Conjugated thiophene derivative, ternary organic active layer material and solar cell
By introducing conjugated thiophene derivatives as the third component in organic solar cells and forming a ternary active layer with PM6 and Y6, the problems of low light stability and efficiency are solved, and efficient photovoltaic conversion and stability improvement are achieved.
Patent Information
- Application Number
- CN202510497915.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-21
- Publication Date
- 2025-07-22
AI Technical Summary
The existing organic solar cells have poor photostability and low energy conversion efficiency, especially in the near-infrared region, and the strong crystallinity of Y6 can easily cause excessive phase separation of the active layer to cause the charge transfer path to break, limiting the improvement of device performance.
Conjugated thiophene derivatives are introduced as the third component, and ternary organic active layer materials are formed with PM6 and Y6. By constructing A-D-A type conjugated thiophene derivatives, the light absorption range is broadened, the blended morphology and exciton dissociation ability are optimized, and a high crystallinity nano interpenetrating network structure is formed.
The photovoltaic efficiency of organic solar cells is significantly improved, with the photovoltaic efficiency exceeding 18%, and the stability and charge transfer capability of the device are improved.
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Figure CN120349327A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of organic solar cells, and particularly relates to an active layer material based on conjugated thiophene derivatives and a ternary organic solar cell. Background Art
[0002] With the continuous increase in global energy demand, the problems of environmental pollution and resource depletion faced by traditional fossil fuels are becoming increasingly severe, and the development of new renewable energy sources has become a global research hotspot. As a clean and renewable energy source, solar energy has great application potential. In this context, organic photovoltaic cells (OPVs) have become an important development direction for future photovoltaic technologies due to their advantages such as light weight, low-cost solution processing, flexibility, wearability, and high degree of freedom in material design. Compared with traditional silicon-based cells, organic photovoltaic cells can achieve efficient solar energy conversion at a lower cost and can flexibly regulate their performance through molecular structure design.
[0003] The active layer is composed of a blend of donor and acceptor materials, and its microscopic morphology such as phase separation size, molecular orientation, and vertical distribution directly determines the light absorption efficiency, exciton dissociation efficiency, and charge migration ability, which are the core factors restricting the photoelectric conversion efficiency (PCE) and stability of the device. Taking the PM6:Y6 system as an example, a relatively high PCE has been obtained due to the wide absorption spectrum of the acceptor Y6, energy level matching with the donor PM6, and high electron mobility. However, it is still limited by the insufficient utilization rate of sunlight in the near-infrared region and the strong crystallinity of Y6, which easily causes excessive phase separation in the active layer, resulting in the breakage of the charge transport path, a decrease in the fill factor, and an acceleration of device aging and other core bottlenecks. In addition, the stability of organic solar cells is also a key consideration and is the key to restricting future commercial applications.
[0004] The ternary strategy is an effective method commonly used to improve device performance. This strategy involves introducing a third component into the main system to broaden light absorption, optimize the blend morphology, or improve exciton dissociation and charge extraction ability, thereby improving device performance and becoming a research hotspot in the field of organic photovoltaics. Although the ternary strategy shows unique advantages in improving energy conversion efficiency, there are currently few third-component materials that can match the energy levels of PM6 and Y6 and broaden the visible light response range of the photoactive layer of solar cells. New third components for organic solar cells are urgently needed. Summary of the Invention
[0005] The purpose of the present invention is to provide a conjugated thiophene derivative that can match the energy levels of PM6 and Y6 and broaden the visible light response range of the photoactive layer of solar cells, as well as a ternary organic active layer material and a solar cell prepared by using this material as the third component of the PM6:Y6 system, in order to solve the problems of poor optical stability and low energy conversion efficiency of organic solar cells.
[0006] The structural formula of the conjugated thiophene derivative provided by the present invention is as follows:
[0007]
[0008] Where R represents C6~C 12 Alkyl; Ar represents
[0009] In the above conjugated thiophene derivatives, Ar represents When, its synthetic route and specific preparation method include the following steps:
[0010]
[0011] Step 1: Dissolve dicarboxymethyl trithiocarbonate completely in 1,2-dimethoxyethane, add triethylamine, stir evenly, and then add n-alkylamine R-NH2, condense and reflux the resulting solution under N2 atmosphere for 4 hours, separate and purify the product, and obtain 3-alkyl rhodanine (compound A). Preferably, the molar ratio of dicarboxymethyl trithiocarbonate, triethylamine, and n-alkylamine is 1:0.1:1.
[0012] Step 2: dissolving thienothiophene-2,5-dicarboxaldehyde (TT-CHO) in anhydrous chloroform, adding pyridine and 3-alkylrhodanine, and refluxing the resulting solution under N2 atmosphere for 3 hours, separating and purifying the product to obtain a conjugated thiophene derivative I. Preferably, the molar ratio of thienothiophene-2,5-dicarboxaldehyde, pyridine and 3-alkylrhodanine is 1:5:10.
[0013] In the above conjugated thiophene derivatives, Ar represents When, its synthetic route and specific preparation method include the following steps:
[0014]
[0015] Step 1: Add thienothiethiophene to anhydrous tetrahydrofuran, cool to -78°C, add the prepared lithium diisopropylamide (LDA) solution, stir at -78°C for 2h, then slowly warm to 0°C, continue stirring for 2h, add anhydrous DMF to the reaction system, then slowly warm the reaction mixture to room temperature, continue stirring the reaction for 12h, separate and purify the product to obtain TTT-CHO. Wherein, the molar ratio of thienothiethiophene to LDA is 3 to 4:1.
[0016] Step 2: Dissolve TTT-CHO in anhydrous chloroform, add pyridine and 3-alkyl rhodanine (compound A), reflux the resulting solution under N2 atmosphere for 3 hours, separate and purify the product, and obtain conjugated thiophene derivative II. Preferably, the molar ratio of TTT-CHO, pyridine and 3-alkyl rhodanine is 1:12 to 15:10.
[0017] Based on the above-mentioned conjugated thiophene derivatives, the present invention provides a ternary organic active layer material, which is composed of a polymer donor PM6, a non-fullerene electron acceptor Y6, and the above-mentioned conjugated thiophene derivatives.
[0018] The structural formula of the polymer donor PM6 is:
[0019]
[0020] The structural formula of the non-fullerene electron acceptor Y6 is:
[0021]
[0022] Furthermore, it is preferred that the above ternary organic active layer material is composed of a polymer donor PM6, a non-fullerene electron acceptor Y6, and the above-mentioned conjugated thiophene derivatives in a mass ratio of 1:1.2:0.05 - 0.07.
[0023] The present invention also provides a ternary organic solar cell. The structural layers of its forward device from bottom to top are a transparent conductive glass substrate, a hole transport layer, an active layer, an electron transport layer, and a metal Ag electrode in sequence. It is characterized in that: the active layer is made of the above ternary organic active layer material.
[0024] Furthermore, the structural layers of the forward device of the ternary organic solar cell provided by the present invention from bottom to top are an ITO glass sheet, a PEDOT:PSS hole transport layer, a ternary organic active layer, a PDINN electron transport layer, and a metal Ag cathode in sequence.
[0025] The preparation method of the ternary organic solar cell of the present invention includes the following steps:
[0026] S1. First, ultrasonically treat the ITO glass sheet in dishwashing liquid, deionized water, acetone, and isopropanol for 20 min, and then treat it with an ultraviolet ozone cleaner for 20 - 30 min.
[0027] S2. Spin-coat the PEDOT:PSS solution onto the ITO glass sheet. The rotation speed of spin-coating is 3000 - 3500 rpm / min, and the spin-coating time is 20 - 40 s; then perform thermal annealing treatment. The annealing temperature is 145 - 155 °C, and the annealing time is 15 - 20 min to obtain the PEDOT:PSS hole transport layer.
[0028] S3. Dissolve the above ternary organic active layer material in chloroform to obtain a photoactive layer solution with a concentration of 14 - 18 mg / mL. Add 0.5% of its volume of 1-chloronaphthalene to the photoactive layer solution, stir for 5 - 8 h, then spin-coat the resulting solution onto the PEDOT:PSS hole transport layer at a spin-coating speed of 2500 - 3500 rpm for 20 - 40 s, and then anneal at 80 - 90 °C for 10 - 15 min to form a ternary organic active layer.
[0029] S4. Dissolve PDINN in methanol to prepare a PDINN solution with a concentration of 0.8 - 1 mg / mL. Spin-coat the PDINN solution onto the ternary organic active layer at a spin-coating speed of 2500 - 3500 rpm / min for 20 - 40 s to form a PDINN electron transport layer.
[0030] S5. Evaporate a metal Ag electrode onto the PDINN electron transport layer to obtain a ternary organic solar cell.
[0031] The beneficial effects of the present invention are as follows:
[0032] 1. The present invention uses thiophene[3,2-b]thiophene or dithieno[3,2-b:2′,3′-d]thiophene as the central electron-donating unit and a rhodanine derivative as the end-group unit to construct an A-D-A type conjugated thiophene derivative. This type of conjugated thiophene derivative has good absorption in the visible light region, can form good absorption complementarity with a low-bandgap acceptor material, and helps to obtain a high short-circuit current. This conjugated thiophene derivative can form good visible light absorption complementarity with the polymer donor material PM6 and the non-fullerene acceptor material Y6, can effectively broaden the visible light response range of the photoactive layer of the solar cell. Using the thin film prepared by mixing this conjugated thiophene derivative with Y6 and PM6 as the photoactive layer of the organic solar cell can significantly improve the performance of the organic solar cell. Compared with the organic binary solar cell whose photoactive layer only contains Y6 and PM6, the ternary organic solar cell whose photoactive layer contains this conjugated thiophene derivative, Y6 and PM6 has a higher photovoltaic efficiency, and the photovoltaic efficiency exceeds 18%.
[0033] 2. The present invention selects conjugated thiophene derivatives as the third component and introduces them into the PM6:Y6 system. Among them, PM6 serves as the donor material of the ternary organic solar cell, and Y6 serves as the acceptor material. The addition of conjugated thiophene derivatives constructs an absorption spectrum complementary system with the donor and acceptor. By broadening the range of the light response band, the light capture efficiency of the entire solar spectrum is significantly improved. The introduction of conjugated thiophene derivatives respectively constructs a precise π-π interaction and a steric hindrance synergistic mechanism with the thiophene structure of PM6 and the conjugated backbone of Y6, directionally regulating the crystallization order of PM6, and at the same time optimizing the arrangement regularity of the conjugated backbone of Y6. A "synergistic dual-regulation" strategy of donor and acceptor is constructed using conjugated thiophene derivatives: on the one hand, the crystallization performance of PM6 and the phase separation of Y6 are simultaneously enhanced, and on the other hand, the interfacial compatibility of the active layer is finely regulated through intermolecular forces to form a highly crystalline nano-interpenetrating network structure. Finally, the addition of conjugated thiophene derivatives improves the energy conversion efficiency of the ternary organic solar cell based on the PM6:Y6 system. Brief Description of the Drawings
[0034] Figure 1 It is a schematic structural diagram of the ternary organic solar cell in Example 3.
[0035] Figure 2 It is the visible light absorption spectra of PM6, Y6, TT-ORH, and TTT-ORH.
[0036] Figure 3 It is the J-V curve diagram of the solar cells prepared in Example 3, Example 1, and the comparative example. Specific Embodiment Method
[0038] The present invention will be described in detail below with reference to the drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.
[0039] Example 1
[0040] Synthesis of Conjugated Thiophene Derivative TT-ORH
[0041]
[0042] Step 1: Dissolve 2.0 g (9 mmol) of dicarboxymethyl trithiocarbonate completely in 20 mL of 1,2-dimethoxyethane (DME). After adding 0.9 g (0.9 mmol) of triethylamine (TEA), stir for 5 min, then add 1.15 g (9 mmol) of n-octylamine. The resulting solution is stirred under reflux in a N2 atmosphere for 4 h. Then, add dichloromethane to extract the reaction mixture. After washing with water and separating the layers, add solid MgSO4 for drying. Filter by suction, rotary evaporate to remove the solvent, and purify the product by column chromatography (dichloromethane: petroleum ether = 3:1) to obtain 2.1 g of yellow oily 3-octyl rhodanine (ORH) with a yield of 83%. The structure characterization data of ORH are as follows: 1 1H NMR (400 MHz, CDCl3): δ (ppm) 3.99 - 3.95 (m, 4H), 1.66 - 1.59 (m, 2H), 1.32 - 1.27 (m, 10H), 0.88 (t, J = 6.9 Hz, 3H).
[0043] Step 2: Dissolve 50 mg (0.25 mmol) of thiophene-2,5-dicarbaldehyde (TT-CHO) in 5 mL of anhydrous chloroform. Add 0.1 mL (1.25 mmol) of pyridine and 0.62 g (2.5 mmol) of ORH. The resulting solution is stirred under reflux in a N2 atmosphere for 3 h. Extract the reaction mixture with dichloromethane. After washing with water and separating the layers, add solid MgSO4 for drying. Filter by suction, rotary evaporate to remove the solvent, and crystallize with chloroform and methanol to obtain 95 mg of red solid, which is the target conjugated thiophene derivative TT-ORH, with a yield of 64%. The structure characterization data of TT-ORH are as follows: 1 1H NMR (400 MHz, CDCl3): δ (ppm) 8.06 (s, 2H), 7.35 - 7.27 (m, 2H), 4.13 - 4.09 (m, 4H), 1.75 - 1.67 (m, 4H), 1.34 - 1.27 (m, 20H), 0.88 (t, J = 6.9 Hz, 6H).
[0044] Example 2
[0045] Synthesis of conjugated thiophene derivative TTT-ORH
[0046]
[0047] Step 1: Under argon protection, 0.3 mL (3.2 mmol) of n-butyllithium solution ((n-BuLi) was slowly added dropwise to a two-necked flask containing 0.1 mL of diisopropylamine and 5 mL of tetrahydrofuran, and the temperature was maintained at 0 °C. Since n-butyllithium is flammable in air, this part must be isolated from oxygen and air; after the dropwise addition was completed, the mixture was stirred at 0 °C for 0.5 h to generate a solution of lithium diisopropylamide (LDA). 50 mg (1 mmol) of terthiophene was added to a two-necked flask containing 20 mL of anhydrous tetrahydrofuran, cooled to -78 °C, and the prepared LDA solution was transferred to this flask by syringe and stirred at -78 °C for 2 h, then slowly warmed to 0 °C and stirred for another 2 h. 0.1 mL of anhydrous DMF was added to the reaction system, and then the reaction mixture was slowly warmed to room temperature and stirred for 12 h. Deionized water was added to the reaction mixture for quenching, and the organic phase was extracted with dichloromethane and washed with saturated sodium chloride aqueous solution and water respectively. The solvent in the organic phase was evaporated under reduced pressure to obtain a crude product. The crude product was washed with anhydrous ether and dichloromethane to remove the residue, and 42 mg of yellow solid TTT-CHO was obtained with a yield of 62.5%. The structural characterization data of TTT-CHO are as follows: 1 HNMR(400MHz,CDCl3):δ(ppm)9.9(s,2H),8.12(m,2H)
[0048] Step 2: 25 mg (0.1 mmol) of TTT-CHO was dissolved in 5 mL of anhydrous chloroform, 0.1 mL (1.25 mmol) of pyridine and 248 mg (1 mmol) of ORH were added dropwise, and the resulting solution was refluxed and stirred for 3 h under a nitrogen atmosphere. The reaction mixture was extracted with dichloromethane, washed with water and separated, and then MgSO4 solid was added for drying. After filtration, the solvent was removed by rotary evaporation, and the product was crystallized with chloroform and methanol to obtain 40.1 mg of yellow solid, which is the target conjugated thiophene derivative TTT-ORH, with a yield of 57%. The structural characterization data of TTT-ORH are as follows: 1 HNMR(400MHz,CDCl3):δ(ppm)8.1(s,2H),7.45-7.35(m,2H),4.13-4.09(m,4H),1.75-1.67(m,4H),1.34-1.27(m,20H),0.88(t,J=6.9Hz,6H).
[0049] Example 3
[0050] As Figure 1As shown, the structural layers of the forward device of the ternary organic solar cell in this embodiment are, from bottom to top in sequence, an ITO glass sheet, a PEDOT:PSS hole transport layer, a ternary organic active layer, a PDINN electron transport layer, and a metal Ag cathode. Its preparation method includes the following steps:
[0051] S1. First, ultrasonically clean the ITO glass sheet in detergent, deionized water, acetone, and isopropanol for 20 minutes each in sequence. After drying with a nitrogen gun, place it in an ultraviolet ozone cleaning machine for treatment for 25 minutes.
[0052] S2. Use the spin-coating method to form a film of PEDOT:PSS solution on the ITO glass sheet. The spin-coating rotation speed is 3000 rpm / min, and the spin-coating time is 30 s; then perform thermal annealing treatment. The annealing temperature is 150 °C, and the annealing time is 20 minutes to obtain the PEDOT:PSS hole transport layer.
[0053] S3. Dissolve PM6, Y6, and TT-ORH in chloroform at a mass ratio of 1:1.2:0.06 to obtain a photoactive layer solution. The concentration of the photoactive layer solution is 16 mg / mL; then transfer the photoactive layer solution to a glove box under a nitrogen atmosphere for heating and stirring. Add 1-chloronaphthalene at 0.5% of the volume of the photoactive layer solution to it, continue stirring for 30 minutes, and then spin-coat the obtained solution onto the PEDOT:PSS hole transport layer. The spin-coating speed is 3000 rpm / min, and the spin-coating time is 30 s. Then perform annealing treatment at 90 °C for 10 minutes to form a ternary organic active layer.
[0054] S4. Dissolve PDINN in methanol to prepare a PDINN solution with a concentration of 1 mg / mL; use the spin-coating method to form a film of the PDINN solution onto the ternary organic active layer. The spin-coating speed is 3000 rpm, and the spin-coating time is 30 s to form a PDINN electron transport layer.
[0055] S5. Evaporate the metal Ag electrode onto the PDINN electron transport layer. The thickness of the Ag electrode is 150 nm to obtain a ternary organic solar cell.
[0056] Example 4
[0057] In step S3 of this embodiment, replace TT-ORH in Example 3 with TTT-ORH synthesized in Example 2 with the same mass, and the other steps are the same as those in Example 3 to prepare a ternary organic solar cell.
[0058] Comparative Example
[0059] In step S3 of Example 3, do not add TT-ORH, and the other steps are the same as those in Example 3 to prepare a ternary organic solar cell.
[0060] The visible light absorption spectra of the above-mentioned PM6, Y6, TT-ORH, and TTT-ORH were tested respectively, and the test results are as Figure 2 shown. From Figure 2 it can be seen that the absorption spectrum range of TT-ORH is 300 - 450 nm, and the absorption spectrum range of TTT-ORH is 300 - 500 nm. When incorporated into the photoactive layer as a ternary donor material, it can effectively broaden the absorption range of PM6 and Y6 in the visible light region, which is beneficial to the improvement of the performance of organic solar cells.
[0061] The solar cells prepared in Example 3, Example 4, and the comparative example were respectively irradiated under white light of 1.5 G (100 mW / cm 2 ²) for J-V curve testing, and the test results are as Figure 3 shown. The performance comparison of the solar cells is shown in Table 1. It should be noted that Figure 3 PM6:Y6:TT-ORRH in it corresponds to Example 3, and PM6:Y6:TTT-ORH corresponds to Example 4. From Figure 3 and Table 1, it can be seen that compared with the binary organic solar cells prepared in the comparative example without doping the third component material, the ternary organic solar cells doped with TT-ORH and TTT-ORH respectively prepared in Example 3 and Example 4 of the present invention have higher photovoltaic efficiency, open circuit voltage, short circuit current, and fill factor, and the performance is more excellent.
[0062] Table 1 Performance comparison of solar cells prepared in Examples 3 - 4 and the comparative example
[0063] Sample <![CDATA[Short-circuit current (mA / cm 2 )]]> Open-circuit voltage (V) Fill factor (%) Photovoltaic efficiency (%) Comparative example 26.3 0.84 75.3 16.63 Example 3 26.8 0.852 76.4 17.44 Example 4 27.3 0.855 77.2 18.01
[0064] In summary, the conjugated thiophene derivative of the present invention, as the third component material, can match the energy levels of the polymer donor material PM6 and the non-fullerene acceptor material Y6, and this conjugated thiophene derivative can form good visible light absorption complementarity with the polymer donor material PM6 and the non-fullerene acceptor material Y6, and can effectively broaden the visible light response range of the photoactive layer of the solar cell. Using the thin film prepared by mixing this conjugated thiophene derivative with Y6 and PM6 as the photoactive layer of the organic solar cell can significantly improve the performance of the organic solar cell. Compared with the organic binary solar cell containing only Y6 and PM6 in the photoactive layer, the ternary organic solar cell containing this conjugated thiophene derivative, Y6, and PM6 in the photoactive layer has a higher photovoltaic efficiency, and the photovoltaic efficiency exceeds 18%.
Claims
1. A conjugated thiophene derivative, characterized in that The structural formula of the derivative is as follows: wherein R represents C6-C 12 alkyl; Ar represents 2. A ternary organic active layer material, characterized in that: The active layer material consists of polymer donor PM6, non-fullerene electron acceptor Y6, and the conjugated thiophene derivative described in claim 1; The structural formula of the polymer donor PM6 is: The structural formula of the non-fullerene electron acceptor Y6 is:
3. A ternary organic solar cell, the structural layers of its forward device are, from bottom to top in sequence, a transparent conductive glass substrate, a hole transport layer, a photoactive layer, an electron transport layer, and a metal Ag electrode, and it is characterized in that: The photoactive layer is made of the ternary organic active layer material described in claim 2.
4. The ternary organic solar cell according to claim 3, characterized in that: The structural layers of the forward device from bottom to top are an ITO glass sheet, a PEDOT:PSS hole transport layer, a ternary organic active layer, a PDINN electron transport layer, and a metal Ag cathode in sequence.
5. The ternary organic solar cell according to claim 3 or 4, characterized in that: In the ternary organic active layer, the mass ratio of polymer donor PM6, non-fullerene electron acceptor Y6, and conjugated thiophene derivative is 1:1.2:0.05 to 0.07.