Tin dioxide electron transport layer regulated and controlled by functional group functionalized conjugated organic molecules and application of tin dioxide electron transport layer in positive perovskite solar cell

Abstract

The invention relates to a tin dioxide electron transport layer regulated and controlled by functional group functionalized conjugated organic molecules and application of the tin dioxide electron transport layer in an upright perovskite solar cell, and belongs to the technical field of perovskite solar cells. According to the invention, hydroxyl, carboxyl or amido is adopted to functionalize a tetraphenyl dinaphthalene structure unit, and the organic molecules can effectively improve the stability and electron transport capability of a SnO2-based electron transport layer through the coordination between multi-site chemical bonding and pi-pi action; meanwhile, the organic molecules can effectively passivate defects, release interface residual stress and promote perovskite crystallization, so that the efficiency and long-term operation stability of the device are improved at the same time. According to the method, the stability and the electron transmission capability of an electron transmission layer are improved through the design of functional group functionalized conjugated organic molecules, a new thought is provided for realizing a perovskite solar cell with high efficiency and stable long-term operation, and a solid foundation is laid for large-scale commercial application of a perovskite photovoltaic technology.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, and relates to a tin dioxide electron transport layer regulated by functionalized conjugated organic molecules and its application in upright perovskite solar cells. Background Technology

[0002] Metal halide perovskite solar cells (PSCs) have garnered significant attention due to their power conversion efficiency (PCE) surging from 3.8% to 27.3%. The electron transport layer (ETL) is a crucial functional layer in nip PSCs, responsible for extracting and transporting photoexcited electrons, thus influencing the cell's photovoltaic performance. SnO2, an inorganic n-type semiconductor material, possesses advantages such as a wide bandgap, high mobility, high conductivity, excellent chemical stability, and high dielectric constant, making it widely used in the fabrication of nip PSCs. However, SnO2 nanoparticle-based ETLs often face challenges such as high defect density, easy aggregation, and film inhomogeneity, which reduce their charge transport capacity, thereby lowering the cell's photovoltaic performance and long-term operational stability, ultimately hindering the commercial application of nip PSCs. In particular, achieving high-performance SnO2-based PSCs under practical operating conditions remains a significant and long-standing challenge. Therefore, there is an urgent need to develop high-performance control molecules to address these issues simultaneously.

[0003] To date, a large body of research has focused on modifying SnO2 ETLs with molecular modulators, primarily including Lewis acids, small organic molecules, polymers, fullerene derivatives, and organic or inorganic salts. While these molecules can effectively passivate defects and inhibit the aggregation of SnO2 nanoparticles, they are often non-conjugated insulating molecules, which hinders electron transport and transfer between adjacent SnO2 nanoparticles, thus reducing the electron transport capacity of the ETL. Therefore, to minimize charge transport losses in the ETL, it is urgent to develop conjugated organic molecules to regulate SnO2 nanoparticles and subsequent ETL. Furthermore, to achieve defect passivation and inhibit SnO2 nanoparticle aggregation, functional groups (-COOH, -OH, -SO3H, -NH2, and -PO4H) that can chemically interact with SnO2 nanoparticles are needed to functionalize organic conjugated molecules, aiming to achieve chemical linkages between adjacent SnO2 nanoparticles.

[0004] In summary, there is an urgent need to develop functionalized conjugated organic molecules to improve the quality of SnO2-based ETLs and promote electron transport, thereby simultaneously enhancing the PCE and stability of orthogonal PSCs. Summary of the Invention

[0005] In view of this, one objective of the present invention is to provide a method for preparing a tin dioxide electron transport layer regulated by functionalized conjugated organic molecules; a second objective of the present invention is to provide a tin dioxide (SnO2) electron transport layer regulated by functionalized conjugated organic molecules; a third objective of the present invention is to provide an application of a tin dioxide (SnO2) electron transport layer regulated by functionalized conjugated organic molecules in a positive perovskite solar cell; a fourth objective of the present invention is to provide a positive perovskite solar cell containing a tin dioxide (SnO2) electron transport layer regulated by functionalized conjugated organic molecules; and a fifth objective of the present invention is to provide a method for preparing a positive perovskite solar cell containing a tin dioxide (SnO2) electron transport layer regulated by functionalized conjugated organic molecules.

[0006] To achieve the above objectives, the present invention provides the following technical solution: 1. A method for preparing a tin dioxide electron transport layer regulated by functionalized conjugated organic molecules, the method comprising the following steps: (1) Mix SnO2 dispersion, RbCl aqueous solution and ammonia aqueous solution evenly to obtain SnO2 mixed solution; (2) Add functionalized conjugated organic molecules to the SnO2 mixed solution described in step (1), mix them evenly, and then perform ultrasonic vibration treatment to obtain SnO2 electron transport layer precursor solution. (3) Spin-coat the SnO2 electron transport layer precursor solution described in step (2) onto a pre-cleaned conductive substrate, and then anneal and ultraviolet ozone irradiation treatment are performed sequentially to obtain a functionalized conjugated organic molecule modified tin dioxide electron transport layer. The functionalized conjugated organic molecules mentioned in step (2) include any one of THPP, TCPP, or TAPP, and their structural formulas are shown below: .

[0007] THPP TCPP TAPP Preferably, in step (1), the mass fraction of the SnO2 dispersion is 5-20%, the concentration of the RbCl aqueous solution is 1-5 mg / mL, the mass fraction of the ammonia aqueous solution is 20-35%, and the volume ratio of the SnO2 dispersion, RbCl aqueous solution and ammonia aqueous solution is 1:1:1. In step (2), the concentration of the functionalized conjugated organic molecule after addition is 0.1~3 mg / mL, the sonication time is 10~40 min, and the oscillation time is 10~30 min; In step (3), the ultraviolet ozone irradiation treatment time is 15~30 min, the spin coating speed is 2500~6500 rpm and the spin coating time is 20~60 s, and the annealing treatment temperature is 80~150 ℃ and the time is 5~30 min.

[0008] 2. The tin dioxide electron transport layer prepared according to the above preparation method, which is regulated by functionalized conjugated organic molecules.

[0009] 3. The application of the tin dioxide electron transport layer regulated by functionalized conjugated organic molecules through functional groups in upright perovskite solar cells.

[0010] 4. A positive perovskite solar cell containing a tin dioxide electron transport layer regulated by functionalized conjugated organic molecules, wherein the positive perovskite solar cell comprises, from bottom to top: a conductive substrate layer, the aforementioned tin dioxide electron transport layer regulated by functionalized conjugated organic molecules, a perovskite light-absorbing layer, a hole transport layer, and a back electrode layer.

[0011] Preferably, the conductive substrate is either ITO or FTO; The perovskite light-absorbing layer is made of ABX3 type perovskite, where A is CH3NH3. + (MA) + CH(NH2)2 + (FA) + ), Cs + or Rb + Any one or more of the following, where B is Pb 2+ Sn 2+ Or Ge 2+ Any one or more of them, X is Cl - ,Br - or I - Any one or more of the following; The hole transport layer is made of 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly(3-hexylthiophene-2,5-diyl) (P3HT), or nickel oxide (NiO). x Any one or more of the following; The material of the back electrode layer is any one of Au, Ag, or low-temperature carbon electrode.

[0012] 5. The method for fabricating the above-mentioned upright perovskite solar cell, wherein the fabrication method comprises the following steps: (1) Pre-treat the transparent conductive glass with ultraviolet ozone or plasma; (2) Add functionalized conjugated organic molecules to SnO2 dispersion, spin-coat it onto the conductive substrate pretreated in step (1), and anneal it to obtain SnO2 electron transport layer modified with functionalized conjugated organic molecules. (3) Spin-coat the perovskite precursor solution onto the SnO2 electron transport layer described in step (2), add antisolvent, and anneal to obtain the perovskite light-absorbing layer. (4) Spin-coat the hole transport layer material solution onto the perovskite light-absorbing layer described in step (3) to obtain the hole transport layer; (5) By fabricating a metal back electrode on the hole transport layer described in step (4), a positive perovskite solar cell containing a tin dioxide electron transport layer regulated by functionalized conjugated organic molecules can be obtained.

[0013] Preferably, in step (1), the pretreatment method is as follows: the conductive substrate is ultrasonically cleaned with detergent, deionized water and anhydrous ethanol for 30-60 min respectively, dried with nitrogen, and treated with ultraviolet ozone for 10-50 min.

[0014] Preferably, in step (3), the perovskite light-absorbing layer is prepared by an anti-solvent method, wherein the anti-solvent is any one or more of chlorobenzene, dichloromethane, toluene, ethyl acetate, chloroform or diethyl ether; In step (4), the concentration of the hole transport layer material in the solution of the hole transport layer material is 5~100 mg / mL.

[0015] Preferably, the spin coating speed is 2000-6500 rpm and the spin coating time is 20-60 s; the annealing temperature is 80-150℃ and the annealing time is 5-30 min.

[0016] The beneficial effects of this invention are as follows: (1) This invention provides a tin dioxide (SnO2) electron transport layer based on functional group functionalized conjugated organic molecules, which mainly functionalizes the tetraphenyl-naphthalene-intercalated unit with hydroxyl, carboxyl or amino groups. The functional group functionalized conjugated organic molecules can effectively improve the stability and electron transport capability of SnO2-based electron transport layer through the synergy between multi-site chemical bonding and π-π interaction. (2) The present invention provides a positive perovskite solar cell containing a SnO2 electron transport layer regulated by functional group-functionalized conjugated organic molecules. The conjugated organic molecules in the electron transport layer of the positive perovskite solar cell can effectively passivate defects, release residual stress at the interface and promote perovskite crystallization, thereby simultaneously improving the efficiency and long-term operating stability of the positive perovskite solar cell device. (3) The positive perovskite solar cell of the present invention containing SnO2 electron transport layer based on functional group functionalized conjugated organic molecules achieves a photoelectric conversion efficiency of not less than 25.68%; the unencapsulated positive perovskite solar cell can still maintain more than 92.6% of the initial efficiency after aging for 2980 hours under 30-35% relative humidity, showing excellent environmental stability; the positive perovskite solar cell still retains more than 90.8% of the initial efficiency after continuous operation at the maximum power point for 1000 hours. (4) The method of modifying SnO2 electron transport layer by functionalizing conjugated organic molecules has the advantages of simple process and good reproducibility, which is of great significance to promoting the industrialization of perovskite solar cells.

[0017] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 In Example 1-3, a represents the optimal configuration and differential charge density of the conjugated organic molecules TAPP, TCPP, and THPP adsorbed on the SnO2 surface; b represents the bonding mode of the conjugated organic molecules TAPP, TCPP, and THPP with SnO2 through π–π interaction in Example 1-3. Figure 2 The images show the dynamic light scattering (DLS) patterns of the SnO2 colloidal solutions in Example 1 and the comparative example. Figure 3 The images show the Sn 3d XPS images of SnO2 and SnO2-THPP films in Example 1 and the comparative example; Figure 4 The O 1s XPS images are of SnO2 and SnO2-THPP films in Example 1 and the comparative example; Figure 5 In Example 1, a and b represent the electrical conductivity (a) and electron mobility (b) of SnO2 and SnO2-THPP films, respectively, in the comparative examples. Figure 6 In Figure 1, a and b are KPFM diagrams of SnO2 and SnO2-THPP films in Example 1 and the comparative example, respectively. Figure 7a and b are AFM images of SnO2 and SnO2-THPP films in Example 1 and the comparative example, respectively; Figure 8 The UV-Vis transmission spectra of SnO2 and SnO2-THPP films in Example 1 and the comparative example are shown. Figure 9 In Figures a and b, Pb 4f XPS and I 3d XPS images of perovskite films with and without THPP modification in Example 1 and the comparative example, respectively; Figure 10 In Example 1 and Comparative Example 2, FTIR values ​​of THPP and THPP+PbI2 films and THPP and THPP+FAI films are respectively obtained from the FTIR of the two films. Figure 11 In the figures a and b, SEM images of the bottom surfaces of the perovskite films with and without THPP modification in the comparative example and Example 1, respectively, are shown. Figure 12 In Figures a and b, respectively, the grain size statistics of the bottom surface of the perovskite film with and without THPP modification in the comparative example and Example 1 are shown. Figure 13 In Figure 1, a and b are SCLC curves of pure electronic devices based on perovskite thin films with or without THPP modification in the comparative example and Example 1, respectively. Figure 14 In the figures a and b, PL mapping images of the bottom surface of the perovskite film with or without THPP modification in the comparative example and Example 1 are respectively. Figure 15 The current density-voltage curves of perovskite solar cells with / without THPP modification in Example 1 and the comparative examples are shown. Figure 16 The stability of perovskite solar cells without THPP modification in Example 1 and the comparative examples in an environment with a humidity of 30-35% is compared. Figure 17 The stability of perovskite solar cells without THPP modification in Example 1 and the comparative examples in continuous tracking at maximum power point; Figure 18 The current density-voltage curves of perovskite solar cells with / without THPP modification in Example 4 and the comparative examples are shown. Figure 19 The current density-voltage curves of perovskite solar cells with / without TAPP modification in Example 5 and the comparative examples are shown. Figure 20 The current density-voltage curves are for perovskite solar cells with / without TCPP modification in Example 6 and the comparative examples. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0020] In the following examples, the functionalized conjugated organic molecules are THPP, TCPP, and TAPP, and their structural formulas are shown below: .

[0021] THPP TCPP TAPP Comparative Examples The specific preparation method for fabricating a positive perovskite solar cell containing an unfunctionalized conjugated organic molecule-controlled SnO2 electron transport layer is as follows: (1) The ITO conductive substrate was ultrasonically cleaned with detergent, deionized water and anhydrous ethanol for 20 min in sequence, dried with nitrogen, treated with ultraviolet ozone for 15 min and cooled for later use. (2) Add 200 μL of ammonia solution with a mass fraction of 28% and 200 μL of RbCl solution with a concentration of 3 mg / mL to 200 μL of SnO2 nanoparticle dispersion with a mass fraction of 12% to obtain a SnO2 dispersion treated with ammonia and RbCl. Filter the dispersion through 0.22 μm PVDF and add 40 μL to the ITO conductive substrate pretreated in step (1). Spin coat at 3000 rpm for 30 s, then anneal at 100 ℃ for 30 min, and finally perform ultraviolet ozone treatment for 20 min to obtain the electron transport layer. (3) Dissolve 18.75 mg MABr, 6.15 mg PbBr2, 19.58 mg CsI, 33 mg MACl, 246.28 mg FAI and 764.45 mg PbI2 in 1 mL of a mixed solvent of DMF and DMSO (V DMF :V DMSO= 4:1), shake for 1 h to obtain a perovskite precursor solution with a concentration of 1.675 mol / L. Then, after filtering the perovskite precursor solution through 0.22 μm PTFE, 40 μL of the solution was added dropwise to the electron transport layer in step (2). The first step was spin-coating at 1000 rpm for 10 s, and the second step was spin-coating at 4000 rpm for 30 s. 80 μL of chlorobenzene antisolvent was added dropwise 16 s before the end of spin-coating. The solution was then annealed at 130 ℃ for 30 min to obtain the perovskite light-absorbing layer. (4) Dissolve 72.3 mg Spiro-OMeTAD in 1 mL of chlorobenzene, and add 28.8 μL of TBP, 17.5 μL of Li-TFSI solution (concentration of 520 mg / mL, solvent of anhydrous acetonitrile) and 20 μL of FK209 (concentration of 200 mg / mL, solvent of anhydrous acetonitrile) to the Spiro-OMeTAD solution. After mixing, drop the solution onto the perovskite light-absorbing layer prepared in step (3), and spin coat at 3000 rpm for 30 s to obtain the hole transport layer. (5) In high vacuum (10 -4 Under the condition of Pa), an Ag electrode with a thickness of 100 nm can be deposited on the hole transport layer in step (4) by thermal evaporation.

[0022] Example 1 In Example 1, compared to the comparative example, THPP was added to a SnO2 nanoparticle dispersion treated with ammonia and RbCl to obtain a SnO2 electron transport layer modified with THPP. All other steps were exactly the same.

[0023] Example 2 In Example 2, compared with Example 1, the concentration of 1 mg / mL THPP was replaced with the concentration of 0.8 mg / mL TAPP to obtain a SnO2 electron transport layer modified with TAPP. All other steps were exactly the same.

[0024] Example 3 Compared with Example 1, Example 3 replaced THPP with TCPP at a concentration of 2 mg / mL to prepare a SnO2 electron transport layer modified with TCPP. All other steps were exactly the same.

[0025] Example 4 Compared with Example 1, Example 4 replaced 1 mg / mL THPP with 0.5 mg / mL THPP. After sonication for 20 min and shaking for 60 s, a SnO2 electron transport layer precursor solution was obtained. All other steps were exactly the same, and a positive perovskite solar cell containing a THPP-regulated tin dioxide electron transport layer was obtained.

[0026] Example 5 Compared with Example 2, Example 5 replaced 0.8 mg / mL TAPP with 0.5 mg / mL TAPP. After sonication for 20 min and shaking for 60 s, a SnO2 electron transport layer precursor solution was obtained. All other steps were exactly the same, and a positive perovskite solar cell containing a tin dioxide electron transport layer regulated by TAPP was obtained.

[0027] Example 6 Compared with Example 3, Example 6 replaced 2 mg / mL TCPP with TCPP at a concentration of 1.5 mg / mL. After sonication for 20 min and shaking for 60 s, a SnO2 electron transport layer precursor solution was obtained. All other steps were exactly the same, and a positive perovskite solar cell containing a TCPP-regulated tin dioxide electron transport layer was obtained.

[0028] Results and Discussion The performance of the upright perovskite solar cells prepared in the above embodiments was tested, and the results are shown below: Figure 1 In Figure a, the optimal configuration and differential charge density of the conjugated organic molecules TAPP, TCPP and THPP adsorbed on the SnO2 surface in Examples 1-3 are shown. Figure 1 In Figure b, the bonding modes of the conjugated organic molecules TAPP, TCPP, and THPP with SnO2 through π–π interactions are shown in Examples 1–3. Table 1 shows the adsorption energies (E) of the conjugated organic molecules (mol) on the SnO2 surface. ads ), the interaction energy between conjugated organic molecules (E) int ) and the total binding energy (E) calculated by the theoretical model b ). Figure 1Figure a shows the adsorption configurations of three conjugated organic molecules on the SnO2 surface. Combined with the data in Table 1, it can be seen that TAPP, TCPP, and THPP are all adsorbed onto the SnO2 surface through four terminal functional groups, with adsorption energies in the order of THPP (-7.53 eV) > TCPP (-7.33 eV) > TAPP (-6.71 eV). This indicates that the interaction between THPP and SnO2 is the strongest. Furthermore, it is easily observed that molecular twisting weakens the interaction between TCPP and SnO2. Further simulations were performed to calculate the interaction mode between the bimolecular molecules and two SnO2 nanoparticles. Figure 1 As shown in b, for THPP, TCPP, and TAPP, bimolecular interactions significantly increase the binding energy with SnO2 compared to unimolecular interactions, mainly due to the π-π interaction between the two conjugated molecules. Compared to TCPP and TAPP, THPP has a higher binding energy (-24.04 eV), which is consistent with the trend of unimolecular interactions. In summary, regulating the conjugation system of molecules not only increases the chemical bonding between adjacent SnO2 nanoparticles but also provides an efficient electron transport channel for adjacent SnO2 nanoparticles, thereby accelerating electron transport and extraction in the electron transport layer.

[0029] Table 1. Adsorption energies (E) of conjugated organic molecules (mol) on the SnO2 surface ads ), the interaction energy between conjugated organic molecules (E) int ) and the total binding energy (E) calculated by the theoretical model b ) Sample E ads (SnO2-mol) / eV]]> E int (mol-mol) / eV]]> E b (SnO2-mol-SnO2) / eV]]> TAPP -6.71 -8.96 -22.38 TCPP -7.33 -8.95 -23.63 THPP -7.53 -8.98 -24.04 Figure 2 The figures show the dynamic light scattering (DLS) images of the SnO2 colloidal solutions in Example 1 and the comparative example. As can be seen from the figures, compared to the SnO2 sample, the THPP-doped SnO2-THPP sample exhibits larger colloidal particles with sizes ranging from 100 to 1000 nm. This is attributed to the chemical cross-linking between SnO2 nanoparticles after the introduction of THPP. The π-π stacking effect of THPP can induce the formation of cross-linked structures between SnO2 nanoparticles, leading to the formation of large colloidal particles, which is beneficial for the rapid charge transport between particles.

[0030] Figure 3 The images show the Sn 3d XPS spectra of SnO2 and SnO2-THPP films in Example 1 and the comparative example. (From...) Figure 3 As can be seen, after THPP modification, the Sn 3d... 5 / 2 and Sn 3d 3 / 2The peaks shifted to higher binding energies by 0.25 eV and 0.26 eV, respectively, indicating an enhanced chemical interaction between THPP and SnO2.

[0031] Figure 4 The images show the O 1s XPS spectra of SnO2 and SnO2-THPP films in Example 1 and the comparative example. Figure 4 As shown, after THPP modification, the oxygen content of the SnO2 lattice increased from 61.66% to 72.15%, while the oxygen vacancy content decreased from 38.34% to 27.85%. This indicates that THPP effectively passivated the undercoordinated Sn in the SnO2 film. 4+ The presence of oxygen vacancy defects should improve the charge transport capability of SnO2 films.

[0032] Figure 5 In the figures, a and b represent the electrical conductivity and electron mobility of SnO2 and SnO2-THPP films in Example 1 and the comparative example, respectively. Figure 5 As shown in Figure a, after THPP modification, the conductivity of the SnO2 film increased from 7.82 × 10⁻⁶. -3 mS·cm -1 Upgraded to 9.43 × 10 -3 mS·cm -1 At the same time, such as Figure 5 The electron mobility shown in b is from 4.60 × 10⁻⁶. -3 cm 2 ·V -1 ·S -1 Increased to 5.29 × 10 -3 cm 2 ·V -1 ·S -1 This confirms that THPP modification accelerates electron transport, which is due to effective defect passivation and chemical cross-linking between SnO2 nanoparticles.

[0033] Figure 6 In Figures a and b, KPFM images of SnO2 and SnO2-THPP films in Example 1 and the comparative example, respectively, are shown. The comparison reveals that the THPP-modified SnO2 film sample exhibits a higher surface potential and a more uniform surface potential distribution, indicating that THPP can effectively regulate and improve the surface electrical properties of SnO2 films, thereby forming channels more conducive to charge transport.

[0034] Figure 7 In Figures a and b, AFM images of the SnO2 and SnO2-THPP films from Example 1 and the comparative example, respectively, are shown. From... Figure 7It can be observed that after modification with THPP, the surface roughness of the SnO₂ film decreases from 0.781 nm to 0.614 nm. The decrease in roughness indicates that THPP modification makes the SnO₂-ETL film denser and more uniform. This flattened surface structure helps to improve the interfacial contact, thereby providing more favorable conditions for charge transport.

[0035] Figure 8 Figures are the UV-visible transmission spectra of SnO₂ and SnO₂-THPP films in Example 1 and the comparative example. THPP was directly added to the SnO₂ colloidal dispersion solution to study the influence law of THPP on the transmittance of the SnO₂ film. From Figure 8 it can be observed that in the visible light range of 300 - 400 nm and 700 - 800 nm, the transmittance of the SnO₂ film modified with THPP is higher than that of the unmodified SnO₂ film.

[0036] Figure 9 In, a and b are the Pb 4f XPS spectra and I 3d XPS spectra of the perovskite films with / without THPP modification in Example 1 and the comparative example. From Figure 9 it can be seen from a that the Pb 4f 7 / 2 and Pb 4f 5 / 2 peaks of the perovskite film modified with THPP shift towards lower binding energy, which is attributed to the formation of a coordination interaction between the electron-donating group -OH in THPP and the uncoordinated Pb 2+ . At the same time, Figure 9 in b, the I 3d 5 / 2 and I 3d 3 / 2 peaks also show a similar shift, indicating that a chemical interaction also occurs between THPP and iodide ions in the perovskite film.

[0037] Figure 10 In, a and b are the FTIR spectra of THPP and THPP+PbI₂ films, THPP and THPP+FAI films in Example 1 and the comparative example. From Figure 10 it can be seen that in the THPP-PbI₂ mixture, the -OH stretching vibration peak undergoes a red shift compared with pure THPP, indicating the formation of a Pb-O coordination bond between THPP and Pb 2+ , thus weakening the -OH bond and reducing its stretching vibration frequency. Similarly, in the THPP-FAI mixture, the -OH stretching vibration peak moves from 3498 cm -1 and 3382 cm -1 to 3345 cm -1 , indicating that the -OH group of THPP interacts with FA + or I -Hydrogen bonding exists between them. These results collectively indicate that THPP interacts with different components of the perovskite, effectively passivating surface defects in the perovskite film, thereby enhancing the charge transport and extraction capabilities from the perovskite to the ETL.

[0038] Figure 11 In Figures a and b, respectively, are SEM images of the bottom surfaces of the perovskite films with and without THPP modification in the comparative example and Example 1. Figure 12 Figures a and b show the grain size statistics of the bottom surface of the perovskite films with and without THPP modification in Comparative Example 1 and Comparative Example 1, respectively. Figure 11 and Figure 12 As can be seen, compared with the control film, the THPP-modified perovskite film exhibits a significant increase in grain size, with the average grain size increasing from 0.936 μm to 1.237 μm. This increased grain size effectively reduces grain boundary density, thereby minimizing the formation of bulk defects. Simultaneously, the THPP-modified perovskite film has a denser bottom surface, enhancing buried interface contact and thus facilitating charge transport.

[0039] Figure 13 In Figures a and b, respectively, are the SCLC curves of pure electronic devices based on perovskite films with or without THPP modification in Comparative Example 1 and Example 1. Figure 13 It can be seen that the defect density of pure electronic devices modified with the conjugated organic molecule THPP is reduced from 4.35 × 10⁻⁶. 15 cm -3 Reduced to 2.92 × 10 15 cm -3 The significant reduction in defect density is mainly attributed to the effective passivation effect of THPP on SnO2 electron transport layer, perovskite film, and interface defects between them.

[0040] Figure 14 In Figures a and b, respectively, are PL mapping images of the bottom surfaces of the perovskite films with and without THPP modification in the comparative example and Example 1. Figure 14 As can be seen, compared with the control sample, the THPP-modified perovskite film exhibits stronger and more uniform PL intensity, which means that non-radiative recombination on the perovskite substrate surface is significantly reduced.

[0041] Figure 15 Table 2 shows the current density-voltage curves of perovskite solar cells with and without THPP modification in Example 1 and the comparative examples. Table 2 shows the photovoltaic parameters of PSCs before and after TAPP, TCPP, and THPP modification. The photovoltaic parameters of the cells were obtained from these graphs, as shown in Table 2. Figure 15As shown in Table 2, the efficiency of perovskite solar cells in Examples 1, 2, and 3 is significantly improved, especially in Example 1.

[0042] Table 2. Photovoltaic parameters of PSCs before and after TAPP, TCPP and THPP modification Figure 16 The stability of perovskite solar cells with and without THPP modification in Example 1 and the comparative examples was measured in an environment with a humidity of 30-35%. After aging for 2980 hours, the THPP-modified cells retained 92.4% of their initial efficiency, while the unmodified cells retained only 64.4% of their initial efficiency, indicating that THPP can effectively improve the environmental stability of the cells.

[0043] Figure 17 The stability of perovskite solar cells with and without THPP modification in Example 1 and the comparative examples during continuous tracking at maximum power point is shown. The results indicate that after 1000 hours of aging, the THPP-modified cell still retains 90.8% of its initial efficiency, while the control cell degrades to 56.3% of its initial efficiency. This demonstrates that THPP modification significantly improves the operational stability of the cells.

[0044] Figure 18 The figures show the current density-voltage curves of perovskite solar cells with and without THPP modification in Example 4 and the comparative examples. Figure 18 As shown, the control cell has a photoelectric conversion efficiency of 23.86% and a short-circuit current density of 25.14 mA / cm². 2 The open-circuit voltage was 1.166 V, and the fill factor was 81.48%. In contrast, after THPP modulation, the photoelectric conversion efficiency was improved to 25.47%, and the short-circuit current density was 25.25 mA / cm². 2 The open-circuit voltage is 1.192 V and the fill factor is 84.72%.

[0045] Figure 19 The figures show the current density-voltage curves of perovskite solar cells with and without TAPP modification in Example 5 and the comparative examples. Figure 19 As shown, the photoelectric conversion efficiency of the control cell is 23.86%, and the short-circuit current density is 25.14 mA / cm². 2 The open-circuit voltage was 1.166 V, and the fill factor was 81.48%. In contrast, after TAPP modulation, the photoelectric conversion efficiency increased to 24.87%, and the short-circuit current density was 25.32 mA / cm². 2 The open-circuit voltage is 1.17 V and the fill factor is 84.03%.

[0046] Figure 20 The figures show the current density-voltage curves of perovskite solar cells with and without TCPP modification in Example 6 and the comparative examples. Figure 20 As shown, the control cell has a photoelectric conversion efficiency of 23.86% and a short-circuit current density of 25.14 mA / cm². 2 The open-circuit voltage was 1.166 V, and the fill factor was 81.48%. In comparison, after TCPP regulation, the photoelectric conversion efficiency increased to 24.91%, and the short-circuit current density was 25.54 mA / cm². 2 The open-circuit voltage is 1.172, and the fill factor is 83.29%.

[0047] In summary, this invention discloses a tin dioxide electron transport layer regulated by functionalized conjugated organic molecules and its application in upright perovskite solar cells, which has the following advantages: (1) This invention provides a tin dioxide (SnO2) electron transport layer based on functional group functionalized conjugated organic molecules, which mainly functionalizes the tetraphenyl-naphthalene-intercalated unit with hydroxyl, carboxyl or amino groups. The functional group functionalized conjugated organic molecules can effectively improve the stability and electron transport capability of SnO2-based electron transport layer through the synergy between multi-site chemical bonding and π-π interaction. (2) The present invention provides a positive perovskite solar cell containing a SnO2 electron transport layer regulated by functional group-functionalized conjugated organic molecules. The conjugated organic molecules in the electron transport layer of the positive perovskite solar cell can effectively passivate defects, release residual stress at the interface and promote perovskite crystallization, thereby simultaneously improving the efficiency and long-term operating stability of the positive perovskite solar cell device. (3) The positive perovskite solar cell of the present invention containing SnO2 electron transport layer based on functional group functionalized conjugated organic molecules achieves a photoelectric conversion efficiency of not less than 25.68%; the unencapsulated positive perovskite solar cell can still maintain more than 92.6% of the initial efficiency after aging for 2980 hours under 30-35% relative humidity, showing excellent environmental stability; the positive perovskite solar cell still retains more than 90.8% of the initial efficiency after continuous operation at the maximum power point for 1000 hours. (4) The method of modifying SnO2 electron transport layer by functionalizing conjugated organic molecules has the advantages of simple process and good reproducibility, which is of great significance to promoting the industrialization of perovskite solar cells.

Claims

1. A method for preparing a tin dioxide electron transport layer regulated by functionalized conjugated organic molecules, characterized in that, The preparation method includes the following steps: (1) Mix SnO2 dispersion, RbCl aqueous solution and ammonia aqueous solution evenly to obtain SnO2 mixed solution; (2) Add functionalized conjugated organic molecules to the SnO2 mixed solution described in step (1), mix them evenly, and then perform ultrasonic vibration treatment to obtain SnO2 electron transport layer precursor solution. (3) Spin-coat the SnO2 electron transport layer precursor solution described in step (2) onto a pre-cleaned conductive substrate, and then anneal and ultraviolet ozone irradiation treatment are performed sequentially to obtain a functionalized conjugated organic molecule modified tin dioxide electron transport layer. The functionalized conjugated organic molecules mentioned in step (2) include any one of THPP, TCPP, or TAPP, and their structural formulas are shown below: THPP TCPP TAPP.

2. The preparation method according to claim 1, characterized in that, In step (1), the SnO2 dispersion has a mass fraction of 5-20%, the RbCl aqueous solution has a concentration of 1-5 mg / mL, the ammonia aqueous solution has a mass fraction of 20-35%, and the volume ratio of the SnO2 dispersion, RbCl aqueous solution and ammonia aqueous solution is 1:1:

1. In step (2), the concentration of the functionalized conjugated organic molecule after addition is 0.1~3 mg / mL, the sonication time is 10~40 min, and the oscillation time is 10~30 min; In step (3), the ultraviolet ozone irradiation treatment time is 15~30 min, the spin coating speed is 2500~6500 rpm and the spin coating time is 20~60 s, and the annealing treatment temperature is 80~150 ℃ and the time is 5~30 min.

3. The tin dioxide electron transport layer prepared by the preparation method according to claim 1 or 2, which is regulated by functionalized conjugated organic molecules.

4. The application of the tin dioxide electron transport layer regulated by functionalized conjugated organic molecules as described in claim 3 in upright perovskite solar cells.

5. A positive perovskite solar cell containing a tin dioxide electron transport layer regulated by functionalized conjugated organic molecules, characterized in that, The upright perovskite solar cell comprises, from bottom to top: a conductive substrate layer, a tin dioxide electron transport layer regulated by functionalized conjugated organic molecules as described in claim 3, a perovskite light-absorbing layer, a hole transport layer, and a back electrode layer.

6. The upright perovskite solar cell according to claim 5, characterized in that, The conductive substrate is either ITO or FTO. The perovskite light-absorbing layer is made of ABX3 type perovskite, where A is CH3NH3. + (MA) + CH(NH2)2 + (FA) + ), Cs + or Rb + Any one or more of the following, where B is Pb 2+ Sn 2+ Or Ge 2+ Any one or more of them, X is Cl - ,Br - Or I - Any one or more of the following; The hole transport layer is made of 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly(3-hexylthiophene-2,5-diyl) (P3HT), or nickel oxide (NiO). x Any one or more of the following; The material of the back electrode layer is any one of Au, Ag, or low-temperature carbon electrode.

7. The method for preparing an upright perovskite solar cell according to any one of claims 5 to 6, characterized in that, The preparation method includes the following steps: (1) Pre-treat the transparent conductive glass with ultraviolet ozone or plasma; (2) Add functionalized conjugated organic molecules to SnO2 dispersion, spin-coat it onto the conductive substrate pretreated in step (1), and anneal it to obtain SnO2 electron transport layer modified with functionalized conjugated organic molecules. (3) Spin-coat the perovskite precursor solution onto the SnO2 electron transport layer described in step (2), add antisolvent, and anneal to obtain the perovskite light-absorbing layer; (4) Spin-coat the hole transport layer material solution onto the perovskite light-absorbing layer described in step (3) to obtain the hole transport layer; (5) By fabricating a metal back electrode on the hole transport layer described in step (4), a positive perovskite solar cell containing a tin dioxide electron transport layer regulated by functionalized conjugated organic molecules can be obtained.

8. The preparation method according to claim 7, characterized in that, In step (1), the pretreatment method is as follows: the conductive substrate is ultrasonically cleaned with detergent, deionized water and anhydrous ethanol for 30-60 min respectively, dried with nitrogen, and treated with ultraviolet ozone for 10-50 min.

9. The method for fabricating an upright perovskite solar cell according to claim 7, characterized in that, In step (3), the perovskite light-absorbing layer is prepared by the anti-solvent method, and the anti-solvent is any one or more of chlorobenzene, dichloromethane, toluene, ethyl acetate, chloroform or diethyl ether; In step (4), the concentration of the hole transport layer material in the solution of the hole transport layer material is 5~100 mg / mL.

10. The method for fabricating an upright perovskite solar cell according to claim 7, characterized in that, All spin coatings were performed at a speed of 2000–6500 rpm for 20–60 s; the annealing temperature was 80–150℃ for 5–30 min.

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