Lithium acetate and alkynyl passivator double-interface modified perovskite solar cell and application thereof

Abstract

The invention discloses a lithium acetate and alkynyl passivator double-interface modified perovskite solar cell and application thereof, the cell comprises a perovskite thin film, and the perovskite thin film is coated with an alkynyl passivator shown in the following formula I. The alkynyl passivator contains a plurality of acetylenic bonds which can be subjected to pi-electron coordination with uncoordinated Pb < 2 + > in the perovskite thin film, hydrogen bonds exist between hydroxyl and I <->, and the hydroxyl and I <-> interact with excessive PbI2, so that a perovskite thin film / hole transport layer (HTL) interface is effectively passivated, interface defects are reduced, and non-radiative recombination is inhibited. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the technical field of perovskite solar cell preparation, and particularly relates to a perovskite solar cell with double-interface modification of lithium acetate and an alkynyl passivator and its application. Background Art

[0002] The perovskite material for perovskite solar cells has received extensive attention due to its low exciton dissociation energy, good absorption coefficient, and high carrier mobility. Since the perovskite solar cell was introduced in 2009, the power conversion efficiency (PCE) of single-junction devices has soared to over 26.0%, approaching that of the state-of-the-art crystalline silicon cells.

[0003] In a conventional (n-i-p) structure perovskite solar cell, SnO2 has proven to be an excellent electron transport layer (ETL) due to its excellent optical transparency, high electron mobility, and suitability for low-temperature processing. However, various trap defects always exist at the SnO2 / perovskite interface, which may lead to poor crystallinity of the perovskite and adverse interfacial reactions. Similarly, the top perovskite / hole transport layer (HTL) interface also contains many defects, hindering carrier transport and increasing non-radiative recombination. Therefore, significant efforts need to be made through interface engineering to achieve high-quality perovskite devices. Summary of the Invention

[0004] To improve the above technical problems, the present invention provides an alkynyl passivator, and its structural formula is shown as Formula I below:

[0005]

[0006] In Formula I, R1, R2, R3, R4, and R5 are the same or different and are independently selected from H, C 1-10 alkyl.

[0007] According to an embodiment of the present invention, R1, R2, R3, R4, and R5 are the same or different and are independently selected from H, C 1-6 alkyl.

[0008] According to an embodiment of the present invention, R1, R2, R4, and R5 are all H, and R3 is C 1-6 alkyl.

[0009] According to an embodiment of the present invention, the structural formula of the alkynyl passivator is specifically as follows:

[0010]

[0011] This compound is denoted as DOTB.

[0012] The present invention also provides a preparation method of the above alkynyl passivator, and the method includes:

[0013] Mix the compound shown in Formula II with an organic solvent, tetramethylethylenediamine and a catalyst for reaction to obtain the alkynyl passivator;

[0014]

[0015] In Formula II, R1, R2, R3, R4, and R5 have the above meanings.

[0016] According to an embodiment of the present invention, the method includes:

[0017] Add the compound shown in Formula II to a mixed solution of an organic solvent and tetramethylethylenediamine, and then add a catalyst for reaction to obtain the alkynyl passivator.

[0018] According to an embodiment of the present invention, the compound shown in Formula II is 4,4'-(4”-(tert-butyl)-4'-(4-(tert-butyl)phenyl)-4-ethynyl-[1,1':2',1”-terphenyl]-3,5-diyl)bis(2-methylbut-3-yn-2-ol) (T-ethynyl), and its structural formula is specifically as follows:

[0019]

[0020] According to an embodiment of the present invention, the organic solvent is selected from at least one of dichloromethane and chloroform.

[0021] According to an embodiment of the present invention, the catalyst is selected from at least one of cuprous chloride, cuprous bromide, etc.

[0022] According to an embodiment of the present invention, the molar volume ratio of the compound shown in II, the catalyst and tetramethylethylenediamine is (50-200) mmol: 1 mmol: (1-10) ml, preferably (50-100) mmol: 1 mmol: (1-6) ml.

[0023] According to an embodiment of the present invention, the temperature of the reaction is 15-35 °C, such as room temperature; the reaction time is 5-30 h.

[0024] According to an embodiment of the present invention, the method further includes post-treatment steps such as washing, drying, solvent removal, purification, etc.; for example, washing with ammonium chloride and / or brine; for example, drying with anhydrous sodium sulfate; also for example, removing the solvent by vacuum evaporation; further, purifying by silica gel chromatography (volume ratio of petroleum ether: ethyl acetate 3:1 to 1:1).

[0025] The present invention also provides an application of the above-mentioned alkynyl passivator in perovskite solar cells. Preferably, it is used as a passivator in perovskite solar cells. More preferably, it is coated on the perovskite thin film in the perovskite solar cell as a passivator.

[0026] The present invention also provides a perovskite solar cell, which includes a perovskite thin film, and the alkynyl passivator is coated on the perovskite thin film.

[0027] According to an embodiment of the present invention, the alkynyl passivator is coated in the form of an alkynyl passivator solution; the alkynyl passivator solution is prepared by dissolving the alkynyl passivator in an organic solvent, and the organic solvent is selected from at least one of chlorobenzene and isopropanol. Preferably, the concentration of the alkynyl passivator solution is 0.01 - 5 mg / mL, more preferably 0.01 - 2 mg / mL, and for example 0.01 - 1 mg / mL.

[0028] According to an embodiment of the present invention, the perovskite solar cell includes a conductive substrate, an electron transport layer, a perovskite thin film coated with the alkynyl passivator, a hole transport layer, and an electrode layer, which are arranged in sequence from bottom to top.

[0029] According to an embodiment of the present invention, the alkynyl passivator is located between the perovskite thin film and the hole transport layer.

[0030] According to an embodiment of the present invention, lithium acetate is also coated on the electron transport layer.

[0031] According to an embodiment of the present invention, the conductive substrate is selected from one of indium tin oxide (ITO) and fluorine-doped indium tin oxide (FTO), and preferably ITO. The thickness of the conductive substrate is 130 - 150 nm, such as 130 nm, 135 nm, 140 nm, 145 nm, 150 nm.

[0032] According to an embodiment of the present invention, the electron transport layer is selected from one of titanium dioxide (TiO2), zinc oxide (ZnO), tungsten trioxide (WO3), zinc stannate (Zn2SnO4), and tin dioxide (SnO2); preferably SnO2.

[0033] According to an embodiment of the present invention, the thickness of the electron transport layer is 20 - 30 nm, such as 20 nm, 22 nm, 25 nm, 28 nm, 30 nm.

[0034] According to an embodiment of the present invention, the perovskite thin film can be a perovskite thin film known in the art, such as FAPbI3, Cs 0.05 FA 0.95 PbI3, FA 0.85 MA 0.15 Pb(I0.95 Br 0.05 )3, the perovskite film is Cs 0.05 FA 0.95 PbI3.

[0035] According to an embodiment of the present invention, the thickness of the perovskite film is 650 - 720 nm, such as 650 nm, 660 nm, 670 nm, 680 nm, 690 nm, 700 nm, 710 nm, 720 nm.

[0036] According to an embodiment of the present invention, the hole transport layer is 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD) or poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), and its thickness is 150 - 200 nm.

[0037] According to an embodiment of the present invention, the electrode layer is gold or silver, and its thickness is 60 - 80 nm.

[0038] The present invention also provides a method for preparing the above perovskite solar cell, the method comprising: coating an alkynyl passivator solution on the perovskite film, and performing annealing treatment to obtain a perovskite film coated with an alkynyl passivator.

[0039] According to an embodiment of the present invention, the temperature of the annealing treatment is 40 - 120 °C, preferably 60 - 100 °C; the annealing time is 1 - 8 min.

[0040] According to an embodiment of the present invention, a p-methoxyphenethylamine iodide (CH3O-PEAI) solution is further added to the alkynyl passivator solution; wherein, the concentration of the alkynyl passivator in the p-methoxyphenethylamine iodide (CH3O-PEAI) solution is 0.01 - 5 mg / mL, preferably 0.01 - 2 mg / mL, and also such as 0.01 - 1 mg / mL. Preferably, the concentration of the p-methoxyphenethylamine iodide (CH3O-PEAI) solution is 1 - 10 mg / mL, preferably 1 - 5 mg / mL; for example, the p-methoxyphenethylamine iodide (CH3O-PEAI) solution is a CH3O-PEAI isopropanol solution.

[0041] According to an embodiment of the present invention, the method for preparing the perovskite solar cell comprises:

[0042] (1) Preparing an electron transport layer on a conductive substrate;

[0043] (2) Preparing a perovskite film on the electron transport layer;

[0044] (3) Coating an alkynyl passivator solution on the perovskite film and performing annealing treatment;

[0045] (4) Fabricate a hole transport layer on the perovskite film coated with an alkynyl passivator;

[0046] (5) Fabricate an electrode on the hole transport layer to obtain the perovskite solar cell.

[0047] According to an embodiment of the present invention, in step (1), the conductive substrate can also be pretreated by ultrasonically cleaning, drying the conductive substrate, and subjecting it to a hydrophilic treatment, for example, subjecting it to a hydrophilic treatment in an ultraviolet ozone or oxygen plasma cleaner for standby.

[0048] In step (1) of the present invention, subjecting the conductive substrate to a hydrophilic treatment is a conventional technique in the art.

[0049] According to an embodiment of the present invention, step (1) further includes coating lithium acetate on the electron transport layer and annealing it.

[0050] Specifically, step (1) is to first fabricate an electron transport layer on the conductive substrate, then coat a lithium acetate solution on the electron transport layer, and anneal it to obtain an electron transport layer coated with lithium acetate.

[0051] Preferably, the concentration of the lithium acetate solution is 0.1 - 5 mg / mL, more preferably 0.5 - 3 mg / mL.

[0052] Preferably, in step (1), the annealing temperature is 40 - 120 °C, preferably 60 - 100 °C; the annealing time is 1 - 8 min.

[0053] According to an embodiment of the present invention, in step (1), the electron transport layer can be fabricated by a method known in the art. For example, the electron transport layer solution is coated on the substrate and annealed to obtain the electron transport layer. The annealing temperature is 100 - 200 °C, preferably 150 - 180 °C; the annealing time is 10 - 40 min.

[0054] According to an embodiment of the present invention, in step (2), the perovskite film can be fabricated by a method known in the art. For example, the perovskite precursor solution is coated on the electron transport layer and annealed to obtain the perovskite film. Preferably, the annealing temperature is 100 - 200 °C, preferably 120 - 150 °C; the annealing time is 10 - 60 min. Preferably, the concentration of the perovskite precursor solution is 1.4 - 2.0 M. Preferably, the method for fabricating the perovskite film includes, but is not limited to, one of spin coating, blade coating, and slot die coating.

[0055] According to an embodiment of the present invention, in step (4), the hole transport layer can be prepared by a method known in the art. For example, the hole transport layer solution is coated on the perovskite film to obtain the perovskite film.

[0056] According to an embodiment of the present invention, in step (5), the electrode can be prepared by a method known in the art.

[0057] The present invention also provides the application of the above-mentioned alkynyl passivator or perovskite solar cell in the optoelectronic field.

[0058] Advantages of the present invention:

[0059] (1) The present invention discloses an alkynyl passivator (such as DOTB) and uses it in perovskite solar cells. The alkynyl passivator contains multiple alkynyl bonds and can perform π-electron coordination with the uncoordinated Pb in the perovskite film. 2+ At the same time, there is a hydrogen bond between the hydroxyl group and I. - They interact with the excessive PbI2, effectively passivating the perovskite film / hole transport layer (HTL) interface, reducing interface defects, and suppressing non-radiative recombination.

[0060] (2) In the perovskite solar cell of the present invention, lithium acetate is also coated on the electron transport layer. The acetate ion has a dual role: it acts as a defect passivator and a crystal growth regulator, and can adjust the morphology of the perovskite film surface, reducing interface defects.

[0061] (3) The carrier lifetime of the perovskite film of the present invention is increased to more than 7.80 μs, and the grain size is enlarged to more than 1.92 μm.

[0062] (4) The perovskite solar cell device of the present invention has extremely small hysteresis and exhibits high photovoltaic efficiency and excellent operational stability.

[0063] (5) In the preparation of the perovskite solar cell of the present invention, lithium acetate and the alkynyl passivator are used to effectively adjust the morphology of the perovskite film, enhance carrier transport, and reduce non-radiative recombination. The results show that the maximum PCE value of the double-interface improved perovskite solar cell is 25.48%. Description of the drawings

[0064] Figure 1 It is the 1H NMR spectrum of DOTB in Preparation Example 1.

[0065] Figure 2 It is the 13C NMR spectrum of DOTB in Preparation Example 1.

[0066] Figure 3 It is the HR-MS spectrum of DOTB in Preparation Example 1.

[0067] Figure 4 It is a schematic diagram of the dual-interface passivation treatment of the solar cell of the present invention.

[0068] Figure 5 a and b are respectively the SEM cross-sectional images of Comparative Example 1 and Example 1. Figure 5 c, d, and e are respectively the scanning electron microscope top-view images of Comparative Example 1, Comparative Example 3, and Example 1.

[0069] Figure 6 a, b, and c are respectively the atomic force microscope (AFM) images of Comparative Example 1, Comparative Example 3, and Example 1. Figure 6 d - e are respectively the Kelvin probe force microscope (KPFM) of Comparative Example 1 and Comparative Example 3. Figure 6 f is the comparison chart of the KPFM potential change between Comparative Example 1 and Comparative Example 3.

[0070] Figure 7 a - c are respectively the X-ray diffraction (XRD) images of Comparative Example 1, Comparative Example 3, and Example 1, as well as the enlarged views of the perovskite and lead iodide peaks in the XRD images. Figure 7 d and e are respectively the two-dimensional GIWAXS patterns of the perovskite thin films of Comparative Example 1 and Example 1.

[0071] Figure 8 a is the PL of the perovskite thin films of Comparative Example 1, Comparative Example 3, Example 1, and Example 4 under 485 nm excitation. Figure 8 b is the average carrier lifetime of the perovskite thin films of Comparative Example 1, Comparative Example 3, Example 1, and Example 4. Figure 8 c is the carrier lifetime chart of the perovskite thin films of Comparative Example 1, Comparative Example 3, Example 1, and Example 4.

[0072] Figure 9 a is the forward and reverse scan efficiency chart of the solar cell device of the LPD device in Example 1. Figure 9 b is the aging performance result of the LPD device in Example 1 and the solar cell device of Comparative Example 1. Figure 9 c is the aging performance result of the LPD device in Example 6 and the solar cell device of Comparative Example 1. Detailed implementation manners

[0073] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to illustrate and explain the present invention exemplarily and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0074] Unless otherwise specified, the raw materials and reagents used in the following embodiments are all commercially available products or can be prepared by known methods.

[0075] Table 1 Raw materials used in the experiment

[0076]

[0077]

[0078] Table 2 Instruments used in the experiment

[0079]

[0080] Preparation Example 1

[0081] Synthesis of the alkynyl passivator DOTB

[0082] Dissolve T-ethynyl (2.73 g, 4.5 mmol) in 30 ml of dichloromethane and 3 ml of tetramethylethylenediamine (TMEDA). After stirring for 15 minutes under air, add copper(I) chloride (10 mg, 0.052 mmol). Stir the mixture at room temperature for 20 hours. Subsequently, dilute the reaction mixture with dichloromethane and wash with ammonium chloride and brine. Combine the organic layers and dry over anhydrous sodium sulfate. Then remove the solvent by evaporation under reduced pressure. Purify by silica gel chromatography (petroleum ether: ethyl acetate, 3:1 to 1:1) to obtain DOTB as a white solid (2.53 g, 93%).

[0083] Figure 1 1H NMR spectrum of DOTB prepared in Preparation Example 1; where δ 7.68 (s, 2H), 7.62 (t, J = 8.4 Hz, 6H), 7.49 (d, J = 8.3 Hz, 4H), 7.43 (d, J = 8.0 Hz, 2H), 7.32 (d, J = 8.2 Hz, 4H), 7.13 (s, 4H), 7.11 (d, J = 8.2 Hz, 4H), 2.38 (s, 4H), 1.59 (s, 24H), 1.38 (s, 18H), 1.33 (s, 18H).

[0084] Figure 2 13C NMR spectrum of DOTB prepared in Preparation Example 1; 13 C NMR (101 MHz, CDCl3) δ 150.88, 150.27, 142.22, 141.19, 141.06, 137.72, 137.48, 136.76, 132.55, 130.67, 129.65, 129.35, 126.89, 126.62, 126.08, 125.97, 125.25, 124.94, 99.07, 81.98, 81.16, 80.19, 65.76, 34.73, 34.68, 31.50, 31.47, 31.28.

[0085] Figure 3 HR-MS spectrum of DOTB prepared in Preparation Example 1.

[0086] From the above Figures 1 - 3 it can be seen that DOTB was successfully prepared.

[0087] Example 1

[0088] (S1) Experimental conditions for the preparation of perovskite solar cells

[0089] SnO2 was spin-coated in air and annealed at 150 °C after spin-coating. During the annealing process, the environmental humidity was maintained at 30 - 40%. After cooling to room temperature, it was transferred to a glove box, and the perovskite layer and hole transport layer were spin-coated in a nitrogen glove box. The temperature in the glove box was controlled at 24 - 26 °C, the moisture content was ≤0.1 ppm, and the oxygen content was ≤0.1 ppm. The perovskite was annealed in air, and the environmental humidity was controlled at 20 - 30%.

[0090] (S2) The preparation process of perovskite solar cells is as follows:

[0091] (S2.1) Cleaning of ITO glass: First, clean it with dishwashing liquid, then rinse it with water, and finally ultrasonically treat it successively in pure water, acetone, and isopropanol. Treat it in an oxygen plasma cleaner for 10 min before use.

[0092] (S2.2) Solution preparation:

[0093] Prepare the electron transport layer solution: Dilute the SnO2 colloidal dispersion, and the volume ratio of SnO2 to ultrapure water is 1:2.

[0094] Prepare the LiAc solution: Dissolve LiAc in deionized water at concentrations of 0.5 mg / ml, 1.0 mg / ml, 1.5 mg / ml, and 2.0 mg / ml respectively.

[0095] Prepare 1.4M Cs 0.05 FA 0.95 FAI3 perovskite precursor solution: Dissolve 19.1 mg CsI, 703.5 mg PbI2, 240.8 mg FAI, 33.1 mg MACl, and 3% PbI2 in 1 mL of DMF / DMSO (volume ratio 8:1), and stir at room temperature for 6 h.

[0096] Prepare the CH3O-PEAI solution: Dissolve the CH3O-PEAI solution in IPA (3 mg / mL) to obtain the CH3O-PEAI isopropanol solution.

[0097] Preparation of CH3O-PEAI solution containing DOTB: First, dissolve DOTB in chlorobenzene, and then dilute it with CH3O-PEAI isopropanol solution to achieve appropriate concentrations of 0.01 mg / ml, 0.05 mg / ml, 0.10 mg / ml, and 0.20 mg / ml.

[0098] Preparation of Spiro-OMeTAD solution: Dissolve 72.3 mg of Spiro-OMeTAD, 28.8 μL of TBP, and 35 μL of Spiro-LiTFSI (260 mg / mL in ACN) in 1 mL of chlorobenzene.

[0099] (S2.3) Spin coating

[0100] (1) Electron transport layer: In air, spin coat the electron transport layer solution (3500 rpm, 30 s) on the cleaned ITO glass, and then perform annealing treatment (150 °C, 30 min). After the annealing is completed, an electron transport layer film is obtained.

[0101] Modify the electron transport layer with LiAc: Spin coat different concentrations of LiAc solutions (0.5 mg / ml, 1.0 mg / ml, 1.5 mg / ml, and 2.0 mg / ml respectively) on SnO2 (3000 rpm, 30 s), and then perform annealing treatment (100 °C, 5 min).

[0102] (2) Preparation of perovskite film (one-step method): Transfer the electron transport layer film to the glove box for operation. Take 1.4 M Cs 0.05 FA 0.95 PbI3 perovskite precursor solution (50 μL) and spin coat it on the electron transport layer. The parameters of the spin coater are set as follows: first 1000 r / min for 10 s, then 5000 r / min for 30 s, and then transfer it to a simple box outside the glove box for annealing at 120 °C for 60 min to obtain a black perovskite film, with the humidity controlled at 20 - 30%.

[0103] (3) Coating with DOTB: After the perovskite film is formed, transfer the sample to the glove box for further treatment. Spin coat different concentrations of CH3O-PEAI solutions containing DOTB (0.01 mg / ml, 0.05 mg / ml, 0.10 mg / ml, and 0.20 mg / ml respectively) on the perovskite film at 4000 rpm for 30 s, and then anneal at 100 °C for 3 min.

[0104] (4) Preparation of hole transport layer: Spin coat the Spiro-OMeTAD solution on the perovskite film at a speed of 4000 rpm for 30 s.

[0105] (5) Electrode preparation: The sample was transferred to a vacuum coating machine and coated with 80 nm of gold under a condition of <2.5×10 -4 Pa. The effective area of the electrode was 0.04 cm 2 . Finally, the structure of the solar cell device was glass / ITO / SnO2 / LiAc / perovskite / DOTB / Spiro-OMeTAD / Au, and the prepared cell was named LPD.

[0106] Comparative Example 1

[0107] The difference between Comparative Example 1 and Example 1 is as follows: In the spin coating of step (S2.3) in Comparative Example 1, in step (1), LiAc was not added to modify the electron transport layer; in step (3), DOTB was not added, and instead, a CH3O-PEAI solution was directly used to coat the perovskite film.

[0108] Examples 2 - 5

[0109] The difference between Examples 2 - 5 and Comparative Example 1 is as follows: In the spin coating of step (S2.3) in Examples 2 - 5, DOTB was added in step (3), that is, a CH3O-PEAI solution containing DOTB (with concentrations of 0.01 mg / ml, 0.05 mg / ml, 0.10 mg / ml, and 0.20 mg / ml respectively) was spin-coated on the perovskite film at 4000 rpm.

[0110] Example 6

[0111] The difference between Example 6 and Example 1 is as follows: Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) was used instead of Spiro-OMeTAD.

[0112] Comparative Examples 2 - 5

[0113] The difference between Comparative Examples 2 - 5 and Comparative Example 1 is as follows: In the spin coating of step (S2.3) in Comparative Examples 2 - 5, LiAc solutions with concentrations of 0.5 mg / ml, 1.0 mg / ml, 1.5 mg / ml, and 2.0 mg / ml were added in step (1) to modify the electron transport layer.

[0114] The performances of the cells prepared in Examples 1 - 5 and Comparative Examples 1 - 5 are shown in Tables 3 and 4 below.

[0115] Table 3 Performance parameter table of the DOTB concentration and the prepared solar cells in Comparative Example 1 and Examples 1 - 5

[0116]

[0117] In Tables 3 and 4, the concentration of lithium acetate in Example 1 was 1.00 mg ml -1, the concentration of DOTB is 0.10 mg / ml -1 .

[0118] As shown in Table 3, compared with Comparative Example 1, the devices after adding DOTB in Examples 2-5 of the present invention have higher open-circuit voltage Voc, fill factor FF, and power conversion efficiency PCE. Specifically, after adding DOTB to the solar cell devices of the present invention, the PCE of the single-interface passivation devices is significantly enhanced, and the best performance is 24.80%, Voc is 1.190 V, and Jsc is 25.33 mA / cm -2 , and FF is 82.31% (i.e., Example 4). The optimal concentration of DOTB is 0.10 mg / mL -1 .

[0119] Table 4 Performance parameter table of LiAc material concentration and the prepared solar cells in Example 1 and Comparative Examples 1-5

[0120]

[0121] As shown in Table 4, compared with Comparative Example 1, the batteries after adding LiAc in Comparative Examples 2-5 have higher open-circuit voltage Voc, short-circuit current Jcs, power conversion efficiency PCE, and fill factor FF. In contrast, the PCE of the best-performing LiAc single-interface passivation device is significantly enhanced, being 24.65%; the Voc is higher, being 1.199 V, and Jsc is 25.29 mA / cm -2 , and FF is 81.28%. The optimal concentration of the LiAc aqueous solution is 1.0 mg / mL -1 .

[0122] After adding 1.00 mg / ml -1 of the LiAc aqueous solution and 0.10 mg / ml -1 of DOTB to the solar cells of the present invention, the devices have higher open-circuit voltage Voc, fill factor FF, and power conversion efficiency PCE, and the performance is more excellent (i.e., Example 1).

[0123] Test Example 1 Characterization of perovskite thin films

[0124] To study the morphological changes of LiA-treated (LP) and LiAc- and DOTB-treated (LPD) perovskite thin films, the present invention used scanning electron microscopy (SEM) to analyze Comparative Example 1 (i.e., Figure 5 control in), Comparative Example 3 (i.e., Figure 5 LP in), and Example 1 (i.e., Figure 5 LPD in) of the perovskite thin films. The test results are as Figure 5 shown, where Figure 5 a and b are the SEM cross-sectional images of Comparative Example 1 and Example 1, respectivelyFigure 5 c, d, and e are the top - view scanning electron microscope images of Comparative Example 1, Comparative Example 3, and Example 1, respectively. Taking Figure 5 c as an example, where the inset represents the grain size statistical distribution map. The SEM cross - sectional image shows the contact interface between the perovskite film and the charge transport layer. The contact interface of Example 1 ( Figure 5 b) has significantly better quality than that of Comparative Example 1 ( Figure 5 a). As shown in the top - view scanning electron microscope image, there are needle - shaped lead iodide particles around the perovskite crystals in the perovskite film of Comparative Example 1 ( Figure 5 c). In Comparative Example 3, the introduction of LiAc ( Figure 5 d) results in a dense and uniform perovskite surface morphology, and its crystal size increases significantly from 1.19 μm to 1.88 μm. We speculate that the interaction between acetate ions and perovskite slows down the crystallization rate of the intermediate phase, thereby promoting the uniform growth of perovskite grains. In addition, the interaction between acetate ions and PbI2 reduces the excess lead iodide, thus optimizing the surface morphology of perovskite. Furthermore, in Example 1, DOTB is introduced on the basis of introducing LiAc. The perovskite film ( Figure 5 e) treated with DOTB has a crystal size increased to 1.92 μm, a more uniform surface morphology, and no pinholes.

[0125] In this invention, atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM) are used to analyze the surface properties of the perovskite films of Comparative Example 1, Comparative Example 3, and Example 1. The AFM measurement results show that the addition of LiAc in Comparative Example 3 reduces the root - mean - square (RMS) roughness of the perovskite film in Comparative Example 1 from 29.2 nm to 26.9 nm ( Figure 6 a and 6b). At the same time, the KPFM measurement results show that after the treatment with LiAc in Comparative Example 3, the surface potential increases and the uniformity of the surface potential is also higher ( Figure 6 d - f). This may be due to the diffusion of Li + into the perovskite film. In addition, the AFM test also finds that the introduction of DOTB on the basis of introducing LiAc in Example 1 can promote the formation of a denser perovskite film, and its surface roughness is further reduced to 21.8 nm ( Figure 6 c). This reduces the leakage current that may be generated due to the contact between the perovskite film and the HTL.

[0126] It can be seen that LiAc and DOTB have obvious effects on the morphology of perovskite films. Specifically, LiAc mainly acts as a grain growth regulator, which increases the size of perovskite crystal grains, thereby improving the bottom contact and further enhancing the overall film quality. In contrast, DOTB can reduce the surface defects of the film, forming a smoother film surface with fewer traps and pinholes, thus providing a seamless interface between the perovskite film and the HTL. This difference in effects highlights the complementary roles of LiAc and DOTB in optimizing the morphology and electronic properties of perovskite films for efficient device performance.

[0127] To further verify the effects of LiAc and DOTB on the crystal structure and crystallinity of perovskite films, the present invention conducted X-ray diffraction (XRD) and grazing incidence wide-angle X-ray scattering (GIWAXS) tests on Comparative Example 1, Comparative Example 3, and Example 1. Among them, Figure 7 a-c respectively represent the X-ray diffraction (XRD) images of Comparative Example 1, Comparative Example 3, and Example 1, as well as the enlarged views of the perovskite and lead iodide peaks in the XRD images. The perovskite film of Comparative Example 1 has an obvious main peak at about 14.1 and a weak peak at about 12.7 ( Figure 7 a), which are related to perovskite and lead iodide respectively. We observed that the addition of LiAc in Comparative Example 3 caused the perovskite peak to shift to a lower angle ( Figure 7 b), indicating that Li + doping caused lattice expansion. We infer that Li + ions may occupy the interstitial positions within the lattice, resulting in lattice expansion. In addition, when LiAc and DOTB additives are present in Example 1, the intensity of the lead iodide peak decreases ( Figure 7 c). This indicates that the strong interaction between LiAc and lead iodide and the strong π-electron interaction between DOTB and Pb can inhibit excessive lead iodide.

[0128] The two-dimensional GIWAXS patterns of the perovskite films of Comparative Example 1 and Example 1 respectively show strong signals corresponding to lead iodide and perovskite ( Figure 7 d and e). It was found that after passivation with LiAc and DOTB, the diffraction of lead iodide almost disappeared, and the perovskite diffraction intensity increased. This finding is consistent with the trend observed in XRD, further demonstrating the optimization of perovskite crystallization and the reduction of excessive lead iodide achieved by adding LiAc and DOTB.

[0129] Carrier transport characterization

[0130] The present invention adopted steady-state photoluminescence (PL) and transient photoluminescence lifetime (TRPL) measurement methods to evaluate the effects of LiAc and DOTB on the carrier recombination and transport properties within perovskite.Figure 8 a shows the PL of the perovskite films of Comparative Example 1, Comparative Example 3, Example 1 and Example 4 under 485 nm excitation. Compared with Comparative Example 1, the perovskite film modified with LiAc and DOTB in Example 1 shows the highest PL peak intensity, indicating that non-radiative recombination is reduced after passivation with LiAc and DOTB. Figure 8 b shows that the average carrier lifetime of the perovskite film modified in Example 1 is longer than that of the perovskite film in Comparative Example 1 (7.80 μs vs 2.37 μs). Due to additional non-radiative recombination at the ITO / SnO2 interface, the ITO / SnO2-based stack shows a faster TRPL decay than that on glass. The carrier lifetime of Example 1 is much lower than that of Comparative Example 1 (390.11 ns vs 115.37 ns)( Figure 8 c), indicating an enhanced charge extraction ability at the ETL interface in Example 1.

[0131] Test Example 2

[0132] The structure of the target perovskite solar cell is

[0133] ITO / SnO2 / LiAc / perovskite / DOTB / Spiro-OMeTAD / Au, named the LPD device, Figure 9 For the forward and reverse scan efficiencies, photovoltaic performance and stability tests of the LPD target device and the Comparative Example 1 solar cell device. The forward and reverse scan efficiencies of the LPD device of Example 1 are as Figure 9 shown in a.

[0134] Combined with Table 5, the LPD device has a higher open-circuit voltage Voc, fill factor FF and power conversion efficiency PCE. Compared with the Comparative Example 1 device, the PCE of the LPD device of the present invention is significantly enhanced, being 25.48%, the Voc is higher, being 1.203 V, and the JSC is 25.54 mA cm -2 , and the FF is 82.91%. It can be seen that using the modified perovskite film of the present invention can increase the device efficiency by 8.7% while significantly reducing the hysteresis.

[0135] Table 5

[0136]

[0137]

[0138] The LPD device also shows stronger stability in the aging test: after 600 h under illumination of a white LED array at 100 mV cm -2 , the LPD device prepared by the present invention retains 84.5% of the original PCE, which is better than the Comparative Example 1 device, which only retains 66.7%( Figure 9 b);

[0139] We used poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) instead of Spiro-OMeTAD (i.e., Example 6), and after heating for 1000 hours, the LPD device still maintained 80.5% of its original efficiency, showing a significant improvement compared to Comparative Example 1 (57.8%) ( Figure 9 c).

[0140] As described above, the embodiments of the present invention have been exemplarily described. However, the protection scope of the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An alkynyl passivator, characterized in that, Its structural formula is shown in the following formula I: In formula I, R1, R2, R3, R4, and R5 are the same or different and are each independently selected from H, C 1-10 alkyl.

2. The alkynyl passivator according to claim 1, wherein Specifically, its structural formula is as follows:

3. The preparation method of the alkynyl passivator according to claim 1 or 2, characterized in that, The method includes: Mixing and reacting the compound shown in formula II with an organic solvent, tetramethylethylenediamine, and a catalyst to obtain the alkyne group passivator; In formula II, R1, R2, R3, R4, and R5 have the above meanings.

4. The method according to claim 3, characterized in that, The catalyst is selected from at least one of cuprous chloride and cuprous bromide. Preferably, the molar volume ratio of the compound shown in II, the catalyst, and tetramethylethylenediamine is (50 - 200) mmol: 1 mmol: (1 - 10) ml.

5. Application of the alkyne group passivator according to claim 1 or 2 in a perovskite solar cell.

6. A perovskite solar cell, characterized in that, The cell includes a perovskite thin film, and the alkyne group passivator according to claim 1 or 2 is coated on the perovskite thin film.

7. The battery according to claim 6, characterized in that, The alkyne group passivator is coated in the form of an alkyne group passivator solution; the alkyne group passivator solution is obtained by dissolving the alkyne group passivator in an organic solvent, and the organic solvent is selected from at least one of chlorobenzene and isopropanol. Preferably, the concentration of the alkyne group passivator solution is 0.01 - 5 mg / mL.

8. The battery according to claim 6, characterized in that The perovskite solar cell includes a conductive substrate, an electron transport layer, a perovskite thin film coated with an alkyne group passivator, a hole transport layer, and an electrode layer, which are arranged in sequence from bottom to top. Preferably, the alkyne group passivator is located between the perovskite thin film and the hole transport layer. Preferably, lithium acetate is also coated on the electron transport layer.

9. The method for preparing a battery according to any one of claims 6-8, characterized in that, The method includes: coating an alkyne group passivator solution on the perovskite thin film, and performing annealing treatment to obtain a perovskite thin film coated with an alkyne group passivator. Preferably, the temperature of the annealing treatment is 40 - 120 °C, and the annealing time is 1 - 8 min. Preferably, a p-methoxyphenethylamine iodide solution is also added to the alkyne group passivator solution; wherein, the concentration of the alkyne group passivator in the p-methoxyphenethylamine iodide (CH3O-PEAI) solution is 0.01 - 5 mg / mL. Preferably, the preparation method of the perovskite solar cell includes: (1) Preparing an electron transport layer on a conductive substrate; (2) Preparing a perovskite thin film on the electron transport layer; (3) Coating an alkyne group passivator solution on the perovskite thin film and performing annealing treatment; (4) Preparing a hole transport layer on the perovskite thin film coated with an alkyne group passivator; (5) Preparing an electrode on the hole transport layer to obtain the perovskite solar cell.

10. Application of the alkyne group passivator according to claim 1 or 2 or the cell according to any one of claims 6 - 8 in the optoelectronic field.

Images