Self-assembly hole transport material containing bidentate conjugated heterocyclic passivation primitive and application of self-assembly hole transport material

Abstract

The invention relates to a self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation primitive and application thereof, conjugated heterocyclic primitives are introduced to two sides of a conjugated parent nucleus of a traditional self-assembled molecule to form a bidentate chelating structure, so that effective passivation of a cation defect state of a perovskite buried bottom interface is realized; besides, the selected passivation elements also have conjugacy and hole transmission characteristics, and can bring different extents of extension to the conjugate plane of a parent nucleus according to different connection modes with the parent nucleus, which is more beneficial to adjusting the dipole moment of the self-assembly molecules and matching with the energy level of a substrate, and improving the transmission and collection efficiency of holes.

Description

Technical Field

[0001] The invention belongs to the field of perovskite solar cells, and in particular relates to a self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit and an application thereof in an inverse perovskite solar cell. Background Art

[0002] In recent years, perovskite solar cells have experienced rapid development, and their photoelectric conversion efficiency has increased from the initial 3.81% to the current 26.1%. The perovskite solar cell device structure adopts a sandwich structure, that is, the perovskite light-absorbing layer is sandwiched between the charge transport layers. This structure includes a hole transport layer and an electron transport layer. According to their relative positions, the device structure of the perovskite solar cell can be further divided into a formal device (nip) and a trans device (pin). Among them, the trans device has received unprecedented attention due to its negligible hysteresis, long-term stable operation, low temperature, low-cost manufacturing process and wide application. Thanks to the emergence of a large number of organic hole transport materials, the power conversion efficiency of the trans device has soared from 3.9% in 2013 to 26.1% in 2023.

[0003] A self-assembled monolayer is an ordered monolayer formed by the chemical adsorption of small organic molecules on a substrate through tail anchoring groups. The functional groups at the head of the self-assembled molecules can promote hole transport. Compared with traditional hole transport materials, the advantage of self-assembled monolayers is their extremely thin layer thickness, which makes the device have the advantages of cost saving, high permeability, and low parasitic resistance; the dipole moment formed by the self-assembled monolayer can adjust the work function of the transparent conductive oxide, making the energy level alignment better; the strong chemical adsorption between the self-assembled monolayer and the substrate enables it to form a thin film with uniform thickness and high conformality even on a rough substrate, which improves the stability and long-term performance of the device. Therefore, self-assembled monolayers have broad application prospects and potential as hole transport materials in perovskite solar cells.

[0004] At the current stage, although self-assembled monolayers have shown great potential as hole transport materials in perovskite solar cells, there are still some problems that need to be solved. In particular, the functional units of the self-assembled molecules lack excellent perovskite defect state passivation groups, resulting in a large number of perovskite buried interface defect states and serious interface non-radiative recombination losses, which in turn causes the inverted perovskite solar cell to have poor working stability under multiple stresses such as long-term light, heat and humidity. Therefore, it is necessary to overcome this problem through further research and technological innovation. The present invention provides a new design concept for self-assembled hole transport materials, which can effectively solve the above-mentioned shortcomings. Summary of the invention

[0005] The purpose of the present invention is to propose a self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit and its application in view of the shortcomings of the background technology. The self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit of the present invention introduces conjugated heterocyclic units on both sides of the conjugated mother core of the traditional self-assembled molecule to form a bidentate chelating structure, thereby achieving effective passivation of the cation defect state of the buried interface of the perovskite; in addition, the selected passivation unit also has conjugation and hole transport properties, and can bring different degrees of expansion to the conjugated plane of the mother core according to the different connection modes with the mother core, which is more conducive to adjusting the dipole moment of the self-assembled molecule and the energy level matching with the substrate, and improving the transmission and collection efficiency of holes.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit, which is composed of a functional group, a connecting group (L1) and an anchoring group (A), wherein the functional group includes a mother core (Ar0) and passivation units (Ar1, Ar2) located on both sides of the mother core; the general formula is:

[0008]

[0009] Wherein, L1-L5 is selected from a single bond, a straight-chain alkyl group having 1 to 20 C atoms, a straight-chain alkoxy group having 1 to 20 C atoms, a straight-chain alkylthio group having 1 to 20 C atoms, a branched or cyclic alkyl group having 3 to 20 C atoms, a branched or cyclic alkoxy group having 3 to 20 C atoms, a branched or cyclic alkylthio group having 3 to 20 C atoms, a substituted or unsubstituted aromatic group having 6 to 20 ring atoms, a substituted or unsubstituted heteroaromatic group having 5 to 20 ring atoms, or a group formed by a combination of the above groups;

[0010] Z n , Z n+1 , Z m , Z m+1 is the connection site, m and n are positive integers, and n+2≤m≤max-1, where max is the maximum serial number of the connection position marked on the mother nucleus Ar0;

[0011] A is an anchoring group, including but not limited to one of the following structures 1 to 8:

[0012]

[0013]

[0014] Ar0 is a parent nucleus, including but not limited to one of the following structures:

[0015]

[0016] Among them, Z 1 -Z 10 , * indicate the connection site;

[0017] The passivation units Ar1 and Ar2 are one of the following structures 1 to 23:

[0018]

[0019]

[0020] The dotted line indicates the connection position between the passivation unit and the mother core.

[0021] Further, the passivation unit is connected to the parent core through L2~L5, and L2~L5 can be empty, a single bond, a straight-chain alkyl group with 1 to 6 C atoms, a straight-chain alkoxy group with 1 to 6 C atoms, a straight-chain alkylthio group with 1 to 6 C atoms, a branched or cyclic alkyl group with 3 to 12 C atoms, a branched or cyclic alkoxy group with 3 to 6 C atoms, a branched or cyclic alkylthio group with 3 to 6 C atoms, an aromatic group with 6 to 10 ring atoms, a heteroaromatic group with 5 to 10 ring atoms, or a group formed by a combination of the above groups.

[0022] Furthermore, the diversity of the connection groups L2 to L5 allows the passivation unit to be connected to the parent core in a variety of ways, specifically:

[0023] L2 and L3 can be single bonds at the same time, which means Ar1 is on Ar0; otherwise, only one of L2 and L3 can be empty, and Ar1 is connected to Z through L2 or L3. n or Z n+1 .

[0024] L4 and L5 can be single bonds at the same time, which means Ar2 is on Ar0; otherwise, only one of L4 and L5 can be empty, and Ar2 is connected to Z through L4 or L5. m or Z m+1 .

[0025] More specifically, the self-assembled hole transport material is one of the following general formulas:

[0026]

[0027] The functional groups in the general formula (II-1) include but are not limited to one of the following structures 1 to 64:

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] Wherein, the *—L1—A formed by the linking group (L1) and the anchoring group (A) in the general formula (II-1), (II-2), and (II-3) includes but is not limited to the following structures:

[0034]

[0035] Preferably, the self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit can be selected from any one of the following compounds 1 to 173:

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051] The present invention also provides the use of the self-assembled hole transport material containing the bidentate conjugated heterocyclic passivation unit in an inverse perovskite solar cell.

[0052] The present invention also provides the use of the self-assembled hole transport material containing the bidentate conjugated heterocyclic passivation unit in organic solar cells, photoreceptors, photodetectors or electroluminescent devices.

[0053] The present invention provides a self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit. Compared with traditional functional groups such as carbazole, benzene ring, naphthalene, etc., the selected functional groups achieve a balance between a large π conjugated plane and multiple passivation units: first, the parent core with an extended conjugated plane will have a stronger power supply, which will not only enhance the intramolecular carrier transport efficiency, but also help to finely adjust the molecular dipole moment, thereby facilitating better energy level matching between the self-assembled monolayer and the substrate; secondly, the extended conjugated plane of the functional group can not only enhance the planar rigidity of the molecular structure itself, but also help to enhance the face-to-face π-π stacking between the assembled molecules, so that the π electron migration ability between the molecules will be enhanced, and the thermal stability of the self-assembled monolayer and the device as a whole will also be improved due to stronger intermolecular interactions; finally, the bidentate chelating structure containing the passivation unit can significantly passivate the cation defect state at the perovskite buried interface, which will play a positive role in improving the efficiency and stability of perovskite solar cells.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) The introduction of double-sided passivation elements on the core effectively improves the passivation ability of hole transport materials on the cation defect states at the perovskite interface, reduces non-radiative recombination, and is beneficial to prolonging the carrier lifetime of the perovskite light absorption layer, thereby improving the overall efficiency and stability of solar cells.

[0056] (2) The introduction of double-sided passivation elements of the core can affect the dipole moment within the self-assembled monolayer. The diversified functional group design makes the energy level alignment at the device interface easier to adjust, thereby improving the interface carrier injection and extraction efficiency and enhancing device performance.

[0057] (3) The introduction of double-sided passivation motifs on the mother core can effectively expand the conjugated plane of the functional group. On the one hand, it plays a positive role in the efficient transmission of holes within the self-assembled molecules, improving the efficiency of hole extraction and transmission. On the other hand, it can also enhance the π-π interaction between self-assembled single molecules, thereby enhancing the stability of the self-assembled monolayer and the device as a whole and extending the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 The structural formula and chemical calculation diagram of the comparative molecule are shown in FIG. 1 ; wherein: (a) the structural formula of the comparative molecule; (b) the highest molecular occupied orbital diagram; (c) the lowest molecular unoccupied orbital diagram; and (d) the surface electrostatic potential diagram.

[0059] Figure 2 It is a schematic diagram of the structural formula and chemical property calculation of Example 1; wherein, (a) the structural formula of the molecule of Example 1; (b) the highest molecular occupied orbital diagram; (c) the lowest molecular unoccupied orbital diagram; and (d) the surface electrostatic potential diagram.

[0060] Figure 3 This is a schematic diagram of the differential charge before and after the molecule of Example 1 interacts with the perovskite.

[0061] Figure 4 It is a schematic diagram of the partial wave state density before and after the molecule of Example 1 interacts with the perovskite. DETAILED DESCRIPTION

[0062] The present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art are within the scope of protection of the present invention.

[0063] Comparative Example: Simulation Analysis of Compound 4PACz

[0064] like Figure 1 (a) is a schematic diagram of the molecular structure of a comparative example; its structure is functional group-connecting group-anchoring group, but its functional group only contains the carbazole mother core.

[0065] Step 1: Use the Visualizer module in the Materials Studio 2018 software package to build a molecular model of the comparative sample molecule;

[0066] Step 2: For the comparative sample molecule constructed in step 1, the single molecule model is structurally optimized by using the Geometry Optimization tool in the DMol3 module to make the molecule reach the energy optimal configuration. The Smart method is used in the optimization process.

[0067] Step 3: Perform frontier orbital analysis on the comparative molecular model that reaches the optimal configuration in step 2 using the Energy tool in the DMol3 module. Figure 1 (b) and Figure 1 (c) shows the HOMO and LUMO orbital compositions of the comparative example molecules.

[0068] Step 4: Perform electrostatic potential analysis on the comparative molecular model that reaches the optimal configuration in step 2 using the Energy tool in the DMol3 module, as shown in Figure 1 (d) shows the potential distribution of the van der Waals surface of the comparative example molecule.

[0069] Example 1: Using the compound No. 131 as the molecule of Example 1, and performing simulation calculation analysis on it

[0070] like Figure 2 (a) is a schematic diagram of the molecular structure of Example 1; its structure is functional group-connecting group-anchoring group; compared with the comparative example, its functional group is no longer composed of carbazole alone, but with carbazole as the parent core, pyridine is symmetrically introduced at the left and right ends of carbazole, forming a bidentate chelating structure.

[0071] Step 1, using the Visualizer module in the Materials Studio 2018 software package to construct a molecular model of the molecule in Example 1;

[0072] Step 2: The structure of the molecule of Example 1 constructed in step 1 is optimized by using the GeometryOptimization tool in the DMol3 module to make the molecule reach the energy optimal configuration. The Smart method is used in the optimization process.

[0073] Step 3: Perform frontier orbital analysis on the molecular model of Example 1 that has reached the optimal configuration in Step 2 using the Energy tool in the DMol3 module. Figure 2 (b) and Figure 2 (c) shows the HOMO and LUMO orbital compositions of the molecule of Example 1, respectively.

[0074] Step 4: The molecular model of Example 1 that has reached the optimal configuration in step 2 is subjected to electrostatic potential analysis using the Energy tool in the DMol3 module, as shown in FIG. Figure 2 (d) shows the van der Waals surface potential distribution of the molecule in Example 1.

[0075] Compared with the comparative example, it can be seen that the conjugated plane of the molecule of Example 1 is effectively expanded, and the functional groups of the molecule of Example 1 show obvious negative potential distribution, namely Lewis base active sites, which can effectively passivate the cation defect states at the buried interface of the perovskite.

[0076] Example 2: Using the compound No. 131 as the molecule of Example 2, and conducting defect state passivation analysis on it

[0077] Step 1: Use the Visualizer module to construct a model of the perovskite-Example 2 molecular interaction system. In order to simplify the calculation, the MAPbBr3 perovskite (001) surface is used to simulate the cation defect state on the perovskite surface. The vacuum layer thickness is The cutoff energy is 600 eV.

[0078] Step 2: Use the GeometryOptimization tool in the DMol3 module to optimize the interaction model constructed in step 1 so that the model reaches the energy optimal configuration. The Smart method is used in the optimization process.

[0079] Step 3: Use the Energy tool in the CASTEP module to perform differential charge calculations on the interaction model that has reached the optimal configuration in step 2. Figure 3 As shown, it can be seen that after the adsorption of the molecule of Example 2, the charges near the perovskite interface defects are transferred to the functional groups of the molecule of Example 2, which is consistent with the electrostatic potential calculated in step 4 of Example 1.

[0080] Step 4: For the interaction model that reaches the optimal configuration in step 2, use the Energy tool in the CASTEP module to perform partial state density calculations. Figure 4 As shown, the deep energy level trap states after molecular passivation in Example 2 are eliminated.

[0081] In summary, through the comparison between the comparative example and Example 1 and the passivation analysis of Example 2, it can be seen that the self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit not only obtains an extended conjugated plane, but also has a significant passivation effect on the cation defect states at the buried interface of the perovskite.

[0082] The above description is only a preferred embodiment of the present invention and does not constitute any other form of limitation to the present invention. Any modification or equivalent change made based on the technical essence of the present invention still falls within the scope of protection required by the present invention.

Claims

1. A self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit, characterized in that: The general formula of the self-assembled hole transport material is: Wherein, Ar1 and Ar2 are passivation units, selected from one of the following structures: The passivation unit is connected to the parent core Ar0 through L2 to L5, and L2 to L5 are empty, a single bond, a straight-chain alkyl group with 1 to 6 C atoms, a straight-chain alkoxy group with 1 to 6 C atoms, a straight-chain alkylthio group with 1 to 6 C atoms, a branched or cyclic alkyl group with 3 to 12 C atoms, a branched or cyclic alkoxy group with 3 to 6 C atoms, a branched or cyclic alkylthio group with 3 to 6 C atoms, an aromatic group with 6 to 10 ring atoms, a heteroaromatic group with 5 to 10 ring atoms, or a group formed by a combination of the above groups.

2. The self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit according to claim 1, characterized in that: L2 and L3 are both single bonds, or only one of L2 and L3 can be empty; L4 and L5 are both single bonds, or only one of L4 and L5 can be empty.

3. The self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit according to claim 1, characterized in that: L1-L5 is selected from a single bond, a straight-chain alkyl group having 1 to 20 C atoms, a straight-chain alkoxy group having 1 to 20 C atoms, a straight-chain alkylthio group having 1 to 20 C atoms, a branched or cyclic alkyl group having 3 to 20 C atoms, a branched or cyclic alkoxy group having 3 to 20 C atoms, a branched or cyclic alkylthio group having 3 to 20 C atoms, a substituted or unsubstituted aromatic group having 6 to 20 ring atoms, a substituted or unsubstituted heteroaromatic group having 5 to 20 ring atoms, or a group formed by a combination of the above groups; Z n , Z n+1 , Z m , Z m+1 is the connection site, m and n are positive integers, and n+2≤m≤max-1, where max is the maximum serial number of the connection position marked on the mother core Ar0.

4. The self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit according to claim 1, characterized in that: A is an anchoring group selected from one of the following structures: Ar0 is a parent nucleus selected from one of the following structures:

5. The self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit according to claim 1, characterized in that: The self-assembled hole transport material is one of the following general formulas:

6. The self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit according to claim 5, characterized in that: The functional group in the general formula (II-1) is selected from one of the following structures:

7. The self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit according to claim 5, characterized in that: In the general formula (II-1), (II-2) and (II-3), *-L1-A is selected from one of the following structures:

8. The self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit according to claim 1, characterized in that: The self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit is selected from one of the following structures:

9. Use of the self-assembled hole transport material containing bidentate conjugated heterocyclic passivation unit according to any one of claims 1 to 8 in an inverse perovskite solar cell.

10. Use of the self-assembled hole transport material containing a bidentate conjugated heterocyclic passivation unit according to any one of claims 1 to 8 in an organic solar cell, a photoreceptor, a photodetector or an electroluminescent device.

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