Mixed A-site cation chiral perovskite diode and preparation method thereof

Abstract

The invention discloses a mixed A-site cation chiral perovskite diode and a preparation method thereof, and relates to the field of electroluminescent technology and manufacturing. The device mainly comprises a cathode, a light-emitting layer, an anode, an electron transport layer and a hole transport layer. A chiral factor is introduced into a traditional perovskite LED device in a mixed A-bit mode, and the LED device capable of directly emitting polarized light is prepared. Compared with an existing commercial CP-LED indirect polarized light emission mode, the efficiency can be better improved, the structure can be better simplified through a direct mode, the characteristic can still be kept after part of chiral cations are introduced, the luminous efficiency of the CP-LED is improved, the color purity is high, and the adjustable luminous wavelength can be achieved by adjusting and controlling the proportion of doped chiral cations.

Description

Technical Field

[0001] The present invention relates to the field of electroluminescence technology and manufacturing, and in particular to a mixed A-site cation chiral perovskite diode and a preparation method thereof. Background Art

[0002] In the field of electroluminescent technology, light-emitting diodes (LEDs) are devices with excellent performance, which are particularly common in daily life, and are widely used in the fields of lighting and imaging. As researchers continue to deepen their research, the types of LEDs have become richer, such as organic light-emitting diodes (OLEDs), quantum dot light-emitting diodes (QLEDs), perovskite light-emitting diodes (PeLEDs), etc. Compared with ordinary LEDs, circularly polarized light-emitting diodes (CP-LEDs) have received widespread attention in related technical fields this year because they can emit circularly polarized light (CPL) that is closer to natural light. They are committed to developing an LED device with better visual experience and comfort. Currently, most commercial LED devices that can emit circularly polarized light obtain this polarized light by fixing a polarizer in front of the light source. This secondary processing method will not only cause the device to lose some brightness and reduce the efficiency of the device, but also increase the complexity of the LED device structure. Therefore, developing an LED that can directly emit circularly polarized light without secondary processing and simplifying the device structure is one of the goals of the next generation of energy-saving lighting and vivid display devices in the future.

[0003] Common LED devices are mainly divided into two structures: Formal structure: anode, hole transport layer, light-emitting layer, electron transport layer, cathode. Transverse structure: cathode, electron transport layer, light-emitting layer, hole transport layer, anode. There are three main ways to process the light-emitting layer: (1) Introducing an additional chiral molecular layer: By adding an additional chiral functional layer to introduce chirality into the device, the chiral molecular layer of this method is difficult to control, and the introduction of an additional new functional layer will lead to energy level mismatch between the upper and lower functional layers, which often fails to achieve the desired effect; (2) Replacing electrodes: By replacing the traditional metal cathode and anode with ferromagnetic electrodes, the device prepared in this way can also directly emit circularly polarized light, but the operating environment requirements of the device are extremely high, requiring low temperature and external strong magnetic field, which undoubtedly increases the operating cost of the device and raises the threshold for device preparation, which goes against the original intention of the next generation of energy-saving, low-cost lighting and display devices. (3) Adding an ordered chiral perovskite functional layer: A layer of ordered chiral perovskite functional layer can be inserted between the hole transport layer and the light-emitting layer or the electron transport layer and the light-emitting layer to introduce chirality. This method is similar to the first method, and still has the problem of energy level mismatch after the introduction of new functional layers. At the same time, the introduced functional layers must be arranged in an orderly manner, which undoubtedly increases the difficulty and complexity of the preparation of CP-LED devices. Summary of the invention

[0004] The purpose of the present invention is to overcome one or more deficiencies of the prior art and to provide a mixed A-site cation chiral perovskite diode and a preparation method thereof, which can directly emit polarized light by innovating the light-emitting layer.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A mixed A-site cation chiral perovskite diode and a preparation method thereof, wherein the functional layers of the diode include: a cathode, an electron transport layer, a light-emitting layer, a hole transport layer and an anode;

[0007] The diode comprises: a cathode, an electron transport layer, a light emitting layer, a hole transport layer and an anode connected in sequence; the anode and the cathode are used to connect the positive electrode and the negative electrode of the power supply respectively;

[0008] The hole transport layer is made of conductive polymer PEDOT:PSS (poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate).

[0009] The light-emitting layer is injected with mixed A-site cations by hot injection, and the material used for the mixed A-site cations is perovskite FAPbBr3;

[0010] Preferably, the hole transport layer may be made of a conductive polymer PVK (poly (9-vinyl carbazole)).

[0011] Preferably, the electron transport layer is made of a conductive polymer TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene).

[0012] Preferably, the material of the sub-electrical transport layer may be lithium fluoride (LiF).

[0013] Preferably, the anode is ITO conductive glass, ITO is attached to the glass, the thickness of ITO is 0-0.70mm, and the resistance is 15Ωsq -1 .

[0014] Preferably, the doped chiral molecule is R / S-methylbenzylamine (R / S-MBA).

[0015] A method for preparing a mixed A-site cation chiral perovskite diode is provided, the method comprising the steps of operating the following functional layers:

[0016] Operate on each functional layer separately:

[0017] Anode: ultrasonically clean the ITO glass using detergent, deionized water, acetone, and isopropanol in sequence, then blow dry with nitrogen and clean with a plasma cleaner for 5 minutes at a power of 120W;

[0018] Hole transport layer: PEDOT:PSS was spin-coated onto ITO at 3000 rpm / 40 s using a spin coater and annealed at 120 °C in air for 30 min. PVK:poly-9-vinylcarbazole chlorobenzene solution was spin-coated onto PEDOT:PSS at 4000 rpm / 40 s and annealed at 170 °C in a nitrogen glove box for 30 min.

[0019] Light-emitting layer: The processed quantum dots were spin-coated onto the PVK film at a speed of 1000 rpm / 40 s and annealed at 70 °C for 10 min;

[0020] Electron transport layer and cathode: 35 nm TPBi, 1 nm LiF and 80 nm Al were deposited in sequence using a thermal evaporation system;

[0021] Finally, the various functional layers are connected in the order of cathode, electron transport layer, light-emitting layer, hole transport layer and anode to make a device.

[0022] Preferably, the functional layer may be introduced by spin coating, thermal evaporation or drop coating.

[0023] The beneficial effects of the present invention are:

[0024] (1) Introducing chirality into traditional perovskite LED devices by mixing A sites;

[0025] (2) We prepared an LED device that can directly emit polarized light. Compared with the indirect emission of polarized light by existing commercial CP-LEDs, the direct emission can better improve efficiency and simplify the structure.

[0026] (3) The light-emitting layer of the device can maintain the narrow half-width and high color purity of perovskite after introducing some chiral cations, which improves the luminous efficiency of CP-LED and increases the color purity.

[0027] (4) The present invention can achieve adjustable luminescence wavelength by adjusting the ratio of doped chiral cations. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the main structure of the perovskite CP-LED device based on A-site mixed cations;

[0029] Figure 2 This is a SEM image of the cross section of a perovskite CP-LED device based on mixed cations at the A site;

[0030] Figure 3 The luminescence photo and luminescence wavelength diagram of the CP-LED device prepared in the embodiment;

[0031] Figure 4 JVL curve diagram of the CP-LED device prepared in Example;

[0032] Figure 5 The working life T of the CP-LED device prepared in the embodiment 50 Graphs;

[0033] Figure 6 CP-EL diagram of the CP-LED device prepared in Example;

[0034] Figure 7 This is a diagram of the circularly polarized luminescence asymmetry factor of the CP-LED device prepared in the example. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0036] A-site cation doping refers to doping R / S-MBA into perovskite in a certain proportion for application in LED devices; for the selection of perovskite system, organic system is preferred; most perovskite systems are applicable, and in this embodiment, FAPbBr3 system is further preferred.

[0037] See also Figure 1 , which is the basic structure of a mixed A-site cation chiral perovskite diode, wherein the functional layers of the diode include: a cathode, an electron transport layer, a light-emitting layer, a hole transport layer and an anode;

[0038] The diode comprises: a cathode, an electron transport layer, a light emitting layer, a hole transport layer and an anode connected in sequence; the anode and the cathode are used to connect the positive electrode and the negative electrode of the power supply respectively;

[0039] The hole transport layer is made of conductive polymer PEDOT:PSS: poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate;

[0040] The light-emitting layer is injected with mixed A-site cations by hot injection, and the material used for the mixed A-site cations is perovskite FAPbBr3.

[0041] The anode is preferably ITO conductive glass, the hole transport layer is preferably conductive polymer PEDOT:PSS (poly 3,4-ethylenedioxythiophene / polystyrene sulfonate) and PVK (poly (9-vinyl carbazole)), the electron transport layer is conductive polymer TPBi (1,3,5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene) and lithium fluoride (LiF), and the cathode is preferably metal Al.

[0042] See also Figure 2 In this embodiment, the glass substrate used in the CP-LED device has a size of 1.6 1.6cm, ITO size is 1.6 0.6cm, the top silvery-white material is the cathode Al, device cross section Figure 2 and Figure 1 Corresponding to the structural diagram in FIG.

[0043] Example

[0044] Perovskite LED is used to demonstrate the technical effect of the CP-LED device of the present invention.

[0045] Anode: ITO glass was ultrasonically cleaned using detergent, deionized water, acetone, and isopropanol in sequence, then dried with nitrogen and cleaned with a plasma cleaner for 5 minutes at a power of 120 W.

[0046] Hole transport layer: PEDOT:PSS was spin-coated onto ITO at 3000 rpm / 40 s using a spin coater and annealed at 120 °C in air for 30 min. PVK (poly(9-vinylcarbazole)) chlorobenzene solution (6 mg·mL-1) was spin-coated onto PEDOT:PSS at 4000 rpm / 40 s and annealed at 170 °C in a nitrogen glove box for 30 min.

[0047] Light-emitting layer: The processed quantum dots were spin-coated onto the PVK film at a speed of 1000 rpm / 40 s and annealed at 70°C for 10 min.

[0048] Electron transport layer and cathode: 35 nm TPBi, 1 nm LiF and 80 nm Al were deposited in sequence using a thermal evaporation system.

[0049] Finally, the functional layers are connected in the order of cathode, electron transport layer, light-emitting layer, hole transport layer and anode to produce the mixed A-site cation chiral perovskite diode device of this embodiment.

[0050] See also Figure 3 , which are the luminescence photographs and luminescence wavelength diagrams of the CP-LED device prepared in this embodiment. After being doped with chiral molecules, its electroluminescence peak is around 517nm.

[0051] See also Figure 4 , showing the JVL curve of the CP-LED device prepared in this example, the maximum brightness is 2605Cd / m -2 .

[0052] See also Figure 5 , showing the working life T of the CP-LED device prepared in this example 50 Curve graph, initial brightness adjusted to 300 Cd / m -2 All devices were operated in constant current density mode (J=6.25 mA / cm -2 ) test, the tested T 50 is 108 s.

[0053] See also Figure 6 , Figure 7 At the same time, the device can produce circularly polarized light after detection. The schematic diagram of circularly polarized light is shown in Figure 6 As shown, the circularly polarized luminescence asymmetry factor diagram is as follows Figure 7 As shown, compared with the traditional perovskite LED device, the CP-LED device of this embodiment has excellent circularly polarized luminescence performance, and the asymmetry factor can reach 2 10 -4 .

[0054] Compared with the traditional perovskite LED device, the chiral factor is introduced by mixing the A position, and the LED device that can directly emit polarized light is prepared. Compared with the indirect emission of polarized light by the existing commercial CP-LED, the direct method can better improve the efficiency and simplify the structure, so that the light-emitting layer of the manufactured device can still maintain this characteristic after introducing some chiral cations with the help of the narrow half-width and high color purity of the perovskite, so that the luminous efficiency of the CP-LED is improved, the color purity is high, and the adjustable emission wavelength can be achieved by adjusting the proportion of doped chiral cations.

[0055] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A mixed A-site cation chiral perovskite diode, characterized in that: The functional layers of the diode include: a cathode, an electron transport layer, a light emitting layer, a hole transport layer and an anode; The diode comprises: a cathode, an electron transport layer, a light emitting layer, a hole transport layer and an anode connected in sequence; the anode and the cathode are used to connect the positive electrode and the negative electrode of the power supply respectively; The hole transport layer is made of conductive polymer PEDOT:PSS: poly (3,4-ethylenedioxythiophene) / polystyrene sulfonate; The light-emitting layer is injected with mixed A-site cations by hot injection, and the material used for the mixed A-site cations is perovskite FAPbBr3.

2. The mixed A-site cation chiral perovskite diode according to claim 1, characterized in that: The hole transport layer material can be a conductive polymer PVK: poly 9-vinyl carbazole.

3. The mixed A-site cation chiral perovskite diode according to claim 1, characterized in that: The material of the electron transport layer is a conductive polymer TPBi: 1,3,5-tri,1-phenyl-1H-benzimidazol-2-yl, benzene.

4. The mixed A-site cation chiral perovskite diode according to claim 1, characterized in that: The material of the sub-electrical transport layer is lithium fluoride.

5. The mixed A-site cation chiral perovskite diode according to claim 1, characterized in that: The anode is ITO conductive glass, ITO is attached to the glass, the thickness of ITO is 0-0.70mm, and the resistance is 15Ωsq -1 .

6. The mixed A-site cation chiral perovskite diode according to claim 1, characterized in that: The doped chiral molecule is R / S-methylbenzylamine.

7. A method for preparing a mixed A-site cation chiral perovskite diode, characterized in that: The method steps include the following steps of operating the following functional layers: Operate on each functional layer separately: Anode: ultrasonically clean the ITO glass using detergent, deionized water, acetone, and isopropanol in sequence, then blow dry with nitrogen and clean with a plasma cleaner for 5 minutes at a power of 120W; Hole transport layer: PEDOT:PSS was spin-coated onto ITO at 3000 rpm / 40 s using a spin coater and annealed at 120 °C in air for 30 min. PVK:poly-9-vinylcarbazole chlorobenzene solution was spin-coated onto PEDOT:PSS at 4000 rpm / 40 s and annealed at 170 °C in a nitrogen glove box for 30 min. Light-emitting layer: The processed quantum dots were spin-coated onto the PVK film at a speed of 1000 rpm / 40 s and annealed at 70 °C for 10 min; Electron transport layer and cathode: 35 nm TPBi, 1 nm LiF and 80 nm Al were deposited in sequence using a thermal evaporation system; Finally, the various functional layers are connected in the order of cathode, electron transport layer, light-emitting layer, hole transport layer and anode to make a device.

8. The method for preparing a mixed A-site cation chiral perovskite diode according to claim 7, characterized in that: The method of introducing the functional layer also includes: spin coating, thermal evaporation and drop coating.

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