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

Abstract

The application discloses a quasi-two-dimensional blue light perovskite light-emitting diode and a preparation method thereof, and a preparation method thereof. The quasi-two-dimensional blue light perovskite light-emitting diode obtained by using A6BfPBr as an additive suppresses cation diffusion, maximally improves passivation effect, and creates a more solid octahedral network. In addition, the quasi-two-dimensional blue light perovskite light-emitting diode contains long organic chain ammonium salt and a large group separation distance, creates an opportunity for passivation of ammonia and perovskite defect site pairing, and thus improves spectral stability of the material. By adding different proportions of Rb in a perovskite precursor, because the ionic radius of Rb is smaller than that of cesium, Rb + is added into three-dimensional CsPbBr3 perovskite to produce alloyed perovskite Rb x Cs 1‑x PbBr3. Due to octahedral titration, the perovskite has a larger band gap, Rb x Cs 1‑x PbBr3 perovskite is manufactured by a solution method. With the increase of the content of Rb + , the optical band gap of the Rb x Cs 1‑x PbBr3 thin film is increased from 2.31 eV to 2.60 eV.

Description

Technical Field

[0001] This invention relates to the field of perovskite luminescent materials and devices, and in particular to a quasi-two-dimensional blue perovskite luminescent diode and its fabrication method. Background Technology

[0002] Metal halide perovskites (MHPs) are promising new semiconductor materials with advantages such as low cost, spectral tunability, and high photoluminescence quantum yield (PLQYs), offering broad application prospects in optoelectronics. Currently, the highest external quantum efficiency (EQE) of green and red perovskite LEDs exceeds 28%, comparable to traditional OLEDs and QLEDs. However, blue-band LEDs emitting 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 LEDs. Therefore, in promoting the commercialization of PeLEDs, issues such as full width at half maximum (FWHM), reducing efficiency roll-off, and extending device lifetime should be considered.

[0003] Generally, there are two methods to obtain blue PeLEDs. The first method is to add chlorine to a bromide-based perovskite to adjust the band gap. However, these mixed halide perovskites exhibit inherent phase instability, especially at the potential, due to halide migration. Therefore, within minutes of device operation, the electroluminescence (EL) spontaneously changes from blue to green. Almost all PeLEDs based on the mixed halide strategy exhibit rapid decay of the EL. Tunneling the quantum well structure to achieve a dimensionality-reduced (quasi-two-dimensional) perovskite is another effective method for producing blue PeLEDs. Blue light emission can be achieved by keeping the quantum well structure in a very low thickness region (n≤2).

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

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

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

[0007] The present invention achieves the above objectives through the following technical solutions:

[0008] A quasi-two-dimensional blue perovskite light-emitting diode and its fabrication method are disclosed, comprising a substrate 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 quasi-two-dimensional blue perovskite light-emitting diode and its fabrication method, including:

[0010] S1. Place the substrate with the ITO anode printed on it into a mixed solution of anhydrous ethanol and deionized water, and sonicate it for 20 minutes with an ultrasonic machine. Then, blow the liquid on its surface with nitrogen.

[0011] S2. Place the dried substrate with the ITO anode printed on it into the UV cleaning agent and clean it with UV ozone for 15 minutes.

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

[0013] S4. Place the product treated in step S2 into a glove box filled with nitrogen and spin coat it with PVK, and anneal it at 160°C for 30 minutes on a hot plate.

[0014] S5. After cooling after the treatment in S3, spin-coat the perovskite precursor solution onto the PVK film at a speed of 4000 rpm and heat at 100°C for 10 minutes.

[0015] S6. Place the product treated in S5 into the vapor deposition equipment and apply a vacuum. When the air pressure is less than 4 × 10⁻⁶, -4 At pa, TPBi, LiF and Al thin films were deposited by vapor deposition with thicknesses of 80 nm, 1 nm and 100 nm, respectively.

[0016] Furthermore, the preparation of the perovskite precursor solution includes the following steps:

[0017] S51. Prepare a 4 ml glass bottle and weigh out 73.4 mg of PbBr2 and put it in;

[0018] S52. Continue weighing 25.5 mg of CsBr and placing it into a glass bottle;

[0019] S53, Continue weighing 13.23 mg of RbBr and placing it into a glass bottle;

[0020] S54. Continue to weigh 7.54 mg of N-aminohexylbenzo[e]-phthalimide hydrobromide and put it into a glass bottle;

[0021] S55. Continue adding 1 ml of DMSO to the glass bottle;

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

[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 structural formula is:

[0027] .

[0028] The beneficial effects of this invention are as follows:

[0029] (1) A quasi-two-dimensional blue perovskite light-emitting diode obtained by using the long-chain ammonium salt N-aminohexylbenzo[e]-phthalimide hydrobromide (A6BfPBr) as an additive suppresses cation diffusion while maximizing passivation effect and creating a more robust octahedral network. Furthermore, the presence of a long organic chain ammonium salt and a large group separation distance creates opportunities for passivated ammonia to pair with perovskite defect sites, thereby improving the spectral stability of the material.

[0030] (2) By adding different proportions of rubidium (Rb) to the perovskite precursor, because Rb (Rb + The ionic radius of 152 pm is smaller than that of cesium (Cs). + (167 pm). Therefore, Rb + Adding three-dimensional CsPbBr3 perovskite is expected to produce alloyed perovskite Rb x Cs 1-x PbBr3, due to octahedral titration, this perovskite exhibits a larger band gap. Rb x Cs 1-x PbBr3 (0≤x≤1) perovskite is produced by a solution process, with the amount of Rb increasing. + With the increase in content, Rb x Cs 1-x The optical bandgap of the PbBr3 film increased from 2.31 eV to 2.60 eV. Attached Figure Description

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

[0032] The following are labeled in the figure: 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 Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] In the description of this invention, it should be understood that the terms "upper," "lower," "inner," "outer," "left," "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the figure, or the orientation or positional relationship that the product of this invention is usually placed in when in use, or the orientation or positional relationship that is commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0038] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, terms such as "set" and "connection" should be interpreted broadly. 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; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0040] like Figure 1 As shown, a quasi-two-dimensional blue perovskite light-emitting diode and its fabrication method include a substrate 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 quasi-two-dimensional blue perovskite light-emitting diode and its fabrication method, including:

[0042] S1. Place the substrate with the ITO anode printed on it into a mixed solution of anhydrous ethanol and deionized water, and sonicate it for 20 minutes with an ultrasonic machine. Then, blow the liquid on its surface with nitrogen.

[0043] S2. Place the dried substrate with the ITO anode printed on it into the UV cleaning agent and clean it with UV ozone for 15 minutes.

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

[0045] S4. Place the product treated in step S2 into a glove box filled with nitrogen and spin coat it with PVK, and anneal it at 160°C for 30 minutes on a hot plate.

[0046] S5. After cooling after the treatment in S3, spin-coat the perovskite precursor solution onto the PVK film at a speed of 4000 rpm and heat at 100°C for 10 minutes.

[0047] S6. Place the product treated in S5 into the vapor deposition equipment and apply a vacuum. When the air pressure is less than 4 × 10⁻⁶, -4 At pa, TPBi, LiF and Al thin films were deposited by vapor deposition with thicknesses of 80 nm, 1 nm and 100 nm, respectively.

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

[0049] S51. Prepare a 4 ml glass bottle and weigh out 73.4 mg of PbBr2 and put it in;

[0050] S52. Continue weighing 25.5 mg of CsBr and placing it into a glass bottle;

[0051] S53, Continue weighing 13.23 mg of RbBr and placing it into a glass bottle;

[0052] S54. Continue to weigh 7.54 mg of N-aminohexylbenzo[e]-phthalimide hydrobromide and put it into a glass bottle;

[0053] S55. Continue adding 1 ml of DMSO to the glass bottle;

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

[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 structural 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, dry it, and place a clean magnetic stir bar inside. Add 73.4 mg PbBr2, 17 mg CsBr, 19.84 mg RbBr, and 40.4 mg PEABr to the glass bottle, and add 1 ml DMSO as a precursor solution. Stir the solution at room temperature for 12 h, and finally filter it through a 0.22 μm filter before transferring it to a clean glass bottle.

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

[0064] The ITO-printed glass substrate was ultrasonically cleaned with deionized water and anhydrous ethanol for 15 min each, and then treated with ultraviolet ozone for 15 min. Filtered PEDOT:PSS was then spin-coated onto the ITO substrate at 4000 rpm for 40 s as a hole transport layer and annealed at 150°C for 15 min. Next, PVK was dissolved in chlorobenzene at a concentration of 4 mg / ml and spin-coated onto the PEDOT:PSS at 1000 rpm for 40 s as a hole injection layer, and annealed at 160°C for 30 min. A perovskite precursor was spin-coated onto the PVK film at 4000 rpm as a light-emitting layer and annealed at 100°C for 10 min. Finally, the spin-coated substrate was transferred to an evaporator, where TPBi, LiF, and Al were sequentially deposited as electron transport layers and metal electrodes, with thicknesses of 80 nm, 1 nm, and 100 nm, respectively.

[0065] Example 2:

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

[0067] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, dry it, and place a clean magnetic sieve inside. Add 73.4 mg PbBr2, 17 mg CsBr, 19.84 mg RbBr, and 3.77 mg A6BfPBr to the glass bottle, and add 1 ml DMSO as a precursor solution. Stir the solution at room temperature for 12 h, and finally filter it through a 0.22 μm filter before transferring it to a clean glass bottle.

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

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

[0070] Example 3:

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

[0072] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, dry it, and place a clean magnetic sieve inside. Add 73.4 mg PbBr2, 17 mg CsBr, 19.84 mg RbBr, and 7.54 mg A6BfPBr to the glass bottle, and add 1 ml DMSO as a precursor solution. Stir the solution at room temperature for 12 h, and finally filter it through a 0.22 micron filter before transferring it to a clean glass bottle.

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

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

[0075] Example 4:

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

[0077] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, dry it, and place a clean magnetic sieve inside. Add 73.4 mg PbBr2, 17 mg CsBr, 19.84 mg RbBr, and 11.31 mg A6BfPBr to the glass bottle, and add 1 ml DMSO as a precursor solution. Stir the solution at room temperature for 12 h, and finally filter it through a 0.22 μm filter before transferring it to a clean glass bottle.

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

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

[0080] Example 5:

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

[0082] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, dry it, and place a clean magnetic sieve inside. Add 73.4 mg PbBr2, 17 mg CsBr, 19.84 mg RbBr, and 15.09 mg A6BfPBr to the glass bottle, and add 1 ml DMSO as a precursor solution. Stir the solution at room temperature for 12 h, and finally filter it through a 0.22 μm filter before transferring it to a clean glass bottle.

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

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

[0085] Example 6:

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

[0087] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, dry it, and place a clean magnetic sieve inside. Add 73.4 mg PbBr2, 8.5 mg CsBr, 26.46 mg RbBr, and 7.54 mg A6BfPBr to the glass bottle, and add 1 ml DMSO as a precursor solution. Stir the solution at room temperature for 12 h, and finally filter it through a 0.22 μm filter before transferring it to a clean glass bottle.

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

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

[0090] Example 7:

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

[0092] Prepare a 4 ml glass bottle, wash it with deionized water and ethanol, dry it, and place a clean magnetic stir bar inside. Add 73.4 mg PbBr2, 25.5 mg CsBr, 13.23 mg RbBr, and 7.54 mg A6BfPBr to the glass bottle, and add 1 ml DMSO as a precursor solution. Stir the solution at room temperature for 12 h, and finally filter it through a 0.22 μm filter before transferring it to a clean glass bottle.

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

[0094] This part is exactly the same as in 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-two-dimensional perovskite blue LEDs

[0097] As can be seen from Table 1 and the attached figures, with the increase of the amount of A6BfPBr added (Examples 2-5), compared with the quasi-two-dimensional blue light-emitting diodes of PEABr, the electroluminescence wavelength of the device did not shift significantly, but the EQE of the LED device was significantly improved. This is because the presence of a longer organic chain amine salt and a larger group separation distance creates opportunities for passivated amine to pair with perovskite defect sites, thereby forming a higher quality perovskite luminescent material. It is worth noting that by changing the proportion of added RbBr (Examples 6, 3, and 7), the EL emission wavelength of the quasi-two-dimensional perovskite blue LED can be adjusted, achieving spectral tunability.

[0098] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for fabricating a quasi-two-dimensional blue perovskite light-emitting diode, characterized in that, include: S1. Place the substrate with the ITO anode printed on it into a mixed solution of anhydrous ethanol and deionized water, and sonicate it for 20 minutes with an ultrasonic machine. Then, blow the liquid on its surface with nitrogen. S2. Place the dried substrate with the ITO anode printed on it into the UV cleaning agent and clean it with UV ozone for 15 minutes. S3. Spin coat a PEDOT:PSS film onto a clean substrate printed with an ITO anode using a spin coater, and anneal it at 150°C for 15 minutes using a hot plate. S4. Place the product treated in step S2 into a glove box filled with nitrogen and spin coat it with PVK, and anneal it at 160°C for 30 minutes on a hot plate. S5. After cooling after the treatment in S3, spin-coat the perovskite precursor solution onto the PVK film at a speed of 4000 rpm and heat at 100°C for 10 minutes. S6. Place the product treated in S5 into the vapor deposition equipment and apply a vacuum. When the air pressure is less than 4 × 10⁻⁶, -4 TPBi, LiF, and Al thin films were deposited at Pa with thicknesses of 80 nm, 1 nm, and 100 nm, respectively. The preparation of the perovskite precursor solution includes the following steps: S51. Prepare a 4 ml glass bottle and weigh out 73.4 mg of PbBr2 and put it in; S52. Continue weighing 25.5 mg of CsBr and placing it into a glass bottle; S53, Continue weighing 13.23 mg of RbBr and placing it into a glass bottle; S54. Continue to weigh 7.54 mg of N-aminohexylbenzo[e]-phthalimide hydrobromide and put it into a glass bottle; S55. Continue adding 1 ml of DMSO to the glass bottle; S56. Finally, add a stir bar to the glass bottle and place it on a stirring table to stir for 12 hours. The chemical formula of the N-aminohexylbenzo[e]-phthalimide hydrobromide is C 18 H 21 BrN2O2, chemical structural formula is: 。 2. The preparation method according to claim 1, characterized in that, The concentration of PbBr2 in the perovskite precursor solution was 73.4 mg / ml.

3. The preparation method according to claim 1, characterized in that, The concentration of CsBr in the perovskite precursor solution ranged from 0 to 42.56 mg / ml.

4. The preparation method according to claim 1, characterized in that, The concentration of RbBr in the perovskite precursor solution ranged from 0 to 33.07 mg / ml.

5. A method for fabricating a quasi-two-dimensional blue perovskite light-emitting diode using the method described in claim 1, characterized in that, It includes a substrate 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.

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