Interface modification layer prepared from alkali metal compound with multiple hydrophilic groups and application of interface modification layer

Abstract

The invention relates to the technical field of photovoltaic cells, and provides an interface modification layer made of an alkali metal compound with multiple hydrophilic groups and application of the interface modification layer, and the material of the interface modification layer made of the alkali metal compound with the multiple hydrophilic groups comprises an alkali metal organic compound with at least two hydrophilic groups, an alkali metal group in the alkali metal organic compound is used for passivating interface defects of the perovskite layer, and a hydrophilic group is used for weakening hydrophobicity of an upper interface of the SAM layer. By using the interface modification layer, the problems that defects exist at the interface between the SAM layer and the perovskite layer, and the defects can capture current carriers to cause energy loss, charge transfer efficiency reduction and the like can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic cells, in particular to an alkali metal compound with multiple hydrophilic groups as an interface modification layer and its application. Background Art

[0002] Inverse perovskite solar cells (PSCs), owing to their high efficiency, low cost, and lightweight design, have seen rapid development in recent years, achieving a record-breaking photoelectric conversion efficiency of 26.14% in just over a decade. However, defects at the interface between the perovskite layer and the self-assembled monolayer (SAM) have been a key factor hindering performance improvements.

[0003] In inverse perovskite solar cells, the SAM layer typically serves as an electron transport layer or hole blocking layer, while the perovskite layer is the main region for light absorption and charge separation. Due to the physical and chemical differences between the SAM layer and the perovskite layer, a large number of defects often exist at the interface, which can trap carriers, leading to energy loss and reduced charge transport efficiency.

[0004] Existing modification strategies often require high temperatures, which can adversely affect the stability and structure of the SAM layer. For example, high-temperature processes may cause the SAM molecules to decompose or reconstruct, thereby affecting their interaction with the perovskite layer. The complexity of interface defects makes it difficult for a single modification strategy to achieve the desired effect. Different defects have different mechanisms of influence on charge transport, so targeted optimization is required for different types of defects. However, existing modification methods often have difficulty in simultaneously addressing multiple types of defects. Summary of the Invention

[0005] The present invention aims to address defects at the interface between the SAM layer and the perovskite layer, which trap carriers, leading to energy loss and reduced charge transfer efficiency. The present invention provides an alkali metal compound with multiple hydrophilic groups as an interface modification layer and its application. The alkali metal groups passivate iodine vacancy defects at the perovskite interface, inhibiting non-radiative carrier recombination at the interface. The multiple hydrophilic groups can reduce the hydrophobicity of the SAM layer through polarity, improving the wettability of the perovskite precursor solution at the interface and reducing pinhole defects during film formation. The hydrophilic groups interact with the molecules in the SAM layer, enhancing interlayer adhesion and preventing interfacial delamination during solution processing.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An alkali metal compound with multiple hydrophilic groups is used as an interface modification layer. The material of the lower interface modification layer includes an alkali metal organic compound with at least two hydrophilic groups. The alkali metal groups in the alkali metal organic compound are used to passivate the interface defects of the perovskite layer, and the hydrophilic groups are used to weaken the hydrophobicity of the upper interface of the SAM layer.

[0008] The present invention adopts an alkali metal compound with multiple hydrophilic groups as an interface modification layer. The alkali metal groups passivate the iodine vacancy defects at the perovskite interface and inhibit the non-radiative recombination of carriers at the interface. The multiple hydrophilic groups can reduce the hydrophobicity of the SAM layer through polarity, improve the wettability of the perovskite precursor solution at the interface, and reduce pinhole defects in the film formation process. The hydrophilic groups form an interactive force with the SAM layer molecules, enhance the interlayer adhesion, and avoid interface peeling during solution processing.

[0009] As a preferred embodiment of the present invention, the alkali metal in the alkali metal organic compound includes potassium, sodium, rubidium or cesium.

[0010] As a preferred embodiment of the present invention, the hydrophilic group is selected from one of carboxyl, phosphoric acid, boric acid, hydroxyl, sulfonic acid and alcohol groups, and the alkali metal organic compound is carboxylate, phosphate, borate, hydroxyl salt, sulfonate or alcohol salt.

[0011] As a preferred embodiment of the present invention, the carboxylate comprises potassium acetate, sodium acetate or potassium citrate.

[0012] As a preferred embodiment of the present invention, the phosphate comprises potassium dihydrogen phosphate or sodium phenyl phosphate.

[0013] As a preferred embodiment of the present invention, the borate comprises sodium tetraphenylborate.

[0014] As a preferred embodiment of the present invention, the sulfonate comprises sodium toluenesulfonate.

[0015] As a preferred embodiment of the present invention, the hydrophilic groups are independently selected from one of carboxyl, phosphoric acid, boric acid, hydroxyl, sulfonic acid and alcohol groups, and at least one of the hydrophilic groups is different from the other hydrophilic groups.

[0016] The present invention also provides an inverse perovskite cell, comprising a substrate, a hole transport layer, a SAM layer, an interface modification layer such as an alkali metal compound with multiple hydrophilic groups as described above, a perovskite layer, an electron transport layer and a metal electrode stacked in sequence.

[0017] The present invention adopts an inverted perovskite cell, which uses an alkali metal organic compound with at least two hydrophilic groups as the lower interface modification layer to eliminate the interface energy barrier between the perovskite and the SAM, improve the electron / hole separation efficiency, reduce the interface carrier trap density, and reduce the open circuit voltage loss, thereby improving the photoelectric conversion efficiency of the perovskite cell.

[0018] As a preferred embodiment of the present invention, the device further comprises a hole blocking layer, wherein the hole blocking layer is disposed between the electron transport layer and the metal electrode.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0020] 1. An alkali metal compound with multiple hydrophilic groups is used as an interface modification layer. The alkali metal groups passivate the iodine vacancy defects at the perovskite interface and inhibit the non-radiative recombination of carriers at the interface. The multiple hydrophilic groups can reduce the hydrophobicity of the SAM layer through polarity, improve the wettability of the perovskite precursor solution at the interface, and reduce pinhole defects during the film formation process. The hydrophilic groups form an interactive force with the SAM layer molecules, enhance the interlayer adhesion, and avoid interface peeling during solution processing.

[0021] 2. An inverted perovskite cell uses an alkali metal organic compound with at least two hydrophilic groups as the lower interface modification layer to eliminate the interface energy barrier between the perovskite and the SAM, improve the electron / hole separation efficiency, reduce the interface carrier trap density, and reduce the open circuit voltage loss, thereby improving the photoelectric conversion efficiency of the perovskite cell. DETAILED DESCRIPTION

[0022] The present invention is described in detail below.

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail in the following examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Example 1

[0025] The present invention adopts an alkali metal compound with multiple hydrophilic groups as the interface modification layer. The material of the lower interface modification layer includes an alkali metal organic compound having at least two hydrophilic groups. The alkali metal groups in the alkali metal organic compound are used to passivate the interface defects of the perovskite layer, and the hydrophilic groups are used to weaken the hydrophobicity of the upper interface of the SAM layer.

[0026] Furthermore, the alkali metal in the alkali metal organic compound includes potassium, sodium, rubidium or cesium.

[0027] Furthermore, the hydrophilic group is selected from one of carboxyl, phosphoric acid, boric acid, hydroxyl, sulfonic acid and alcohol groups, and the alkali metal organic compound is carboxylate, phosphate, borate, hydroxyl salt, sulfonate or alcohol salt.

[0028] Furthermore, the carboxylate comprises potassium acetate, sodium acetate or potassium citrate.

[0029] Furthermore, the phosphate comprises potassium dihydrogen phosphate or sodium phenyl phosphate.

[0030] Furthermore, the borate comprises sodium tetraphenylborate.

[0031] Furthermore, the sulfonate comprises sodium toluenesulfonate.

[0032] Furthermore, the hydrophilic groups are independently selected from one of carboxyl, phosphoric acid, boric acid, hydroxyl, sulfonic acid and alcohol groups, and at least one of the hydrophilic groups is different from the other hydrophilic groups.

[0033] The alkali metal groups are used to passivate the iodine vacancy defects at the perovskite interface, thereby inhibiting the non-radiative recombination of carriers at the interface. The multi-hydrophilic groups can reduce the hydrophobicity of the SAM layer through polarity, improve the wettability of the perovskite precursor solution at the interface, and reduce pinhole defects during the film formation process. The hydrophilic groups form an interactive force with the SAM layer molecules, enhance the interlayer adhesion, and avoid interface peeling during solution processing.

[0034] Example 2

[0035] The inverted perovskite cell used in the present invention comprises a substrate, a hole transport layer, a SAM layer, an interface modification layer such as an alkali metal compound with multiple hydrophilic groups as described above, a perovskite layer, an electron transport layer and a metal electrode stacked in sequence.

[0036] Furthermore, it also includes a hole blocking layer, which is arranged between the electron transport layer and the metal electrode.

[0037] Using an alkali metal organic compound with at least two hydrophilic groups as the lower interface modification layer eliminates the interface energy barrier between perovskite and SAM, improves the electron / hole separation efficiency, reduces the interface carrier trap density, and reduces the open circuit voltage loss, thereby improving the photoelectric conversion efficiency of the perovskite cell.

[0038] In this embodiment, the preparation process of the perovskite cell is as follows: the substrate is selected from fluorine-doped tin oxide (FTO) glass, the substrate is ultrasonically cleaned with anhydrous ethanol for 60 minutes, the substrate is fully dried in an oven, and then the substrate is treated with ultraviolet-ozone for 20 minutes; a 25nm thick NiO layer is deposited on the top surface of the substrate by magnetron sputtering. x layer as the hole transport layer.

[0039] The SAM layer was prepared by spin coating [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz) to form a SAM layer at 3000 rpm for 30 seconds and drying with nitrogen gas.

[0040] The interface modification layer was prepared by dissolving 10 mg of potassium acetate in 1 mL of isopropanol and ultrasonically treating the solution for 30 minutes to obtain a 10 mg / mL solution. The potassium acetate solution was spin-coated on the SAM layer (2000 rpm×20 seconds) and annealed at 100° C. for 10 minutes to form an interface modification layer.

[0041] The perovskite precursor solution is prepared by weighing a certain amount of PbI2, PbBr2, MAI, FAI, CsI and MABr respectively and dissolving them in a mixed solution of N,N-dimethylformamide and N-methylpyrrolidone to obtain the perovskite precursor solution.

[0042] Preparation of the perovskite film: coating the perovskite precursor solution on the top surface of the interface modification layer by blade coating or slit coating, and forming a film by vacuum assisted crystallization of the perovskite precursor solution to which the ionic curing agent is added. The vacuum degree of the vacuum assisted crystallization method is 10 -3 The annealing temperature of the perovskite film is 100° C., the annealing time is 20 min, and the thickness of the obtained perovskite film is 500 nm.

[0043] The material of the electron transport layer in this embodiment is C 60 The electron transport layer is deposited on the top surface of the perovskite layer by vacuum evaporation, and the thickness of the electron transport layer is 30 nm. In this embodiment, the hole blocking layer is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), and the thickness of the hole blocking layer is 8 nm.

[0044] The material of the metal electrode is silver, which is prepared on the top surface of the hole blocking layer by vacuum evaporation to obtain the perovskite cell.

[0045] The above are only preferred embodiments of the present invention and are 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 in the scope of protection of the present invention.

Claims

1. An alkali metal compound with multiple hydrophilic groups as an interface modification layer, characterized in that: The material of the lower interface modification layer comprises an alkali metal organic compound having at least two hydrophilic groups. The alkali metal groups in the alkali metal organic compound are used to passivate the interface defects of the perovskite layer, and the hydrophilic groups are used to reduce the hydrophobicity of the upper interface of the SAM layer.

2. The alkali metal compound with multiple hydrophilic groups according to claim 1 is used as the interface modification layer, characterized in that: The alkali metal in the alkali metal organic compound includes potassium, sodium, rubidium or cesium.

3. The alkali metal compound with multiple hydrophilic groups according to claim 2 is used as the interface modification layer, characterized in that: The hydrophilic group is selected from one of carboxyl, phosphoric acid, boric acid, hydroxyl, sulfonic acid and alcohol groups, and the alkali metal organic compound is carboxylate, phosphate, borate, hydroxyl salt, sulfonate or alcohol salt.

4. The alkali metal compound with multiple hydrophilic groups as claimed in claim 3 is used as the interface modification layer, characterized in that: The carboxylate salt comprises potassium acetate, sodium acetate or potassium citrate.

5. The alkali metal compound with multiple hydrophilic groups as claimed in claim 3 is used as the interface modification layer, characterized in that: The phosphate includes potassium dihydrogen phosphate or sodium phenyl phosphate.

6. The alkali metal compound with multiple hydrophilic groups as claimed in claim 3 is used as the interface modification layer, characterized in that: The borate salt comprises sodium tetraphenylborate.

7. The alkali metal compound with multiple hydrophilic groups as claimed in claim 3 is used as the interface modification layer, characterized in that: The sulfonate salt comprises sodium toluenesulfonate.

8. The alkali metal compound with multiple hydrophilic groups as claimed in claim 2 is used as the interface modification layer, characterized in that: The hydrophilic groups are independently selected from one of carboxyl, phosphoric acid, boric acid, hydroxyl, sulfonic acid and alcohol groups, and the group selected by at least one of the hydrophilic groups is different from the groups selected by the other hydrophilic groups.

9. An inverse perovskite battery, characterized in that: The invention comprises a substrate, a hole transport layer, a SAM layer, an alkali metal compound with multiple hydrophilic groups as claimed in any one of claims 1 to 8 as an interface modification layer, a perovskite layer, an electron transport layer and a metal electrode stacked in sequence.

10. The inverse perovskite battery according to claim 9, characterized in that: The device further comprises a hole blocking layer, which is arranged between the electron transport layer and the metal electrode.