A quasi-n-i-p structure inverted organic solar cell and a preparation method thereof

Abstract

The application discloses a quasi-n-i-p structure inverted organic solar cell and a preparation method thereof, and relates to the technical field of solar cells. 61 The BM is used as an n-type layer, the D18:L8-BO blend system is used as a bulk heterojunction intermediate layer, and the PBQx-TCl is used as a p-type layer, which are stacked in sequence. The application adopts a solvent-free layer-by-layer pressing technology to construct a quasi-n-i-p active layer stack comprising an acceptor-rich layer, a bulk heterojunction layer and a donor-rich layer. The vertical design architecture optimizes the energy level alignment to realize efficient charge extraction, while suppressing interface degradation, and finally realizes a conversion efficiency of 19.9%.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a quasi-nip structure inverted organic solar cell and its fabrication method. Background Technology

[0002] Organic solar cells are considered one of the most promising photovoltaic technologies due to their lightweight, flexibility, and solution-processability. In recent years, the development of non-fullerene acceptors has significantly improved device efficiency, exceeding 20%. However, traditional upright structures typically use acidic PEDOT:PSS as the hole transport layer. This material is prone to corroding ITO electrodes and is highly hygroscopic, leading to deterioration in device stability. To improve stability, research has shifted to inverted organic solar cells, which use more stable metal oxides as the electron transport layer. Nevertheless, inverted structures still face a series of inherent challenges. First, during the film formation process of traditional bulk heterojunction active layers, the molecular weight difference between donor and acceptor materials tends to lead to unfavorable vertical phase separation. That is, donors are enriched on the electron transport layer side while acceptors are enriched on the hole transport layer side. This distribution results in interfacial energy level mismatch, severely hindering charge transport and exacerbating nonradiative recombination. Second, the surface of metal oxides typically contains a large number of hydroxyl groups and trapped states, becoming centers for charge trapping and interfacial recombination, limiting device performance improvement. Furthermore, constructing a nip-type active layer is an ideal approach to achieve better energy level alignment. However, traditional solution-sequential processing methods struggle to obtain a clear and controllable vertical composition distribution due to severe interlayer miscibility of organic materials. Although existing studies have improved the efficiency of inverted devices to around 18.5% through interface defect passivation strategies (such as using Al2O3 nanocrystals or in-situ forming of SiO2), this remains a challenge. x N y However, difficulties remain in suppressing vertical phase separation within the bulk heterojunction and achieving cascaded energy level alignment throughout the active layer, which has become a key bottleneck limiting further breakthroughs in the efficiency of inverted organic solar cells. Summary of the Invention

[0003] To address the above shortcomings, this invention provides a quasi-NIP structure inverted organic solar cell and its fabrication method, solving the problem of insufficient efficiency in existing inverted organic solar cells. The specific technical solution is as follows: A quasi-nip structure inverted organic solar cell, comprising, from bottom to top, an ITO cathode, a ZnO electron transport layer, a nip-type active layer, a MoO3 hole transport layer, and an Ag anode; the nip-type active layer is made of PC. 61 The structure consists of BM as the n-type layer, D18:L8-BO blend system as the intermediate layer of the bulk heterojunction, and PBQx-TCl ​​as the p-type layer, stacked sequentially.

[0004] This invention also provides a method for fabricating the aforementioned quasi-nip structure inverted organic solar cell, comprising the following steps: (1) Pretreatment of ITO substrate: The ITO substrate is ultrasonically cleaned and dried for later use; (2) Preparation of Glass / ITO / ZnO: ZnO solution was coated on the surface of ITO substrate at 4500 rpm / 20 seconds, annealed, and then transferred to a glove box to cool to room temperature to obtain Glass / ITO / ZnO. (3) Configure a nip-type active layer on Glass / ITO / ZnO: S1, Configure PCs respectively 61 BM solution (receptor enrichment layer solution), D18:L8-BO solution (body heterojunction photoactive layer solution), and PBQx-TCl ​​solution (donor enrichment layer solution). S2, First, the PC 61 BM solution was spin-coated onto the Glass / ITO / ZnO to obtain Glass / ITO / ZnO / PC. 61 BM; S3. Spin-coat the D18:L8-BO solution onto the pretreated PDMS substrate at 3500 rpm for 20 seconds, and then laminate it onto Glass / ITO / ZnO / PC. 61 On BM, PDMS was stripped off to obtain Glass / ITO / ZnO / PC61BM / D18:L8-BO; S4. Spin-coat the PBQx-TCl ​​solution onto the pretreated PDMS substrate (polydimethylsiloxane as the substrate material) at 3500 rpm for 20 seconds, and then laminate it onto Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO was applied, and PDMS was stripped away to obtain Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO / PBQx-TCl; (4) Depositing a MoO3 hole transport layer and an Ag anode on a nip-type active layer: The Glass / ITO / ZnO / PC 61 BM / D18:L8-BO / PBQx-TCl ​​was used to sequentially deposit MoO3 and silver electrodes in a vacuum evaporation chamber, while controlling the chamber pressure to be <2×10⁻⁶. -4 Pa yields a structure of Glass / ITO / ZnO / PC. 61 Inverted organic solar cells of BM / D18:L8-BO / PBQx-TCl / MoO3 / Ag.

[0005] Preferably, in step (1), the ITO substrate pretreatment involves sequentially using a cleaning agent solution, deionized water, acetone, deionized water, and isopropanol to perform ultrasonic cleaning on the ITO substrate, with each step lasting 10-20 minutes, to obtain an ultrasonically cleaned ITO substrate; then, the ultrasonically cleaned ITO substrate is dried using a nitrogen gun, and then placed in the ultraviolet ozone cleaning machine chamber for 25-35 minutes, and then taken out for use.

[0006] Preferably, in step (2), the ZnO solution is prepared as follows: in a 500 mL beaker, 5-15 mmol of anhydrous zinc acetate is dissolved in 125 mL of methanol and heated to 60-70 °C. Then, potassium hydroxide methanol solution with a mass-to-volume ratio of (1-1.1) g:50 mL is slowly added dropwise and reacted for 15-25 min. Then, 1-3 mL of ethanolamine is added, and the mixture is concentrated to a volume of 45-55 mL. Ethyl acetate is added to precipitate the product. After centrifugation, the supernatant is discarded. The precipitate is mixed with anhydrous ethanol and dissolved by ultrasonic treatment to obtain a ZnO solution with a concentration of 25-35 mg / mL.

[0007] Preferably, in step (2), the annealing temperature is 140-160℃ and the annealing time is 15-25min.

[0008] Preferably, in step S1, the PC 61 The preparation method of BM solution is as follows: In a glove box, PC... 61 BM was dissolved in chloroform and stirred at 40-60℃ for 1-2 hours to prepare PC with a concentration of 3-8 mg / mL. 61 BM solution; The preparation method of the D18:L8-BO solution is as follows: In a glove box, D18:L8-BO with a mass ratio of (0.5-1):1.2 is dissolved in chloroform and stirred at a constant temperature of 40-60℃ for 1-2 hours to prepare a mixed solution with a concentration of 5-10 mg / mL. The PBQx-TCl ​​solution is prepared by adding chloroform to the PBQx-TCl ​​solid in a glove box and stirring at a constant temperature of 40-60℃ for 1-2 hours to prepare a PBQx-TCl ​​solution with a concentration of 1-3 mg / mL.

[0009] Preferably, in steps S3 and S4, the pretreated PDMS substrate is prepared by cutting PDMS into segments that match the size of the glass slide, adhering them to the glass slide, subjecting them to 10-20 min of ultraviolet ozone plasma treatment, transferring them to a glove box, and immersing them in isopropanol (IPA) for 15-25 min.

[0010] Preferably, in step (4), the vapor deposition thickness of the MoO3 is 1-3 nm; the vapor deposition thickness of the silver electrode is 90-110 nm.

[0011] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention, through a lamination process, successfully constructs a clear "acceptor / bulk heterojunction / donor" vertical heterojunction in an inverted structure for the first time, achieving through-type cascaded energy level alignment from cathode to anode and greatly optimizing the charge transport path. PC 61 The introduction of BM and PBQx-TCl ​​not only improves interfacial contact but also synergistically modulates interfacial energy levels, significantly enhancing charge extraction efficiency and suppressing recombination losses. Carrier dynamics analysis shows that this structure exhibits higher carrier mobility, significantly reduced bimolecular recombination rate, and lower trapped state density, enabling inverted organic solar cells based on this structure to achieve a photoelectric conversion efficiency as high as 19.9%, the highest efficiency reported for inverted devices to date. Furthermore, it demonstrates excellent performance in long-term stability tests, retaining over 92% of its initial efficiency after 1000 hours of storage in an inert environment. This invention provides a practical new strategy for fabricating high-performance, highly stable inverted organic solar cells.

[0012] 2. The PC in this invention 61 The BM layer is located on the ZnO surface. Its function is to modify and reduce the interfacial work function, improve the surface energy compatibility with the upper active layer, thereby reducing the electron extraction barrier and reducing the interfacial resistance. The bulk heterojunction layer D18:L8-BO serves as the main region for light absorption and exciton generation. The top PBQx-TCl ​​layer is a p-type layer whose energy level matches the MoO3 hole transport layer, which can optimize the hole extraction path and prevent electron leakage to the anode.

[0013] 3. This invention fabricates PC on an ITO substrate coated with ZnO. 61 BM thin films were prepared, and then D18:L8-BO blend films and PBQx-TCl ​​films were independently prepared on elastomeric polydimethylsiloxane (PDMS) substrates. Then, by precisely controlling the bonding and peeling processes, these film layers were sequentially transferred to substrates pre-deposited with ZnO and PC. 61 On BM's ITO substrate, ITO / ZnO / PC is finally formed. 61 The complete nip stacked structure of BM / D18:L8-BO / PBQx-TCl / MoO3 / Ag effectively avoids interlayer miscibility in sequential solution processing, ensuring the clarity and integrity of the interfaces of each functional layer. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a comprehensive analytical diagram of the chemical structure, surface properties (contact angle), and device physics (active layer structure) of the material involved in this invention; Figure 2 The graph shows a performance comparison of the solar cells prepared in Example 3 and Comparative Examples 1, 2, and 3. Figure 3 The charge carrier dynamics diagrams are shown for the inverted devices prepared in Example 3 and Comparative Examples 1, 2, and 3. Figure 4 The thin film morphology diagrams are of the solar cells prepared in Example 3 and Comparative Examples 1, 2, and 3. Figure 5 The image shows the GIWAXS characteristics of the hybrid thin film solar cells prepared in Example 3 and Comparative Examples 1, 2, and 3. Figure 6 The graph shows the stability measurement results of the inverted devices prepared in Example 3 and Comparative Example 1 after storage in nitrogen (dark environment) for 1000 hours. Detailed Implementation

[0016] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Unless otherwise defined, all technical terms used below have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in the present invention are commercially available or can be prepared by existing methods.

[0017] Example 1 This embodiment of a quasi-nip structure inverted organic solar cell includes, from bottom to top, an ITO cathode, a ZnO electron transport layer, a nip-type active layer, a MoO3 hole transport layer, and an Ag anode; the nip-type active layer is made of PC 61 BM is stacked sequentially as an n-type layer, D18:L8-BO blend system is stacked as the intermediate layer of bulk heterojunction, and PBQx-TCl ​​is stacked as a p-type layer. The quasi-NIP structure inverted organic solar cell is fabricated using a solvent-free layer-by-layer lamination technique, specifically including the following steps: (1) Pretreatment of ITO substrate: The ITO substrate was ultrasonically cleaned sequentially with cleaning agent solution, deionized water, acetone, deionized water and isopropanol. Each step lasted 10 min to obtain ultrasonically cleaned ITO substrate. Then the ultrasonically cleaned ITO substrate was dried with nitrogen gun and then placed in the chamber of ultraviolet ozone cleaner for 25 min. It was then taken out for use. (2) Preparation of Glass / ITO / ZnO: ZnO solution was coated on the surface of ITO substrate at 4500 rpm / 20 seconds, annealed at 140℃ for 25 min, and then transferred to a glove box to cool to room temperature to obtain Glass / ITO / ZnO. The ZnO solution was prepared as follows: 5 mmol of anhydrous zinc acetate was dissolved in 125 mL of methanol in a 500 mL beaker and heated to 60 °C. Then, potassium hydroxide methanol solution with a mass-to-volume ratio of 1 g:50 mL was slowly added dropwise and reacted for 15 min. Then, 1 mL of ethanolamine was added and the mixture was concentrated to 45 mL. Ethyl acetate was added to precipitate the product. The product was centrifuged and the supernatant was discarded. The precipitate was mixed with anhydrous ethanol and dissolved by sonication to obtain a ZnO solution with a concentration of 25 mg / mL. (3) Configure a nip-type active layer on Glass / ITO / ZnO: S1, Configure PCs respectively 61 BM solution (receptor enrichment layer solution), D18:L8-BO solution (bulk heterojunction photoactive layer solution), and PBQx-TCl ​​solution (donor enrichment layer solution) were used to pretreat the PDMS substrate. The PC 61 The preparation method of BM solution is as follows: In a glove box, PC... 61 BM was dissolved in chloroform and stirred at 40°C for 2 hours to prepare PC with a concentration of 3 mg / mL. 61 BM solution; The preparation method of the D18:L8-BO solution is as follows: In a glove box, D18:L8-BO with a mass ratio of 0.5:1.2 is dissolved in chloroform and stirred at a constant temperature of 40°C for 2 hours to prepare a mixed solution with a concentration of 5 mg / mL. The PBQx-TCl ​​solution is prepared by adding chloroform to the PBQx-TCl ​​solid in a glove box and stirring at 40°C for 2 hours to prepare a PBQx-TCl ​​solution with a concentration of 1 mg / mL. The pretreatment method for the PDMS substrate is as follows: PDMS is cut into segments that match the size of the glass slide, adhered to the glass slide, and then subjected to ultraviolet ozone plasma treatment for 10 minutes. After that, it is transferred to a glove box and immersed in isopropanol (IPA) for 15 minutes to obtain the pretreated PDMS substrate. S2, First, the PC 61 BM solution was spin-coated onto the Glass / ITO / ZnO to obtain Glass / ITO / ZnO / PC. 61 BM; S3. Spin-coat the D18:L8-BO solution onto the pretreated PDMS substrate at 3500 rpm for 20 seconds, and then laminate it onto Glass / ITO / ZnO / PC. 61 On BM, PDMS was stripped off to obtain Glass / ITO / ZnO / PC61BM / D18:L8-BO; S5. Spin-coat the PBQx-TCl ​​solution onto the pretreated PDMS substrate at 3500 rpm for 20 seconds, and then laminate it onto Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO was applied, and PDMS was stripped away to obtain Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO / PBQx-TCl; (4) Depositing a MoO3 hole transport layer and an Ag anode on a nip-type active layer: The Glass / ITO / ZnO / PC 61 BM / D18:L8-BO / PBQx-TCl ​​was used to sequentially deposit 1nm MoO3 and 90nm silver electrodes in a vacuum evaporation chamber, while controlling the chamber pressure to be <2×10⁻⁶. -4 Pa yields a structure of Glass / ITO / ZnO / PC. 61 Inverted organic solar cells of BM / D18:L8-BO / PBQx-TCl / MoO3 / Ag.

[0018] Example 2 This embodiment of a quasi-nip structure inverted organic solar cell includes, from bottom to top, an ITO cathode, a ZnO electron transport layer, a nip-type active layer, a MoO3 hole transport layer, and an Ag anode; the nip-type active layer is made of PC 61 BM is stacked sequentially as an n-type layer, D18:L8-BO blend system is stacked as the intermediate layer of bulk heterojunction, and PBQx-TCl ​​is stacked as a p-type layer. The quasi-NIP structure inverted organic solar cell is fabricated using a solvent-free layer-by-layer lamination technique, specifically including the following steps: (1) Pretreatment of ITO substrate: The ITO substrate was ultrasonically cleaned sequentially with cleaning agent solution, deionized water, acetone, deionized water and isopropanol. Each step lasted 20 min to obtain ultrasonically cleaned ITO substrate. Then the ultrasonically cleaned ITO substrate was dried with nitrogen gun and then placed in the chamber of ultraviolet ozone cleaner for 35 min. It was then taken out for use. (2) Preparation of Glass / ITO / ZnO: ZnO solution was coated on the surface of ITO substrate at 4500 rpm / 20 seconds, annealed at 160℃ for 15 min, and then transferred to a glove box to cool to room temperature to obtain Glass / ITO / ZnO. The ZnO solution was prepared as follows: 15 mmol of anhydrous zinc acetate was dissolved in 125 mL of methanol in a 500 mL beaker and heated to 70 °C. Then, potassium hydroxide methanol solution with a mass-to-volume ratio of 1.1 g:50 mL was slowly added dropwise and reacted for 25 min. Then, 3 mL of ethanolamine was added and the mixture was concentrated to 55 mL. Ethyl acetate was added to precipitate the product. The product was centrifuged and the supernatant was discarded. The precipitate was mixed with anhydrous ethanol and dissolved by sonication to obtain a ZnO solution with a concentration of 35 mg / mL. (3) Configure a nip-type active layer on Glass / ITO / ZnO: S1, Configure PCs respectively 61 BM solution (receptor enrichment layer solution), D18:L8-BO solution (bulk heterojunction photoactive layer solution), and PBQx-TCl ​​solution (donor enrichment layer solution) were used to pretreat the PDMS substrate. The PC 61 The preparation method of BM solution is as follows: In a glove box, PC... 61 BM was dissolved in chloroform and stirred at 60°C for 1 hour to prepare PC with a concentration of 8 mg / mL. 61 BM solution; The preparation method of the D18:L8-BO solution is as follows: In a glove box, D18:L8-BO with a mass ratio of 1:1.2 is dissolved in chloroform and stirred at 60°C for 1 hour to prepare a mixed solution with a concentration of 10 mg / mL. The PBQx-TCl ​​solution is prepared by adding chloroform to the PBQx-TCl ​​solid in a glove box and stirring at 60°C for 1 hour to prepare a PBQx-TCl ​​solution with a concentration of 3 mg / mL. The pretreatment method for the PDMS substrate is as follows: PDMS is cut into segments that match the size of the glass slide, adhered to the glass slide, and then subjected to ultraviolet ozone plasma treatment for 20 minutes. After that, it is transferred to a glove box and immersed in isopropanol (IPA) for 25 minutes to obtain the pretreated PDMS substrate. S2, First, the PC 61 BM solution was spin-coated onto the Glass / ITO / ZnO to obtain Glass / ITO / ZnO / PC. 61 BM; S3. Spin-coat the D18:L8-BO solution onto the pretreated PDMS substrate at 3500 rpm for 20 seconds, and then laminate it onto Glass / ITO / ZnO / PC. 61 On BM, PDMS was stripped off to obtain Glass / ITO / ZnO / PC61BM / D18:L8-BO; S5. Spin-coat the PBQx-TCl ​​solution onto the pretreated PDMS substrate at 3500 rpm for 20 seconds, and then laminate it onto Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO was applied, and PDMS was stripped away to obtain Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO / PBQx-TCl; (4) Depositing a MoO3 hole transport layer and an Ag anode on a nip-type active layer: The Glass / ITO / ZnO / PC 61 BM / D18:L8-BO / PBQx-TCl ​​was used to sequentially deposit 3 nm MoO3 and 110 nm silver electrodes in a vacuum evaporation chamber, while controlling the chamber pressure to be <2 × 10⁻⁶. -4 Pa yields a structure of Glass / ITO / ZnO / PC. 61 Inverted organic solar cells of BM / D18:L8-BO / PBQx-TCl / MoO3 / Ag.

[0019] Example 3 This embodiment of a quasi-nip structure inverted organic solar cell includes, from bottom to top, an ITO cathode, a ZnO electron transport layer, a nip-type active layer, a MoO3 hole transport layer, and an Ag anode; the nip-type active layer is made of PC 61 BM is stacked sequentially as an n-type layer, D18:L8-BO blend system is stacked as the intermediate layer of bulk heterojunction, and PBQx-TCl ​​is stacked as a p-type layer. The quasi-NIP structure inverted organic solar cell is fabricated using a solvent-free layer-by-layer lamination technique, specifically including the following steps: (1) Pretreatment of ITO substrate: The ITO substrate was ultrasonically cleaned sequentially with cleaning solution, deionized water, acetone, deionized water and isopropanol. Each step lasted 15 min to obtain ultrasonically cleaned ITO substrate. Then the ultrasonically cleaned ITO substrate was dried with nitrogen gun and then placed in the chamber of ultraviolet ozone cleaner for 30 min. The substrate was then taken out for use. (2) Preparation of Glass / ITO / ZnO: ZnO solution was coated on the surface of ITO substrate at 4500 rpm / 20 seconds, annealed at 150℃ for 20 min, and then transferred to a glove box to cool to room temperature to obtain Glass / ITO / ZnO. The ZnO solution was prepared as follows: 10 mmol of anhydrous zinc acetate was dissolved in 125 mL of methanol in a 500 mL beaker and heated to 65 °C. Then, potassium hydroxide methanol solution with a mass-to-volume ratio of 1.1 g:50 mL was slowly added dropwise and reacted for 20 min. Then, 2 mL of ethanolamine was added and the mixture was concentrated to 50 mL. Ethyl acetate was added to precipitate the product. The product was centrifuged and the supernatant was discarded. The precipitate was mixed with anhydrous ethanol and dissolved by sonication to obtain a ZnO solution with a concentration of 30 mg / mL. (3) Configure a nip-type active layer on Glass / ITO / ZnO: S1, Configure PCs respectively 61 BM solution (receptor enrichment layer solution), D18:L8-BO solution (bulk heterojunction photoactive layer solution), and PBQx-TCl ​​solution (donor enrichment layer solution) were used to pretreat the PDMS substrate. The PC 61 The preparation method of BM solution is as follows: In a glove box, PC... 61 BM was dissolved in chloroform and stirred at 50°C for 2 hours to prepare PC with a concentration of 5 mg / mL. 61 BM solution; The preparation method of the D18:L8-BO solution is as follows: In a glove box, D18:L8-BO with a mass ratio of 1:1.2 is dissolved in chloroform and stirred at 50°C for 2 hours to prepare a mixed solution with a concentration of 9 mg / mL. The PBQx-TCl ​​solution is prepared by adding chloroform to the PBQx-TCl ​​solid in a glove box and stirring at 50°C for 2 hours to prepare a PBQx-TCl ​​solution with a concentration of 2 mg / mL. The pretreatment method for the PDMS substrate is as follows: PDMS is cut into segments that match the size of the glass slide, adhered to the glass slide, and then subjected to ultraviolet ozone plasma treatment for 15 minutes. After that, it is transferred to a glove box and immersed in isopropanol (IPA) for 20 minutes to obtain the pretreated PDMS substrate. S2, First, the PC 61 BM solution was spin-coated onto the Glass / ITO / ZnO to obtain Glass / ITO / ZnO / PC. 61 BM; S3. Spin-coat the D18:L8-BO solution onto the pretreated PDMS substrate at 3500 rpm for 20 seconds, and then laminate it onto Glass / ITO / ZnO / PC. 61 On BM, PDMS was stripped off to obtain Glass / ITO / ZnO / PC61BM / D18:L8-BO; S5. Spin-coat the PBQx-TCl ​​solution onto the pretreated PDMS substrate at 3500 rpm for 20 seconds, and then laminate it onto Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO was applied, and PDMS was stripped away to obtain Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO / PBQx-TCl; (4) Depositing a MoO3 hole transport layer and an Ag anode on a nip-type active layer: The Glass / ITO / ZnO / PC 61 BM / D18:L8-BO / PBQx-TCl ​​was used to sequentially deposit 2 nm MoO3 and 100 nm silver electrodes in a vacuum evaporation chamber, while controlling the chamber pressure to be <2 × 10⁻⁶. -4 Pa yields a structure of Glass / ITO / ZnO / PC. 61 Inverted organic solar cells of BM / D18:L8-BO / PBQx-TCl / MoO3 / Ag.

[0020] Comparative Example 1: The difference between this comparative example solar cell and Example 3 is that PC is not placed on both sides of D18:L8-BO. 61 The solar cell structure obtained by BM and PBQx-TCl ​​is: Glass / ITO / ZnO / D18:L8-BO / MoO3 / Ag.

[0021] Comparative Example 2: The difference between this comparative example solar cell and Example 3 is that the PC is not placed on the D18:L8-BO side. 61The structure of the solar cell obtained by BM is: Glass / ITO / ZnO / D18:L8-BO / PBQx-TCl / MoO3 / Ag.

[0022] Comparative Example 3: The difference between this comparative example solar cell and Example 3 is that PBQx-TCl ​​is not placed on the D18:L8-BO side. The structure of the resulting solar cell is: Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO / MoO3 / Ag.

[0023] Comparative Example 4: The difference between this comparative example solar cell and Example 3 is that a non-fullerene acceptor Y6 is used instead of PC. 61 The structure of the solar cell obtained by BM is: Glass / ITO / ZnO / Y6 / D18:L8-BO / PBQx-TCl / MoO3 / Ag.

[0024] Comparative Example 5: The difference between this comparative example solar cell and Example 3 is that the polymer donor PM6 is used instead of PBQx-TCl, and the structure of the resulting solar cell is: Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO / PM6 / MoO3 / Ag.

[0025] Comparative Example 6: The difference between this comparative example solar cell and Example 3 is that a coating method is used instead of a lamination method.

[0026] The photovoltaic parameters of the solar cells prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were measured respectively (data were taken from the average value of 10 devices). The results are shown in Table 1. Table 1 shows the results of D18:L8-BO devices with and without PC coating on both sides under simulated AM 1.5G illumination (100 mW cm⁻²). 61 Optimize the photovoltaic parameters of the device when using BM and PBQx-TCl.

[0027] Table 1 Comparison of photovoltaic parameters for each group of devices Note: The disclosed inverted organic solar cell 1 is derived from the following literature: J. Huang, J. Fu, B. Yuan, H. Xia, T. Chen, Y. Lang, H. Liu, Z. Ren, Q. Liang, K. Liu, Z. Guan, G. Zou, HT Chandran, TWB Lo, X. Lu, C.-S. Lee, H.-L. Yip, Y.-K. Peng, G. Li, Nat Commun 2024, 15 , 10565. The disclosed inverted organic solar cell 2 is derived from the literature: J. Wu, Y. Li, F. Tang, Y. Guo, H. Wu, L. Yuan, G. Liu, Z. He, X. Peng, Adv Funct Materials 2025, 35 ,2504623. As can be seen from the data of Examples 1 to 3 in Table 1, the present invention uses solvent-free layer-by-layer lamination technology to construct an inverted solar cell containing an ITO cathode, a ZnO electron transport layer, a nip-type active layer, a MoO3 hole transport layer, and an Ag anode structure. This vertical design architecture optimizes energy level alignment to achieve efficient charge extraction while suppressing interface degradation, ultimately achieving a conversion efficiency of 19.9%.

[0028] As can be seen from the data of Example 3 and Comparative Examples 1 to 5, the nip-type active layer of the present invention uses PC 61 Using BM as the n-type layer, the D18:L8-BO blend system as the bulk heterojunction interlayer, and PBQx-TCl ​​as the p-type layer, the resulting solar cell exhibits superior photoelectric conversion efficiency. Among these, PC... 61 The BM layer is located on the ZnO surface. Its function is to modify and reduce the interfacial work function, improve the surface energy compatibility with the upper active layer, thereby reducing the electron extraction barrier and reducing the interfacial resistance. The top PBQx-TCl ​​layer, as a p-type layer, has an energy level that matches the MoO3 hole transport layer, which can optimize the hole extraction path and prevent electrons from leaking to the anode, thereby improving the photoelectric conversion efficiency.

[0029] As can be seen from the data of Example 3 and Comparative Example 6, compared with spin coating, the present invention uses solvent-free layer-by-layer lamination technology to prepare inverted solar cells, realizing through-through cascaded energy level alignment from cathode to anode, which greatly optimizes the charge transport path.

[0030] As can be seen from the data of Example 3 and the inverted organic solar cells 1 and 2 disclosed in the prior art, the performance of the battery of the present invention is superior to the best-performing inverted solar cell in the prior art.

[0031] Figure 1 This is a comprehensive analysis diagram of the chemical structure, surface properties (contact angle), and device physics (active layer structure) of the materials involved in this invention, wherein: (a) represents D18, L8-BO, PBQx-TCl, and PC. 61 (a) Chemical structure of BM; (b) Energy level distribution of each functional layer; (c) ZnO, ZnO / PC 61 Contact angles of BM, D18:L8-BO, PBQx-TCl, and MoO3 surfaces to water and formamide (FA); Schematic diagram of active layer structure: (d) is the A / Control layer, (e) is the Control / D layer, and (f) is the A / Control / D layer. From Figure 1 It can be seen that: in inverted organic solar cells, an advanced donor-acceptor hybrid D18:L8-BO is used as the bulk heterojunction (BHJ) core, and PC is integrated separately. 61 BM and PBQx-TCl, as an interface layer rich in receptors and donors, were used to construct a quasi-nip active structure; its chemical structure is as follows: Figure 1 As shown in figure a. The ionization energy (IE) of the active layer and the working function (WF) of the cathode interlayer material were determined by ultraviolet photoelectron spectroscopy (UPS), as follows. Figure 1 As shown in b. (As shown in...) Figure 1 As shown in Figure c, the contact angles of each layer were measured using water and formamide (FA). The resulting PC... 61 BM / D18:L8-BO, D18:L8-BO / PBQx-TCl ​​and PC 61 The active layer structure of BM / D18:L8-BO / PBQx-TCl ​​laminate is as follows: Figure 1 As shown in df.

[0032] Note: Control represents the D18:L8-BO body heterojunction (BHJ), and A represents the receptor-rich layer (PC). 61 BM), where D represents the donor enrichment layer (PBQx-TCl).

[0033] Figure 2 The following are performance comparison graphs of solar cells prepared in Example 3 and Comparative Examples 1, 2, and 3, where: (a) and (b) show the calculated exciton generation rate contour plots of the Control group and the A / Control / D group devices, respectively; (c) with / without PC 61Current density-voltage curves of D18:L8-BO inverted organic solar cells of BM and PBQx-TCl: Control group, Control / D group, A / Control group, and A / Control / D group; (d) Power conversion efficiency statistics of 10 devices (top) and power conversion efficiency reported by inverted organic photodiodes (bottom); (e) Dark-state JV characteristic curves; (f) External quantum efficiency (EQE) spectrum; (g) and (h) Hole and electron mobilities extracted using the space charge-confined current (SCLC) model based on the dark-state JV curves of hole-type and electron-type devices, respectively; (i) Surface photovoltage (SPV) response curves under modulated illumination. Figure 2 It can be seen that four different device structures were compared systematically: the control group, the control group with material D alone (Control / D), the control group with material A alone (A / Control), and the composite structure with both materials A and D (A / Control / D). The graphs typically consist of multiple subgraphs, testing the current density-voltage characteristics or other key parameters of these devices under both light-on and dark-state conditions to evaluate their respective photoelectric conversion capabilities. The results show that the device employing the synergistic treatment of A and D achieved a peak photoelectric conversion efficiency of 19.9%, a figure that significantly outperforms not only the control group but also devices with only A or D introduced. This strongly demonstrates the synergistic gain effect of materials A and D in inverted organic solar cells—material A may improve hole transport or active layer morphology, while material D may optimize electron extraction or interfacial contact. Together, they reduce carrier recombination, increase short-circuit current and fill factor, ultimately achieving efficient and stable cell performance.

[0034] Note: Control represents the D18:L8-BO body heterojunction (BHJ), and A represents the receptor-rich layer (PC). 61 BM), where D represents the donor enrichment layer (PBQx-TCl).

[0035] Figure 3 The diagram shows the charge carrier dynamics in the inverted devices prepared in Example 3 and Comparative Examples 1, 2, and 3. It also shows the charge carrier dynamics in the inverted organic solar cell containing D18:L8-BO, with / without PC. 61BM and PBQx-TCl ​​layers; where: (a) Normalized transient photocurrent (TPC) decay curve; (b) Normalized transient photovoltage (TPV) decay curve; (c) Transient curve of linear boost photo-induced carrier extraction (photo-CELIV) current; (d) Curve of extracted carrier density versus delay time, with the solid line representing the bimolecular recombination fitting result; (e) Curve of bimolecular recombination rate coefficient versus carrier density obtained from photo-CELIV measurement; (f) Density of states distribution obtained from impedance spectroscopy and Mott-Schottky characteristics; (g) Deep-level trap state analysis performed by deep-level transient spectroscopy (DLTS); (h) Relationship between DLTS signal amplitude and applied bias voltage under different device structures; (i) Comprehensive comparison of bimolecular recombination intensity, DLTS response, and density of states distribution of all devices. Figure 3 It is evident that the incorporation of PBQx-TCI significantly impacts the carrier dynamics and trapped state characteristics of the PCBM / BHJ system. Specifically, regarding carrier lifetime, the pure PCBM / BHJ sample exhibits multiple lifetime values ​​(0.39, 0.57, 0.68, 2.64, 2.73, 5.11 µs), reflecting a multi-exponential decay process. However, after introducing PBQx-TCI, the lifetime distribution range of the sample significantly expands, showing both a faster decay component (0.30 µs) and a slower component (8.07 µs), indicating that PBQx-TCI may simultaneously promote more efficient charge transfer and introduce new recombination channels or trapped states. Regarding the trapped energy levels, the addition of PBQx-TCI extends the energy level range from 24.1–26.4 meV for pure PCBM / BHJ to 23.0–30.8 meV, exhibiting both shallower and deeper trap distributions, indicating that it alters the trapped state distribution of the system. Furthermore, carrier concentration data were only found in the PCBM / BHJ sample (3.35 × 10¹). 6 Up to 4.59×10¹ 6 The concentration of PBQx-TCI samples was measured in cm⁻³, while no relevant data were available for the PBQx-TCI samples, making direct comparison of concentration changes impossible. In summary, the introduction of PBQx-TCI significantly modulates the charge dynamics of the PCBM / BHJ system, potentially influencing charge separation and recombination processes by optimizing trapped states or introducing new energy levels, thereby having a potential impact on photovoltaic performance.

[0036] Figure 4 Images show the thin film morphology of solar cells prepared in Example 3 and Comparative Examples 1, 2, and 3, where: (a, b) are cross-sectional views of the compositional distribution of the A / Control / D film and the Control film at different film thicknesses; (cf) are atomic force microscopy height images of the Control film, A / Control film, Control / D film, and A / Control / D film. Figure 4 It can be seen that the control film exhibits a relatively uniform vertical distribution, consistent with the traditional vertical distribution characteristics of the BHJ structure. Conversely, the A / Control / D film shows significant vertical inhomogeneity, with the top PBQx-TCl ​​concentration dominating. This indicates that the inverted A / Control / D device achieves enrichment of p-type material near the top anode, supporting favorable vertical phase separation and thus improving carrier transport efficiency. Furthermore, AFM testing shows that the root mean square roughness (Rq) of the control film is 4.16 nm. After PBQx-TCl ​​layer composite, this value decreases to 3.70 nm, resulting in a smoother surface morphology. Similarly, spin-coating PC61BM before substrate composite reduces Rq to 2.80 nm, while the nip film exhibits the lowest Rq value (2.38 nm). This increased roughness indicates the presence of excessive phase separation domains, potentially leading to charge recombination before reaching the D / A interface. The lower Rq value suggests that the introduction of PC... 61 BM and PBQx-TCl ​​can improve the compatibility of the active layer material and enhance the contact between the active layer and the interfacial transport layer, thereby improving charge transport performance. This also indicates that the introduction of PC... 61 BM and PBQx-TCl ​​can optimize the morphology of control films, demonstrating the key role of quasi-nip active stacked layers in morphology optimization.

[0037] Figure 5 The images show the hybrid thin-film GIWAXS characteristic diagrams of the solar cells prepared in Example 3 and Comparative Examples 1, 2, and 3, where: (ad) 2D-GIWAXS patterns of the A / Control / D, A / Control, Control / D, and Control films; (e) in-plane line cut views of the A / Control / D, A / Control, Control / D, and Control films. Figure 5 It can be seen that all films exhibit obvious π-π packing peaks in the OOP direction, indicating the presence of aggregation orientation parallel to the substrate. The crystal coherence length (CCL) of the control film was measured to be 17.13 Å. PC was introduced... 61 The CCL value increased to 19.29 Å after BM. This confirmed the improved interfacial contact with ZnO, enhanced aggregation of the active layer, and increased crystallinity. However, further addition of PBQx-TCl ​​produced different results. When PBQx-TCl ​​was further introduced onto the active layer, the CCL values ​​of the Control / D and A / Control / D films were 17.40 Å and 18.09 Å, respectively, which were relatively lower than the values ​​of A / Control. This is attributed to the unique crystallinity of PBQx-TCl.

[0038] Figure 6The graph shows the stability measurement results of the inverted devices prepared in Example 3 and Comparative Example 1 after storage in nitrogen (dark environment) for 1000 hours. The recorded JV curves are: (a) Control group; (b) A / Control / D group; (c) power conversion efficiency, open-circuit voltage, open-circuit potential density, and fill factor degradation trends in the two groups of inverted devices; the shaded area represents the error range of the three independent devices. Figure 6 It can be seen that both types of inverted organic solar cells maintain a stable V. OC Value, and J SC The difference in FF loss ultimately led to a decrease in PCE. The PCE of the control group device dropped to 76%, while the A / Control / D device maintained a PCE of 92%. Similarly, after 1000 hours, the FF and J losses in the control group device... SC The values ​​were 81% and 95%, respectively. The optimized group devices showed a significant improvement in FF and J. SC The accuracy rates were 93% and 98% respectively. This demonstrates that the stability of the A / Control / D device is superior to that of the control group device.

[0039] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A quasi-NIP structure inverted organic solar cell, characterized in that, The inverted organic solar cell comprises, from bottom to top, an ITO cathode, a ZnO electron transport layer, a nip-type active layer, a MoO3 hole transport layer, and an Ag anode; the nip-type active layer is made of PC. 61 The structure consists of BM as the n-type layer, D18:L8-BO blend system as the intermediate layer of the bulk heterojunction, and PBQx-TCl ​​as the p-type layer, stacked sequentially.

2. A method for fabricating a quasi-nip structure inverted organic solar cell as described in claim 1, characterized in that, Includes the following steps: (1) Pretreatment of ITO substrate: The ITO substrate is ultrasonically cleaned and dried for later use; (2) Preparation of Glass / ITO / ZnO: ZnO solution is coated on the surface of ITO substrate, annealed, and then transferred to a glove box to cool to room temperature to obtain Glass / ITO / ZnO; (3) Configure a nip-type active layer on Glass / ITO / ZnO: S1, Configure PCs respectively 61 BM solution, D18:L8-BO solution and PBQx-TCl ​​solution; S2, First, the PC 61 BM solution was spin-coated onto the Glass / ITO / ZnO to obtain Glass / ITO / ZnO / PC. 61 BM; S3. Spin-coat the D18:L8-BO solution onto the pretreated PDMS substrate, and then laminate it onto Glass / ITO / ZnO / PC. 61 On BM, PDMS is stripped and removed to obtain Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO; S4. Spin-coat the PBQx-TCl ​​solution onto the pretreated PDMS substrate, and then laminate it onto Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO was applied, and PDMS was stripped away to obtain Glass / ITO / ZnO / PC. 61 BM / D18:L8-BO / PBQx-TCl; (4) Depositing a MoO3 hole transport layer and an Ag anode on a nip-type active layer: The Glass / ITO / ZnO / PC 61 BM / D18:L8-BO / PBQx-TCl ​​was used to sequentially deposit MoO3 and silver electrodes in a vacuum evaporation chamber, while controlling the chamber pressure to be <2×10⁻⁶. -4 Pa yields a structure of Glass / ITO / ZnO / PC. 61 Inverted organic solar cells of BM / D18:L8-BO / PBQx-TCl / MoO3 / Ag.

3. The method for fabricating a quasi-NIP structure inverted organic solar cell according to claim 2, characterized in that, In step (1), the ITO substrate pretreatment is performed by sequentially using a cleaning agent solution, deionized water, acetone, deionized water and isopropanol to ultrasonically clean the ITO substrate, with each step lasting 10-20 minutes, to obtain an ultrasonically cleaned ITO substrate; then the ultrasonically cleaned ITO substrate is dried using a nitrogen gun, and then placed in the chamber of an ultraviolet ozone cleaner for 25-35 minutes, and then taken out for use.

4. The method for fabricating a quasi-nip structure inverted organic solar cell according to claim 2, characterized in that, In step (2), the ZnO solution is prepared as follows: In a 500 mL beaker, 5-15 mmol of anhydrous zinc acetate is dissolved in 125 mL of methanol and heated to 60-70 °C. Then, potassium hydroxide methanol solution with a mass-to-volume ratio of (1-1.1) g:50 mL is slowly added dropwise. The reaction is carried out for 15-25 min. Then, 1-3 mL of ethanolamine is added. The mixture is then concentrated to a volume of 45-55 mL. Ethyl acetate is added to precipitate the product. The product is centrifuged, the supernatant is discarded, and the precipitate is mixed with anhydrous ethanol and dissolved by ultrasonic treatment to obtain a ZnO solution with a concentration of 25-35 mg / mL.

5. The method for fabricating a quasi-NIP structure inverted organic solar cell according to claim 2, characterized in that, In step (2), the annealing temperature is 140-160℃ and the annealing time is 15-25min.

6. The method for fabricating a quasi-nip structure inverted organic solar cell according to claim 2, characterized in that, In step S1, the PC 61 The preparation method of BM solution is as follows: In a glove box, PC... 61 BM was dissolved in chloroform to prepare PC at a concentration of 3-8 mg / mL. 61 BM solution; The preparation method of the D18:L8-BO solution is as follows: In a glove box, D18:L8-BO with a mass ratio of (0.5-1):1.2 is dissolved in chloroform to prepare a mixed solution with a concentration of 5-10 mg / mL. The PBQx-TCl ​​solution is prepared by adding chloroform to PBQx-TCl ​​solid in a glove box to prepare a PBQx-TCl ​​solution with a concentration of 1-3 mg / mL.

7. The method for fabricating a quasi-nip structure inverted organic solar cell according to claim 2, characterized in that, In steps S3 and S4, the pretreated PDMS substrate is prepared by cutting PDMS into segments that match the size of the glass slide, adhering them to the glass slide, subjecting them to 10-20 min of ultraviolet ozone plasma treatment, transferring them to a glove box, and immersing them in isopropanol for 15-25 min.

8. The method for fabricating a quasi-nip structure inverted organic solar cell according to claim 2, characterized in that, In step (4), the vapor deposition thickness of the MoO3 is 1-3 nm; the vapor deposition thickness of the silver electrode is 90-110 nm.

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