CN112018253B

CN112018253B - Based on Mg 2+ Preparation method of blue light-emitting diode of doped quasi-two-dimensional perovskite material

Info

Publication number: CN112018253B
Application number: CN202010906301.6A
Authority: CN
Inventors: 胡俊涛; 林钰涵; 吴涵; 罗派峰; 许凯; 王向华
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2020-09-01
Filing date: 2020-09-01
Publication date: 2022-09-30
Anticipated expiration: 2040-09-01
Also published as: CN112018253A

Abstract

The invention discloses a method based on Mg ²⁺ A method for preparing a blue light-emitting diode doped with a quasi-two-dimensional perovskite material belongs to the technical field of perovskite light-emitting device preparation processes, and Mg is doped ²⁺ PEA of (A) ₂ CsPb ₂ Br ₇ The film is used as a luminescent layer to prepare blue-light PeLEDs. Due to doped Mg ²⁺ Substitution of Pb in perovskite lattices ²⁺ Resulting in a broadening of the band gap and a blue shift of the spectrum. And, doped with Mg ²⁺ The formation energy of the surface defects of the perovskite crystal is increased, the formation of defect states is effectively inhibited, the non-radiative recombination is reduced, and the efficiency of the device is improved.

Description

Based on Mg 2+ Preparation method of blue light-emitting diode of doped quasi-two-dimensional perovskite material

Technical Field

The invention relates to the technical field of perovskite luminescent device preparation processes, in particular to a perovskite luminescent device based on Mg ²⁺ A method for preparing a blue light emitting diode doped with a quasi-two-dimensional perovskite material comprises doping a blue light emitting diode with Mg ²⁺ Quasi-two-dimensional perovskite PEA of ₂ CsPb ₂ Br ₇ The blue perovskite light emitting diode is prepared as a light emitting layer.

Background

In recent years, perovskite has been widely paid attention to in the field of light emitting diodes due to the characteristics of adjustable light emitting spectrum, high luminescent color purity, high fluorescence quantum efficiency and the like. At present, great progress has been made in the research on perovskite light emitting diodes (PeLEDs), the external quantum phase rate of which has reached more than 20%. However, it is still a challenge to realize stable and efficient blue-light PeLED compared with green light and red light. Compared with the traditional three-dimensional perovskite, the quasi-two-dimensional perovskite has the advantages of higher stability in a water-oxygen environment, and higher exciton binding energy and carrier recombination efficiency. In addition, because the size of the quasi-two-dimensional perovskite crystal particle is smaller, and the quantum confinement effect is added, the spectrum of the quasi-two-dimensional perovskite crystal particle can generate blue shift, and the quasi-two-dimensional perovskite crystal particle is a favorable material for preparing blue-light Peleds.

The commonly used method for preparing blue PeLEDs is to use perovskite mixed with chloride ions and bromide ions as the light-emitting layer. However, under the action of an electric field, the perovskite is separated into a chlorine-rich phase and a bromine-rich phase due to ion migration, so that the spectrum changes along with the voltage, and the spectral stability and efficiency of the blue-light PeLEDs are influenced. The other method is to dope macromolecular organic cations in the full-bromine quasi-two-dimensional perovskite to widen the band gap and realize a blue light device. However, the incorporation of macromolecular organic cations can degrade the conductivity of the quasi-two-dimensional perovskite, thereby affecting device efficiency.

Disclosure of Invention

The invention aims to make up for the defects of the prior art and provides a Mg-based alloy ²⁺ The preparation method of the blue light-emitting diode of the doped quasi-two-dimensional perovskite material is to prepare the blue light-emitting diode by using the PEA of the quasi-two-dimensional perovskite ₂ CsPb ₂ Br ₇ Middle doped with Mg ²⁺ A high efficiency blue light emitting diode is obtained.

The invention is realized by the following technical scheme:

based on Mg ²⁺ The preparation method of the blue light-emitting diode of the doped quasi-two-dimensional perovskite material comprises the following steps:

(1) cleaning an ITO glass substrate:

sequentially using ITO cleaning fluid and clear water to carry out ultrasonic treatment on the ITO glass substrate for 10min, then using nitrogen to blow dry, and placing on a heating table at 120 ℃ for 10 min;

(2) carrying out ultraviolet ozone treatment on the ITO glass substrate:

placing the ITO glass substrate treated in the step (1) in an ultraviolet light cleaning machine for treatment for 15 min;

(3) spin coating a hole injection layer:

and (3) spin-coating PEDOT on the ITO glass substrate treated in the step (2): PSS is used as a hole injection layer, spin-coating is carried out at the rotating speed of 2500rap for 60s, and then annealing is carried out on a heating table at the temperature of 120 ℃ for 15-20 min;

(4) preparing a quasi-two-dimensional perovskite precursor solution:

reacting PbBr ₂ CsBr and PEABr are dissolved in anhydrous DMSO according to the molar ratio of 2:1:2, and the mixture is placed on a hot table at 70 ℃ to be stirred for 2 hours to obtain PEA ₂ CsPb ₂ Br ₇ Precursor solution;

(5) spin coating a light emitting layer:

transferring the ITO glass substrate treated in the step (1) to a glove box, and spin-coating the ITO glass substrate doped with Mg ²⁺ The perovskite layer of (a). In the step, MgBr is firstly added ₂ Dissolving in anhydrous DMSO, and doping with PEA ₂ CsPb ₂ Br ₇ In the precursor solution, here we dope with Mg ²⁺ Molar amount of Mg ²⁺ And Pb ²⁺ The total molar amount ratios were 0,10% and 20%, respectively. The spin speed used during spin coating was 3000rap, and the spin coating time was 60 s. After spin coating, the ITO glass substrate is placed on a hot table and annealed at 70 ℃ for 5 min;

(6) evaporating an electron transport layer, an electron injection layer and a cathode:

and (4) transferring the ITO glass substrate treated in the step (3) into a vacuum coating machine, and sequentially evaporating TPBi, LiF and Al, wherein the thicknesses are 40nm, 1nm and 100nm respectively. And taking out the device after the evaporation is finished, and packaging the device.

The principle of the invention is as follows: the quasi-two-dimensional perovskite crystal particle size is smaller, and the spectrum of the quasi-two-dimensional perovskite crystal particle is subjected to blue shift due to the quantum confinement effect, so that the quasi-two-dimensional perovskite crystal particle is an advantageous material for preparing a blue light-emitting diode. Doping with Mg ²⁺ Part of Pb in the perovskite lattice ²⁺ Is coated with Mg ²⁺ Substitution results in a broadening of the band gap and a further blue-shift of the spectrum. Mg (magnesium) ²⁺ The doping of the perovskite crystal increases the formation energy of the surface defects of the perovskite crystal, effectively reduces the surface defects, thereby reducing the non-radiative recombination and improving the performance of the device.

The invention has the advantages that: the invention adopts the quasi-two-dimensional perovskite as the luminescent layer of the device, which has higher stability in the water-oxygen environment and higher exciton binding energy and carrier recombination efficiency; mixing Mg ²⁺ The doped perovskite is doped into quasi-two-dimensional perovskite, and the surface defects of the perovskite thin film are passivated while the spectrum blue shift is carried out, so that the performance of the device is further improved. Pb ²⁺ Is coated with Mg ²⁺ Substitution, reduction of Pb ²⁺ The content is more beneficial to environmental protection.

Drawings

Fig. 1 is a block diagram of the device.

FIG. 2 is a PL diagram of perovskite thin films with different doping concentrations.

FIG. 3 is a diagram of the ultraviolet absorption spectrum of perovskite thin film with different doping concentrations.

Detailed Description

The following provides a detailed description of embodiments of the invention. The embodiment provides a detailed implementation mode and a specific operation process based on the technical scheme of the invention. The scope of the present invention includes, but is not limited to, the following examples.

Based on Mg in practice ²⁺ The preparation method of the blue light-emitting diode doped with the quasi-two-dimensional perovskite material comprises the following steps:

(1) cleaning an ITO glass substrate:

sequentially using ITO cleaning liquid and clear water to carry out ultrasonic treatment on the ITO glass substrate for 10min, then using nitrogen to blow dry, and placing on a heating table at 120 ℃ for 10 min.

(2) Carrying out ultraviolet ozone treatment on the ITO glass substrate:

and (2) placing the ITO glass substrate treated in the step (1) in an ultraviolet light cleaning machine for treatment for 15min, wherein the step can effectively decompose organic matter residues on the surface of the ITO glass substrate and improve the work function of the surface of the ITO glass substrate.

(3) Spin coating a hole injection layer:

the hole injection layer is made of PEDOT: PSS, spin coating speed is 2500rap, time is 60s, film thickness is 40nm, and after the spin coating is finished, the film is placed on a 120 ℃ hot bench for annealing for 15-20 min.

(4) Preparing a quasi-two-dimensional perovskite precursor solution:

reacting PbBr ₂ Dissolving CsBr and PEABr in anhydrous DMSO at a molar ratio of 2:1:2, and stirring at 70 deg.C for 2 hr to obtain PEA ₂ CsPb ₂ Br ₇ And (3) precursor solution.

(5) Spin coating a light emitting layer:

transferring the ITO glass substrate treated in the step (3) to a glove box, and spin-coating the ITO glass substrate doped with Mg ²⁺ The perovskite layer of (a). In the step, MgBr is firstly added ₂ Dissolving in anhydrous DMSO at a concentration of 25Mg/mL, respectively as Mg ²⁺ Molar weight of Mg ²⁺ And Pb ²⁺ The ratio of the total molar amount of 0,10% and 20% is PEA ₂ CsPb ₂ Br ₇ Precursor solution and MgBr ₂ The solutions were mixed. The spin speed was 3000rap for 60 s. After spin coating, the ITO glass substrate is placed on a hot bench and annealed at 70 ℃ for 5 min. PL and uv absorption spectra of the perovskite thin film as shown in fig. 2 and 3, which have a plurality of absorption peaks and PL peaks, indicate that the perovskite thin film prepared has a layered structure. Due to Mg ²⁺ Doping to replace part of Pb in perovskite lattice ²⁺ Resulting in broadening of band gap and hence in doping of Mg ²⁺ The late PL peak was significantly blue shifted.

and sequentially evaporating TPBi, LiF and Al which are respectively used as an electron transport layer, an electron injection layer and a cathode, wherein the thicknesses of the electron transport layer, the electron injection layer and the cathode are respectively 40nm, 1nm and 100nm, and packaging the device after evaporation. The device structure is shown in fig. 1.

Claims

1. Based on Mg ²⁺ The preparation method of the blue light-emitting diode of the doped quasi-two-dimensional perovskite material is characterized by comprising the following steps of:

(1) spin-coating a hole injection layer material on an ITO glass substrate, and annealing for 15-20 min at a temperature of 120 ℃ to obtain a hole injection layer;

(2) subjecting PEA to ₂ CsPb ₂ Br ₇ Precursor solution and MgBr ₂ Mixing the DMSO solution to obtain Mg ²⁺ Doped PEA ₂ CsPb ₂ Br ₇ Precursor solution; mixing the obtained Mg ²⁺ Doped PEA ₂ CsPb ₂ Br ₇ Spin-coating the precursor solution to the surface of the hole injection layer in the step (1), and annealing for 5min at a 70 ℃ hot stage to obtain a light-emitting layer;

(3) and (3) sequentially evaporating an electron transport layer, an electron injection layer and a cathode on the surface of the luminescent layer in the step (2).

2. Mg-based according to claim 1 ²⁺ The preparation method of the blue light-emitting diode of the doped quasi-two-dimensional perovskite material is characterized by comprising the following steps of: in the step (1), the hole injection layer is made of poly (3, 4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT: PSS).

3. Mg-based according to claim 1 ²⁺ The preparation method of the blue light-emitting diode of the doped quasi-two-dimensional perovskite material is characterized by comprising the following steps of: the rotating speed of the spin coating of the hole injection layer material in the step (1) is 2500rap, and the time is 60 s.

4. Mg-based according to claim 1 ²⁺ The preparation method of the blue light-emitting diode of the doped quasi-two-dimensional perovskite material is characterized by comprising the following steps of: PEA described in step (2) ₂ CsPb ₂ Br ₇ The preparation method of the precursor solution is to mix PbBr ₂ CsBr and PEABr in a molar ratio of 2:1:2 in anhydrous DMSO, and stirring the solution on a hot plate at 70 ℃ for 2 hours to obtain PEA ₂ CsPb ₂ Br ₇ And (3) precursor solution.

5. The Mg-based of claim 1 ²⁺ The preparation method of the blue light-emitting diode of the doped quasi-two-dimensional perovskite material is characterized by comprising the following steps of: mg described in the step (2) ²⁺ Doped PEA ₂ CsPb ₂ Br ₇ Mg in precursor solution ²⁺ Molar amount of Mg ²⁺ And Pb ²⁺ The total molar amount ratios were 10% and 20%, respectively.

6. Mg-based according to claim 1 ²⁺ The preparation method of the blue light-emitting diode of the doped quasi-two-dimensional perovskite material is characterized by comprising the following steps of: adding Mg as described in step (2) ²⁺ Doped PEA ₂ CsPb ₂ Br ₇ Spin coating rotation speed of precursor solution to surface of hole injection layer3000rap for 60 s.

7. Mg-based according to claim 1 ²⁺ The preparation method of the doped quasi-two-dimensional perovskite material blue light-emitting diode is characterized by comprising the following steps of: in the step (3), the electron transport layer is TPBi, the electron injection layer is LiF, the cathode is Al, and the thicknesses of the electron transport layer, the electron injection layer and the cathode are respectively 40nm, 1nm and 100 nm.