An interface modification material for a trans-perovskite solar cell NiO x layer

Abstract

This invention belongs to the field of perovskite solar cells and discloses a NiO method suitable for inverted perovskite solar cells. x This invention discloses an interface modification material for modifying nickel oxide and improving its hole transport performance. The interface modification material includes functional groups, linking groups, and anchoring groups; wherein the functional group is a methoxy-substituted dibenzocarbazole, the linking group is an alkyl chain, and the anchoring group is a phosphate group. The interface modification material in this invention is a self-assembled monolayer interface material (SAM), which can be used as a nickel oxide (NiO) interface material. x The interface modification layer, especially when applied to inverted perovskite solar cells, can promote interface hole extraction and transport efficiency and significantly improve the perovskite crystal growth quality, thereby greatly enhancing NiO. x The device's energy conversion efficiency and thermal stability effectively solve the technical problems of low efficiency and low thermal stability in existing inverted perovskite solar cells.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of perovskite solar cells, and more particularly relates to an interface modification material for the NiO x layer of a trans perovskite solar cell. BACKGROUND

[0002] Perovskite solar cells (PVSCs) have been developed since 2009, and their energy conversion efficiency (PCE) has reached 26.1%, with great commercialization potential. Among them, trans perovskite solar cells (adopting a p-i-n structure; formal devices adopt an n-i-p structure) have the advantages of simple preparation process, high device stability, no obvious hysteresis effect, and suitability for preparing flexible and stacked devices, and have attracted widespread attention.

[0003] It is known in the prior art that nickel oxide (NiO x ) is widely used as a common hole transport material (HTM) for trans PVSCs due to its low cost, simple preparation process, and good stability. However, due to the mismatch between NiO x and the perovskite energy level and poor interface contact, the efficiency of NiO x devices still has a significant gap compared to devices based on poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA); and the composition of NiO x is relatively complex (usually containing NiO, Ni(OH)2, NiOOH, and Ni2O3, etc.), and the complex chemical environment on the surface also affects the thermal stability of the device. Therefore, improving the efficiency and thermal stability of NiO x trans devices is crucial for the development of low-cost, high-efficiency trans perovskite solar cells. SUMMARY

[0004] In view of the above defects or improvement needs of the prior art, the purpose of the present application is to provide an interface modification material for the NiO x layer of a trans perovskite solar cell, wherein by using an interface modification material with a specific chemical structure, methoxy-substituted diphenyl carbazole is used as a functional group, an alkyl chain is used as a connecting structure, and a phosphoric acid group is used as an anchoring group, the obtained interface modification material is a self-assembled monolayer interface material (SAM), which can be used as an interface modification layer for nickel oxide (NiO x ), and can be particularly applied in trans perovskite solar cells (for example, can be applied as an interface modification layer between the NiO x hole transport layer and the perovskite layer in trans perovskite solar cells), which can promote interface hole extraction and transport efficiency and improve perovskite crystalline growth quality, thereby significantly improving the efficiency of NiO xThe energy conversion efficiency and thermal stability of the device effectively solve the technical problems of low efficiency and low thermal stability of the existing transverse perovskite solar cell. 2 The authentication energy conversion efficiency of the small-area transverse perovskite battery with an effective area of 0.04cm

[0005] To achieve the above-mentioned purpose, according to the application, an application of an interface modification material in modifying nickel oxide and improving the hole transport performance of nickel oxide is provided, characterized in that the interface modification material comprises a functional group, a connecting group and an anchoring group; wherein the functional group is a methoxy-substituted diphenylbenzocarbazole, the connecting group is an alkyl chain, and the anchoring group is a phosphoric acid group; the functional group is connected with the anchoring group through the connecting group.

[0006] As a further preferred embodiment of the application, the interface modification material has a chemical structure as shown in general formula (A):

[0007]

[0008] wherein n is an integer from 1 to 20.

[0009] As a further preferred embodiment of the application, the application is specifically for a transverse perovskite solar cell, and the nickel oxide is used as a hole transport layer in the transverse perovskite solar cell.

[0010] As a further preferred embodiment of the application, the interface modification material is in the form of an interface modification material ethanol solution, and a thin film is formed on the hole transport layer by a spin coating method, and is annealed at 80-120 DEG C for 10-15 minutes, so as to form an interface modification layer modified on the hole transport layer.

[0011] Preferably, the concentration of the interface modification material in the interface modification material ethanol solution is 0.1-1mg / mL.

[0012] After the annealing treatment, the interface modification layer is further cleaned with ethanol, so as to wash away the unanchored interface modification material.

[0013] As a further preferred embodiment of the application, the interface modification material is located between the hole transport layer and the perovskite light-absorbing layer.

[0014] As a further preferred embodiment of the application, the application can improve the energy conversion efficiency of the transverse perovskite solar cell.

[0015] As a further preferred embodiment of the present application, the application can improve the thermal stability of the trans-perovskite solar cell.

[0016] Compared with the prior art, the above technical solutions conceived by the present application can achieve the following

[0017] Advantages:

[0018] (1) In the present application, the interface modification material with methoxy-substituted dibenzocarbazole as a functional group, an alkyl chain as a connecting structure, and a phosphoric acid group as an anchoring group is used as the interface modification layer of the NiO x , which can effectively adjust the energy level of the NiO x , improve the interface hole extraction and transmission efficiency, and at the same time, the use of the interface modification material can also improve the perovskite film quality and significantly improve the device efficiency. The self-assembled monolayer material MeO-4PADBC exemplified in the following examples of the present application, when applied as an interface layer in a trans-perovskite solar cell, can achieve an authenticated energy conversion efficiency of 25.6% under the simulated sunlight AM 1.5G irradiation condition with an illumination intensity of 100 mW cm -2 , which is one of the highest efficiencies of the trans-perovskite solar cell devices reported so far (compared with the PCE efficiency of 21.6% of the unmodified NiO x device).

[0019] (2) The interface modification material (SAM) with a specific chemical structure in the present application has a strong anchoring effect with the NiO x substrate, which can significantly improve the interface stability. In the following examples, the stability of the device was tested according to the ISOS-L-2I protocol, and the experimental results showed that the thermal stability of the NiO x / SAM-based device was significantly higher than that of the NiO x device, which improved the possibility of practical application of the NiO x device.

[0020] (3) The self-assembled monolayer interface modification layer with a specific structure in the present application, when applied in a trans-perovskite solar cell, can optimize the energy level arrangement of the NiO x interface, improve the perovskite growth quality and interface stability, and effectively solve the technical problems of poor efficiency and low thermal stability of existing trans-perovskite solar cells.

[0021] Due to the mismatch of the energy levels of the nickel oxide hole transport layer and the perovskite and the poor interface contact, the present application uses a hole transport unit based on dibenzocarbazole as the interface modification layer material, and the twisted skeleton structure of dibenzocarbazole is beneficial to enhancing the interaction with the perovskite, improving the interface charge transport efficiency and device stability, and improving the efficiency of the NiOx The highest device efficiency of MeO-4PADBC was improved to 25.6% (as exemplified in the following examples). According to theoretical calculation, the binding energy of the self-assembled monomolecular material MeO-4PADBC exemplified in the following examples of the present application and perovskite is -7.19 eV, and the binding energy is higher, and higher binding energy can bring better technical effect. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Synthetic route of MeO-4PADBC of Example 1.

[0023] Figure 2 NMR hydrogen spectrum of intermediate 2 of Example 1.

[0024] Figure 3 NMR hydrogen spectrum of MeO-4PADBC of Example 1.

[0025] Figure 4 NMR carbon spectrum of MeO-4PADBC of Example 1.

[0026] Figure 5 High resolution mass spectrum of MeO-4PADBC in Example 1.

[0027] Figure 6 UPS diagram of NiO x in Example 2; in the diagram, WF represents work function, and VB represents valence band (the same below).

[0028] Figure 7 UPS diagram of NiO x / MeO-4PADBC in Example 2.

[0029] Figure 8 SEM diagram of perovskite grown on NiO x and NiO x / MeO-4PADBC in Example 3.

[0030] Figure 9 Device structure schematic diagram of trans perovskite solar cell in Example 4.

[0031] Figure 10 Device J-V curve diagram based on NiO x and NiO x / MeO-4PADBC in Example 4.

[0032] Figure 11 Binding energy of MeO-4PADBC and NiO x in Example 5.

[0033] Figure 12The MeO-4PADBC and perovskite binding energy in Example 5.

[0034] Figure 13 The NiO-based device in Example 5 x The efficiency change of the device under different temperature conditions; in the figure, the data after "T" of each curve (such as T90, T85, etc.) is the percentage of the initial efficiency of the device PCE after working for 1200h under the corresponding temperature condition (such as 90%, 85%, etc.).

[0035] Figure 14 The NiO-based device in Example 5 x The efficiency change of the / MeO-4PADBC device under different temperature conditions; in the figure, the data after "T" of each curve (such as T90, T85, etc.) is the percentage of the initial efficiency of the device PCE after working for 1200h under the corresponding temperature condition (such as 90%, 85%, etc.). DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0037] The interface modification material in the present application has a methoxy-substituted diphenylbenzocarbazole as a functional group, an alkyl chain as a linking group, and a phosphoric acid group as an anchoring group. Its chemical structure can be, for example, as shown in general formula (A):

[0038]

[0039] In the formula, n can be an integer from 1 to 20.

[0040] In a preferred embodiment, n = 3, and the corresponding interface modification material has a structure as shown in formula MeO-4PADBC:

[0041]

[0042] When actually preparing the interface modification layer using the above interface modification material, an ethanol solution (the concentration can be 0.1-1 mg / mL) of the corresponding self-assembled monolayer material can be prepared first, and a thin film is formed on the nickel oxide by a spin coating method, and annealed at 80-120°C for 10-15 minutes. Then, the thin film can be cleaned using an ethanol solution to remove the unanchored self-assembled monolayer material, and the interface modification layer is obtained.

[0043] The following are examples:

[0044] Example 1

[0045] Synthesis of compound MeO-4PADBC:

[0046] The synthesis route of compound MeO-4PADBC is shown in Figure 1 which the synthesis of intermediate 1 is reported in the literature (e.g. Adv. Synth. Catal. 2006, 348, 2457-246 and Org. Lett. 2015, 17, 3090-3093); the intermediate 1 used in the following examples was synthesized in-house following the prior art.

[0047] Synthesis of intermediate 2:

[0048] Intermediate 1 (0.65 g, 2 mmol), 1,4-dibromobutane (10 mL), tetrabutylammonium bromide (0.16 g, 0.5 mmol) and 50% aqueous KOH solution (1.1 ml, 20 mmol) were added to a 50 mL round bottom flask and heated to 70 °C overnight. After the reaction was completed, water and dichloromethane were added for extraction, anhydrous sodium sulfate was added for drying, filtered, and the solvent was rotary evaporated, then separated by silica gel column, eluent was selected as petroleum ether and dichloromethane mixed solvent (volume ratio of 1:1), to obtain 0.7 g of white solid. 1 H NMR (600 MHz, Chloroform-d) δ 9.07 (d, J = 9.1 Hz, 2H), 7.82 (d, J = 8.8 Hz, 2H), 7.67 (d, J = 8.8 Hz, 2H), 7.40 (d, J = 2.7 Hz, 2H), 7.35 (dd, J = 9.1, 2.7 Hz, 2H), 4.57 (t, J = 7.1 Hz, 2H), 4.00 (s, 6H), 3.37 (t, J = 6.5 Hz, 2H), 2.12 (dd, J = 9.2, 6.0 Hz, 2H), 1.98 - 1.85 (m, 2H).

[0049] Synthesis of MeO-4PADBC:

[0050] Intermediate 2 (0.7 g, 1.5 mmol) and triethyl phosphite (10 mL) were added to a 50 mL round bottom flask and heated to 140 °C overnight. After removing the solvent under reduced pressure, the product was separated by silica gel column with a mixture of dichloromethane and ethyl acetate (1:2 by volume) as eluent to obtain a yellow viscous liquid. The product was dissolved in dry 1,4-dioxane under nitrogen, and trimethylsilyl bromide (1.5 mL, 11 mmol) was added dropwise to the reaction solution. The reaction solution was stirred at room temperature for 22 hours, and after the reaction was completed, 2 mL of methanol was added and stirred for another 2 hours. Subsequently, deionized water was added dropwise to the reaction solution, and after the solution became turbid, it was stirred for another 2 hours. Filtration was performed, and the crude product was recrystallized in a mixture of tetrahydrofuran and dichloromethane to obtain 0.4 g of white solid. 1 H NMR (400 MHz, DMSO-d6) δ 8.93 (d, J = 9.1 Hz, 2H), 7.98 (d, J = 8.9 Hz, 2H), 7.90 (d, J = 8.9 Hz, 2H), 7.58 (d, J = 2.7 Hz, 2H), 7.36 (dd, J = 9.2, 2.7 Hz, 2H), 4.66 (t, J = 7.2 Hz, 2H), 3.94 (s, 7H), 1.99 - 1.84 (m, 2H), 1.67 - 1.49 (m, 4H). 13 C NMR (150 MHz, DMSO-d6) δ 155.07, 135.76, 130.62, 125.51, 123.34, 116.52, 116.42, 115.85, 112.31, 108.88, 55.25, 42.25, 30.72, 30.62, 27.84, 26.94, 20.47. HRMS (APCI): (M-H) - = 462.1475 (calcd for C 26 H 25 NO5P - ,462.1472).

[0051] Example 2

[0052] The MeO-4PADBC material obtained in Example 1 was subjected to ultraviolet photoelectron spectroscopy test, and the NiO x material was subjected to ultraviolet photoelectron spectroscopy test to obtain the work function and energy level of NiO x and NiO x / MeO-4PADBC.

[0053] The NiO x materials used in the examples of the present application are all purchased from Liaoning Optimal Technology Co., Ltd. The work function and energy level of NiO x in this example are obtained by ultraviolet photoelectron spectroscopy test of NiOx The work function and energy level of NiO x The NiO x The powder was dispersed in deionized water with a concentration of 10 mg / mL, and the solution was spin-coated on an ITO substrate at a speed of 2000 rpm for 30 s, and then annealed in air at 150 °C for 30 min to obtain a NiO x film.

[0054] The NiO x / MeO-4PADBC film sample was tested. The work function and energy level of NiO x / MeO-4PADBC film sample were obtained. The work function and energy level of NiO x / MeO-4PADBC film sample were obtained. The work function and energy level of NiO x / MeO-4PADBC film sample were obtained. The work function and energy level of NiO x / MeO-4PADBC film sample were obtained.

[0055] The energy level of NiOxand NiOx / MeO-4PADBC was tested using a VG ESCALAB 220i XL surface analysis system, as shown in Figure 6 and Figure 7 The calculated HOMO energy levels of NiOxand NiOx / MeO-4PADBC were -5.62 and -5.45 eV, respectively. The experimental results show that the HOMO energy level of NiO x / MeO-4PADBC after modification is more matched with the perovskite valence band (-5.45 eV), which is conducive to the transmission of interface holes.

[0056] Example 3

[0057] For the MeO-4PADBC obtained in Example 1, this embodiment studies the effect of the introduction of interface modification materials on the growth quality of perovskite crystals:

[0058] We obtained the scanning electron microscope (SEM) top view ( Figure 9 ) of the perovskite grown on the NiOxand NiO x / MeO-4PADBC film by a Thermo Fisher Quattro scanning electron microscope. As can be seen from the figure, the grain size of NiOx / MeO-4PADBC is larger. The experimental results show that the introduction of MeO-4PADBC interface modification layer can promote the growth of perovskite, which is conducive to improving the efficiency of the device.

[0059] wherein the perovskite thin film is formed on the NiO thin film prepared in Example 2 x thin film sample, NiO x thin film sample, NiO x thin film or NiO x thin film. The perovskite thin film is formed on the NiO thin film or / MeO-4PADBC thin film by spin-coating a perovskite precursor solution on the NiO thin film or / MeO-4PADBC thin film, respectively. The perovskite thin film is formed by spin-coating a perovskite precursor solution with a chemical formula of Cs 0.05 FA 0.85 MA 0.1 PbI3. The perovskite precursor solution is spin-coated at a speed of 1000 rpm for 5 s and then at a speed of 5000 rpm for 30 s. Before the end of the spin-coating, 200 μL of chlorobenzene is used as an anti-solvent. The thin film is then transferred to a hot stage at 100 °C for 15 min to obtain the perovskite thin film.

[0060] Example 4

[0061] For the / MeO-4PADBC obtained in Example 1, the device efficiency of the trans-planar perovskite solar cell based on NiO x and NiO x / MeO-4PADBC is tested.

[0062] A schematic diagram of the structure of the trans-planar perovskite solar cell device prepared is shown in Figure 9 , wherein the hole blocking layer is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), the electron transport layer is C 60 , the passivation layer is a mixture of CF3-PEAI and MAI, the perovskite layer material has a molecular formula of Cs 0.05 FA 0.85 MA 0.1 PbI3, the interface modification layer material is / MeO-4PADBC, and the hole transport layer is NiO x . The specific device preparation process is to prepare the hole transport layer, the interface modification layer / MeO-4PADBC (if any) and the perovskite layer using the methods described in Example 2 and Example 3, and then dissolve CF3-PEAI (2 mg / mL) and MAI (1 mg / mL) in a mixed solvent of IPA and DMF (volume ratio of 150:1) and spin-coat at a speed of 5000 rpm for 30 s, and then anneal at 100 °C for 10 min to form the passivation layer. The C60 electron transport layer 25 nm), the BCP hole blocking layer 6nm) and silver electrode 100nm) were prepared by vacuum evaporation.

[0063] The J-V curve of the device with MeO-4PADBC as the interface modification layer (the effective area of the device is 0.04 cm 2 ) under simulated solar light AM1.5G irradiation conditions with an intensity of 100 mW cm -2 -1is shown in Figure 10 , and the PCE thereof is as high as 25.6%, and a certificate report with a PCE of 25.6% issued by the Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences is obtained, wherein the open circuit voltage (Voc) is 1.19 V, and the fill factor (FF) is 83.54%. The Voc, FF and PCE of the NiO x device prepared under the same conditions are obviously inferior to those of the NiO x / MeO-4PADBC device, and the PCE thereof is only 21.6%. It should be noted that the NiO x device is the same as the NiO x / MeO-4PADBC device in terms of the materials and thicknesses of the layers except that the NiO x device does not have a "SAM interface modification layer", and the effective area of the device is also 0.04 cm 2 .

[0064] It can be seen that the PCE of the NiO x interface modification layer applied to the transverse perovskite solar cell is one of the highest efficiencies of the transverse structure devices at present. This is due to the fact that the MeO-4PADBC improves the hole extraction and transport efficiency of the interface, and the introduction of the MeO-4PADBC improves the growth quality of the perovskite.

[0065] Example 5

[0066] For the MeO-4PADBC (i.e., SAM material) obtained in Example 1, this example tests the device stability of the transverse planar perovskite solar cell based on NiO x and NiO x / MeO-4PADBC.

[0067] The chemical anchoring of the SAM to the substrate is an important factor for improving the thermal stability of the device, and therefore, we evaluate the anchoring strength of MeO-4PADBC to NiO x at temperatures of 300 K and 340 K by theoretical calculation, and the calculation results are shown in Figure 11 . The results show that the binding energy of MeO-4PADBC to NiOx is still -20.3 eV at a temperature of 340 K, which indicates that the SAM is well anchored to the NiO xThe thermal stability of the interface is very high. In addition, we also calculated the binding energy of MeO-4PADBC and perovskite. As shown in Figure 12 , the binding energy of MeO-4PADBC and perovskite is-7.19 eV, which is conducive to improving the interface stability.

[0068] The formula for calculating the binding energy is

[0069] E ad = E iso+slab -E iso -E slab

[0070] Where E iso+slab , E iso and E slab are the energy of the SAM-attached substrate, the energy of the SAM and the energy of the substrate alone, respectively. The molecular simulation uses the structural calculation and quantum mechanics-molecular dynamics simulation software package (version 5.4.4).

[0071] Subsequently, we tested the device stability of the two devices at different temperatures according to the ISOS-L-2I protocol standard. In order to reduce the influence of the passivation layer on the device stability, the device used in the experiment of the present embodiment does not contain a passivation layer structure compared with the device of Example 4. As shown in Figure 13 and 14 , the device based on NiO x / MeO-4PADBC has significantly higher stability at different temperatures than the NiO x device (for example, at 100℃ for 1200h, the PCE of the NiO x / MeO-4PADBC device is still 60% of the initial efficiency; while the PCE of the NiO x device is only 50% of the initial efficiency). This experiment shows that the introduction of MeO-4PADBC as an interface layer can not only significantly improve the device efficiency, but also greatly improve the thermal stability of the device, providing an important idea for the commercialization of trans perovskite solar cells.

[0072] In addition, the above examples are only examples, for example, changing the length of the alkyl chain in the linking group (n = 10, 20, etc. in general formula A) will not significantly change the hole transport properties of the material and the strong anchoring ability with NiO x . Therefore, it can be inferred that SAMs using different alkyl chain lengths of the linking group can also be used as NiO x interface layers for trans perovskite solar cells as MeO-4PADBC of the present application.

[0073] The nickel oxide suitable for the present application can be various nickel oxides (NiO x) hole transporting material.

[0074] It is to be understood that the above description is intended to be illustrative and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading the above description. The scope of the application should therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with their full scope of equivalents. The disclosure of all articles and references referred to herein are incorporated by reference in their entirety.

Claims

1. An interface modification material is applied to modify nickel oxide and improve the hole transport performance of nickel oxide in a trans-perovskite solar cell, the nickel oxide is used as a hole transport layer in a trans-perovskite solar cell, characterized in that, The interface modification material comprises a functional group, a connecting group and an anchoring group; the functional group is a methoxy-substituted dibenzocarbazole, the connecting group is an alkyl chain, and the anchoring group is a phosphonic acid group; the functional group is connected with the anchoring group through the connecting group; the interface modification material is located between a hole transport layer and a perovskite light-absorbing layer; the twisted skeleton structure of dibenzocarbazole is conducive to enhancing the interaction with the perovskite; The interface modification material has a chemical structure as shown in general formula (A): General formula (A) wherein n is an integer from 1 to 20.

2. The use according to claim 1, characterized in that, The interface modification material is in the form of an interface modification material ethanol solution, and a thin film is formed on the hole transport layer by a spin coating method, and then annealing is performed at 80-120 ℃ for 10-15 minutes, so as to form an interface modification layer modified on the hole transport layer.

3. The use according to claim 2, wherein The concentration of the interface modification material in the interface modification material ethanol solution is 0.1-1 mg / mL. After the annealing treatment, the interface modification layer is further cleaned with ethanol, so as to wash away the unanchored interface modification material.

4. The use according to claim 3, wherein the compound is ###0002### The application can improve the energy conversion efficiency of a trans perovskite solar cell.

5. The use according to claim 3, wherein the compound is ###0002### The application can improve the thermal stability of a trans perovskite solar cell.

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