Preparation and application of quasi-two-dimensional perovskite material based on mixed interval strategy

Abstract

The invention is applicable to the technical field of photoelectric device materials, and provides preparation and application of a quasi-two-dimensional perovskite material based on a mixed spacing strategy, according to the method, monoammonium and diammonium cations are mixed to realize an RP-DJ mixed-phase structure, Van der Waals gaps between [PbBr6] 4-octahedrons are reduced, and the performance of the PbBr6-octahedrons is improved. Therefore, the structural rigidity and the carrier transport efficiency of the perovskite material are enhanced. Meanwhile, phase distribution of perovskite is narrowed through introduction of diammonium cations, and energy transfer among different phases is accelerated. And finally, by optimizing the mixing ratio of the two cations, high-brightness, high-stability and high-efficiency blue light emission is realized.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic device materials technology, and particularly relates to the preparation and application of a quasi-two-dimensional perovskite material based on a hybrid spacing strategy. Background Technology

[0002] Quasi-two-dimensional metal halide perovskite materials hold great promise for applications in light-emitting diodes (LEDs) and displays due to their high photoluminescence quantum yield, tunable optical bandgap, excellent color purity, and low-cost solution processability. However, the photoelectric properties of LEDs using perovskite materials as the emitting layer are still far inferior to those of state-of-the-art organic light-emitting diodes (OLEDs). This is mainly due to the uneven phase distribution of perovskite films, resulting in low energy transfer efficiency and excessive non-radiative recombination defects. Furthermore, perovskite materials exhibit poor stability and are prone to n-phase recombination under high-temperature conditions, especially during device operation where the unavoidable Joule heating causes emission peak shifts and rapid performance degradation. These drawbacks severely hinder the further development and application of quasi-two-dimensional perovskite LEDs.

[0003] For quasi-two-dimensional blue perovskite light-emitting diodes (LEDs), there are mainly two structural types: RP phase and DJ phase. Among them, the RP phase structure is the most widely studied, and the maximum external quantum efficiency of RP-based blue perovskite LEDs has reached over 20%. However, due to halide phase separation and van der Waals gaps between different domains, its stability is poor, which remains the main obstacle to its further application. Compared with the RP phase, the DJ phase structure eliminates van der Waals gaps, but the formation energy of the quasi-two-dimensional phase varies with [PbBr6]. 4- The increase in octahedral layers significantly increases the difficulty of forming the intermediate n-phase (e.g., n=3 phase), thus creating an energy transfer gap between the small n-phase and the luminescent phase, which seriously affects the luminous efficiency of the device. Summary of the Invention

[0004] The purpose of this invention is to provide a preparation and application of quasi-two-dimensional perovskite materials based on a hybrid spacing strategy, aiming to solve the problems mentioned in the background art.

[0005] The present invention is implemented as follows: a method for preparing quasi-two-dimensional perovskite materials based on a hybrid spacing strategy includes the following specific steps:

[0006] Step 1: Dissolve 0.15 mmol of 1-pentylamine hydrobromide and 0.075 mmol of 1,5-pentanediamine hydrobromide together with 0.15 mmol of lead bromide and 0.15 mmol of cesium bromide in 1 mL of DMSO (dimethyl sulfoxide) solution to obtain pure RP phase and pure DJ phase perovskite precursor solutions, respectively.

[0007] Step 2: Mix the RP phase and DJ phase precursor solutions at a ratio of 3:1 and stir overnight at 40°C to obtain the perovskite precursor solution.

[0008] Step 3: The perovskite precursor solution was spin-coated onto the substrate surface in three steps: 300 rpm for 5 seconds, 500 rpm for 5 seconds, and 4000 rpm for 80 seconds. In the last 30 seconds, 150 μL of ethyl acetate was added as an antisolvent to guide the crystallization of the perovskite. Annealing was then performed to obtain the quasi-two-dimensional perovskite material.

[0009] In a further technical solution, in step 3, the annealing operation is carried out at a temperature of 90°C for 5 minutes.

[0010] In a further technical solution, in step 3, the annealing operation is performed on the hot plate of the glove box.

[0011] Another objective of this invention is to provide an application of a quasi-two-dimensional perovskite material based on a hybrid spacing strategy, wherein the quasi-two-dimensional perovskite material prepared by the above method is used as a light-emitting layer in a light-emitting diode.

[0012] A further technical solution involves the following steps in the fabrication method of the light-emitting layer of the light-emitting diode:

[0013] Step a: The conductive glass substrate with the etched anode electrode ITO (indium tin oxide) was repeatedly cleaned with deionized water, ethanol and dichloromethane, respectively, and then cleaned with a UV ozone generator for 15 minutes.

[0014] Step b: PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, 1.3-1.7 wt%) aqueous solution was spin-coated onto the substrate surface obtained in step a, and annealed at 150°C for 20 minutes; Step c: PVK (6 mg) was mixed and dissolved in 1 mL of chlorobenzene solution, and deposited onto the substrate surface obtained in step b by spin-coating, and annealed at 150°C for 20 minutes;

[0015] Step d: The perovskite precursor solution was spin-coated onto the substrate surface obtained in step c using a three-step procedure: 300 rpm for 5 s, 500 rpm for 5 s, and 4000 rpm for 80 s. In the last 30 seconds, 150 μL of ethyl acetate was added as an antisolvent to guide the crystallization of the perovskite. The substrate was then annealed on a hot plate at 90°C for 5 minutes in a glove box.

[0016] Step e: Place the thin film obtained in step d into a vapor deposition apparatus to vapor deposit a TPBi electron transport layer (tris(1-phenyl-1H-benzimidazol-2-yl)benzene) and a cathode electrode.

[0017] This invention provides a method for preparing and applying quasi-two-dimensional perovskite materials based on a mixed-spacer strategy. This method mixes monoammonium and diammonium cations to achieve an RP-DJ mixed-phase structure, reducing the [PbBr6] content. 4- The van der Waals gaps between the octahedrons enhance the structural rigidity and carrier transport efficiency of the perovskite material. Simultaneously, the introduction of diammonium cations narrows the phase distribution of the perovskite, accelerating energy transfer between different phases. Ultimately, by optimizing the mixing ratio of the two cations, high brightness, high stability, and high efficiency blue light emission were achieved. Attached Figure Description

[0018] Figure 1 The EQE-current density characteristic curves are for the RP phase, mixed phase, and DJ phase.

[0019] Figure 2 The current density-voltage-luminance characteristic curves for the -RP phase, mixed phase, and DJ phase are shown.

[0020] Figure 3 T for RP phase, mixed phase and DJ phase 50 Atlas;

[0021] Figure 4 The EL spectra of RP phase, mixed phase, and DJ phase devices under different bias voltages are shown. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0024] An embodiment of the present invention provides a method for preparing quasi-two-dimensional perovskite materials based on a hybrid spacing strategy, comprising the following specific steps:

[0025] Step 1: Dissolve 1-pentylamine hydrobromide (0.15 mmol) and 1,5-pentanediamine hydrobromide (0.075 mmol) together with lead bromide (0.15 mmol) and cesium bromide (0.15 mmol) in 1 mL of DMSO (dimethyl sulfoxide) solution to obtain pure RP phase and pure DJ phase perovskite precursor solutions, respectively.

[0026] Step 2: Mix the RP phase and DJ phase precursor solutions at a ratio of 3:1 and stir overnight at 40°C to obtain the perovskite precursor solution.

[0027] Step 3: The perovskite precursor solution was spin-coated onto the substrate surface in three steps: 300 rpm for 5 seconds, 500 rpm for 5 seconds, and 4000 rpm for 80 seconds. In the last 30 seconds, 150 μL of ethyl acetate was added as an antisolvent to guide the crystallization of the perovskite. Annealing was then performed to obtain the quasi-two-dimensional perovskite material.

[0028] In a preferred embodiment of the present invention, in step 3, the annealing temperature is 90°C and the time is 5 minutes.

[0029] In a preferred embodiment of the present invention, in step 3, the annealing operation is performed on the hot plate of the glove box.

[0030] Another embodiment of the present invention provides an application of a quasi-two-dimensional perovskite material based on a hybrid spacing strategy. The quasi-two-dimensional perovskite material prepared by the above method is used as a light-emitting layer in a light-emitting diode.

[0031] In a preferred embodiment of the present invention, the method for preparing the light-emitting layer of the light-emitting diode includes the following steps:

[0032] Step a: The conductive glass substrate with the etched anode electrode ITO (indium tin oxide) was repeatedly cleaned with deionized water, ethanol and dichloromethane, respectively, and then cleaned with a UV ozone generator for 15 minutes.

[0033] Step b: PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, 1.3-1.7 wt%) aqueous solution was deposited onto the substrate surface obtained in step a by spin coating and annealed at 150°C for 20 minutes.

[0034] Step c: PVK (6 mg) was mixed and dissolved in 1 mL of chlorobenzene solution and deposited onto the substrate surface obtained in step b by spin coating, and annealed at 150 °C for 20 minutes;

[0035] Step d: The perovskite precursor solution was spin-coated onto the substrate surface obtained in step c using a three-step procedure: 300 rpm for 5 s, 500 rpm for 5 s, and 4000 rpm for 80 s. In the last 30 seconds, 150 μL of ethyl acetate was added as an antisolvent to guide the crystallization of the perovskite. The substrate was then annealed on a hot plate at 90°C for 5 minutes in a glove box.

[0036] Step e: Place the thin film obtained in step d into a vapor deposition apparatus to vapor deposit a TPBi electron transport layer (tris(1-phenyl-1H-benzimidazol-2-yl)benzene) and a cathode electrode.

[0037] Prepare the RP phase, mixed phase (i.e., the DJ phase) respectively according to the above steps, such as... Figure 1 As shown, it was discovered that perovskite light-emitting diodes based on mixed-phase structures exhibit significantly improved core performance indicators, namely EQE, with a maximum external quantum efficiency reaching 20.8%. Figure 2 As shown, the mixed-phase perovskite light-emitting diode exhibits lower current density and a greater increase in luminous intensity with increasing voltage under the same voltage, indicating a significant improvement in its photoelectric performance. Figure 3 As shown, the T of the mixed-phase device 50 The latency of the RP-phase device increased from 17.8 minutes to 38.7 minutes, while that of the DJ-phase device was only 7.3 minutes, indicating that the mixed-phase strategy improved the device's operational stability. Furthermore, the spectral stability of the device was evaluated by measuring the EL spectrum and calculating the peak shift at different voltages. Figure 4 As shown, the EL spectrum of the RP phase device shifted from 497 nm to 501 nm, but when the driving voltage increased from 3.5 V to 5.2 V, the EL spectra of the mixed-phase and DJ phase devices remained unchanged, indicating that the mixed-phase strategy achieved excellent spectral stability.

[0038] The above description is only a preferred 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 protection scope of the present invention.

Claims

1. A method for preparing quasi-two-dimensional perovskite material based on a mixed spacer strategy, characterized in that, The method comprises the following specific steps: Step 1: 0.15 mmol of 1-pentylamine hydrobromide and 0.075 mmol of 1,5-pentanediamine hydrobromide are respectively dissolved in 1 mL of DMSO solution together with 0.15 mmol of lead bromide and 0.15 mmol of cesium bromide to obtain pure RP phase and pure DJ phase perovskite precursor solutions respectively; Step 2: the RP phase and DJ phase precursor solutions are mixed in a mixing ratio of 3:1, and stirred at 40℃ overnight to obtain a perovskite precursor solution; Step 3: the perovskite precursor solution is spin-coated onto the surface of a substrate by a three-step operation procedure of 300 rpm for 5 s, 500 rpm for 5 s and 4000 rpm for 80 s, and 150 microliters of ethyl acetate is added dropwise as an anti-solvent to guide perovskite crystallization at the last 30 seconds, followed by annealing operation, to obtain a quasi-two-dimensional perovskite material.

2. The method for preparing quasi-two-dimensional perovskite materials based on a hybrid spacing strategy according to claim 1, characterized in that, In the step 3, the temperature of the annealing operation is 90℃, and the time is 5 minutes.

3. The method for preparing quasi-two-dimensional perovskite materials based on a hybrid spacing strategy according to claim 2, characterized in that, In the step 3, the annealing operation is performed on a hot plate in a glove box.

4. Use of a quasi-2D perovskite material based on a hybrid spacer strategy, the quasi-2D perovskite material being prepared according to the method of any one of claims 1 to 3, characterized in that The quasi-two-dimensional perovskite material is applied as a light-emitting layer in a light-emitting diode.

5. The use of a quasi-two-dimensional perovskite material based on a mixed spacer strategy according to claim 4, characterized in that, The preparation method of the light-emitting layer of the light-emitting diode comprises the following steps: Step a: a conductive glass substrate etched with an anode electrode ITO is repeatedly cleaned with deionized water, ethanol and dichloromethane, and then cleaned by an ultraviolet ozone machine for 15 minutes; Step b: a PEDOT:PSS aqueous solution is deposited on the surface of the substrate obtained in step a by spin coating, and annealed at 150℃ for 20 minutes; Step c: 6 mg of PVK is mixed in 1 mL of chlorobenzene solution, and deposited on the surface of the substrate obtained in step b by spin coating, and annealed at 150℃ for 20 minutes; Step d: the perovskite precursor solution is spin-coated onto the surface of the substrate obtained in step c by a three-step operation procedure of 300 rpm for 5 s, 500 rpm for 5 s and 4000 rpm for 80 s, and 150 microliters of ethyl acetate is added dropwise as an anti-solvent to guide perovskite crystallization at the last 30 seconds, followed by annealing at 90℃ on a hot plate in a glove box for 5 minutes; Step e: the thin film obtained in step d is placed in an evaporation instrument to evaporate a TPBi electron transport layer and a cathode electrode.

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