Branched aliphatic polyether polyol additive-based perovskite film layer and perovskite light-emitting diode

Abstract

The invention discloses a perovskite film layer based on a branched aliphatic polyether polyol additive and a perovskite light-emitting diode, and relates to the technical field of light emitting of diodes. The perovskite film layer provided by the invention comprises a BAPP additive, the grain boundary of the perovskite film is optimized by introducing branched aliphatic polyether polyol (BAPP), the grain boundary in the perovskite film layer is regulated and controlled through a branched chain skeleton connected through an ether bond, a waterproof protection barrier is formed around grains, and the performance of the perovskite film is improved. Meanwhile, defects are passivated by utilizing the coordination effect of a large number of terminal hydroxyl groups or other functional groups and perovskite crystal grains, and the service life of the PeLEDs is prolonged by enhancing the moisture resistance of the perovskite crystal grains. According to the perovskite light-emitting diode provided by the invention, the perovskite film layer is used as the light-emitting layer, and the BAPP is added into the perovskite film layer, so that the moisture resistance is improved, the service life of the PeLEDs is greatly prolonged, and commercial application of the perovskite material and the PeLEDs in the fields of display, illumination, optical communication and the like is effectively promoted.

Description

Technical Field

[0001] The invention relates to the technical field of diode light emitting, and in particular to a perovskite film layer and a perovskite light emitting diode based on a branched fatty polyether polyol additive. Background Art

[0002] In recent years, perovskite semiconductor technology has received widespread attention from researchers around the world, and optoelectronic devices based on perovskite materials have achieved leapfrog development. In terms of light-emitting applications, perovskite materials have the characteristics of easy processing, high luminescence quantum yield, narrow luminescence spectrum, low cost, and compatibility with flexible structures, making them a strong competitor for light-emitting diode technology. At present, the external quantum yield of perovskite light-emitting diodes (PeLEDs) in the blue, green, and red light bands has exceeded 20%, an achievement that has met the needs of commercial applications. However, in terms of lifetime, most of the reported PeLEDs have a half-life (T 50 ) is still at the level of tens to hundreds of hours. How to improve the life of PeLEDs becomes the key to its further commercialization.

[0003] Studies have shown that moisture penetration at grain boundaries is one of the main reasons for the short life of PeLEDs. The wet processing technology of perovskite materials inevitably leads to the existence of a large number of grain boundaries in its film, and the grain boundaries are the penetration channels for external moisture and oxygen. The attenuation starts from here and then spreads to the entire film, causing material failure. At the same time, oxygen and ultraviolet rays with the participation of water molecules will aggravate the degradation of the perovskite layer, further shortening the life of PeLEDs. Therefore, optimizing the grain boundaries in perovskite films and reducing moisture penetration are effective ways to extend the life of devices.

[0004] Additive engineering is an effective method to control the growth of perovskite crystals. It can directly reach the interior of the perovskite film and has the advantages of simple process, high process compatibility and controllable cost. The commonly used method is to introduce linear molecules to fill the grain boundaries, but because the linear polymer molecular chains are long and easy to entangle, the processing performance is poor, and it is easy to crack under the influence of external stress or environmental factors, and the protection effect on the grain boundaries is limited.

[0005] There is an urgent need to find suitable additives to fill grain boundaries and reduce the permeation channels of water and oxygen in perovskite films. Summary of the invention

[0006] The technical problem to be solved by the present invention is to select which additive to effectively reduce the permeation channels of water and oxygen in the perovskite film.

[0007] In order to solve the above problems, the present invention proposes the following technical solutions:

[0008] In a first aspect, the present invention provides a perovskite film layer based on a branched fatty polyether polyol additive, wherein the perovskite film layer includes a BAPP additive, and the structural formula of the BAPP additive is as follows:

[0009]

[0010] In the formula, the R group is -OH, -C n H 2n At least one of OH and cyclic alcohol groups.

[0011] A further technical solution is that the molecular weight of the BAPP additive is 400-10000.

[0012] A further technical solution is that the branching degree of the BAPP additive is 10-60%.

[0013] The perovskite film provided by the present invention contains a BAPP (branched aliphatic polyether polyols, BAPP) additive, and BAPP regulates the grain boundaries in the perovskite film through a branched chain skeleton connected by an ether bond, has good molecular skeleton support and covering ability, forms a water-proof protective barrier around the grains, can effectively reduce the permeation channels of water and oxygen in the perovskite film, and forms an effective hydrophobic barrier around the perovskite grains to block water infiltration. At the same time, the side chain group of BAPP contains a large number of hydroxyl ends that passivate defects through coordination with perovskite grains, which is conducive to slowing down the erosion of water on the grain boundaries. In addition, BAPP has good solubility, rheological properties, and high process compatibility.

[0014] In a second aspect, the present invention also provides a method for preparing the perovskite film layer described in the first aspect, comprising the following steps: adding 1-10wt% of a BAPP additive to a perovskite precursor solution, coating the mixture on a base surface after uniform mixing, drying and forming the mixture, and then annealing the mixture to obtain the perovskite film layer.

[0015] A further technical solution is that the specific operation of the drying and molding is drying at room temperature for 1-10 minutes.

[0016] A further technical solution is that the annealing temperature of the annealing treatment is 40-100° C. and the annealing time is 3-30 minutes.

[0017] A further technical solution is that the perovskite precursor solution comprises a perovskite precursor inorganic salt and a solvent, and the concentration of the perovskite precursor inorganic salt is 1-30wt%.

[0018] A further technical solution is that the solvent is selected from at least one of NMP, MACl and DMF.

[0019] A further technical solution is that the perovskite precursor inorganic salt includes FABr, PbBr 2 、CsI、CsBr 、 PbI 2 , MAI, MABr or at least one of the following.

[0020] In a third aspect, the present invention further provides a perovskite light-emitting diode, comprising the perovskite film layer described in the first aspect, or comprising the perovskite film layer prepared by the preparation method described in the second aspect.

[0021] Compared with the prior art, the technical effects achieved by the present invention include:

[0022] The perovskite film layer based on a branched fatty polyether polyol additive provided by the present invention optimizes the grain boundaries of the perovskite film by introducing a branched fatty polyether polyol (BAPP) as an additive, regulates the grain boundaries in the perovskite film layer through a branched chain skeleton connected by ether bonds, forms a water-proof protective barrier around the grains, and simultaneously utilizes a large number of terminal hydroxyl groups or other functional groups to coordinate with the perovskite grains to passivate defects, thereby enhancing its moisture resistance and improving the life of PeLEDs.

[0023] The present invention adds branched polymer BAPP into the perovskite film layer, which can significantly improve the storage stability of the perovskite film and also help maintain and improve the overall performance of the device.

[0024] The perovskite light-emitting diode provided by the present invention uses a perovskite film layer as a light-emitting layer. Since BAPP is added to the perovskite film layer, the moisture resistance is improved, thereby greatly improving the life of PeLEDs, effectively promoting the commercial application of perovskite materials and PeLEDs in the fields of display, lighting, optical communication, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0026] Figure 1 The performance characterization results of the perovskite film obtained in Example 1 and Comparative Example 1 of the present invention; in the figure, a is the SEM image (top-view) of the perovskite film of Example 1; b is the SEM image (top-view) of the perovskite film of Comparative Example 1; c is the comparison of the luminescent properties of the perovskite film of Example 1 and Comparative Example 1.

[0027] Figure 2 Schematic diagram of the structure of a perovskite light-emitting diode. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Similar component numbers in the drawings represent similar components. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0029] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0030] It should also be understood that the terms used in this description of the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present invention. As used in the description of the embodiments of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms of "a", "an" and "the" are intended to include plural forms.

[0031] The embodiment of the present invention provides a perovskite film layer based on a branched fatty polyether polyol additive, wherein the perovskite film layer includes a BAPP additive, and the structural formula of the BAPP additive is as follows:

[0032]

[0033] In the formula, the R group is -OH, -C n H 2n At least one of OH and cyclic alcohol groups.

[0034] In a specific embodiment, the molecular weight of the BAPP additive is 400-10000, for example, 400, 1000, 1500, 3000, 5000, 8000, 10000.

[0035] In a specific embodiment, the degree of branching of the BAPP additive is 10-60%, such as 10%, 30%, 40%, 60%.

[0036] It should be noted that too low molecular weight and branching degree of BAPP will be detrimental to BAPP filling and grain coating of perovskite grain boundaries, reducing the moisture barrier effect. At the same time, the coordination effect between the peripheral functional groups of BAPP and perovskite becomes weaker, reducing the passivation effect on the surface defects of the perovskite crystal. In addition, the continuous increase in molecular weight will reduce the electrical properties of the perovskite film layer, which is not conducive to the efficiency optimization of optoelectronic devices; at the same time, the degree of branching increases, and the coordination interaction between the peripheral functional groups and the perovskite grains is enhanced. When it increases to a certain extent, it will hinder the grain boundary process of the perovskite grains themselves, thereby affecting the semiconductor properties of the perovskite. Therefore, the molecular weight of BAPP is more suitable in 400-10000, preferably 5000-8000, and the degree of branching is more suitable in 10-60%, preferably 30-50%.

[0037] The amount of BAPP added to the perovskite film is equally important for the morphology of the perovskite film and the resulting device performance. A small amount of BAPP added, such as less than 1wt%, will lead to insufficient effect, while an excessive amount of BAPP added, such as more than 10wt%, will easily cause phase separation between the polymer and the perovskite, resulting in polymer clusters on the film surface, and ultimately reducing device performance. Therefore, when preparing the perovskite film, the amount of BAPP added is preferably 1-10wt%, preferably 3-7wt%.

[0038] The preparation of perovskite film layers usually adopts wet processing technology, such as spin coating, blade coating, inkjet printing, etc., in which the perovskite slurry is coated on the base layer, dried to form a film, and then annealed.

[0039] In a specific embodiment, the coating thickness is 80-200 nm, for example, 80 nm, 120 nm, 150 nm, 180 nm, 200 nm.

[0040] In a specific embodiment, the specific operation of the drying and forming is drying at room temperature for 1-10 minutes, and the thickness of the perovskite film layer after drying is 20-40 nm.

[0041] In a specific embodiment, the annealing temperature of the annealing treatment is 40-100° C., and the annealing time is 3-30 minutes.

[0042] In this embodiment, the perovskite slurry includes a perovskite precursor solution and a BAPP additive, wherein the content of the BAPP additive is 1-10wt%, the perovskite precursor solution contains a perovskite precursor inorganic salt and a solvent, wherein the concentration of the perovskite precursor inorganic salt in the perovskite slurry is 1-30wt%. The solvent is generally composed of NMP, MACl, and DMF, wherein the concentration of NMP in the perovskite slurry is 10-20wt%, the concentration of MACl in the perovskite slurry is 10-15wt%, and the remainder is DMF.

[0043] In a specific embodiment, the perovskite precursor inorganic salt includes FABr, PbBr 2 、CsI、CsBr 、 PbI 2 , MAI, MABr or at least one of the following.

[0044] The present invention also provides a perovskite light emitting diode (PeLEDs). Figure 2 As shown, a multi-layer film stacking structure is adopted, wherein the material of the anode electrode can be selected from FTO, ITO, etc., and the hole transport layer is PEDOT:PSS, NiO, MoO 3 The perovskite material is the perovskite film layer prepared above, and the electron transport layer is TPBi, B 3 PYMPM, BCP, etc.; the cathode electrode uses Ag or Al / LiF mixed materials, etc.

[0045] Example 1

[0046] This embodiment provides a perovskite film layer based on a branched fatty polyether polyol additive and a preparation method thereof.

[0047] Perovskite slurry: 30wt% perovskite precursor inorganic salt (FABr, PbBr 2 ), 5wt% BAPP additive, 20wt% NMP, 15wt% MACl, 30wt% DMF.

[0048] In the BAPP additive, R in the structural formula is a cyclic alcohol group, the molecular weight is 8000, the PDI is 3.3, and the branching degree is 40%.

[0049] The preparation method of the perovskite slurry is: first prepare a perovskite precursor solution, then add the BAPP additive into the perovskite precursor solution, and mix well to obtain the perovskite slurry.

[0050] Preparation method of perovskite film layer: the above perovskite slurry is coated on the surface of the base layer by spin coating process, and dried at room temperature for 1-10 minutes to form a film with a film thickness of 30nm after drying, and then annealed at 80°C in air for 15 minutes to obtain a perovskite film layer.

[0051] Comparative Example 1

[0052] Comparative Example 1 provides a perovskite film layer without additives and a preparation method thereof.

[0053] Perovskite slurry: 30wt% perovskite precursor inorganic salt (FABr, PbBr 2 ), 20wt% NMP, 15wt% MACl, 35wt% DMF.

[0054] The preparation method of the perovskite slurry and the preparation method of the perovskite film layer in Comparative Example 1 are the same as those in Example 1.

[0055] The performance of the perovskite film obtained in Example 1 and Comparative Example 1 was characterized. Figure 1 .

[0056] according to Figure 1 It can be seen from a and b that the perovskite film prepared in Example 1 of the present invention has a more uniform and dense morphology, and basically no harmful "pinholes" can be seen, while the perovskite film prepared in Comparative Example 1 has more harmful "pinholes". These pore structures will become permeation channels for water and oxygen, resulting in poor moisture resistance.

[0057] The perovskite films obtained in Example 1 and Comparative Example 1 were placed in air for 3 months, and the changes in luminous efficiency were detected. Figure 1 . Figure 1 As shown in c, the luminous efficiency of the perovskite film obtained in Example 1 of the present invention did not decrease after being placed in the air for 3 months, while the luminous performance of the perovskite film in Comparative Example 1 decreased significantly.

[0058] Therefore, the perovskite film layer based on the branched fatty polyether polyol additive provided by the present invention contains BAPP, which can construct an effective water barrier by optimizing the grain boundaries of the perovskite film, greatly improving the stability and service life of the perovskite film layer (luminescence), thereby improving the service life of PeLEDs. The present invention effectively solves the stability problem of the device when moisture and oxygen invade the perovskite film layer. By improving the reliability of the perovskite film layer, the present invention can accelerate the commercialization process of these perovskite devices containing perovskite film layers, and has important application potential in the fields of semiconductor display, lighting, optical communication, etc. In addition, due to the good flexibility and low viscosity of the BAPP additive of the present invention, it is also particularly suitable for preparing the light-emitting layer of flexible perovskite devices, providing application possibilities for the development of future flexible display technology.

[0059] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0060] The above is a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A perovskite film layer based on a branched fatty polyether polyol additive, characterized in that: The perovskite film layer includes a BAPP additive, and the structural formula of the BAPP additive is as follows: In the formula, the R group is -OH, -C n H 2n At least one of OH and cyclic alcohol groups.

2. The perovskite film layer according to claim 1, characterized in that: The molecular weight of the BAPP additive is 400-10000.

3. The perovskite film layer according to claim 1, characterized in that: The degree of branching of the BAPP additive is 10-60%.

4. The method for preparing a perovskite film layer according to any one of claims 1 to 3, characterized in that: The following steps are involved: 1-10 wt % of BAPP additive is added to the perovskite precursor solution, mixed evenly and coated on the surface of the base layer, dried and formed, and then annealed to obtain the perovskite film layer.

5. The preparation method according to claim 4, characterized in that: The specific operation of the drying and molding is drying at room temperature for 1-10 minutes.

6. The preparation method according to claim 4, characterized in that: The annealing temperature of the annealing treatment is 40-100° C., and the annealing time is 3-30 minutes.

7. The preparation method according to claim 4, characterized in that: The perovskite precursor solution comprises a perovskite precursor inorganic salt and a solvent, and the concentration of the perovskite precursor inorganic salt is 1-30 wt %.

8. The preparation method according to claim 7, characterized in that: The solvent is selected from at least one of NMP, MACl and DMF.

9. The preparation method according to claim 7, characterized in that: The perovskite precursor inorganic salt includes at least one of FABr, PbBr2, CsI, CsBr, PbI2, MAI, and MABr.

10. A perovskite light-emitting diode, characterized in that: The invention comprises the perovskite film layer according to any one of claims 1 to 3, or comprises the perovskite film layer prepared by the preparation method according to any one of claims 4 to 8.

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