Organic solar cell, organic photovoltaic device and preparation method thereof

Abstract

The present application relates to an organic solar cell, an organic photovoltaic device and a method for preparing the same. The organic solar cell includes a photoactive layer, which is prepared by mixing a polymer donor / acceptor material and a third component material in a predetermined ratio; wherein the third component material is configured such that its absorption spectrum is partially in the non-visible light region, has a higher miscibility with the acceptor material than with the donor material, and can transfer charge with the polymer donor / acceptor material. The present disclosure introduces a third component material into the existing active layer donor / acceptor material, thereby effectively suppressing charge recombination loss while maintaining high transparency, achieving higher energy conversion efficiency, and improving device performance.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and more specifically, to an organic solar cell, an organic photovoltaic device and a preparation method thereof. Background Art

[0002] Transparent organic photovoltaics (TOPVs) have attracted widespread attention due to their great application potential in many fields. Whether the average visible transmission (AVT) of the device is higher than 50% is an important indicator of whether it can be used effectively. In order to obtain efficient transparent organic photovoltaics, researchers usually optimize the active layer materials, device optical engineering, transparent top electrodes, etc. The active layer is the core part of organic photovoltaics. By changing the donor and acceptor materials, the absorption spectrum of the active layer can be effectively adjusted to selectively absorb photons in the non-visible light region (i.e., the ultraviolet and near-infrared regions), thereby achieving higher AVT in the visible light region while producing better power conversion efficiency (PCE).

[0003] A study has successfully prepared TOPVs with adjustable AVT in the range of 40~85% using near-infrared absorbing donor PTB7-Th and acceptor IEICO-4F as active layer materials. When the AVT was 80.4%, TOPVs achieved a PCE of 2.38%. However, when the AVT was further increased to 85%, the device could no longer work properly. The highest AVT of TOPVs reported in the literature is 82%, and the PCE is only 0.43%. However, if TOPVs are to be used in low-power electronic devices (such as electronic displays or smart windows), they need to have a high transparency AVT and color rendering index (CRI) close to glass. No TOPVs that meet this requirement have been reported so far. To achieve this goal, both manufacturing process and material selection are particularly critical.

[0004] Reducing the thickness of the active layer is an effective way to improve the AVT of the device. However, as the thickness of the active layer decreases, there is a certain competition between the device's photon absorption and carrier transmission. When the thickness of the active layer is reduced to a certain extent, in addition to the short-circuit current density (Short-circuit current density, J SC ) decreases, the interface recombination loss of the device will increase and lead to an open-circuit voltage (Open-circuit voltage, V OC) and fill factor (FF) are significantly reduced, resulting in leakage and making the device unable to work normally.

[0005] Therefore, a new type of efficient organic photovoltaic device is needed, which can achieve higher power conversion efficiency (PCE) while maintaining high transparency (AVT) and improve the overall performance of the device. Summary of the invention

[0006] The present disclosure provides an organic solar cell, an organic photovoltaic device and a preparation method thereof, which introduces a third component material into the existing active layer donor / acceptor material, thereby effectively suppressing charge recombination loss and improving device performance while maintaining high transparency of the photovoltaic device. At the same time, the introduction of the third component material can improve the stacking orientation of the donor and acceptor, optimize the phase morphology of the active layer, and improve the operational stability and data reproducibility of the device.

[0007] In a first embodiment of the present disclosure, an organic solar cell is provided, which includes a photoactive layer, wherein the photoactive layer is prepared by mixing a polymer donor / acceptor material and a third component material in a predetermined ratio; wherein the third component material is configured so that its absorption spectrum is partially in the non-visible light region, its miscibility with the acceptor material is better than its miscibility with the donor material, and charge transfer can occur between the third component material and the polymer donor / acceptor material.

[0008] In a second embodiment of the present disclosure, an organic photovoltaic device is provided, comprising a substrate and an organic solar cell as described in the first embodiment arranged on the substrate.

[0009] In the third scheme of the present disclosure, a method for preparing an organic photovoltaic device is provided, and the organic photovoltaic device is the organic photovoltaic device described in the second scheme, and the preparation method comprises the following steps: forming a transparent conductive base layer on the substrate; forming one of a hole transport layer and an electron transport layer on the transparent conductive base layer to obtain a first intermediate base; forming the photoactive layer on the first intermediate base; forming the other of the hole transport layer and the electron transport layer on the photoactive layer to obtain a second intermediate base; forming the top transparent electrode layer on the intermediate base; and patterning and etching the top transparent electrode layer.

[0010] Compared with the prior art, the organic solar cell and organic photovoltaic device provided by the present disclosure have the following beneficial effects:

[0011] (1) Based on the ternary component strategy, a third component material is added to the polymer donor / acceptor material, which not only increases the thickness of the photoactive layer film, but also inhibits the excessive aggregation of the acceptor and prolongs the life of the exciton;

[0012] (2) The small molecule third component material also promotes the pi-pi stacking of the donor / acceptor materials to be more orderly, improves the crystallinity, inhibits trap-assisted recombination, and improves the device performance. V OC and FF, enabling high-transmittance organic photovoltaic devices to operate stably;

[0013] (3) Produce highly transparent organic photovoltaics with AVT close to 90%, PCE exceeding 1%, and CRI exceeding 98%, and ensure high data reproducibility;

[0014] (4) The present disclosure can provide a reference for the simple preparation and application of stable high-transmittance organic photovoltaics, organic detectors, organic field-effect transistors and other optoelectronic devices, and can serve as a potential implementation method for building integrated photovoltaic windows. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. When appropriate, the same reference numerals are used in all drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present device or method. In the drawings:

[0016] Figure 1 is a schematic structural diagram of an organic photovoltaic device including an organic solar cell according to an embodiment of the present disclosure;

[0017] Figure 2 A JV curve diagram of an organic photovoltaic device including an organic solar cell in the prior art at different photoactive layer thicknesses;

[0018] Figure 3 is a flow chart of a method for preparing an organic photovoltaic device according to an embodiment of the present disclosure;

[0019] Figure 4 is a flow chart of a method for preparing a photoactive layer according to an embodiment of the present disclosure;

[0020] Figure 5 is a normalized absorption spectrum diagram of a polymer donor / acceptor material and a third component material of an organic solar cell according to an embodiment of the present disclosure;

[0021] Figure 6 is a JV curve diagram of the transparent organic photovoltaic device in Examples 1 to 4 and Comparative Example 4 of the present disclosure;

[0022] Figure 7It is a graph of external quantum efficiency (EQE) of the transparent organic photovoltaic devices of Examples 1 to 4 and Comparative Example 4 of the present disclosure;

[0023] Figure 8 It is a T spectrum diagram of the transparent organic photovoltaic device of Examples 1 to 4 and Comparative Example 4 of the present disclosure;

[0024] Fig. 9 Comparison of optical and electrical parameters of the transparent organic photovoltaic devices of Examples 1 to 4 of the present disclosure and Comparative Example 4;

[0025] Fig.10 is the thickness of the corresponding photoactive layer film in Examples 1 to 4 and Comparative Example 4 of the present disclosure;

[0026] Fig.11 The absorption cutoff edge ( λ onset ) and the optical band gap ( );

[0027] Fig.12 The photoluminescence spectra of the photoactive layer films in Example 1 and Comparative Example 4 of the present disclosure;

[0028] Fig.13 is the open circuit voltage of the transparent organic photovoltaic device in Example 1 and Comparative Example 4 of the present disclosure ( V OC ) with light intensity ( P light ) changing trends;

[0029] Fig.14 1-D GIWAXS cross-sectional view of the photoactive layer film along the out-of-plane direction in Example 1 and Comparative Example 4 of the present disclosure;

[0030] Fig.15 The interplanar spacing ( d -spacing) and crystal coherence length (CCL). DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiment of the present application clearer, the technical solution of the embodiment of the present application will be clearly and completely described in conjunction with the drawings of the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, not all of the embodiments. Based on the described embodiment of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0032] Unless otherwise defined, the technical terms or scientific terms used in this application should be understood by people with ordinary skills in the field to which this application belongs. "First", "second" and similar words used in this application do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0033] In order to keep the following description of the embodiments of the present application clear and concise, the present application omits detailed descriptions of known functions and known components.

[0034] Figure 1 FIG. 1 shows a schematic structural diagram of a transparent organic photovoltaic device 100 provided by the present disclosure. Figure 1 As shown, the organic photovoltaic device 100 includes a substrate 110 and an organic solar cell 120 arranged on the substrate 110, and the organic solar cell 120 is configured to absorb sunlight and convert it into electrical energy for output. Specifically, the organic solar cell 120 may include, from bottom to top, a transparent conductive substrate layer 121, one of a hole transport layer 122 and an electron transport layer 123, a photoactive layer 124, another of the hole transport layer 122 and the electron transport layer 123, and a top transparent electrode layer 125 stacked in sequence.

[0035] Figure 1 Specifically, a positive cell structure of transparent conductive substrate layer 121 / hole transport layer 122 / photoactive layer 124 / electron transport layer 123 / top transparent electrode layer 125 is shown; however, it should be understood that the organic solar cell 120 of the present disclosure may also adopt an inverted cell structure of transparent conductive substrate layer 121 / electron transport layer 123 / photoactive layer 124 / hole transport layer 122 / top transparent electrode layer 125, which is not limited in the present disclosure.

[0036] In a specific embodiment, the substrate 110 of the organic photovoltaic device 100 is a transparent and insulating material on which the solar cell is deposited. The substrate 110 can be a flexible substrate, such as a combination of one or more of PET, PI and PEN, or a hard substrate, such as inorganic glass and organic glass.

[0037] In a specific embodiment, the transparent conductive base layer 121 of the organic solar cell 120 may include a combination of one or more of metal oxides, thin metal films, metal nanowires, carbon nanotubes and graphene; similarly, the top transparent electrode layer 125 of the organic solar cell 120 may also include a combination of one or more of metal oxides, thin metal films, metal nanowires, carbon nanotubes and graphene.

[0038] In a specific embodiment, the hole transport layer 122 of the organic solar cell 120 may include PEDOT:PSS, NiO x , WO3, MoO3, Poly-TPD, PTAA, CuSCN and Spiro-OMeTAD.

[0039] In a specific embodiment, the electron transport layer 123 of the organic solar cell 120 may include a combination of one or more of ZnO, PEIE, PDINO, PDINN, and PFN-Br.

[0040] In traditional organic photovoltaic devices, the photoactive layer of organic solar cells is composed of binary component materials (i.e., polymer donor / acceptor materials). Figure 2 The JV curves of the organic photovoltaic device under the conditions of photoactive layer with different thicknesses (corresponding to Comparative Examples 1-4 described below in descending order of thickness) are shown. It can be seen from the figure that as the thickness of the photoactive layer decreases, the AVT of the device gradually increases, but the electrical parameters ( V OC , J SC and FF) have different degrees of attenuation, especially V OC This is because there will be serious charge recombination loss in this process, which will cause leakage in the device and make the device unable to work normally.

[0041] Therefore, in the photoactive layer 124 provided in the present disclosure, in order to overcome the above-mentioned defects, a third component material is added to the original photoactive layer material (i.e., only including the polymer donor / acceptor material) in a predetermined proportion, and the third component material is configured so that its absorption spectrum is partially in the non-visible light region, its miscibility with the acceptor material is better than its miscibility with the donor material, and charge transfer can occur between the third component material and the polymer donor / acceptor material.

[0042] The introduction of the third component material not only increases the thickness of the photoactive layer film, but also inhibits the excessive aggregation of the donor / acceptor materials and prolongs the life of the excitons. At the same time, the small molecule third component material also makes the pi-pi stacking of the donor / acceptor materials more orderly, improves the crystallinity, inhibits trap-assisted recombination, and improves the device. V OC and FF, enabling high-transmittance organic photovoltaic devices to operate stably.

[0043] First, similar to the photoactive layer material of the conventional binary component system, the polymer donor / acceptor material should be selected so that its absorption spectrum is partially in the non-visible light region. At the same time, in the present disclosure, the absorption spectrum of the third component material can also be partially in the non-visible light region, so that it can absorb non-visible light without significantly affecting the transmittance of the organic photovoltaic device including the organic solar cell to visible light, thereby maintaining an AVT that is substantially the same as that of the ultra-thin organic solar cell with a photoactive layer film of the binary component system (even if a small part of the absorption spectrum of the third component material is in the visible light region, since the amount of its addition is very small compared to the polymer donor / acceptor material, its absorption of visible light can be ignored).

[0044] In an optional embodiment, the polymer donor / acceptor material can be selected to have an absorption cutoff edge in its absorption spectrum located in the ultraviolet or near-infrared region, and the third component material can be selected to have an absorption cutoff edge in its absorption spectrum also located in the ultraviolet or near-infrared region. In this way, at least in part, it can be ensured that the organic photovoltaic device including the photoactive layer thin film composed of the material of the ternary component system has a higher transmittance in the visible light region.

[0045] Preferably, the absorption cutoff edge of the polymer donor / acceptor material is in the near-infrared region, and the absorption cutoff edge of the third component material is in the ultraviolet region.

[0046] In addition, the third component material should also satisfy the requirement that its miscibility with the acceptor material is better than its miscibility with the donor material. In this way, it can destroy the excessive aggregation of the acceptor material, so that the spectral absorption cutoff edge of the active layer gradually blue-shifts with the addition of the third component material, and the band gap increases. At the same time, it suppresses the aggregation luminescence quenching effect of the acceptor material, which is beneficial for the diffusion of excitons to the interface, thereby suppressing the charge recombination loss. In addition, the third component material should also match the energy level of the polymer donor / acceptor material, and charge transfer can occur between the two, thereby contributing a small amount of current. In this way, the open circuit voltage can be increased. V OC , short-circuit current density J SC And the fill factor FF.

[0047] In a preferred embodiment, the third component material can also improve the pi-pi stacking order of the polymer donor / acceptor material, that is, promote the pi-pi stacking of the polymer donor / acceptor material to be more orderly, improve the crystallinity, inhibit trap-assisted recombination, and further improve the device. V OC And FF.

[0048] Figure 3 1 is a flow chart of a method 200 for preparing an organic photovoltaic device 100 according to the present disclosure. The method 200 comprises the following steps S210 to S260.

[0049] S210 , forming a transparent conductive base layer 121 on the substrate 110 .

[0050] S220 , forming one of the hole transport layer 122 and the electron transport layer 123 on the transparent conductive substrate layer 121 to obtain a first intermediate substrate.

[0051] S230, forming a photoactive layer 124 on the first intermediate substrate;

[0052] S240, forming the other of the hole transport layer 122 and the electron transport layer 123 on the photoactive layer 124 to obtain a second intermediate substrate;

[0053] S250, forming a top transparent electrode layer 125 on the second intermediate substrate; and

[0054] S260 , pattern-etching the top transparent electrode layer 125 .

[0055] The photoactive layer 124 of the present disclosure may be prepared by the following method 300: Figure 4 shown.

[0056] S310, dissolving a polymer donor / acceptor material into a solvent to obtain a first precursor solution;

[0057] S320, adding a third component material to the first precursor solution in a predetermined ratio, and stirring sufficiently to obtain a second precursor solution; and

[0058] S330 , disposing a second precursor solution on the first intermediate substrate to form a photoactive layer 124 .

[0059] In a preferred embodiment, the polymer donor / acceptor material is PTB7-Th / IEICO-4F, and the third component material includes a combination of one or more of Poly-TPD (poly[bis(4-phenyl)(4-butylphenyl)amine]), PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]) and TPA-TPD (1,3-bis(4-(diphenylamino)phenyl)-5-(2-ethylhexyl)-4H-thiophene[3,4-c]pyrrole-4,6(5H)-dione).

[0060] The TPA-TPD film here is prepared with electron-donating triphenylamine as the end group and electron-withdrawing thieno[3,4-c]pyrrole-4,6-dione as the main core, with an optical band gap of 2.48 eV and an absorption cutoff edge at 500 nm ( Figure 5 ), mainly absorbing ultraviolet light and transmitting most visible light. TPA-TPD can be combined with the near-infrared absorption receptor Y6 to prepare transparent organic photovoltaics with an AVT of more than 70% and a PCE of 3.31% using a dual-band absorption strategy.

[0061] The following will take the polymer donor / acceptor material as PTB7-Th / IEICO-4F and the third component material as TPA-TPD as an example to describe in detail the organic solar cell, organic photovoltaic device and preparation method thereof provided by the present disclosure. It should be understood by those skilled in the art that other polymer donor / acceptor materials and third component materials that meet the above conditions can be applied to the description of the embodiments below.

[0062] In addition, in the following description, the device structure of glass / ITO / PEDOT:PSS / TPA-TPD:PTB7-Th:IEICO-4F / ZnO / AgNWs will be used for illustration.

[0063] In S220, before forming the hole transport layer 122, the transparent conductive base layer 121 formed on the glass substrate should also be cleaned and treated with oxygen plasma, including cleaning the sample with detergent, using deionized water and anhydrous ethanol for ultrasonic cleaning for 5 to 10 minutes each, and then blowing it dry. Place it in the cavity of the plasma surface treatment instrument, evacuate it for 1 to 2 minutes, then reduce the pressure to below 200 mbar, and select the mid-range power (10.5 W) for oxygen plasma treatment for 2 to 5 minutes.

[0064] Then, the preparation of the hole transport layer 122 includes mixing PEDOT:PSS (4083) and deionized water in a volume ratio of 1:1, filtering and depositing on the transparent conductive substrate layer 121 by dynamic coating at a speed of 4000 rpm, and annealing at 120-150° C. for 2-5 min to obtain a first intermediate substrate.

[0065] In S230 , the preparation of the photoactive layer 124 includes: 1) fixing the mass ratio of PTB7-Th and IEICO-4F to 1:1.5, dissolving them in a mixed solvent of chlorobenzene and 1-chloronaphthalene to prepare a first precursor solution with a concentration of x mg / mL ( S310 ). According to the total mass of PTB7-Th and IEICO-4F, y wt% of the third component material TPA-TPD is added, and it is used after being fully stirred to obtain a second precursor solution (S320), wherein the x is 2, 2.5, 3 and 3.5, and the y is 0, 10, 15, 20 and 30; 2) the TPA-TPD:PTB7-Th:IEICO-4F mixed solution (second precursor solution) is spin-coated on the hole transport layer 122 (PEDOT:PSS) of the first intermediate substrate at a speed of 2000 rpm (S330), and annealed at 100~140°C for 5~10 min to obtain a thin film of the photoactive layer 124 with a thickness of 4~15 nm.

[0066] In S240, the preparation of the electron transport layer 123 includes: dispersing ZnO nanoparticles in n-butanol and a small amount of chloroform to prepare a 10-20 mg / mL colloidal solution, and depositing it on the photoactive layer 124 by dynamic coating at a speed of 3000-5000 rpm to obtain a second intermediate substrate.

[0067] In S250, the preparation of the top transparent electrode layer 125 includes: dispersing AgNWs in water or ethanol, and a single solvent or a mixed solvent can be used for dispersion, such as mixing water-based or alcohol-based AgNWs in different proportions and concentrations, and then depositing them on the electron transport layer 124 of the second intermediate substrate at a speed of 2000-3000 rpm.

[0068] Finally, in S260 , the top transparent electrode layer 125 is pattern-etched by laser to complete the preparation of the transparent organic photovoltaic device 100 .

[0069] The following will introduce in detail Examples 1-4 and Comparative Examples 1-4 provided by the present disclosure, wherein Examples 1-4 are the preparation processes of organic photovoltaic devices with the addition of the third component material TPA-TPD, and Comparative Examples 1-4 are the preparation processes of organic photovoltaic devices without the addition of the third component material.

[0070] Example 1

[0071] (1) Configuration of solutions for each functional layer

[0072] 1. Preparation of hole transport layer solution

[0073] Prepare a diluted PEDOT:PSS (Al 4083) solution (solid content of about 0.7-0.8 wt%) using deionized water.

[0074] 2. Preparation of Photoactive Layer Solution

[0075] Accurately weigh PTB7-Th:IEICO-4F with a mass ratio of 1:1.5 and dissolve it in a mixed solvent of chlorobenzene / 1-chloronaphthalene, where the volume ratio of chlorobenzene to 1-chloronaphthalene is 96:4. The concentration of the active layer solution (first precursor solution) is 3.5 mg / mL. Based on the total mass of PTB7-Th and IEICO-4F in the solution, TPA-TPD is added to the first precursor solution at a mass fraction of 10 wt%, and the obtained mixed solution (second precursor solution) is stirred at 45 °C for 4 h and then used.

[0076] 3. Preparation of Electron Transport Layer Solution

[0077] ZnO nanoparticles were dispersed in n-butanol and a small amount of chloroform to prepare a mixed solution with a concentration of 5-15 mg / mL, and the solution was allowed to stand at room temperature for 0.5 h before use.

[0078] 4. Preparation of Metal Nanowire Solution

[0079] For the preparation of transparent electrodes, three AgNWs dispersions need to be prepared. Dispersion 1 is 0.5 mg / mL of alcohol-based AgNWs. Dispersions 2 and 3 are prepared by mixing dispersion 1 with low-concentration aqueous AgNWs (0.2 and 0.4 mg / mL) at a volume ratio of 3:1.

[0080] (2) Preparation of transparent organic photovoltaic devices

[0081] First, the surface-etched high-transmittance ITO transparent conductive glass with stripes was ultrasonically cleaned with deionized water and anhydrous ethanol in turn, purged with dry N2, and treated in an oxygen plasma environment for 2 min. Then, PEDOT:PSS was spin-coated on the ITO surface under atmospheric conditions, spin-coated at a speed of 4000 r / min for 0.5 min, and annealed at 150 °C for 5 min to form a hole transport layer 122. Next, the second precursor solution was spin-coated on the PEDOT:PSS layer, spin-coated at a speed of 2000 r / min for 1 min, and annealed at 140 °C for 5 min to form a photoactive layer 124. Subsequently, four layers of ZnO were spin-coated on the photoactive layer 124 at a speed of 4000 r / min to form an electron transport layer 123. Finally, multiple layers of dispersion 1, dispersion 2, and dispersion 3 are spin-coated in sequence at a rotation speed of 2500 r / min to form a transparent electrode layer 125 on the top of AgNWs, thereby completing the preparation of the transparent organic photovoltaic device 100.

[0082] (3) Performance characterization of transparent organic photovoltaic devices

[0083] The thickness of the active layer film was characterized by atomic force microscopy (Bruker Dimension® Icon™) and probe profilometer (Tencor TM P-17) and field emission high-resolution transmission electron microscope (Talos F200XG2) were used to detect the thickness of each functional layer of the cell. The A / T / R spectra of transparent organic photovoltaics were characterized using UV-vis-NIR spectrophotometer Cary 6000i with a scanning range of 300~1100 nm and a scanning speed of 1 nm / s. A solar simulator (Newport, M94043A) was used to simulate AM 1.5G (100 mW / cm 2 ) lighting environment, and the photovoltaic performance of the cell was tested with the Keithley 2400 digital source meter to obtain the JV curve of the cell. The test area is 0.0517 cm 2 The scanning range was −0.2~+1.2 V and the scanning speed was 10 mV / s. The external quantum efficiency of the battery was characterized using Newport's fully integrated quantum efficiency measurement instrument (Quantx-300). Before the test, the spot of Quanx-300 was narrowed and calibrated using a standard silicon battery.

[0084] Embodiment 2-4

[0085] A transparent organic photovoltaic device was prepared in the same manner as described in Example 1, except that in "2. Preparation of photoactive layer solution" in "(1) Configuration of each functional layer solution", "TPA-TPD was added to the first precursor solution at a mass fraction of 10 wt %", the mass fraction of 15, 20 and 30 wt % was used instead of 10 wt %, and the solution was used in "(2) Preparation of transparent organic photovoltaic device".

[0086] Comparative Example 1

[0087] A transparent organic photovoltaic device was prepared in the same manner as described in Example 1, except that in “2. Preparation of photoactive layer solution” in “(1) Configuration of each functional layer solution”, “Accurately weigh PTB7-Th:IEICO-4F with a mass ratio of 1:1.5 and dissolve it in a mixed solvent of chlorobenzene / 1-chloronaphthalene, wherein the volume ratio of chlorobenzene to 1-chloronaphthalene is 96:4. The concentration of the active layer solution is 2 mg / mL, and the mixed solution is stirred at 45°C for 4 h before use”, and this solution is used in “(2) Preparation of transparent organic photovoltaic”.

[0088] Comparative Examples 2 to 4

[0089] A transparent organic photovoltaic device was prepared in the same manner as described in Comparative Example 1, except that in “2. Preparation of solution for photoactive layer” in “(1) Configuration of each functional layer solution” in Comparative Example 1, active layer solution concentrations of 2.5, 3, and 3.5 mg / mL were used instead of 2 mg / mL, and the solution was used in “(2) Preparation of transparent organic photovoltaic”.

[0090] In Examples 1-4, a third component material TPA-TPD with ultraviolet absorption was added to the near-infrared absorbing polymer donor / acceptor material (PTB7-Th:IEICO-4F). The normalized absorption spectra of the three are as follows: Figure 5 As shown. Judging from the absorption spectrum, the addition of TPA-TPD will not significantly affect the transmittance of transparent photovoltaic devices in visible light.

[0091] Below Figure 6-Figure 15 The performance characterization results of the organic photovoltaic devices of Examples 1-4 and Comparative Example 4 are described, wherein Comparative Example 4 corresponds to a predetermined proportion of TPA-TPD added of 0 wt %, and Examples 1-4 correspond to predetermined proportions of TPA-TPD added of 10 wt %, 15 wt %, 20 wt % and 30 wt %, respectively.

[0092] from Figure 6~Figure 9 It can be seen that as the content of TPA-TPD increases (0~15 wt%), the transparent organic photovoltaic device V OC , J SC and FF are improved to varying degrees, and AVT changes little, and CRI is also improved. In Example 2, when the content of TPA-TPD in the photoactive layer reaches 15 wt%, the ternary device V OC Increase to ~0.7 V, J SC 2.54 mA / cm 2 , FF increased to 0.58, PCE increased by ~17% compared to binary devices, AVT approached 90%, and CRI exceeded 98. Continuing to increase the content of TPA-TPD (20 wt % and 30 wt %), the organic photovoltaic device V OC Slow improvement, J SC On the contrary, it decreased, so it was confirmed that the optimal predetermined ratio of TPA-TPD added was 15 wt%.

[0093] Depend on Fig.10 It can be seen that with the introduction of TPA-TPD, the thickness of the photoactive layer gradually increases and the data reproducibility is improved. Fig.11 and Fig.12 It can be seen that the introduction of TPA-TPD destroys the excessive aggregation of the acceptor material IEICO-4F, making the active layer absorption cutoff edge λ onset As the content of TPA-TPD increases, the band gap gradually blue shifts. To this end, the aggregation luminescence quenching effect of the small molecule IEICO-4F acceptor material is suppressed, resulting in the photoluminescence intensity (PL intensity) of the ternary active layer film to increase by nearly 1 times under the optimal TPA-TPD addition ratio, which is conducive to the diffusion of excitons to the interface and the charge recombination loss is suppressed to a certain extent. Figure 7 It can be seen that TPA-TPD, as a donor small molecule, can transfer charge with IEICO-4F due to its energy level matching with the receptor, contributing a small amount of current. V OC The changes in FF are also affected by the orientation of the donor and acceptor stacking in the photoactive layer. Figure 14~Figure 15 The GIWAXS data show that after the introduction of the optimal content of TPA-TPD, the donor and acceptor molecules in the photoactive layer are more inclined to face-on orientation, and the interplanar spacing of pi-pi stacking (010 diffraction peak) is d -spacing is reduced from 3.63 Å to 3.60 Å, which is beneficial to exciton dissociation and charge transfer, and improves FF. The crystal coherence length CCL of the photoactive layer film increases significantly before and after the addition of TPA-TPD, that is, the crystal size and crystallinity increase, the charge separation state lifetime is extended, and the charge transfer is promoted while suppressing the charge recombination loss. Fig.13 It also confirms that the introduction of TPA-TPD reduces the ideal factor n of the system from 1.59 to 1.39, indicating that the trap-assisted recombination of the system is suppressed, the voltage loss is reduced, and it is beneficial to V OC and FF improvement.

[0094] In summary, the introduction of TPA-TPD not only increases the thickness of the photoactive layer film, but also inhibits the excessive aggregation of the acceptor and prolongs the life of the exciton. At the same time, the small molecule TPA-TPD also makes the pi-pi stacking of the donor and acceptor materials more orderly, improves the crystallinity, inhibits trap-assisted recombination, and improves the device. V OC and FF, enabling high-transmittance organic photovoltaic devices to operate stably.

[0095] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.

[0096] In addition, although each operation is described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. Under certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although some specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the present invention. Some features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination mode.

[0097] Although the subject matter has been described in language specific to structural features and / or methodological logical actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. On the contrary, the specific features and actions described above are merely example forms of implementing the claims.

[0098] Several embodiments of the present application have been described in detail above, but the present application is not limited to these specific embodiments. Those skilled in the art can make various variations and modifications to the embodiments based on the concept of the present application, and these variations and modifications should all fall within the scope of protection claimed by the present application.

Claims

1. An organic solar cell comprising a photoactive layer, characterized in that The photoactive layer is prepared by mixing a polymer donor / acceptor material and a third component material in a predetermined ratio, wherein the polymer donor / acceptor material is PTB7-Th / IEICO-4F, and the third component material is TPA-TPD; Wherein, the third component material is configured such that its absorption spectrum is partially in the non-visible light region, its miscibility with the acceptor material is better than its miscibility with the donor material, and charge transfer can occur between the polymer donor / acceptor material; The third component material is configured to inhibit excessive aggregation of the polymer donor / acceptor material, gradually blue-shift the spectral absorption cutoff edge of the photoactive layer, extend the life of the excitons, and improve the pi-pi stacking of the polymer donor / acceptor material.

2. The organic solar cell according to claim 1, characterized in that The organic solar cell has an average visible light transmittance of more than 85%.

3. The organic solar cell according to claim 1, characterized in that The organic solar cell includes a transparent conductive substrate layer, one of a hole transport layer and an electron transport layer, the photoactive layer, the other of the hole transport layer and the electron transport layer, and a top transparent electrode layer which are sequentially stacked.

4. An organic photovoltaic device, characterized in that: The invention comprises a substrate and the organic solar cell according to any one of claims 1 to 3 arranged on the substrate.

5. A method for preparing an organic photovoltaic device, wherein the organic photovoltaic device is the organic photovoltaic device according to claim 4, characterized in that: The following steps are involved: forming a transparent conductive base layer on the substrate; forming one of a hole transport layer and an electron transport layer on the transparent conductive substrate layer to obtain a first intermediate substrate; forming the photoactive layer on the first intermediate substrate; forming the other of the hole transport layer and the electron transport layer on the photoactive layer to obtain a second intermediate substrate; forming a top transparent electrode layer on the second intermediate substrate; and The top transparent electrode layer is patterned and etched.

6. The preparation method according to claim 5, characterized in that: The photoactive layer is prepared by the following steps: Dissolving the polymer donor / acceptor material in a solvent to obtain a first precursor solution; Adding the third component material to the first precursor solution in a predetermined ratio and stirring the mixture sufficiently to obtain a second precursor solution; as well as The second precursor solution is disposed on the first intermediate substrate to form the photoactive layer.

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