Ultraviolet irradiation crosslinking electron transport layer material and preparation method thereof

Abstract

The invention discloses an ultraviolet irradiation cross-linked electron transport layer material and a preparation method thereof, and belongs to the technical field of organic photoelectric materials, the molecular formula of the ultraviolet irradiation cross-linked electron transport layer material is shown in the specification, the electron transport layer material is subjected to ultraviolet irradiation to obtain the cross-linked electron transport layer material, and possibility is provided for long-term stability of photovoltaic devices. And meanwhile, a more regular interface dipole can be effectively provided, so that the work function (Ag / Cu / Au) of the metal electrode is effectively reduced, the photoelectric conversion efficiency of the organic solar cell is improved, and the synthesis process is simple and efficient and has no pollution to the environment.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic materials technology, specifically a cross-linked electron transport layer material under ultraviolet light irradiation and its preparation method. Background Technology

[0002] Organic solar cells (OSCs) have become a focus of research and industry in recent years due to their significant advantages, including low cost, large-area fabrication via solution processing, and flexibility. Currently, the photoelectric conversion efficiency of a single conventional OSC device has successfully exceeded 19%, a result that strongly suggests its broad commercial application prospects. In the design and development of OSCs, in addition to actively exploring novel photoactive layer materials, effectively improving the charge extraction and transport efficiency at the interface is equally crucial. Among these, the electron transport layer, as the key connection between the active layer and the electrode, plays an indispensable role in promoting the selective collection and transport of electrons and reducing the interfacial energy barrier.

[0003] Traditional electron transport materials, such as common metal oxides (e.g., zinc oxide, ZnO), while possessing some electron transport capabilities, have inherent drawbacks. For example, ZnO is frequently used in inverted structure devices; however, its photocatalytic properties accelerate the decomposition of active materials under prolonged light exposure, severely impacting device stability and lifespan. Furthermore, some small organic molecule electron transport materials, despite exhibiting good performance in certain aspects, often suffer from poor solubility and suboptimal film quality, hindering large-scale solution processing. Introducing functional groups with specific structures into the polymer backbone to prepare electron transport materials presents challenges due to complex synthesis processes and high costs, significantly limiting their practical application and commercialization.

[0004] In practical applications, with the ever-increasing performance requirements of OSCs devices, especially the growing demand for thick-film processing, it is crucial to develop an electron transport layer material with strong work function modification capabilities, weak or no absorption in the visible light region, high conductivity, and good stability. Simultaneously, improving the interfacial compatibility between the material and the active layer and reducing interfacial defects are also important issues that urgently need to be addressed to further optimize device performance. Summary of the Invention

[0005] This invention provides an ultraviolet light-irradiated crosslinked electron transport layer material and its preparation method, in order to overcome the defects in the prior art.

[0006] This invention is achieved through the following technical solution:

[0007] A UV-irradiated crosslinked electron transport layer material, characterized in that its molecular formula is:

[0008]

[0009] In the ultraviolet light-irradiated crosslinked electron transport layer material described above, R1, R2, R3, R4, R5, R6, R7, and R8 are unsubstituted or substituted C1-C. 20 Alkyl chain or unsubstituted or substituted C1-C 20 Alkoxy chain; Ar is an unsubstituted or substituted heterocyclic aryl group consisting of 6 to 60 carbon atoms and containing 1 to 6 heteroatoms, and is an unsubstituted or substituted monocyclic or polycyclic heteroaromatic group; X1 and X2 represent counterionic groups.

[0010] In the ultraviolet light-irradiated crosslinked electron transport layer material described above, R1, R2, R3, R4, R5, R6, R7, and R8 are any one of methyl, ethyl, propyl, hexyl, butyl, pentyl, pentoxy, and hexoxy.

[0011] In the ultraviolet light-irradiated crosslinked electron transport layer material described above, Ar is any one of unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl, unsubstituted or substituted anthraceneyl, and unsubstituted or substituted pyreneyl.

[0012] In the ultraviolet light-irradiated cross-linked electron transport layer material described above, the heteroatoms in Ar are any one of B, N, P, S, Si, and Se.

[0013] In the ultraviolet light-irradiated cross-linked electron transport layer material described above, the molecular formula of Ar is any one of the following:

[0014]

[0015] As described above, in an ultraviolet light-irradiated cross-linked electron transport layer material, X1 and X2 are F - Cl - ,Br - I - OH - HSO4 - OTf - HCO3 - BF4 - ,Tf2N - and NO3 - Any one of them.

[0016] The ultraviolet light-irradiated cross-linked electron transport layer material described above has any of the following molecular formulas:

[0017]

[0018] A method for preparing an ultraviolet light-irradiated crosslinked electron transport layer material, the reaction formula of which is as follows:

[0019]

[0020] The method for preparing an ultraviolet light-irradiated crosslinked electron transport layer material as described above includes the following steps:

[0021] Step 1: The compound of Formula 1 is mixed with the compound of Formula 2 and / or the compound of Formula 3 at a molar ratio of 1:4-10 and reacted at a temperature of 60-180℃ for 6-48 hours to obtain the compound of Formula 4.

[0022] Step 2: Compound 4 is mixed with compound 5 and / or compound 6 in a molar ratio of 1:1 and reacted at a temperature of 60-180℃ for 6-48 hours to obtain compound 7.

[0023] Step 3: Irradiate compound 7 with ultraviolet light at 10-400 nm for 1-30 minutes to obtain compound 8.

[0024] The advantages of this invention are: This invention obtains cross-linked electron transport layer materials through ultraviolet light irradiation, providing a possibility for the long-term stability of photovoltaic devices. Simultaneously, it can effectively provide more regular interfacial dipoles, thereby effectively reducing the work function of the metal electrode (Ag / Cu / Au), improving the photoelectric conversion efficiency of organic solar cells, and the synthesis process is simple, efficient, and environmentally friendly. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structural characterization of compound 3 in Example 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the structural characterization of compound 5 in Example 1 of the present invention;

[0028] Figure 3 This is a schematic diagram of the structural characterization of compound 3 in Example 2 of the present invention;

[0029] Figure 4 This is a schematic diagram of the structural characterization of compound 5 in Example 2 of the present invention;

[0030] Figure 5This is a schematic diagram of the structure of the cathode interface layer PDIN in Embodiment 4 of the present invention;

[0031] Figure 6 This is a schematic diagram of the JV curve of the organic solar cell prepared by the present invention using PDIN as the cathode interface layer.

[0032] Figure 7 This is a schematic diagram of the JV curve of organic solar cells prepared by using P-PDI as the cathode interface layer in this invention.

[0033] Figure 8 This is a schematic diagram of the JV curve of organic solar cells prepared by using P-NDI as the cathode interface layer in this invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] This invention provides a method for preparing a UV-irradiated crosslinked electron transport layer material (denoted as P-PDI), comprising synthesis according to the following synthetic route:

[0037]

[0038] Specifically as follows:

[0039] Step 1: Synthesis of Compound 3: 3,4,9,10-tetracarboxylic anhydride (0.78 g, 2 mmol), N,N-dimethyl-1,3-diaminopropane (0.82 g, 8 mmol), and 15 ml of n-butanol were placed in a 100 mL single-necked round-bottom flask. The solution was heated at 100 °C for 20 hours, then cooled to room temperature and poured into 200 ml of ice water. The red precipitate was filtered off and washed successively with ultrapure water and methyl tert-butyl ether to obtain compound 3 (0.92 g, yield 82.0%). The structure of the prepared compound 3 was characterized (e.g., ...). Figure 1 As shown), the details are as follows: 1HNMR(400MHz,Chloroform-d / 2,2,2-TRIFLUOROETHANOL-D3)δ8.41(d,4H),8.29(d,4H),4.22(t,4H),2.67–2.54(m,4H),2.36(s,12H),2.07–1.91(m,4H);

[0040] Step 2: Synthesis of Compound 5: Compound 3 (0.56 g, 1 mmol), 3-bromomethyl-3-methyl-1-oxetane (0.66 g, 4 mmol), and 10 mL of trifluoroethanol were placed in a 50 mL single-necked round-bottom flask. The solution was heated at 70 °C for 16 hours, then cooled to room temperature and poured into 200 mL of ice water. The red precipitate was filtered off and washed successively with ultrapure water and methyl tert-butyl ether to obtain pure compound 5 (0.85 g, yield 96.0%). The structure of the prepared compound 5 was characterized (e.g., ...). Figure 2 As shown), the details are as follows: 1 HNMR(400MHz,Chloroform-d)δ8.65(d,4H),8.56(d,4H),4.25(d,4H),3.95(q,4H),2.48(t,4H),2.28(s,6H),1.97(s,4H),1.74(s,12H),1.27(s,8H);

[0041] Step 3: Synthesis of compound P-PDI: Compound 5 was irradiated with 254nm ultraviolet light for 1 minute to obtain compound P-PDI.

[0042] Example 2

[0043] This invention provides a method for preparing a UV-irradiated crosslinked electron transport layer material (denoted as P-NDI), comprising synthesis according to the following synthetic route:

[0044]

[0045] Specifically as follows:

[0046] Step 1: Synthesis of Compound 3: 1,4,5,8-naphthalenetetracarboxylic anhydride (0.54 g, 2 mmol), N,N-dimethyl-1,3-diaminopropane (0.82 g, 8 mmol), and 15 ml of n-butanol were placed in a 100 mL single-necked round-bottom flask. The solution was heated at 100 °C for 20 hours, then cooled to room temperature and poured into 200 ml of ice water. The red precipitate was filtered off and washed successively with ultrapure water and methyl tert-butyl ether to obtain pure compound 3 (0.73 g, yield 84.0%). The structure of the prepared compound 3 was characterized (e.g., ...). Figure 3 As shown), the details are as follows:1 HNMR(400MHz,Chloroform-d / 2,2,2-TRIFLUOROETHANOL-D3)δ8.77(s,4H),4.22(t,4H),2.78–2.44(m,4H),2.30(s,12H),2.05–1.87(m,4H);

[0047] Step 2: Synthesis of Compound 5: Compound 3 (0.44 g, 1 mmol), 3-bromomethyl-3-methyl-1-oxetane (0.66 g, 4 mmol), and 10 mL of trifluoroethanol were placed in a 50 mL single-necked round-bottom flask. The solution was heated at 70 °C for 16 hours, then cooled to room temperature and poured into 200 mL of ice water. The precipitate was filtered and washed successively with ultrapure water and methyl tert-butyl ether to obtain pure compound 5 (0.73 g, yield 95.0%). The structure of the prepared compound 5 was characterized (e.g., ...). Figure 4 As shown), the details are as follows: 1 HNMR(400MHz,Chloroform-d)δ8.76(s,4H),4.46(d,4H),4.40(s,4H),4.31–4 .20(m,4H),3.65(s,4H),2.45(t,4H),2.24(s,12H),1.93(p,4H),1.44(s,6H);

[0048] Step 3: Synthesis of compound P-NDI: Compound 5 was irradiated with 254nm ultraviolet light for 1 minute to obtain compound P-NDI.

[0049] Example 3

[0050] This embodiment provides a method for fabricating an organic solar cell, including:

[0051] The OSC employs an indium tin oxide (ITO) / hole transport layer / active layer / cathode interface layer / metal electrode. First, the ITO-coated glass substrate is sequentially cleaned with an aqueous solution containing detergent, ultrapure water, acetone, and isopropanol, dried with nitrogen, and then treated in a UV ozone generator for 15 minutes. In a nitrogen atmosphere, a hole transport layer (2PACZ) solution of 0.27 mg / ml is prepared using ethanol and statically coated onto the ITO-coated glass substrate. After annealing at 100°C for 10 minutes, the hole transport layer is formed. Then, a DIB solution of 12.5 mg / ml was prepared using chloroform at a mass ratio of PM6:L8-BO of 1:1.2, which was then used to prepare an active layer solution of 16 mg / ml. This solution was spin-coated onto a glass substrate with a modified ITO coating and annealed at 100°C for 10 min to form the active layer. Next, a solution of compound 5 prepared with methanol of 1 mg / ml was spin-coated, and then irradiated with 254 nm ultraviolet light for 1 min to obtain a cross-linked electron transport layer. Finally, 100 nm of Ag was deposited as a metal electrode.

[0052] Example 4

[0053] This embodiment refers to Embodiment 3, the difference being that the cathode interface layer is replaced with PDIN, and the structural formula is shown in [reference needed]. Figure 5 .

[0054] Performance testing

[0055] The photovoltaic parameters of the organic solar cells were measured, as shown in Table 1.

[0056] Table 1 shows the white light (1.5G, 100mW / cm²) on the solar simulator. -2 Photovoltaic parameters of PM6:L8-BO devices prepared with different cathode interface layers under irradiation.

[0057]

[0058] JV characteristics were tested in an N2-filled glove box with a Keithley 2400 source meter under simulated AM1.5G illumination using a 300W Xe lamp solar simulator (SS-F5-3A, ENLITECH), with intensity corrected for certified standard silicon solar cells.

[0059] See results Figure 6 , Figure 7 and Figure 8 ,Depend on Figure 6 , Figure 7 and Figure 8 As can be seen, the JV curves of organic solar cells based on different cathode interface layers (PDIN, P-PDI and P-NDI) are shown in Table 1.

[0060] In summary, organic solar cells prepared using P-PDI and P-NDI have higher efficiency, indicating that the ultraviolet light-crosslinked electron transport layer material provided by this invention can improve the efficiency of organic solar cells.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A UV-irradiated cross-linked electron transport layer material, characterized in that: Its molecular formula is:

2. The ultraviolet light-irradiated cross-linked electron transport layer material according to claim 1, characterized in that: R1, R2, R3, R4, R5, R6, R7, and R8 are unsubstituted or substituted C1-C. 20 Alkyl chain or unsubstituted or substituted C1-C 20 Alkoxy chain; Ar is an unsubstituted or substituted heterocyclic aryl group consisting of 6 to 60 carbon atoms and containing 1 to 6 heteroatoms, and is an unsubstituted or substituted monocyclic or polycyclic heteroaromatic group; X1 and X2 represent counterionic groups.

3. The ultraviolet light-irradiated cross-linked electron transport layer material according to claim 1, characterized in that: R1, R2, R3, R4, R5, R6, R7 and R8 are any one of methyl, ethyl, propyl, hexyl, butyl, pentyl, pentoxy and hexoxy.

4. The ultraviolet light-irradiated crosslinked electron transport layer material according to claim 2, characterized in that: The Ar is any one of unsubstituted or substituted phenyl, unsubstituted or substituted naphthyl, unsubstituted or substituted anthraquinone, and unsubstituted or substituted pyrene.

5. The ultraviolet light-irradiated cross-linked electron transport layer material according to claim 2, characterized in that: The heteroatoms in Ar are any one of B, N, P, S, Si, and Se.

6. The ultraviolet light-irradiated cross-linked electron transport layer material according to claim 2, characterized in that: The molecular formula of Ar is any of the following:

7. The ultraviolet light-irradiated crosslinked electron transport layer material according to claim 2, characterized in that: X1 and X2 are F - Cl - ,Br - I - OH - HSO4 - OTf - HCO3 - BF4 - ,Tf2N - and NO3 - Any one of them.

8. The ultraviolet light-irradiated crosslinked electron transport layer material according to claim 1, characterized in that: Its molecular formula is any one of the following:

9. A method for preparing an ultraviolet light-irradiated cross-linked electron transport layer material, characterized in that: The reaction formula is as follows:

10. The method for preparing an ultraviolet light-irradiated crosslinked electron transport layer material according to claim 9, characterized in that: Includes the following steps: Step 1: The compound of Formula 1 is mixed with the compound of Formula 2 and / or the compound of Formula 3 at a molar ratio of 1:4-10 and reacted at a temperature of 60-180℃ for 6-48 hours to obtain the compound of Formula 4. Step 2: Compound 4 is mixed with compound 5 and / or compound 6 in a molar ratio of 1:1 and reacted at a temperature of 60-180℃ for 6-48 hours to obtain compound 7. Step 3: Irradiate compound 7 with ultraviolet light at 10-400 nm for 1-30 minutes to obtain compound 8.

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