / modified mixed layer

[0043] The mixed layer solution is dropped on the pretreated substrate with anode coating, spin-coated and annealed to obtain the hole transport layer / modified mixed layer;

[0044] The spin-coating rotation speed is 2000-6000 rpm, and the spin-coating time is 20-40 s; the annealing temperature is 110-150℃, and the annealing time is 10-30 min; 0.01-0.20 ml of the mixed layer solution is spin-coated per 4 cm2.

[0045] The mixed layer solution is a mixture of the amino acid solution and the hole transport layer solution, and the volume ratio of the two is 9-11:1; the concentration of the amino acid solution is 10-100 mg / 1 ml;

[0046] Preparation of the electron transport layer:

[0047] The electron transport layer is deposited by evaporation, and the evaporation speed is 0.1-1 angstrom per second.

[0048] The thickness of the cathode layer is 70-120nm.

[0049] The pretreatment is ultrasonic treatment, and then hydrophilic treatment is performed.

[0050] The hydrophilic treatment is oxygen plasma treatment, ultraviolet ozone treatment or amphiphilic active agent treatment.

[0051] The present application has the following advantages:

[0052] The present application adds an interface between the light-emitting layer and the hole transport layer of the perovskite light-emitting diode, improves the interface potential barrier, passivates the interface defects, improves the carrier transport efficiency, enhances the electroluminescence and photoluminescence efficiency, and further improves the device brightness, current efficiency and other performances, optimizes the multi-source vacuum evaporation method, adjusts the ratio of Cs and Pb to generate a suitable APbBr3, A4PbBr6(A=B:Cs; B=Na Rb) composite phase, and improves the fluorescence quantum yield and current injection efficiency by mutual adjustment. Experimental verification shows that the device performance can be increased by 3-6 times or more, for example, the current efficiency of the device without the modification layer is 1.2 cd / A, and the brightness is 2500 cd / m 2 , and the current efficiency of the device with the modification layer is 12.08 cd / A, and the brightness is 12915 cd / m 2 . BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 is a perovskite light-emitting diode device structure prepared by the present application;

[0054] Figure 2 is a current density-voltage relationship diagram of Comparative Example 1 (curve 1) and Example 1 (curve 2) and Example 2 (curve 3);

[0055] Figure 3 is a current efficiency-voltage relationship diagram of Comparative Example 1 (curve 1) and Example 1 (curve 2) and Example 2 (curve 3);

[0056] Figure 4 is a brightness-voltage relationship diagram of Comparative Example 1 (curve 1) and Example 1 (curve 2) and Example 2 (curve 3). DETAILED DESCRIPTION

[0057] The structure of the perovskite light-emitting diode of the present application is shown in Figure 1 , from bottom to top, ITO, PEDOT:PSS, amino acid modification layer, perovskite, TPBI / LiF, AL.

[0058] Comparative Example 1

[0059] The preparation method of the perovskite light-emitting diode of the present comparative example comprises the following steps:

[0060] ① Put the ultrasonic-treated glass substrate (20*20mm) with a transparent anode layer (185nm thick, single ITO 4*20mm), i.e. indium tin oxide (ITO), which has been subjected to ultraviolet ozone treatment, on a spin coater, and spin-coat 0.05ml of a hole transport layer medicine at a rotation speed of 6000 revolutions per minute. The hole transport layer is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). In the present example, a 30nm-thick hole transport layer of PEDOT:PSS is spin-coated, and is subjected to annealing at 140℃.

[0061] ② Put the substrate into a vacuum evaporation chamber, and start evaporating the perovskite light-emitting layer. Put CsBr and PbBr2 into two boats in the evaporation chamber, respectively. By evaporating different proportions of cesium and lead, different phases will be formed. As the proportion of CsBr:PbBr2 increases, CsPbBr3, Cs4PbBr6 will be formed in turn. In the present example, the thickness proportion of CsBr:PbBr2 is kept at 1.5:1, and 6nm of CsBr is evaporated first, followed by 4nm of PbBr2, and the process is repeated 5 times in turn, according to the principle of first Cs and then Pb. The thickness of the perovskite light-emitting layer is 50nm.

[0062] ③ After the perovskite layer is evaporated in vacuum, the device is subjected to annealing treatment after being reacted in vacuum for 2 hours. The temperature is between 100-120℃. Annealing can help the perovskite to crystallize and promote the flatness of the interface to be more uniform. The preferred annealing temperature is 110℃.

[0063] ④ After annealing is completed, the electron transport layer is prepared. In the present example, TPBI and LiF are selected, and the thickness is 40nm. The evaporation speed is less than 1 angstrom per second. The cathode can be selected from Al, Ag, etc. In the present example, Al is selected as the cathode, and the thickness is 100nm.

[0064] Comparative Example 2

[0065] The preparation method of the perovskite light-emitting diode of the present comparative example comprises the following steps:

[0066]

[0067]

[0068]

[0069]

[0070] Example 1

[0071] The second preparation method of the perovskite light-emitting diode comprises the following steps:

[0072]

[0073] ​​​​​②The glass substrate (20*20mm) with transparent anode layer (185nm thick, single ITO 4*20mm) of indium tin oxide (ITO) treated by ultrasonic was placed on the spin coater after ultraviolet ozone treatment. 0.05ml of the mixed solution obtained in the previous step was evenly coated on the entire piece. The spin coater was rotated at 6000rpm for 30s, and then annealed at 140℃ for 10min to form a hole transport layer and an interface modification mixed layer on the anode with a thickness of 45nm.

[0074] ③The substrate with the mixed layer obtained in the previous step was placed in a vacuum evaporation chamber. The above substrate was placed in the vacuum evaporation chamber to start evaporation of the perovskite light-emitting layer. CsBr and PbBr2 (about 500mg) were placed in two boats respectively in the evaporation chamber. When the vacuum degree reached 5*10 -4 Pa, the evaporation started. By evaporating different proportions of cesium and lead, different phases were formed. As the evaporation proceeded, the mass of CsBr and PbBr2 on the substrate gradually increased, and CsPbBr3 and Cs4PbBr6 were formed in turn. In this example, the thickness ratio of CsBr to PbBr2 was kept at 1.5:1. According to the principle of first Cs then Pb, 6nm of CsBr was first evaporated, followed by 4nm of PbBr2, and the cycle was repeated 5 times. The perovskite light-emitting layer had a thickness of 50nm.

[0075] ④After the vacuum evaporation of the perovskite layer, the device was annealed in a vacuum environment for 2 hours. The annealing temperature was between 100-120℃. Annealing can help the perovskite to crystallize and promote the flatness of the interface to be more uniform. The preferred annealing temperature of the present application is 110℃.

[0076] ⑤After annealing, the electron transport layer was prepared. TPBI and LiF were selected as the electron transport layer. By increasing the temperature of TPBI to increase the evaporation rate, the temperature range of the present application was 100-140℃, and the rate was kept at 0.8-1 angstrom per second. The total evaporation thickness was 39nm. Then LiF was deposited with a thickness of 1nm and an evaporation rate of 0.1 angstrom per second.

[0077] ⑥Al was selected as the cathode. After placing a mask plate under the substrate, the cathode was evaporated. The cathode and anode were cross-shaped to facilitate testing. The evaporation rate was less than 15 angstrom per second, and the thickness was 100nm.

[0078] Example 2

[0079] The second preparation method of perovskite light-emitting diode comprises the following steps:

[0080] The 4-aminobutyric acid is prepared by mixing 50 mg of a drug powder and 1 ml of deionized water. 0.1 ml of the 4-aminobutyric acid solution and 1 ml of PEDOT:PSS are mixed and stirred to form a hole transport layer. The amino acid solution can be doped in the water-soluble PEDOT:PSS solution and then spin-coated. 100 microliters of 4-aminobutyric acid with a concentration of 50 mg / ml and 1000 microliters of PEDOT:PSS are mixed to obtain a mixed solution

[0081] The glass substrate (20*20 mm) with a transparent anode layer (185 nm thick, single ITO 4*20 mm) of indium tin oxide (ITO) is placed on a spin coater after ultrasonic treatment and ultraviolet ozone treatment. 0.05 ml of the mixed solution obtained in the above step is evenly coated on the entire piece, and the hole transport layer and interface modification mixed layer are formed on the anode by spin coating at a speed of 6000 rpm for 30 s and annealing at a high temperature of 140°C for 10 min, with a thickness of 42 nm.

[0082] The substrate with the mixed layer obtained in the above step is placed in a vacuum evaporation chamber, and the above substrate is placed in the vacuum evaporation chamber to start evaporation of the perovskite light-emitting layer. CsBr and PbBr2 (about 500 mg) are placed in two boats in the evaporation chamber, and evaporation is started when the vacuum degree reaches 5*10 -4 Pa. Different phases are formed by evaporating different proportions of cesium and lead. As the evaporation proceeds, the mass of CsBr and PbBr2 on the substrate gradually increases, and CsPbBr3 and Cs4PbBr6 will be formed in turn. In this example, the thickness ratio of CsBr to PbBr2 is kept at 1.25:1, and 6 nm of CsBr is evaporated first, followed by 4 nm of PbBr2, and the process is repeated 5 times in turn. The perovskite light-emitting layer has a thickness of 50 nm.

[0083] After the perovskite layer is evaporated in a vacuum environment, the device is annealed for 2 hours at a temperature of 100-120°C. Annealing can help the perovskite to crystallize and promote the flatness of the interface to be more uniform. The preferred annealing temperature of the present application is 110°C.

[0084] After annealing, an electron transport layer is prepared. TPBI and LiF are selected as the electron transport layer in the present application. The evaporation rate is increased by increasing the temperature of TPBI. The temperature range of the present application is 100-140°C, and the rate is kept at 0.8-1 angstrom per second. The thickness of the evaporated TPBI is 39 nm, and then LiF is deposited with a thickness of 1 nm and an evaporation rate of 0.1 angstrom per second.

[0085] 6. The application selects Al as the cathode, and after placing the mask plate below the substrate, the cathode is evaporated, the cathode and anode are cross-shaped to facilitate testing, the evaporation rate is less than 15 angstroms per second, and the thickness is 100 nm.

[0086] Example 3

[0087] The first preparation method of the perovskite light emitting diode comprises the following steps:

[0088] 1. The preparation process of the glycine solution is to stir 50 mg of drug powder and 1 ml of deionized water uniformly.

[0089] 2. The ultrasonic treated glass substrate (20*20 mm) with a transparent anode layer (185 nm thick, single ITO is 4*20 mm), namely indium tin oxide (ITO), is placed on a spin coater after ultraviolet ozone treatment, the entire piece is uniformly coated with PEDOT:PSS through a 0.22 micron filter, spin coating is performed at a speed of 6000 revolutions per minute for 30 seconds through the spin coater, and after high temperature annealing at 140 DEG C for 10 minutes, a hole transport layer is formed on the anode.

[0090] 3. The substrate with the hole transport layer after annealing is placed on a spin coater, 0.1 ml of 50 mg / ml glycine is taken by a pipette gun and spin coated on the substrate, spin coating is performed at a speed of 8000 revolutions per minute for 30 seconds through the spin coater, and after high temperature annealing at 100 DEG C for 5 minutes, an interface modification layer is formed.

[0091] 4. The substrate with the hole transport layer and the interface modification layer obtained above is placed into a vacuum evaporation chamber, the above substrate is placed into the vacuum evaporation chamber to start evaporation of the perovskite light emitting layer. CsBr and PbBr2 (about 500 mg) are respectively placed into two boats in the evaporation chamber, evaporation is started when the vacuum degree reaches 5*10 -4 Pa, different phases are formed by different evaporation ratios of cesium and lead, the mass of CsBr and PbBr2 on the substrate gradually increases with the evaporation, and CsPbBr3 and Cs4PbBr6 will be formed in turn. In this example, the thickness ratio of CsBr to PbBr2 is kept at 1.5:1, 6 nm of CsBr is evaporated first according to the principle of Cs first and Pb second, 4 nm of PbBr2 is evaporated in turn, and the evaporation is cycled 5 times, and the thickness of the perovskite light emitting layer is 50 nm.

[0092] 5. After the perovskite layer is evaporated in a vacuum environment, the device is annealed for 2 hours, the temperature is between 100-120 DEG C, and annealing can help perovskite crystallization and promote the flatness of the interface to be more uniform, and the annealing temperature of the application is preferably 110 DEG C.

[0093] ⑥The present application selects TPBI and LiF as the electron transport layer, and increases the evaporation rate by increasing the temperature of TPBI, the temperature range is 100-140℃, the rate is kept at 0.8-1 angstrom per second, and the total evaporation thickness is 39nm, then LiF is continuously deposited, the thickness is 1nm, and the evaporation rate is 0.1 angstrom per second.

[0094] ⑦The present application selects Al as the cathode, and evaporates the cathode after placing a mask plate under the substrate, so that the cathode and anode are cross-shaped, which is convenient for testing, the evaporation rate is less than 15 angstrom per second, and the thickness is 100nm.

[0095] Example 4

[0096] The second preparation method of the perovskite light emitting diode comprises the following steps:

[0097] ①The preparation process of 5-aminovaleric acid is that 50mg of drug powder and 1ml of deionized water are stirred uniformly. 0.1ml of the solution of 5-aminovaleric acid and 1ml of PEDOT:PSS are mixed and stirred, the hole transport layer comprises poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS). The amino acid solution can be doped in the water-soluble PEDOT:PSS solution and then spin-coated. 100 microliters of 5-aminovaleric acid with a concentration of 50mg / ml and 1000 microliters of PEDOT:PSS are mixed to obtain a mixed solution.

[0098] ②The glass substrate (20*20mm) with a transparent anode layer (185nm thick, single ITO is 4*20mm) of ultrasonic treatment, namely indium tin oxide (ITO), is placed on a spin coater after ultraviolet ozone treatment, 0.05ml of the mixed solution obtained in the above step is evenly coated on the whole piece, spin coating is performed at a speed of 6000 revolutions per minute for 30s by a spin coater, and after 10 minutes of high-temperature annealing at 140℃, a hole transport layer and an interface modification mixed layer are formed on the anode, and the thickness is 43nm.

[0099] ③The substrate with the mixed layer obtained in the above step is placed into a vacuum evaporation chamber, the above substrate is placed into the vacuum evaporation chamber, and a perovskite light emitting layer is evaporated. CsBr and PbBr2 (about 500mg) are respectively placed into two boats in the evaporation chamber, evaporation is started when the vacuum degree reaches 5*10 -4 Pa, different phases are formed by different evaporation ratios of cesium and lead, the mass of CsBr and PbBr2 on the substrate gradually increases during evaporation, and CsPbBr3 and Cs4PbBr6 will be formed in turn. In this example, the thickness ratio of CsBr:PbBr2 is kept at 1.5:1, 6nm of CsBr is evaporated first according to the principle of Cs first and then Pb, 4nm of PbBr2 is evaporated, and the process is cycled 5 times in turn, and the thickness of the perovskite light emitting layer is 50nm.

[0100] ④After the perovskite layer is deposited by vacuum evaporation, the device is annealed after reacting in a vacuum environment for 2 hours, at a temperature of 100-120℃. The annealing can help the perovskite crystallization to promote the flatness of the interface to be more uniform. The preferred annealing temperature of the present application is 110℃.

[0101] ⑤The present application selects TPBI and LiF as the electron transport layer. By increasing the temperature to increase the evaporation rate of TPBI, the temperature range of the present application is 100-140℃, and the rate is kept at 0.8-1 angstrom per second. The total evaporation thickness is 39nm. Then LiF is continuously deposited, with a thickness of 1nm and an evaporation rate of 0.1 angstrom per second.

[0102] ⑥The present application selects Al as the cathode. After placing a mask plate under the substrate, the cathode is deposited. The cathode and anode are cross-shaped to facilitate testing. The evaporation rate is less than 15 angstrom per second, and the thickness is 100nm.

[0103] From the above multiple examples and comparative examples, it can be understood that:

[0104] Figure 3 is the current efficiency diagram of Comparative Example 1 and Examples 1 and 2. From Figure 3 it can be seen that the electroluminescence of the perovskite thin film of Examples 1 and 2 treated by the anode interface modification layer 4-aminobutyric acid has a significant improvement in electroluminescent efficiency compared with the perovskite thin film of the comparative example without treatment. The current efficiency of the device without adding the amino acid modification layer is 1.2cd / A, and the turn-on voltage is 3.2V. However, after adding 100mg / ml of 4-aminobutyric acid, the current efficiency of the device reaches 12.08cd / A, and the turn-on voltage drops to 2.8V. It shows that 4-aminobutyric acid can effectively passivate the defects between the perovskite light-emitting layer and the hole transport layer, reduce the potential barrier, and thus greatly improve the current efficiency.

[0105] In addition, from Figure 2 , Figure 4 it can be seen that the perovskite light-emitting diode treated by the amino acid anode interface modification layer can greatly enhance the conductivity of the perovskite layer and has higher brightness. As shown in Figure 4 the brightness of the device with the amino acid modification layer is 2500cd / m 2 , and the turn-on voltage is 3.2V. The brightness of the device with 100mg / ml of 4-aminobutyric acid reaches 12915cd / m 2 . It shows that the amino acid anode interface modification layer effectively improves the light-emitting performance of the device. The optimization performance of the perovskite layer of the present application has the potential to be further improved, and is being continuously optimized.

[0106] Obviously, the above-mentioned embodiments are only examples for clearly illustrating the present application and are not intended to limit the present application. Based on the above description, one of ordinary skill in the art can make other different forms of changes or modifications. Here, it is not necessary or possible to enumerate all the embodiments. The obvious changes or modifications derived from the above should be within the protection scope of the present application

[0107] The details of the present application are described in the following.

Claims

1. A perovskite light-emitting diode comprising a modification layer, characterized in that the diode is one of the following two: The first one is: from top to bottom, a metal cathode, an electron transport layer, a perovskite light-emitting layer, an interface modification layer, a hole transport layer, an anode and a substrate; Or, the second one is: from top to bottom, a metal cathode, an electron transport layer, a perovskite light-emitting layer, a hole transport / interface modification mixed layer, an anode and a substrate; In the first one, the interface modification layer is an amino acid compound; In the second one, the hole transport / interface modification mixed layer is a mixture of a hole transport material and an amino acid compound; In the first one or the second one, the amino acid compound is one or two of 4-aminobutyric acid, glycine and 5-aminopentanoic acid; In the first diode, the thickness of the interface modification layer is 1-10 nm; the thickness of the hole transport layer is 25-50 nm; In the second diode, the thickness of the hole transport / interface modification mixed layer is 30-60 nm; The metal cathode is Al or Ag, and the thickness is 70-120 nm; The substrate is glass; The anode is ITO, and the thickness is 20-500 nm; The perovskite light-emitting layer is a composite phase of APbBr3 and A4PbBr6; the molar ratio of the two is 1:0.1-0.25; wherein The composition of A is Cs, Na and Rb, and the molar ratio of Cs:Na:Rb is 9-6:2:1; the thickness is 30-100 nm; The electron transport layer is substance C and substance D; the thickness is 10-50 nm; The substance C is 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBI) or 4,7-diphenyl-1,10-phenanthroline (Bphen); the substance D is one or several of LiF, CsF, Cs2CO3 and Liq; The material of the hole transport layer is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), NiOx nanoparticles, polyvinyl carbazole (PVK) or poly(bis(4-phenyl)(4-butylphenyl)amine) (Poly-TPD); The preparation method of the perovskite light-emitting diode comprising a modification layer is one of the following two methods: Method one, (1) preparing a hole transport layer on a substrate with an anode coating; (2) preparing an interface modification layer on the hole transport layer; (3) evaporating and growing a perovskite light-emitting layer on the interface modification layer; (4) sequentially evaporating an electron transport layer and a cathode layer above the perovskite light-emitting layer; Or, method two (1) preparing a hole transport / interface modification mixed layer on a substrate with an anode coating; (2) preparing a perovskite light-emitting layer on the hole transport / interface modification mixed layer; (3) sequentially evaporating an electron transport layer and a cathode layer above the perovskite light-emitting layer; In the method one, the preparation step of the interface modification layer comprises: forming the interface modification layer by spin coating an amino acid compound solution on the hole transport layer through a spin coater and annealing at 80-110°C. The amino acid compound solution is prepared by adding 10-100 mg of the amino acid compound into 1 mL of deionized water; the rotation speed of the spin coater is 5000-8000 revolutions per minute, and the spin coating time is 20-40 seconds; and 0.01-0.20 mL of the amino acid compound solution is spin coated per 4 square centimeters. In the second method, the preparation method of the hole transport / interface modification mixed layer comprises: The mixed layer solution is dropped on the substrate with the anode coating, and then spin coated and annealed at 110-150 DEG C for 10-30 minutes to obtain the hole transport / interface modification mixed layer. The spin coating speed is 2000-6000 revolutions per minute, the spin coating time is 20-40 seconds, and 0.01-0.20 mL of the mixed layer solution is spin coated per 4 square centimeters. The mixed layer solution is a mixture of the hole transport material solution and the amino acid compound solution, and the volume ratio of the two is 9-11:1; the concentration of the amino acid compound solution is 10-100 mg / 1 mL.

2. The perovskite light emitting diode comprising a modification layer according to claim 1, wherein the modification layer is formed on the perovskite light emitting layer. In the preparation method, in the first method, the preparation of the hole transport layer comprises: The hole transport layer solution is dropped on the substrate with the anode coating, spin coated at 2000-6000 revolutions per minute for 20-40 seconds, and then annealed at 110-150 DEG C for 10-30 minutes to obtain the hole transport layer. In the first method or the second method, The preparation of the perovskite light-emitting layer comprises the following steps: In the evaporation chamber, PbBr2 and substance M are respectively placed, and the substrate is covered with a hole transport layer, an interface modification layer, or a mixed hole transport / interface modification layer. When the vacuum degree reaches 5*10 -4 Pa, evaporation is started, and after the evaporation is completed, the vacuum chamber is placed for 1-2 hours, and then annealing is performed at a temperature of 90-120℃ for 20-40 minutes to obtain a perovskite light-emitting layer; the thickness of the perovskite light-emitting layer is 30-100nm; the substance M is CsBr and BBr, B= Na and Rb; The evaporation rate of CsBr is 0.8-1.5 angstrom per second, the evaporation rate of PbBr2 is 0.5-1 angstrom per second, and the evaporation rate of BBr is 0.8-1.5 angstrom per second. The preparation of the electron transport layer comprises: The electron transport layer is deposited by evaporation, and the evaporation speed is 0.1-1 angstrom per second.

3. The perovskite light-emitting diode with a modified layer as described in claim 1, characterized in that, In step (1) of the first method or the second method, the substrate is pretreated, and the pretreatment is ultrasonic treatment followed by hydrophilic treatment. The hydrophilic treatment is oxygen plasma treatment, ultraviolet ozone treatment, or amphiphilic active agent treatment.

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