A kind of translucent organic solar cell and its preparation method

Abstract

The application belongs to the technical field of organic photovoltaic devices, and specifically discloses a kind of semi-transparent organic solar cell and its preparation method.The semi-transparent organic solar cell includes transparent substrate, bottom electrode, hole transport layer, organic active layer, composite top electrode and polymer optical adjustment layer arranged in sequence.The composite top electrode includes first inorganic oxide layer, metal nanowire conductive network layer and second inorganic oxide layer arranged in sequence;The first inorganic oxide layer is ZnO-PEI layer, which is arranged close to the organic active layer and serves as an electron transport layer;The second inorganic oxide layer is a pure ZnO layer;The polymer optical adjustment layer is placed on the second inorganic oxide layer of the composite top electrode;The refractive index of the polymer optical adjustment layer is lower than that of the electron transport layer;The material of the polymer optical adjustment layer is polymethyl methacrylate.

Description

Technical Field

[0001] This invention relates to the field of organic photovoltaic device technology, specifically to a semi-transparent organic solar cell and its preparation method, and more particularly to a semi-transparent organic solar cell with high transmittance, high efficiency, and high mechanical flexibility having a fully solution-processed optical adjustment layer and its preparation method. Background Technology

[0002] Semi-transparent organic photovoltaics (ST-OPVs) have attracted much attention due to their potential applications in building-integrated photovoltaics (BIPV) and portable power supplies. A key performance indicator for ST-OPVs is light utilization efficiency (LUE = AVT × PCE), which is the product of average visible light transmittance (AVT) and power conversion efficiency (PCE). To improve LUE, an optical coupling layer (OCL) is typically introduced on top of the transparent electrode to modulate the light field distribution within the device, enhancing near-infrared (NIR) photon capture and reducing parasitic absorption of visible light. Currently, traditional ST-OPVs often use vacuum-deposited inorganic materials (such as MoOx, TeO2) or one-dimensional photonic crystals as OCLs. However, the preparation of these inorganic OCLs relies on high-vacuum evaporation processes, which not only undermines the advantages of organic photovoltaics' "low cost, all-solution processing" but also makes them unsuitable for flexible electronic devices due to the inherent brittleness of inorganic oxides (they are prone to micron-level cracks leading to failure when bent).

[0003] Existing semi-transparent devices based on silver nanowires (AgNW) typically employ a "sandwich structure" (such as ZnO / AgNW / ZnO) to replace vapor-deposited metal electrodes. While achieving high transmittance and conductivity, effective optical tuning strategies are lacking. Due to the complex porous three-dimensional morphology of AgNW networks, traditional optical tuning layers and their design methods for planar electrodes are not entirely applicable. Furthermore, while currently reported AgNW-based devices achieve high transmittance (>50%), they often struggle to simultaneously maintain high photoelectric conversion efficiency, and a fully solution-processed optical tuning scheme compatible with flexible substrates is lacking.

[0004] On the other hand, CN119584757A discloses a solar cell structure that includes a metal protective layer as a patterned mask, but its function is limited to process assistance and electrical contact enhancement, and it does not have optical adjustment capabilities. Furthermore, its structure is not suitable for high-transmittance semi-transparent devices.

[0005] Existing technologies suffer from several problems, including complex optical adjustment layer fabrication processes that rely on vacuum evaporation, resulting in high costs and low efficiency; poor mechanical flexibility of inorganic optical adjustment layers, making them unsuitable for flexible devices; difficulty in ensuring optical matching and film quality for non-planar electrodes such as silver nanowires; and difficulty in achieving high efficiency and low LUE for semi-transparent devices processed entirely in solution while maintaining high transmittance (AVT>50%). Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a semi-transparent organic solar cell and its fabrication method, to solve the problems of complex optical adjustment layer fabrication process, poor mechanical flexibility, and low light field utilization in the prior art. In terms of materials and structure, this invention aims to solve the optical matching and planarization problems of the AgNW electrode surface by introducing a polymer layer with a specific refractive index (such as PMMA) to form a "high-low" refractive index gradient interface with the sandwich-structured AgNW composite electrode, while simultaneously endowing the device with excellent mechanical flexibility.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] In a first aspect, the present invention provides a semi-transparent organic solar cell, comprising: sequentially stacked layers of: Transparent substrate; Bottom electrode; Hole transport layer; Organic active layer; A composite top electrode comprising a first inorganic oxide layer, a metal nanowire conductive network layer, and a second inorganic oxide layer sequentially stacked; wherein the first inorganic oxide layer is a ZnO-PEI layer, disposed close to the organic active layer, serving as an electron transport layer; and the second inorganic oxide layer is a pure ZnO layer; and A polymer optical adjustment layer is disposed on the second inorganic oxide layer of the composite top electrode; the refractive index of the polymer optical adjustment layer is lower than that of the electron transport layer; the material of the polymer optical adjustment layer is polymethyl methacrylate (PMMA).

[0009] The composite top electrode has a sandwich structure of inorganic oxide / silver nanowire / inorganic oxide.

[0010] The refractive index of the electron transport layer is 2.0-2.1, and the refractive index of the polymer optical adjustment layer is 1.45-1.5.

[0011] The thickness of the polymer optical adjustment layer is from 50 nm to 230 nm, preferably from 100 nm to 120 nm.

[0012] The amount of polyethyleneimine (PEI) doped in the ZnO-PEI layer is 1-2 wt% of the ZnO mass.

[0013] The polymer optical adjustment layer is coated on the surface of the composite top electrode by a solution method. Its refractive index is lower than that of the electron transport layer, and it is used to adjust the optical field distribution inside the device.

[0014] The transparent substrate is one or more of glass, polyethylene terephthalate, and polyethylene naphthalate.

[0015] The bottom electrode is a transparent conductive oxide film, preferably indium tin oxide (ITO), fluorine-doped tin oxide (FTO), or aluminum-doped zinc oxide (AZO), with ITO being more preferred.

[0016] The material of the hole transport layer is PEDOT:PSS.

[0017] When the organic active layer comprises donor material PTB7-Th and acceptor materials ATT-9 and AQx-6, the organic active layer comprises donor material PTB7-Th and acceptor materials ATT-9 and / or AQx-6.

[0018] The weight ratio of PTB7-Th, ATT-9, and AQx-6 is 1:1.26-1.54:0.18-0.22.

[0019] Furthermore, the conductive network layer of the metal nanowire is composed of metal nanowires, which are one or more of silver nanowires, copper nanowires, or gold nanowires; preferably, silver nanowires.

[0020] Further, the metal nanowires have an average diameter of 15-40 nm and a length of 10-50 μm. Preferably, the metal nanowires have an average diameter of 25-35 nm and a length of 20-30 μm.

[0021] Furthermore, the metal nanowire conductive network layer is formed by solution coating to form a conductive network with nanoscale pores; the second inorganic oxide layer fills the pores of the metal nanowire conductive network layer.

[0022] Secondly, a method for preparing the aforementioned semi-transparent organic solar cell is provided, comprising the following steps: Step 1: Form a hole transport layer on the surface of the bottom electrode on a transparent substrate; Step 2: Coat the hole transport layer with an organic active layer; Step 3: Coat the organic active layer with ZnO-PEI dispersion, and after annealing, form a first inorganic oxide layer, which serves as an electron transport layer; Step 4: Coat the first inorganic oxide layer with a metal nanowire dispersion, and anneal it to form a metal nanowire conductive network layer; Step 5: Coat the conductive network layer with pure ZnO nanoparticle dispersion, and after annealing, form a second inorganic oxide layer. The second inorganic oxide layer fills the pores of the conductive network layer with the metal nanowire; thus obtaining the composite top electrode. Step 6: Coat the second inorganic oxide layer with PMMA solution, and anneal it to form a polymer optical conditioning layer; All coating steps are solution spin coating processes, achieving full solution processing.

[0023] In step 1, the bottom electrode on the transparent substrate is an indium tin oxide (ITO) electrode.

[0024] In step 6, the coating solvent for the PMMA solution is an orthogonal solvent that has no solubility for the underlying film layer.

[0025] The orthogonal solvent is one of n-butyl acetate, n-heptane, and tetrahydrofuran.

[0026] Preferably, the orthogonal solvent is n-butyl acetate.

[0027] In step 4, the metal nanowire dispersion is a silver nanowire dispersion with a concentration of 5-10 mg / mL, and the spin coating speed is 2000-4000 rpm; the average diameter of the metal nanowire is 25-35 nm and the length is 20-30 μm.

[0028] The annealing temperatures in steps 3, 4, and 5 are independently selected from 90°C to 150°C, and the annealing time is from 5 minutes to 15 minutes.

[0029] In step 6, the thickness of the polymer optical conditioning layer is controlled by adjusting the concentration of the PMMA solution; the concentration of the PMMA solution is from 10 mg / mL to 30 mg / mL.

[0030] In step 3, the ZnO-PEI dispersion was prepared by the following method: the zinc source was dissolved in an alcohol solvent and stirred at a constant temperature of 40-80℃; then, an alcohol solution of alkali metal hydroxide was slowly added dropwise to the above solution, and the reaction was carried out for 1-4 hours; after the reaction was completed, ZnO nanoparticles were obtained by centrifugation and redispersed in an alcohol solvent, and ultrasonic treatment was performed to obtain a ZnO nanoparticle dispersion with a concentration of 10-30 mg / mL; polyethyleneimine (PEI) was added to the above ZnO nanoparticle dispersion at a ratio of 1-3 wt% of ZnO mass, and stirred evenly to obtain the ZnO-PEI dispersion.

[0031] Further, the zinc source is one of zinc acetate, zinc acetate dihydrate, zinc nitrate, or zinc chloride; the alcohol solvent is one of methanol, ethanol, or isopropanol; the alkali metal hydroxide is potassium hydroxide or sodium hydroxide, and the concentration of its alcohol solution is 0.2-0.8 mol / L.

[0032] In step 5, the concentration of the ZnO nanoparticle dispersion is 10-30 mg / mL.

[0033] As one embodiment of the present invention, the method for preparing the semi-transparent organic solar cell includes the following steps: Step 1: Fabrication of the hole transport layer A hole transport material solution is spin-coated onto the bottom electrode surface on a transparent substrate, and a hole transport layer is formed after annealing. Preferably, the hole transport material is a PEDOT:PSS aqueous solution, which is annealed at 140-160℃ for 10-20 minutes after spin-coating to form a hole transport layer with a thickness of 20-40 nm. Step 2: Preparation of the organic active layer An active layer solution is spin-coated onto the hole transport layer and annealed to form an organic active layer. The active layer solution contains a donor material, an acceptor material, and an organic solvent. Preferably, the donor material is PTB7-Th, and the acceptor materials are ATT-9 and AQx-6, dissolved in chloroform at a weight ratio of 1:1.26-1.54:0.18-0.22, with 0.4-0.6 vol% of 1-chloronaphthalene added as an additive. After spin-coating, the solution is annealed at 85-95°C for 8-12 minutes to form a bulk heterojunction active layer with a thickness of 80-100 nm. Step 3: Preparation of the first inorganic oxide layer (electron transport layer) A ZnO-PEI dispersion was spin-coated onto the organic active layer and then annealed to form a first inorganic oxide layer. Step 4: Fabrication of the conductive network layer of metal nanowires A metal nanowire dispersion was spin-coated onto the first inorganic oxide layer, and after annealing, a metal nanowire conductive network layer was formed. Step 5: Preparation of the second inorganic oxide layer A pure ZnO nanoparticle dispersion is spin-coated onto the metal nanowire conductive network layer, and after annealing, a second inorganic oxide layer is formed. The second inorganic oxide layer fills the pores of the metal nanowire conductive network layer, thus obtaining a composite top electrode. Step 6: Fabrication of the polymer optical adjustment layer A PMMA solution is spin-coated onto the second inorganic oxide layer, and after annealing, a polymer optical conditioning layer is formed. All coating steps are solution spin coating processes, achieving full solution processing.

[0034] Thirdly, the application of the aforementioned semi-transparent organic solar cells in building-integrated photovoltaics, flexible wearable devices, or portable electronic devices is provided.

[0035] Compared with the prior art, the present invention has the following beneficial effects: 1. All-solution processing, simple process and low cost: The optical adjustment layer is prepared by spin coating, which does not require vacuum equipment and conforms to the trend of low-cost manufacturing of organic photovoltaics; 2. Significantly improved optical performance: The refractive index of the polymer optical adjustment layer is 1.4 to 1.5, and the refractive index of the electron transport layer is 1.8 to 2.2, forming a "high-low" refractive index interface; through the "high-low" refractive index interface design, the optical field modulation capability is enhanced, and Jsc and AVT are improved simultaneously, with LUE reaching 4.47% (AVT>50%). 3. Excellent mechanical flexibility: The polymer optical adjustment layer has good flexibility and retains more than 60% efficiency after 3000 bending cycles; 4. High film quality: PMMA and other materials have good wettability on hydrophilic electrode surfaces, which can effectively smooth the AgNW electrode and reduce surface roughness; 5. Strong structural versatility: It is applicable to a variety of active layer systems and substrate types, and has good process compatibility. Attached Figure Description

[0036] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the structure of the semi-transparent organic solar cell in Embodiment 1 of the present invention; Figure 2 The following are performance test graphs of the flexible substrate ST-OPV device in Example 2, where a) JV curve; b) EQE curve.

[0037] Figure 3 The bending stability test results of the flexible device in Embodiment 2 of the present invention; Figure 4 The images show the contact angle test of PMMA in Example 1, optical microscope images of the corresponding polymer optical adjustment layer, and height diagrams of the step profiler test (composite electrode and polymer layer). Figure 5 For Comparative Example 1, the contact angle test of PDMS, the corresponding optical microscope images of the polymer optical adjustment layer thin film, and the height map of the step meter test (composite electrode and polymer layer) are shown. Figure 6For Comparative Example 2, contact angle test of TPU, corresponding optical microscope images of polymer optical adjustment layer thin film, and height map of step meter test (composite electrode and polymer layer). Figure 7 The optical and electrical parameters of the PMMA-modified composite electrode are shown below; where a) transmittance spectra of the composite electrode at different PMMA thicknesses; b) AVT and sheet resistance of the composite electrode at different PMMA thicknesses; c) cross-sectional SEM images of the semi-transparent device before and after PMMA modification. Figure 8 The image shows the TDTD optical field simulation diagram of Example 1; where a) is the optical field distribution of the unmodified and 100nm PMMA-modified devices; and b) is the carrier generation of the control group and experimental group 3 devices. Figure 9 The following are performance test graphs of the rigid ST-OPV device in Example 1, where a) JV curve; b) EQE curve; c) photon count check of the control group device; and d) photon count check of the device in test group 3. Detailed Implementation

[0038] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0039] Example 1: Fabrication of a Rigid Substrate Semi-Transparent Organic Solar Cell 1. Preparation of zinc oxide (ZnO) precursor solution Preparation of ZnO nanoparticle dispersion: Zinc acetate dihydrate was weighed and dissolved in methanol, and stirred at a constant temperature in an oil bath at 61℃. Subsequently, a 0.4 mol / L potassium hydroxide (KOH) methanol solution was slowly added dropwise to the above solution, and the reaction was continued for 2 hours. After the reaction was completed, ZnO nanoparticles were obtained by centrifugation and redispersed in methanol. The dispersion was then ultrasonicated to obtain a ZnO nanoparticle dispersion with a concentration of 15 mg / mL.

[0040] ZnO-PEI dispersion: Polyethyleneimine (PEI) was added to the above ZnO nanoparticle dispersion at a ratio of 1 wt% of ZnO mass, and stirred evenly to obtain ZnO-PEI dispersion for later use.

[0041] 2. Preparation of silver nanowire (AgNW) dispersion Commercially available silver nanowires (average diameter ~30 nm, length 20-30 μm) dispersions were diluted with isopropanol to a concentration of 5 mg / mL and sonicated for 10 minutes to ensure uniform dispersion.

[0042] 3. Preparation of Optical Conditioning Layer (OCL) Solution Polymethyl methacrylate (PMMA) particles were dissolved in n-butyl acetate and stirred continuously at 120°C for 2 hours to prepare a series of solutions with concentrations ranging from 10-20 mg / mL. n-Butyl acetate, as an orthogonal solvent, is insoluble in the underlying organic active layer and the ZnO layer, ensuring interfacial integrity during multilayer solution processing. Optically modified composite electrodes were then prepared using a ZnO-PEI / AgNW / ZnO / PMMA structure. Figure 7 The optical and electrical parameters of the PMMA-modified composite electrode are shown below; including: a) transmittance spectra of the composite electrode at different PMMA thicknesses; b) AVT and sheet resistance of the composite electrode at different PMMA thicknesses; c) cross-sectional SEM images of the semi-transparent device before and after PMMA modification; and obtained by... Figure 7 It can be seen that the electrodes have good optical and electrical properties.

[0043] 4. Fabrication of Rigid Substrate Semi-Transparent Organic Solar Cells Taking rigid devices as an example, the device structure ( Figure 1 ): Glass / ITO / PEDOT:PSS / PTB7-Th:ATT-9:AQx-6 / ZnO-PEI / AgNW / ZnO / PMMA.

[0044] The specific steps are as follows: a) Substrate cleaning and pre-electrode treatment: The ITO glass substrate was ultrasonically cleaned sequentially with detergent, deionized water, acetone and isopropanol, followed by oxygen plasma treatment.

[0045] A PEDOT:PSS aqueous solution (AI 4083) was spin-coated onto the treated ITO surface and annealed at 150°C for 15 minutes to form a hole transport layer of approximately 30 nm thickness.

[0046] b) Preparation of the active layer: The donor material PTB7-Th and the acceptor materials ATT-9 and AQx-6 were dissolved in chloroform at a weight ratio of 1:1.4:0.2, and 0.5 vol% of 1-chloronaphthalene (CN) was added as an additive. The prepared solution was spin-coated onto the PEDOT:PSS layer and annealed at 90°C for 10 minutes to form a bulk heterojunction active layer with a thickness of approximately 90 nm.

[0047] c) Fabrication of the composite top electrode: First, a ZnO-PEI dispersion was spin-coated onto the active layer and annealed at 100°C for 10 minutes to form an electron transport layer of about 30 nm thickness. The refractive index of the electron transport layer (ZnO-PEI) was 2.0-2.1.

[0048] Subsequently, 20 μL of AgNW dispersion was spin-coated (2000 rpm) and annealed at 100°C for 5 minutes to form a conductive network layer.

[0049] Finally, a second layer of ZnO dispersion (20 μL) was spin-coated to fill the pores between the AgNW networks, and then annealed at 100°C for 10 minutes to form a complete "ZnO / AgNW / ZnO" sandwich structure composite top electrode. Figure 7 (This reflects the optical and electrical properties of the individual composite top electrode). d) Preparation of the optical adjustment layer: PMMA solutions of different concentrations (10-20 mg / mL) were spin-coated onto the surface of the composite top electrode at speeds of 2000 rpm-4000 rpm, followed by annealing at 90°C for 5 minutes to form a polymer optical adjustment layer. By controlling the concentration and spin speed, polymer optical adjustment layers of varying thicknesses were formed. Measurements using an ellipsometer showed that the film thickness varied from approximately 70 nm to 230 nm with concentration. Simultaneously, a device without a PMMA coating was prepared as a control (denoted as "w / o"). Figure 8 The optical field distribution and carrier generation of a semi-transparent device were simulated using FDTD. Performance characterization and results The fabricated device was subjected to current density-voltage (JV) characteristics testing (AM 1.5G, 100 mW / cm²) and transmission spectroscopy testing.

[0050] Table 1. Photoelectric properties of semi-transparent devices with different optical modification layer thicknesses

[0051] When the thickness of the PMMA optical tuning layer (refractive index 1.49) was optimized to 110 nm (experimental group 3), the device achieved the best performance: the open-circuit voltage (VOC) was 0.637 V, and the short-circuit current density (JSC) increased to 19.6 mAcm. - ², with a fill factor (FF) of 0.655 and a power conversion efficiency (PCE) of 8.15%.

[0052] Under the same optimization conditions, the average visible light transmittance (AVT, 380-780 nm) of the device in (experimental group 3) increased from 52.2% without the PMMA layer to 54.8%. Figure 9The following are performance test diagrams for rigid ST-OPV devices: a) JV curve, b) EQE curve; c) photon count check of the control group device; d) photon count check of the device in test group 3.

[0053] Based on the above data, the light utilization efficiency (LUE = PCE × AVT) of the device in (experimental group 3) reached 4.47%. Compared with the control device without an optical conditioning layer (LUE of 3.78%), the performance improvement is significant, which is the highest value reported to date for all-solution processed ST-OPV with AVT > 50% (Table 2).

[0054] Table 2

[0055] Example 2: Fabrication of a flexible substrate semi-transparent organic solar cell The rigid ITO glass substrate in Example 1 was replaced with a flexible transparent polyethylene terephthalate (PET) substrate with ITO coating (purchased from South China Xiangcheng Technology Co., Ltd.).

[0056] Except for the substrate replacement, the preparation materials, process parameters and conditions of the other functional layers (PEDOT:PSS, active layer, ZnO-PEI / AgNW / ZnO composite electrode, polymer optical adjustment layer (refractive index 1.49) are consistent with those of test group 3 in Example 1.

[0057] The performance test results are as follows: Initial performance: The initial PCE of the fabricated flexible semi-transparent organic solar cell was 6.49%, and the AVT was 51.1%. Figure 2 The following are performance test graphs of the flexible substrate ST-OPV device in Example 2, where a) is the JV curve and b) is the EQE curve.

[0058] Bending stability: The device was subjected to continuous bending tests around a cylinder with a diameter of 6 mm (bending radius of 3 mm). After 3000 bending cycles in air, the device still retained approximately 60% of its initial PCE, demonstrating good mechanical durability. Figure 3 ).

[0059] Comparative Example 1: PDMS as an optical conditioning layer The difference between this comparative example and test group 3 of Example 1 is that polymethyl methacrylate (PMMA, refractive index 1.49) particles were replaced with polydimethylsiloxane (PDMS, refractive index 1.41, soluble in n-heptane).

[0060] That is, in step d) the preparation of the optical adjustment layer: a solution of n-heptane (solid content 20 mg / mL) of polydimethylsiloxane (PDMS) is spin-coated onto the surface of the composite top electrode.

[0061] The remaining preparation steps, material system and process parameters are completely consistent with those in Example 1.

[0062] Device performance: The final device has a PCE of 7.82%, an AVT of 53.1%, and a calculated LUE of 4.15%. While its performance is better than the device without an optical adjustment layer, it is significantly lower than Example 1 using PMMA; the JV and EQE curves show... Figure 9 .

[0063] Comparative Example 2 The difference between this comparative example and test group 3 of Example 1 is that the polymethyl methacrylate (PMMA, refractive index 1.49) particles were replaced with thermoplastic polyurethane (TPU, refractive index 1.55, dissolved in tetrahydrofuran).

[0064] That is, in step d) the preparation of the optical adjustment layer: a tetrahydrofuran solution (solid content 20 mg / mL) of thermoplastic polyurethane (TPU) on the surface of the composite top electrode.

[0065] The remaining preparation steps, material system and process parameters are completely consistent with those in Example 1.

[0066] Device performance: Poor film quality seriously affected the light field modulation effect and may introduce leakage channels. The final device PCE is 7.35%, AVT is 51.9%, and the calculated LUE is only 3.81%.

[0067] Observation of film formation quality of different polymer materials in Example 1, Comparative Example 1, and Comparative Example 2: Figure 4 The images show the contact angle test of PMMA in Example 1, optical microscope images of the corresponding polymer optical adjustment layer, and height diagrams of the step profiler test (composite electrode and polymer layer). Figure 5 For Comparative Example 1, the contact angle test of PDMS, the corresponding optical microscope images of the polymer optical adjustment layer thin film, and the height map of the step meter test (composite electrode and polymer layer) are shown. Figure 6The images show contact angle tests of TPU in Comparative Example 2, optical microscope images of the corresponding polymer optical modulation layer film, and height maps obtained using a step meter (composite electrode and polymer layer). In Comparative Example 1, the PDMS solution exhibits poor wettability on the hydrophilic ZnO electrode surface, resulting in insufficient adhesion to the underlying layer and generally poor film uniformity. PMMA, due to its excellent wettability on the ZnO surface (contact angle <20°) and good film-forming stability, can form a uniform, defect-free film, significantly reducing the electrode surface roughness (Rq) from ~7.07 nm to ~1.49 nm. This characteristic is crucial for achieving efficient optical field modulation and obtaining a high LUE (4.47%). PDMS and TPU, due to their respective interface or film-forming defects, cannot achieve the same effect.

[0068] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that these are merely illustrative examples, and any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A semi-transparent organic solar cell, characterized in that, Including those set up in a stacked manner: Transparent substrate; Bottom electrode; Hole transport layer; Organic active layer; A composite top electrode comprising a first inorganic oxide layer, a metal nanowire conductive network layer, and a second inorganic oxide layer stacked sequentially; wherein the first inorganic oxide layer is a ZnO-PEI layer disposed close to the organic active layer, serving as an electron transport layer; and the second inorganic oxide layer is a pure ZnO layer. as well as A polymer optical adjustment layer is disposed on the second inorganic oxide layer of the composite top electrode; the refractive index of the polymer optical adjustment layer is lower than that of the electron transport layer; the material of the polymer optical adjustment layer is polymethyl methacrylate.

2. The semi-transparent organic solar cell according to claim 1, characterized in that, The refractive index of the electron transport layer is 2.0-2.1, and the refractive index of the polymer optical adjustment layer is 1.45-1.

5.

3. The semi-transparent organic solar cell according to claim 1, characterized in that, The thickness of the polymer optical adjustment layer is 70 nm to 230 nm.

4. The semi-transparent organic solar cell according to claim 1, characterized in that, The transparent substrate is one or more of glass, polyethylene terephthalate, and polyethylene naphthalate; The material of the hole transport layer is PEDOT:PSS.

5. The semi-transparent organic solar cell according to claim 1, characterized in that, The organic active layer comprises donor material PTB7-Th and acceptor material ATT-9 and / or AQx-6; When the organic active layer comprises donor material PTB7-Th and acceptor materials ATT-9 and AQx-6, the weight ratio of PTB7-Th, ATT-9, and AQx-6 is 1:1.4:0.

2.

6. The semi-transparent organic solar cell according to claim 1, characterized in that, The amount of polyethyleneimine (PEI) doped in the ZnO-PEI layer is 1-2 wt% of the ZnO mass.

7. A method for preparing a semi-transparent organic solar cell as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Form a hole transport layer on the surface of the bottom electrode on a transparent substrate; Step 2: Coat the hole transport layer with an organic active layer; Step 3: Coat the organic active layer with ZnO-PEI dispersion, and after annealing, form a first inorganic oxide layer, which serves as an electron transport layer; Step 4: Coat the first inorganic oxide layer with a metal nanowire dispersion, and anneal it to form a metal nanowire conductive network layer; Step 5: Coat the conductive network layer of the metal nanowire with a pure ZnO nanoparticle dispersion, and after annealing, form a second inorganic oxide layer to obtain a composite top electrode; Step 6: Coat the second inorganic oxide layer with PMMA solution, and anneal it to form a polymer optical conditioning layer; All coating steps are solution spin coating processes, achieving full solution processing.

8. The preparation method according to claim 7, characterized in that, In step 6, the coating solvent for the PMMA solution is an orthogonal solvent that has no solubility for the underlying film layer; the orthogonal solvent is one of n-butyl acetate, n-heptane, and tetrahydrofuran.

9. The preparation method according to claim 7, characterized in that, In step 4, the concentration of the metal nanowire dispersion is 5-10 mg / mL, and the spin coating speed is 2000-4000 rpm; the average diameter of the metal nanowires is 20-30 nm, and the length is 20-30 μm; the metal nanowires are one or more of silver nanowires, copper nanowires, and gold nanowires. The annealing temperature in steps 3, 4 and 5 is independently selected from 90°C to 150°C, and the annealing time is 5 minutes to 15 minutes. In step 6, the thickness of the polymer optical conditioning layer is controlled by adjusting the concentration of the PMMA solution; the concentration of the PMMA solution is from 10 mg / mL to 30 mg / mL.

10. The application of a semi-transparent organic solar cell as described in any one of claims 1-6 or a semi-transparent organic solar cell prepared by the preparation method described in any one of claims 7-9 in building-integrated photovoltaics, flexible wearable devices, or portable electronic devices.

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