Quasi-two-dimensional blue-light perovskite light-emitting diode and preparation method thereof

Abstract

The invention discloses a quasi-two-dimensional blue-light perovskite light-emitting diode and a preparation method thereof, and the quasi-two-dimensional blue-light perovskite light-emitting diode obtained by using A6BfPBr as an additive inhibits cation diffusion, improves the passivation effect to the greatest extent, and creates a firmer octahedral network. In addition, long organic chain ammonia salt and large group separation distance are contained, and opportunities are created for pairing passivated ammonia and perovskite defect sites, so that the spectral stability of the material is improved; rb with different proportions is added into a perovskite precursor, and the ionic radius of Rb is smaller than that of cesium, so that alloying perovskite RbxCs1-xPbBr3 is expected to be generated by adding Rb < + > into three-dimensional CsPbBr3 perovskite, due to octahedral titration, the perovskite has a larger band gap, the RbxCs1-xPbBr3 perovskite is manufactured by a solution method, and along with the increase of the content of Rb < + >, the optical band gap of the RbxCs1-xPbBr3 film is increased from 2.31 eV to 2.60 eV.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite light-emitting materials and devices, and in particular to a quasi-two-dimensional blue light perovskite light-emitting diode and a preparation method thereof. Background Art

[0002] Metal halide perovskites (MHPs) are a promising new semiconductor material with the characteristics of low cost, spectral tunability and high photoluminescence quantum yields (PLQYs), which have broadened optoelectronic application scenarios. At present, the highest external quantum efficiency (EQE) of green perovskite LEDs (PeLEDs) and red PeLEDs exceeds 28%, which is comparable to traditional OLEDs and QLEDs. However, LEDs emitting in the blue band at around 470 nm still lag behind green and red PeLEDs. Low color purity, moderate external efficiency and poor device lifetime are serious obstacles to the commercialization of perovskite light-emitting diodes. Therefore, when promoting the commercial development of PeLEDs, issues such as full width at half maximum (FWHM), reducing efficiency roll-off and extending the service life of the device should be considered.

[0003] Generally speaking, there are two approaches to obtain blue PeLEDs. The first approach is to tune the band gap by adding chlorine to bromine-based perovskites. However, these mixed-halide perovskites exhibit intrinsic phase instabilities, especially under potential, which is caused by halide migration. As a result, the electroluminescence (EL) spontaneously shifts from blue to green within a few minutes of device operation. Almost all PeLEDs based on the mixed-halide strategy exhibit rapid electroluminescence decay. Adjusting the quantum well structure to achieve reduced-dimensional (quasi-two-dimensional) perovskites is another effective approach to produce blue PeLEDs, and blue light emission can be achieved by keeping the quantum well structure in an extremely low thickness region (n≤2).

[0004] Previously, blue PeLED devices suffered from poor performance and low spectral stability, and a practical remedy was urgently needed.

[0005] Therefore, it is necessary to develop a quasi-two-dimensional blue light perovskite light-emitting diode and a preparation method thereof to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to design a quasi-two-dimensional blue light perovskite light-emitting diode and a preparation method thereof in order to solve the above problems.

[0007] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0008] A quasi-two-dimensional blue light perovskite light-emitting diode and a preparation method thereof, comprising a substrate printed with an ITO anode, a PEDOT:PSS hole transport layer, a PVK hole transport layer, a perovskite light-emitting layer, a TPBi electron transport layer, a LiF electron transport layer, and an Al cathode, which are sequentially connected from one side to the other.

[0009] A method for preparing a quasi-two-dimensional blue light perovskite light-emitting diode and a method for preparing the same, comprising:

[0010] S1. Place the substrate printed with ITO anode into a mixed solution of anhydrous ethanol and deionized water, and use an ultrasonic machine to ultrasonicate for 20 minutes, and then blow dry the liquid on its surface with nitrogen;

[0011] S2, placing the dried substrate printed with ITO anode into UV cleaning agent and cleaning with UV ozone for 15 minutes;

[0012] S3, spin-coat a PEDOT:PSS film on a clean substrate printed with an ITO anode using a coater, and anneal it on a hot stage at 150°C for 15 minutes;

[0013] S4, placing the product treated in step S2 into a glove box filled with nitrogen, spin-coating PVK, and annealing on a hot stage at 160° C. for 30 minutes;

[0014] S5, after being cooled by the treatment of S3, spin coating the perovskite precursor solution on the PVK film at a rotation speed of 4000 rpm, and heating at 100° C. for 10 minutes;

[0015] S6: Place the product treated in S5 into the evaporation equipment and evacuate the air. When the air pressure is less than 4×10 -4 TPBi, LiF and Al films were evaporated at pa with thicknesses of 80nm, 1nm and 100nm, respectively.

[0016] Further, the preparation of the perovskite precursor solution comprises the following steps:

[0017] S51. Prepare a 4 ml glass bottle and weigh 73.4 mg PbBr2 into it;

[0018] S52, continue to weigh 25.5 mg CsBr into the glass bottle;

[0019] S53, continue to weigh 13.23 mg RbBr into the glass bottle;

[0020] S54, continue to weigh 7.54 mg of N-aminohexylbenzo[e]-phthalimide hydrobromide into the glass bottle;

[0021] S55, continue to add 1 ml of DMSO into the glass bottle;

[0022] S56. Finally, add a stirring bar to the glass bottle and place it on a stirring table and stir for 12 h.

[0023] Preferably, the concentration of PbBr2 in the perovskite precursor solution is 73.4 mg / ml.

[0024] Preferably, the concentration of CsBr in the perovskite precursor solution is 0-42.56 mg / ml.

[0025] Preferably, the concentration of RbBr in the perovskite precursor solution is 0-33.07 mg / ml.

[0026] Preferably, the chemical formula of N-aminohexylbenzo[e]-phthalimide hydrobromide is C 18 H 21 BrN2O2, chemical structure formula is:

[0027] .

[0028] The beneficial effects of the present invention are:

[0029] (1) The quasi-two-dimensional blue light perovskite light-emitting diode obtained by using long-chain ammonium salt N-aminohexylbenzo[e]-phthalimide hydrobromide (A6BfPBr) as an additive inhibits cation diffusion while maximizing the passivation effect and creating a more robust octahedral network. In addition, the long organic chain ammonium salt and large group separation distance create opportunities for the pairing of passivated ammonia with perovskite defect sites. This improves the spectral stability of the material;

[0030] (2) By adding different proportions of rubidium (Rb) to the perovskite precursor, because Rb (Rb + , 152 pm) has a smaller ionic radius than cesium (Cs + , 167 pm). Therefore, Rb + Incorporation of three-dimensional CsPbBr3 perovskite is expected to produce alloyed perovskite Rb x Cs 1-x PbBr3, this perovskite has a larger band gap due to octahedral titration. Rb x Cs 1-x PbBr3 (0≤x≤1) perovskite is prepared by solution process. + The increase in Rb content x Cs 1-x The optical band gap of PbBr3 film increases from 2.31 eV to 2.60 eV. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1It is a schematic structural diagram of the quasi-two-dimensional blue light perovskite light-emitting diode in the present invention.

[0032] The markings in the figure are: 1. Substrate with ITO anode printed on it, 2. PEDOT:PSS hole transport layer, 3. PVK hole transport layer, 4. Perovskite quantum dot light-emitting layer, 5. TPBi electron transport layer, 6. LiF electron transport layer, 7. Al cathode. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0036] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the figures, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0037] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0038] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0040] like Figure 1 As shown, a quasi-two-dimensional blue light perovskite light-emitting diode and a preparation method thereof include a substrate printed with an ITO anode, a PEDOT:PSS hole transport layer, a PVK hole transport layer, a perovskite light-emitting layer, a TPBi electron transport layer, a LiF electron transport layer, and an Al cathode, which are sequentially connected from one side to the other.

[0041] A method for preparing a quasi-two-dimensional blue light perovskite light-emitting diode and a method for preparing the same, comprising:

[0042] S1. Place the substrate printed with ITO anode into a mixed solution of anhydrous ethanol and deionized water, and use an ultrasonic machine to ultrasonicate for 20 minutes, and then blow dry the liquid on its surface with nitrogen;

[0043] S2, placing the dried substrate printed with ITO anode into UV cleaning agent and cleaning with UV ozone for 15 minutes;

[0044] S3, spin-coat a PEDOT:PSS film on a clean substrate printed with an ITO anode using a coater, and anneal it on a hot stage at 150°C for 15 minutes;

[0045] S4, placing the product treated in step S2 into a glove box filled with nitrogen, spin-coating PVK, and annealing on a hot stage at 160° C. for 30 minutes;

[0046] S5, after being cooled by the treatment of S3, spin coating the perovskite precursor solution on the PVK film at a rotation speed of 4000 rpm, and heating at 100° C. for 10 minutes;

[0047] S6: Place the product treated in S5 into the evaporation equipment and evacuate the air. When the air pressure is less than 4×10 -4 TPBi, LiF and Al films were evaporated at pa with thicknesses of 80nm, 1nm and 100nm, respectively.

[0048] In some embodiments, the preparation of the perovskite precursor solution comprises the following steps:

[0049] S51. Prepare a 4 ml glass bottle and weigh 73.4 mg PbBr2 into it;

[0050] S52, continue to weigh 25.5 mg CsBr into the glass bottle;

[0051] S53, continue to weigh 13.23 mg RbBr into the glass bottle;

[0052] S54, continue to weigh 7.54 mg of N-aminohexylbenzo[e]-phthalimide hydrobromide into the glass bottle;

[0053] S55, continue to add 1 ml of DMSO into the glass bottle;

[0054] S56. Finally, add a stirring bar to the glass bottle and place it on a stirring table and stir for 12 h.

[0055] In some embodiments, the concentration of PbBr2 in the perovskite precursor solution is 73.4 mg / ml.

[0056] In some embodiments, the concentration of CsBr in the perovskite precursor solution is 0-42.56 mg / ml.

[0057] In some embodiments, the concentration of RbBr in the perovskite precursor solution is 0-33.07 mg / ml.

[0058] In some embodiments, the chemical formula of N-aminohexylbenzo[e]-phthalimide hydrobromide is C 18 H 21 BrN2O2, chemical structure formula is:

[0059] .

[0060] Example 1 (control group):

[0061] (1) Preparation of perovskite precursor solution:

[0062] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, blow it dry, and put a clean magnet in it. Put 73.4 mg PbBr2, 17 mg CsBr, 19.84 mg RbBr and 40.4 mg PEABr into the glass bottle and add 1 ml DMSO as the precursor solution. Put the solution on a stirring table and stir it at room temperature for 12 h. Finally, filter it through a 0.22 μm filter head and put it into a clean glass bottle.

[0063] (2) Preparation of quasi-two-dimensional perovskite blue light-emitting diodes:

[0064] The glass substrate printed with ITO was ultrasonically cleaned with deionized water and anhydrous ethanol for 15 mins, and treated with ultraviolet ozone for 15 mins. The filtered PEDOT:PSS was then spin-coated on the ITO substrate (at a speed of 4000 rpm for 40 s) as a hole transport layer and annealed at 150 degrees Celsius for 15 mins. Then, PVK was dissolved in chlorobenzene at a concentration of 4 mg / ml and spin-coated on PEDOT:PSS at a speed of 1000 rpm for 40 s as a hole injection layer, and annealed at 160 degrees Celsius for 30 mins. The perovskite precursor was spin-coated on the PVK film at a speed of 4000 rpm as a light-emitting layer, and annealed at 100 degrees Celsius for 10 mins. Finally, the spin-coated substrate was transferred to the evaporator, and TPBi, LiF and Al were evaporated in sequence as the electron transport layer and metal electrode, with thicknesses of 80 nm, 1 nm and 100 nm, respectively.

[0065] Embodiment 2:

[0066] (1) Preparation of perovskite precursor solution:

[0067] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, blow it dry, and put a clean magnet in it. Put 73.4 mg PbBr2, 17 mg CsBr, 19.84 mg RbBr and 3.77 mg A6BfPBr into the glass bottle and add 1 ml DMSO as the precursor solution. Put the solution on a stirring table and stir it at room temperature for 12 h. Finally, filter it through a 0.22 μm filter head and put it into a clean glass bottle.

[0068] (2) Preparation of quasi-two-dimensional perovskite blue light-emitting diodes:

[0069] This part is exactly the same as Example 1.

[0070] Embodiment 3:

[0071] (1) Preparation of perovskite precursor solution:

[0072] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, blow it dry, and put a clean magnet in it. Put 73.4 mg PbBr2, 17 mg CsBr, 19.84 mg RbBr and 7.54 mg A6BfPBr into the glass bottle and add 1 ml DMSO as the precursor solution. Put the solution on a stirring table and stir it at room temperature for 12 h. Finally, filter it through a 0.22 μm filter head and put it into a clean glass bottle.

[0073] (2) Preparation of quasi-two-dimensional perovskite blue light-emitting diodes:

[0074] This part is exactly the same as Example 1.

[0075] Embodiment 4:

[0076] (1) Preparation of perovskite precursor solution:

[0077] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, blow it dry, and put a clean magnet in it. Put 73.4 mg PbBr2, 17 mg CsBr, 19.84 mg RbBr and 11.31 mg A6BfPBr into the glass bottle and add 1 ml DMSO as the precursor solution. Put the solution on a stirring table and stir it at room temperature for 12 h. Finally, filter it through a 0.22 μm filter head and put it into a clean glass bottle.

[0078] (2) Preparation of quasi-two-dimensional perovskite blue light-emitting diodes:

[0079] This part is exactly the same as Example 1.

[0080] Embodiment 5:

[0081] (1) Preparation of perovskite precursor solution:

[0082] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, blow it dry, and put a clean magnet in it. Put 73.4 mg PbBr2, 17 mg CsBr, 19.84 mg RbBr and 15.09 mg A6BfPBr into the glass bottle and add 1 ml DMSO as the precursor solution. Put the solution on a stirring table and stir it at room temperature for 12 h. Finally, filter it through a 0.22 μm filter head and put it into a clean glass bottle.

[0083] (2) Preparation of quasi-two-dimensional perovskite blue light-emitting diodes:

[0084] This part is exactly the same as Example 1.

[0085] Embodiment 6:

[0086] (2) Preparation of perovskite precursor solution:

[0087] Prepare a 4 ml glass bottle, clean it with deionized water and ethanol, blow it dry, and put a clean magnet in it. Put 73.4 mg PbBr2, 8.5 mg CsBr, 26.46 mg RbBr and 7.54 mg A6BfPBr into the glass bottle and add 1 ml DMSO as the precursor solution. Put the solution on a stirring table and stir it at room temperature for 12 h. Finally, filter it through a 0.22 μm filter head and put it into a clean glass bottle.

[0088] (2) Preparation of quasi-two-dimensional perovskite blue light-emitting diodes:

[0089] This part is exactly the same as Example 1.

[0090] Embodiment 7:

[0091] (3) Preparation of perovskite precursor solution:

[0092] Prepare a 4 ml glass bottle, clean it with deionized water and ethanol, blow it dry, and put a clean magnet in it. Put 73.4 mg PbBr2, 25.5 mg CsBr, 13.23 mg RbBr and 7.54 mg A6BfPBr into the glass bottle and add 1 ml DMSO as the precursor solution. Put the solution on a stirring table and stir it at room temperature for 12 h. Finally, filter it through a 0.22 μm filter head and put it into a clean glass bottle.

[0093] (2) Preparation of quasi-two-dimensional perovskite blue light-emitting diodes:

[0094] This part is exactly the same as Example 1.

[0095] EL peak wavelength (nm) External quantum efficiency of LED devices Example 1 476 1.8% Example 2 475 7% Example 3 476 11.9% Example 4 477 9% Example 5 476 8.2% Example 6 491 10.3% Example 7 460 9.5%

[0096] Table 1 EL performance of quasi-2D perovskite blue LEDs

[0097] It can be seen from Table 1 and the accompanying drawings that: as the amount of A6BfPBr added increases (Examples 2-5), compared with the quasi-two-dimensional blue light-emitting diode of PEABr, the electroluminescent wavelength of the device does not shift significantly, and the EQE of the LED device is significantly improved. This is because the long organic chain ammonia salt and the large group separation distance create opportunities for the pairing of passivated ammonia and perovskite defect sites, thereby forming a higher quality perovskite light-emitting material. It is worth noting that if the proportion of added RbBr is changed (Example 6, Example 3 and Example 7), the EL emission wavelength of the quasi-two-dimensional perovskite blue light LED can be adjusted to achieve tunable spectrum.

[0098] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A quasi-two-dimensional blue perovskite light-emitting diode and a method for preparing the same, characterized in that: The invention comprises a substrate printed with an ITO anode, a PEDOT:PSS hole transport layer, a PVK hole transport layer, a perovskite light-emitting layer, a TPBi electron transport layer, a LiF electron transport layer and an Al cathode which are sequentially connected from one side to the other side.

2. The method for preparing the quasi-two-dimensional blue perovskite light-emitting diode and the method for preparing the same according to claim 1, characterized in that: include: S1. Place the substrate printed with ITO anode into a mixed solution of anhydrous ethanol and deionized water, and use an ultrasonic machine to ultrasonicate for 20 minutes, and then blow dry the liquid on its surface with nitrogen; S2, placing the dried substrate printed with ITO anode into UV cleaning agent and cleaning with UV ozone for 15 minutes; S3, spin-coat a PEDOT:PSS film on a clean substrate printed with an ITO anode using a coater, and anneal it on a hot stage at 150°C for 15 minutes; S4, placing the product treated in step S2 into a glove box filled with nitrogen, spin-coating PVK, and annealing on a hot stage at 160° C. for 30 minutes; S5, after being cooled by the treatment of S3, spin coating the perovskite precursor solution on the PVK film at a rotation speed of 4000 rpm, and heating at 100° C. for 10 minutes; S6: Place the product treated in S5 into the evaporation equipment and evacuate the air. When the air pressure is less than 4×10 -4 TPBi, LiF and Al films were evaporated at pa with thicknesses of 80nm, 1nm and 100nm, respectively.

3. The method for preparing the quasi-two-dimensional blue perovskite light-emitting diode and the method for preparing the same according to claim 2, characterized in that: The preparation of the perovskite precursor solution includes the following steps: S51. Prepare a 4 ml glass bottle and weigh 73.4 mg PbBr2 into it; S52, continue to weigh 25.5 mg CsBr into the glass bottle; S53, continue to weigh 13.23 mg RbBr into the glass bottle; S54, continue to weigh 7.54 mg of N-aminohexylbenzo[e]-phthalimide hydrobromide into the glass bottle; S55, continue to add 1 ml of DMSO into the glass bottle; S56. Finally, add a stirring bar to the glass bottle and place it on a stirring table and stir for 12 h.

4. The method for preparing the quasi-two-dimensional blue perovskite light-emitting diode and the method for preparing the same according to claim 2, characterized in that: The concentration of PbBr2 in the perovskite precursor solution was 73.4 mg / ml.

5. The method for preparing the quasi-two-dimensional blue perovskite light-emitting diode and the method for preparing the same according to claim 2, characterized in that: The concentration of CsBr in the perovskite precursor solution ranged from 0 to 42.56 mg / ml.

6. The method for preparing the quasi-two-dimensional blue perovskite light-emitting diode and the method for preparing the same according to claim 2, characterized in that: The concentration of RbBr in the perovskite precursor solution ranged from 0 to 33.07 mg / ml.

7. The method for preparing the quasi-two-dimensional blue perovskite light-emitting diode and the method for preparing the same according to claim 3, characterized in that: The chemical formula of N-aminohexylbenzo[e]-phthalimide hydrobromide is C 18 H 21 BrN2O2, chemical structure formula is: 。

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