Organic solar cell based on halogenated additive and preparation method thereof

Abstract

The invention relates to the technical field of preparation of organic solar cells, in particular to an organic solar cell based on a halogenated additive, and the structure level of a forward device of the solar cell sequentially comprises a transparent conductive substrate, a hole transport layer, an organic active layer, an electron transport layer and a metal electrode from bottom to top, the organic active layer comprises a polymer donor PM6, a non-fullerene electron acceptor L8-BO and a halogenated additive DFBB. Through addition of a halogenated additive DFBB, strong non-covalent bonding is formed by unique sigma-hole interaction of the halogenated additive DFBB and a receptor L8-BO, and meanwhile, the molecular stacking orientation of the active layer can be accurately regulated and controlled by the polymer electrostatic potential extreme value of the halogenated additive DFBB. The halogenated additive DFBB preferentially generates strong sigma-hole interaction with acceptor molecules, ordered accumulation of L8-BO is remarkably enhanced, meanwhile, the crystallization behavior of the donor PM6 is balanced through the synergistic halogen effect, a bicontinuous interpenetrating network structure is formed, and the photo-generated exciton yield is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic solar cell preparation, and specifically to an organic solar cell based on a halogenated additive and a preparation method thereof. Background Art

[0002] Organic solar cells (OSCs) have shown broad application prospects in the field of distributed photovoltaics due to their advantages such as flexibility, light weight, and solution processability. In recent years, with the innovation of non-fullerene acceptor materials, the energy conversion efficiency of single-junction OSCs has exceeded 20%, but their practical applications are still limited by the precise control of the active layer morphology and long-term stability issues. The multi-scale morphology of the active layer, such as the molecular packing order, phase separation size, and vertical distribution, directly affects the exciton dissociation efficiency, charge transport, and collection performance. However, during the film-forming process of donor and acceptor materials, due to the difference in crystallization rates, molecular disordered packing or phase separation mismatch often occurs, leading to charge recombination and performance degradation. There is an urgent need to develop efficient morphology control strategies to achieve highly efficient and stable OSCs.

[0003] The additive strategy has become an important means to optimize the active layer morphology due to its dynamic regulation ability. Among them, volatile solid additives can regulate the crystallization behavior of donors and acceptors through non-covalent intermolecular interactions. At the same time, by balancing the crystallization rate difference between donors and acceptors and optimizing the phase separation size to be close to the exciton diffusion length, the exciton dissociation efficiency and charge collection ability can be significantly improved. However, the existing additive design often faces the bottleneck of synergistically improving efficiency and stability. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides an organic solar cell based on a halogenated additive and a preparation method thereof, which solves the problem of poor photo-stability of organic solar cells and constructs a highly efficient and stable organic solar cell based on the PM6:L8-BO system.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: An organic solar cell based on a halogenated additive, the structural layers of the forward device of the solar cell from bottom to top are a transparent conductive substrate, a hole transport layer, an organic active layer, an electron transport layer, and a metal electrode in sequence, and the organic active layer includes a polymer donor PM6, a non-fullerene electron acceptor L8-BO, and a halogenated additive DFBB;

[0006] The chemical structural formula of the polymer donor PM6 is as follows:

[0007]

[0008] The chemical structural formula of the non-fullerene electron acceptor L8-BO is as follows:

[0009]

[0010] The chemical structural formula of the halogenated additive DFBB is as follows:

[0011]

[0012] Preferably, the structural layers of the forward solar cell device are, from bottom to top in sequence, ITO glass, PEDOT:PSS hole transport layer, organic active layer, PDI NN electron transport layer, and metal Ag cathode.

[0013] Preferably, the mass ratio of PM6:L8-BO:DFBB in the organic active layer is 1:(1.15 - 1.25):(1.5 - 2.1).

[0014] Preferably, a preparation method of an organic solar cell based on a halogenated additive includes the following steps:

[0015] S1. Ultrasonically treat the ITO glass sheet successively with dishwashing liquid, deionized water, acetone, and isopropyl alcohol, and then treat it with a plasma cleaner;

[0016] S2. Use the static spin-coating method to form a film of PEDOT:PSS on the ITO glass sheet, and then perform heat annealing treatment to form a hole transport layer;

[0017] S3. Dissolve PM6 and L8-BO together in a chloroform solution according to a mass ratio of 1:(1.15 - 1.25), then add DFBB according to a mass ratio of 1:(1.15 - 1.25):(1.5 - 2.1) for PM6:L8-BO:DFBB, then transfer the sample to a glove box under a nitrogen atmosphere for stirring, and then spin-coat it onto the hole transport layer PEDOT:PSS to form a bulk heterojunction active layer;

[0018] S4. Dissolve PD INN in a methanol solvent, and use the dynamic spin-coating method to form a film of the PDINN solution on the active layer to form an electron transport layer;

[0019] S5. Evaporate the metal Ag electrode onto the PD INN electron transport layer.

[0020] Preferably, in the step S2, the rotation speed of static spin-coating is 3500 - 4500 rpm, the annealing temperature is 145 - 155 °C, and the annealing time is 20 min.

[0021] Preferably, in the step S3, the material concentration of the bulk heterojunction active layer is 15 - 17 mg / mL.

[0022] Preferably, in the step S3, the spin coating speed of the bulk heterojunction active layer is 3000 - 4000 rpm, the annealing temperature is 90 - 110 °C, and the annealing time is 10 min.

[0023] Preferably, in the step S4, the concentration of the methanol solvent is 0.5 - 1.5 mg / mL, the spin coating speed is 2500 - 3500 rpm, and the spin coating time is 40 s.

[0024] The present invention provides an organic solar cell based on a halogenated additive and a preparation method thereof. It has the following beneficial effects:

[0025] 1. By adding the halogenated additive DFBB, the unique σ-hole interaction forms strong non-covalent bonds with the acceptor L8-BO, and at the same time, the extreme value of its polymer electrostatic potential can accurately regulate the molecular packing orientation of the active layer.

[0026] 2. By preferentially generating strong σ-hole interactions between the halogenated additive DFBB and the acceptor molecules, the ordered packing of L8-BO is significantly enhanced. At the same time, the crystallization behavior of the donor PM6 is balanced through the synergistic halogen effect, forming a bicontinuous interpenetrating network structure, thereby improving the yield of photo-generated excitons.

[0027] 3. By inducing the active layer to form a high phase purity and optimized phase separation size through the halogenated additive DFBB, the exciton dissociation efficiency is significantly improved, and at the same time, balanced carrier migration is achieved, thereby improving the photovoltaic performance of the PM6:L8-BO system.

[0028] 4. The blend film treated with the halogenated additive DFBB shows excellent thermal stability, and its complete volatility avoids the influence of additive residues on long-term stability. Description of the Drawings

[0029] Figure 1 It is the structure bulk heterojunction diagram of the forward device of the organic solar cell of the present invention;

[0030] Figure 2 It is the normalized ultraviolet-visible light absorption spectrogram of the thin film made of PM6, L8-BO, and DFBB in the solar cell of the present invention;

[0031] Figure 3 It is the short-circuit current (J SC ) - open-circuit voltage (V OC ) curve graph of the devices based on PM6:L8-BO:DFBB in the solar cells of Comparative Example 1 and Examples 1 to 3 of the present invention, where a is Comparative Example 1 and b are Examples 1 to 3;

[0032] Figure 4This is the decay curve graph of the device efficiency of the solar cells prepared in Example 2 of the present invention and Comparative Example 1 under light illumination conditions. Detailed implementation manners

[0033] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] The polymer donor PM6 of the experimental materials used in this example was purchased from Dongguan Fuan Optoelectronic Technology Co., Ltd., and the acceptor L8-BO was purchased from Shenzhen Yirou Photovoltaic Technology Co., Ltd. The hole transport layer PEDOT:PSS was purchased from Heraeus Company. DBB and DFBB were purchased from Alfa Aesar (China) Chemical Co., Ltd.

[0035] Take PDINN and dissolve it in methanol, stir at room temperature until clear and transparent, and prepare a 1mg / mL methanol solution for standby.

[0036] According to the mass ratios of PM6:L8-BO:DFBB of 1:1.2:1.5, 1:1.2:1.8, and 1:1.2:2.1, respectively weigh the donor PM6, the acceptor L8-BO, and the halogenated additive DFBB, add chloroform, and heat and stir at 50°C for 3h to prepare the devices of the bulk heterostructure.

[0037] Example 1:

[0038] The embodiment of the present invention provides a preparation method of an organic solar cell based on a halogenated additive, including the following steps:

[0039] S1. Ultrasonically treat the glass sheet successively with dishwashing liquid, deionized water, acetone, and isopropanol, and then treat it with a plasma cleaner.

[0040] S2. Use the static spin-coating method to form a film of PEDOT:PSS on the ITO glass sheet, with a rotation speed of 4000rpm, hold for 40s, and then heat and anneal at 150°C for 20min to form a hole transport layer, and then transfer it into a vacuum glove box.

[0041] S3. Dissolve PM6 and L8-BO together in a chloroform solution at a mass ratio of PM6:L8-BO of 1:1.2, then add DFBB at a mass ratio of PM6:L8-BO:DFBB of 1:1.2:1.5. Then transfer the sample to a glove box under a nitrogen atmosphere and stir. Then spin-coat the active layer solution at a speed of 3500 rpm for 30 s. Finally, anneal the sample on a heating stage at 100 °C for 10 min to form a bulk heterojunction active layer.

[0042] S4. Prepare a 1 mg / mL methanol solution of D I NO, and use the dynamic spin-coating method to form a film of the PDINN solution on the active layer at a rotation speed of 3000 rpm for 40 s to form an electron transport layer.

[0043] S5. Evaporate the metal Ag electrode onto the PD INN electron transport layer.

[0044] Example 2:

[0045] The embodiment of the present invention provides a method for preparing an organic solar cell based on a halogenated additive. Prepare a control device according to the method of Example 1, except that the mass ratio of PM6:L8-BO:DFBB in the active layer of the bulk heterojunction device is 1:1.2:1.8.

[0046] Example 3:

[0047] The embodiment of the present invention provides a method for preparing an organic solar cell based on a halogenated additive. Prepare a control device according to the method of Example 1, except that the mass ratio of PM6:L8-BO:DFBB in the active layer of the bulk heterojunction device is 1:1.2:2.1.

[0048] Comparative Example 1:

[0049] The embodiment of the present invention provides a method for preparing an organic solar cell, including the following steps:

[0050] S1. Ultrasonically treat the glass slide successively with dishwashing liquid, deionized water, acetone and isopropanol, and then treat it with a plasma cleaner.

[0051] S2. Use the static spin-coating method to form a film of PEDOT:PSS on the ITO glass slide at a rotation speed of 4000 rpm for 40 s, and then heat and anneal it at 150 °C for 20 min to form a hole transport layer, and then transfer it to a vacuum glove box.

[0052] S3. Dissolve PM6 and L8-BO together in a chloroform solution at a mass ratio of PM6:L8-BO of 1:1.2. Then spin-coat the active layer solution at a speed of 3500 rpm for 30 s. Finally, anneal the sample on a heating stage at 100 °C for 10 min to form a bulk heterojunction active layer.

[0053] S4. Prepare a 1 mg / mL methanol solution of DINO. Use the method of dynamic spin-coating to form a film of the PDINN solution on the active layer at a rotation speed of 3000 rpm for 40 s to form an electron transport layer.

[0054] S5. Evaporate the metal Ag electrode onto the PDINN electron transport layer.

[0055] Figure 1 This is the bulk heterojunction diagram of the forward device structure of the organic solar cell prepared in Example 1 of the present invention, where 1 is a transparent conductive substrate, 2 is a hole transport layer, 3 is an organic active layer, 4 is an electron transport layer, and 5 is a metal electrode Ag.

[0056] Figure 2 This is the normalized ultraviolet-visible absorption spectrum of the thin film made of the donor PM6, acceptor L8-BO, and halogenated additive DFBB in the organic solar cell of the present invention.

[0057] Perform photovoltaic performance testing on the device:

[0058] The light source is AM1.5G, and the sunlight intensity is 100 mW / cm 2 simulated sunlight. The intensity of the light source is tested and corrected by a standard silicon cell. The testing instrument is a Keithley 2400 source meter type tester.

[0059] Through testing, the (J SC )-voltage (V OC ) curves of the devices in Comparative Example 1 and Examples 1 to 3 are obtained, as shown in Figure 3 shown.

[0060] Compare and detect the attenuation of the device efficiency of the solar cells prepared in Example 2 and Comparative Example 1 under light conditions. The results are as shown in Figure 4 shown.

[0061] Through testing, the performance of the devices prepared in Examples 1-3 and the control device in Comparative Example 1 is shown in the following table: including open-circuit voltage (V OC ), short-circuit current (J SC ), fill factor (FF), and power conversion efficiency (PCE), where: PCE = V OC * J SC * FF / P in (Pin (is the light intensity of the incident light).

[0062]

[0063] As can be seen from the above table, when the halogenated additive DFBB is added to the PM6:L8-BO binary system, as the content of DFBB gradually increases, the open-circuit voltage basically remains unchanged, and the fill factor and short-circuit current density are greatly affected. When the mass ratio of PM6:L8-BO:DFBB is 1:1.2:1.8, the short-circuit current density of the bulk heterojunction device reaches 26.40 mA cm -2 , the fill factor reaches 80.83%, and the energy conversion efficiency reaches 19.20%, indicating that the addition of the halogenated additive DFBB successfully improves the performance of the device.

[0064] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An organic solar cell based on halogenated additives, characterized in that: The structural layers of the forward device of the solar cell are, from bottom to top, a transparent conductive substrate, a hole transport layer, an organic active layer, an electron transport layer, and a metal electrode, wherein the organic active layer includes a polymer donor PM6, a non-fullerene electron acceptor L8-BO, and a halogenated additive DFBB; The chemical structural formula of the polymer donor PM6 is as follows: The chemical structural formula of the non-fullerene electron acceptor L8-BO is as follows: The chemical structural formula of the halogenated additive DFBB is as follows:

2. The organic solar cell based on halogenated additives according to claim 1, characterized in that: The structural layers of the forward device of the solar cell are ITO glass, PEDOT:PSS hole transport layer, organic active layer, PDINN electron transport layer and metal Ag cathode from bottom to top.

3. The organic solar cell based on halogenated additives according to claim 1, characterized in that: The mass ratio of PM6:L8-BO:DFBB in the organic active layer is 1:(1.15-1.25):(1.5-2.1).

4. The method for preparing an organic solar cell based on a halogenated additive according to claim 1, characterized in that: The following steps are involved: S1. The ITO glass sheet was ultrasonically treated with detergent, deionized water, acetone and isopropanol in sequence, and then treated with a plasma cleaner; S2. PEDOT:PSS is formed on an ITO glass sheet by static spin coating, and then heated and annealed to form a hole transport layer; S3. PM6 and L8-BO were dissolved in a chloroform solution at a mass ratio of 1:(1.15-1.25), and then DFBB was added at a mass ratio of PM6:L8-BO:DFBB of 1:(1.15-1.25):(1.5-2.1). The sample was then transferred to a glove box in a nitrogen atmosphere and stirred, and then spin-coated onto the hole transport layer PEDOT:PSS to form a bulk heterojunction active layer; S4. dissolving PDINN in a methanol solvent, and forming a film of the PDINN solution on the active layer by a dynamic spin coating method to form an electron transport layer; S5. Evaporate a metal Ag electrode onto the PDINN electron transport layer.

5. The method for preparing an organic solar cell based on a halogenated additive according to claim 4, characterized in that: In the step S2, the rotation speed of the static spin coating is 3500-4500 rpm, the annealing temperature is 145-155° C., and the annealing time is 20 min.

6. The method for preparing an organic solar cell based on a halogenated additive according to claim 1, characterized in that: In the step S3, the material concentration of the bulk heterojunction active layer is 15-17 mg / mL.

7. The method for preparing an organic solar cell based on a halogenated additive according to claim 4, characterized in that: In the step S3, the spin coating speed of the bulk heterojunction active layer is 3000-4000 rpm, the annealing temperature is 90-110° C., and the annealing time is 10 min.

8. The method for preparing an organic solar cell based on a halogenated additive according to claim 4, characterized in that: In the step S4, the concentration of the methanol solvent is 0.5-1.5 mg / mL, the spin coating speed is 2500-3500 rpm, and the spin coating time is 40 s.

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