Organometallic complexes, methods for their preparation and use

Abstract

The application discloses an organic metal complex and a preparation method and application thereof. The organic metal complex is synthesized based on 2-(thiophene-2-yl)thiazole and is added to an active layer of an organic solar cell as a novel solid additive. The power conversion efficiency of the organic solar cell to which the additive is added is significantly improved. When the thickness of the active layer reaches 300 nanometers, the power conversion efficiency is still relatively high. In particular, the effect of the TTz-Pt additive is particularly remarkable. When the thickness of the active layer reaches 300 nanometers, the conversion efficiency can reach 18.84%. The application provides a simple and effective method, effectively prolongs the exciton diffusion length, realizes the preparation of a high-efficiency thick-film organic solar cell, and promotes the commercialization of the organic solar cell.

Description

Technical Field

[0001] This invention relates to the field of organic polymer photovoltaic device technology, and in particular to organometallic complexes, their preparation methods and applications. Background Technology

[0002] Organic solar cells (OSCs) have attracted attention as a clean and renewable energy technology due to their inherent flexibility, cost-effectiveness, and solution processability. With advancements in materials design (donor and acceptor materials) and device engineering, power conversion efficiency (PCE) of 20% has been achieved in single-junction OSCs. However, despite the high efficiency achieved in thin-film organic solar cells, increasing the thickness of the active layer typically degrades device performance, hindering large-scale production. To realize the commercialization of organic solar cells, it is necessary to develop highly efficient thick-film organic solar cells with a thickness of several hundred nanometers to enhance photon absorption and promote more exciton diffusion to the D / A interface. However, the short exciton diffusion length, space charge accumulation, and severe charge carrier recombination of organic materials significantly limit the device parameters of thick-film organic solar cells.

[0003] Exciton diffusion is a key parameter affecting the photovoltaic performance of thick-film organic solar cells. The probability of excitons diffusing to the D / A interface depends on the exciton diffusion length, which is positively correlated with the exciton diffusion coefficient (D) and exciton lifetime (τ). Previous studies have shown that improving material crystallinity, reducing energy disorder, and lowering trap density effectively enhance the exciton diffusion coefficient, thereby further increasing the exciton diffusion length. Furthermore, synthesizing novel photovoltaic materials is an effective strategy to extend exciton lifetime and thus exciton diffusion length, but this increases synthesis complexity and cost. Therefore, there is an urgent need to develop a simple and effective method that can simultaneously improve material crystallinity, reduce trap density, modulate exciton diffusion behavior, and optimize morphology. Summary of the Invention

[0004] To overcome the aforementioned problems in the prior art, this invention proposes organometallic complexes, their preparation methods, and applications.

[0005] The technical solution adopted by this invention to solve its technical problem is: an organometallic complex, the structural formula of which is:

[0006] .

[0007] Wherein, the metal X is selected from any one of Pt, Pd, Cu, Fe, Ni, Co, and Zn;

[0008] The R unit is selected from any one of straight-chain or branched alkyl groups having 1-3 carbon atoms.

[0009] A method for preparing organometallic complexes, characterized in that the preparation of the organometallic complexes as described above specifically includes:

[0010] Step 1: Under nitrogen protection, 2-bromothiazole, 2-(tributyltinyl)thiophene or (thieno[3,2-B]thieno-2-yl)tributyltin and a catalytic amount of tetratriphenylphosphine palladium were added to a flask; anhydrous toluene was added, and the reaction mixture was stirred at 110°C for 24 hours; after cooling, the mixture was poured into ultrapure water and extracted with dichloromethane; the organic layer was dried over anhydrous MgSO4; the solvent was removed by vacuum evaporation, and the crude product was purified by silica gel column chromatography to obtain compound 2-(thieno-2-yl)thiazole or 2-(thieno[3,2-B]thieno-2-yl)thiazole;

[0011] Step 2: Add the aqueous solution of K2XCl4 to the acetic acid solution of 2-(thiophene-2-yl)thiazole or 2-(thiopheno[3,2-b]thiophene-2-yl)thiazole obtained in Step 1, and reflux under nitrogen. Filter to obtain the dimer, wash with acetic acid and ethanol, and dry under vacuum. Reflux the dimer and sodium acetylacetonate in acetone, remove the solvent under reduced pressure, and purify the complex by silica gel chromatography to obtain the organometallic complex.

[0012] An application of an organometallic complex as described above in the fabrication of thick-film organic solar cells.

[0013] Preferably, the specific preparation method of thick-film organic solar cells includes:

[0014] Step 1: Clean the ITO-coated glass substrate with ultrasonic waves in detergent, deionized water, acetone and isopropanol, and then dry it with nitrogen.

[0015] Step 2: The glass substrate obtained in Step 1 is subjected to oxygen plasma treatment, PEDOT:PSS is spin-coated on the glass substrate, and after drying, the substrate is transferred to a glove box filled with nitrogen.

[0016] Step 3: Spin-coat an active layer with an organometallic complex onto the substrate obtained in step 2, and then perform a thermal annealing treatment;

[0017] Step 4: Spin-coat PDINN solution onto the substrate obtained in step 3, and form a top electrode by evaporating 100 nanometers of Ag.

[0018] Preferably, the amount of organometallic complex added in step 3 is 1.5%-4.5% of the body weight.

[0019] Preferably, the active layer is one of D18-Cl:L8-BO, PM6:L8-BO, and D18:L8-BO:IDIC.

[0020] Preferably, the thickness of the active layer is 100-300 nanometers.

[0021] The beneficial effects of this invention are that it synthesizes an organometallic complex based on 2-(thiophene-2-yl)thiazole and adds it as a novel solid additive to the active layer of organic solar cells. The power conversion efficiency of organic solar cells with this additive is significantly improved, and the power conversion efficiency remains high even when the active layer thickness reaches 300 nm. The TTz-Pt additive is particularly effective, achieving a conversion efficiency of 18.84% with an active layer thickness of 300 nm. This invention proposes a simple and effective method to extend the exciton diffusion length, enabling the fabrication of high-efficiency thick-film organic solar cells and promoting the commercialization of organic solar cells. Attached Figure Description

[0022] Figure 1 These are 2D GIWAXS images of embodiments of the present invention; wherein (a) is a 2D GIWAXS image of Comparative Example 1, (b) is a 2D GIWAXS image of Example 1, and (c) is a 2D GIWAXS image of Example 6.

[0023] Figure 2 These are 1D wire cut diagrams of Comparative Example 1, Example 1, and Example 6;

[0024] Figure 3 The Urbach energies for Comparative Example 1, Example 1, and Example 6;

[0025] Figure 4 The trap state density diagrams are for Comparative Example 1, Example 1, and Example 6.

[0026] Figure 5 JV curves for Comparative Example 1, Example 1, and Example 6;

[0027] Figure 6 EQE spectra of Comparative Example 1, Example 1, and Example 6;

[0028] Figure 7 Comparative Example 1, Example 1, and Example 6 J ph -V eff curve;

[0029] Figure 8 TPC curves for organic solar cells in Comparative Example 1, Example 1, and Example 6;

[0030] Figure 9 TPV curves for Comparative Example 1, Example 1, and Example 6

[0031] Figure 10 Comparative Example 1, Example 1, and Example 6 J SCDependence curve of light intensity;

[0032] Figure 11 Comparative Example 1, Example 1, and Example 6 V OC The curve of light intensity;

[0033] Figure 12 Photo-CELIV curves for Comparative Example 1, Example 1, and Example 6;

[0034] Figure 13 The TPV curves for Comparative Example 2, Example 2, and Example 7;

[0035] Figure 14 Electron mobility curves for Comparative Example 2, Example 2, and Example 7 Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] This embodiment discloses an organometallic platinum complex, with the following specific structural formula:

[0038] .

[0039] Specific preparation methods include:

[0040] Step 1: Under nitrogen protection, 2-bromothiazole, 2-(tributyltinyl)thiophene, and a catalytic amount of tetra(triphenylphosphine)palladium were added to a flask. Anhydrous toluene was then added, and the reaction mixture was stirred at 110°C for 24 hours. After cooling, the mixture was poured into ultrapure water and extracted with dichloromethane. The organic layer was dried over anhydrous MgSO4. The solvent was removed by vacuum evaporation, and the crude product was purified by silica gel column chromatography to give compound 2-(thiophene-2-yl)thiazole (TTz).

[0041] Step 2: Add the aqueous solution of potassium tetrachloroplatinate to the acetic acid solution of TTz and reflux under nitrogen. Filter off the precipitate solid of Pt(II)-dichlorobridged dimer, wash with acetic acid and ethanol, and dry under vacuum. Reflux the dimer and sodium acetylacetonate in acetone, remove the solvent under reduced pressure, and purify the complex by silica gel chromatography to obtain the organometallic platinum complex TTz-Pt.

[0042] The synthesis route is shown below:

[0043]

[0044] The organometallic platinum complex TTz-Pt is used to prepare thick-film organic solar cells. Specific preparation methods include:

[0045] Step 1: Clean the ITO-coated glass substrate with ultrasonic waves in detergent, deionized water, acetone and isopropanol for 15 minutes each, and then dry it with nitrogen.

[0046] Step 2: The glass substrate obtained in Step 1 is subjected to oxygen plasma treatment for 60 seconds, and a 30-nanometer thick layer of PEDOT:PSS is spin-coated on the glass substrate. After baking at 150°C for 15 minutes, the substrate is transferred to a glove box filled with nitrogen.

[0047] Step 3: Spin-coat the substrate obtained in step 2 with an active layer of TTz-Pt, and perform thermal annealing treatment;

[0048] Step 4: Spin-coat the PDINN solution onto the substrate obtained in Step 3, and form the top electrode by evaporating 100 nanometers of Ag. Define the active area (4 square millimeters) of the device using a shadow mask.

[0049] The active layer can be selected from one of D18-Cl:L8-BO, PM6:L8-BO, or D18:L8-BO:IDIC.

[0050] Taking the active layer system as D18-Cl:L8-BO as an example, different concentrations of TTz and TTz-Pt additives were added to the active layer, and the performance was tested. The results are shown in Table 1.

[0051] Table 1. D18-Cl:L8-BO OSCs (active layer thickness 100 nm) with different additives at AM 1.5 G 100 mW cm -2 Photovoltaic parameters under illumination

[0052]

[0053] As can be seen from Table 1, the parameters of the organic solar cell are optimal when the concentration of additive TTz-Pt is 3%. Therefore, the additive concentration of 3% was selected for both the example and the comparative example.

[0054] Example 1

[0055] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18-Cl:L8-BO system. The D18-Cl:L8-BO (1:1.2, weight ratio, D18-Cl concentration is 5 mg / mL) active layer is dissolved in chloroform, and 3% by weight of TTz-Pt donor is added, and the mixture is spin-coated into a 100 nm thick film.

[0056] Example 2

[0057] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18-Cl:L8-BO system. The D18-Cl:L8-BO (1:1.2, weight ratio) active layer is dissolved in chloroform, and 3% by weight of TTz-Pt donor is added. The mixture is then spin-coated into a 300-nanometer thick film, wherein the concentration of D18-Cl is 8 mg / mL.

[0058] Example 3

[0059] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the PM6:L8-BO system. The PM6:L8-BO (1:1.2, weight ratio, PM6 concentration of 8 mg / mL) active layer is dissolved in chloroform, and 3% by weight of TTz-Pt donor is added, and the mixture is spin-coated into a 300 nm thick film.

[0060] Example 4

[0061] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18:L8-BO:IDIC system, the D18:L8-BO:IDIC (1:1:0.2, weight ratio) active layer, 3 weight percentage of TTz-Pt donor is added, and a 100-nanometer thick film is spin-coated, wherein the concentration of D18 is 5 mg / mL.

[0062] Example 5

[0063] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18:L8-BO:IDIC system, the D18:L8-BO:IDIC (1:1:0.2, weight ratio) active layer, 3 weight percentage of TTz-Pt donor is added, and a 300 nm thick film is spin-coated, wherein the concentration of D18 is 8 mg / mL.

[0064] Example 6

[0065] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18-Cl:L8-BO system. The D18-Cl:L8-BO (1:1.2, weight ratio, D18-Cl concentration is 5 mg / mL) active layer is dissolved in chloroform, and 3% by weight of TTz of the donor is added, and the mixture is spin-coated into a 100 nm thick film.

[0066] Example 7

[0067] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18-Cl:L8-BO system. The D18-Cl:L8-BO (1:1.2, weight ratio) active layer is dissolved in chloroform, and 3% by weight of TTz of the donor is added. The mixture is then spin-coated into a 300-nanometer thick film, wherein the concentration of D18-Cl is 8 mg / mL.

[0068] Example 8

[0069] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the PM6:L8-BO system. The PM6:L8-BO (1:1.2, weight ratio, PM6 concentration of 8 mg / mL) active layer is dissolved in chloroform, and 3% by weight of TTz of the donor is added, and the mixture is spin-coated into a film 300 nm thick.

[0070] Example 9

[0071] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18:L8-BO:IDIC system. The active layer of D18:L8-BO:IDIC (1:1:0.2, weight ratio) is added with 3% TTz of the donor and spin-coated into a 100-nanometer thick film, wherein the concentration of D18 is 5 mg / mL.

[0072] Example 10

[0073] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18:L8-BO:IDIC system. The active layer of D18:L8-BO:IDIC (1:1:0.2, weight ratio) is added with 3% TTz of the donor and spin-coated into a film with a thickness of 300 nanometers. The concentration of D18 is 8 mg / mL.

[0074] Comparative Example 1

[0075] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18-Cl:L8-BO system. The D18-Cl:L8-BO (1:1.2, weight ratio, D18-Cl concentration of 5 mg / mL) active layer is dissolved in chloroform and spin-coated into a 100 nm thick film.

[0076] Comparative Example 2

[0077] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18-Cl:L8-BO system. The D18-Cl:L8-BO (1:1.2, weight ratio) active layer is dissolved in chloroform and spin-coated into a 300-nanometer thick film, wherein the concentration of D18-Cl is 8 mg / mL.

[0078] Comparative Example 3

[0079] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the PM6:L8-BO system. The PM6:L8-BO (1:1.2, weight ratio, PM6 concentration of 8 mg / mL) active layer is dissolved in chloroform and spin-coated into a 300 nm thick film.

[0080] Comparative Example 4

[0081] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18:L8-BO:IDIC system, and the D18:L8-BO:IDIC (1:1:0.2, weight ratio) active layer is spin-coated into a film with a thickness of 100 nanometers, wherein the concentration of D18 is 5 mg / mL.

[0082] Comparative Example 5

[0083] Based on the above-mentioned method for preparing thick-film organic solar cells, in this embodiment, the active layer is selected from the D18:L8-BO:IDIC system, and the D18:L8-BO:IDIC (1:1:0.2, weight ratio) active layer is spin-coated into a film with a thickness of 300 nanometers, wherein the concentration of D18 is 8 mg / mL.

[0084] Tests were conducted on Examples 1-10 and Comparative Examples 1-5, and the results are shown in the accompanying drawings and Tables 2-3 of the specification.

[0085] The effects of platinum additives on the molecular orientation and stacking behavior of the active layer were investigated using GIWAXS. Figure 1 As shown, the 2D GIWAXS of Comparative Example 1, Example 1, and Example 6 exhibited π-π stacked (010) peaks in the OOP direction, indicating that the preferred out-of-plane molecular orientations that facilitate charge transport in the mixture films are well maintained after different additive treatments. The wire-cut profiles of the three films are shown in... Figure 2 In the OOP direction, Comparative Example 1, Example 1, and Example 6 exhibited a 010 peak, located at qz = 1.720, 1.732, and 1.729 Å, respectively. -1 The π-π stacking distances were 3.650, 3.627, and 3.634 Å, respectively. Furthermore, the calculated CCLs for the 010 peak were 18.97, 28.13, and 25.93 Å for Comparative Example 1, Example 1, and Example 6, respectively. The smaller π-π stacking distances and larger CCLs indicate that the addition of TTz-Pt results in a more compact molecular stack and higher crystallinity in the D18-Cl:L8-BO film, which is beneficial for promoting charge transport and thus improving device performance.

[0086] Considering the differences in crystallinity among Comparative Example 1, Example 1, and Example 6, the Urbach energy (E) was calculated using Fourier transform photocurrent spectroscopy external quantum efficiency (FTPS-EQE) spectroscopy. U To study energy disorder. For example... Figure 3 As shown, the calculated E U The values ​​were 22.29 meV, 20.89 meV, and 21.15 meV for Comparative Example 1, Example 1, and Example 6, respectively. The reduced energy disorder in Example 1 is consistent with the improved crystallinity, which can improve the charge transport process. Furthermore, the trapped state density (Nt) is also related to carrier transport behavior, such as... Figure 4 The calculated Nt values ​​were 5.23 × 10⁻⁶ for Comparative Example 1, Example 1, and Example 6, respectively. 16 3.97×10 16 and 4.67×10 16 cm -3 The reduced Nt in Example 1 suppressed charge recombination and improved exciton diffusion and charge transport processes. These results, combined with the surface addition of TTz-Pt, enhanced device performance. Combining these advantages, the addition of TTz-Pt improves crystallinity, reduces energy disorder and trap state density, contributing to a larger exciton diffusion coefficient and thus extending the exciton diffusion length.

[0087] Performance testing was conducted on TTz-Pt additive-based organic solar cells using D18-Cl:L8-BO. ​​The current density-voltage (JV) curves are shown below. Figure 5 As shown, based on the photovoltaic parameters in Table 2, Comparative Example 1 achieved a power conversion efficiency of 18.18%, J SC 26.05 mA cm -2 V OC The voltage is 0.916 V, and the FF is 76.2%. In comparison, Example 6 achieves a higher power conversion efficiency of 18.77%, J SC 26.23 mA cm -2 V OC The voltage was 0.922 V, and the power factor (FF) was 77.6%. Example 1 achieved a power conversion efficiency of 19.63%, accompanied by improved J. SC 26.61 mA cm -2 V OC The voltage is 0.929 V, and the FF is 79.4%.

[0088] The external quantum efficiency (EQE) spectrum of the best device is shown in Figure 6 In the 500-800 nm region, Example 1 exhibited a higher EQE response than Comparative Example 1 and Example 6, indicating a more efficient photon-to-carrier conversion, which brings enhanced J to Example 1.SC Furthermore, the integral J of the EQE curves of Comparative Example 1, Example 1, and Example 6 is compared. SC The values ​​were 25.13, 25.70, and 25.51 mA cm, respectively. -2 J, as measured by the JV curve SC Consistent.

[0089] To investigate the exciton dissociation probability (P) in corresponding organic solar cells diss The photocurrent density (J) was measured. ph ) and effective voltage (V eff ( ) curve. For example Figure 7 As shown, P in Example 1 diss The value was 99.49%, higher than Comparative Example 1 (96.50%) and Example 6 (97.89%). Furthermore, charge collection (P... coll The probability value of () increased from 81.34% in Comparative Example 1 to 84.17% in Example 1 and 83.13% in Example 6. Example 1 had a higher P diss and P coll This indicates more efficient exciton dissociation and charge collection, which can be attributed to the extended exciton diffusion length.

[0090] To investigate the effects of TTz-Pt additives on charge extraction and charge carrier lifetime in organic solar cells, transient photocurrent (TPC) and transient photovoltage (TPV) measurements were performed. Figure 8-9 As shown, the charge extraction times for Comparative Example 1, Example 1, and Example 6 were 0.52, 0.35, and 0.42 μs, respectively. Furthermore, the charge carrier lifetimes fitted from the TPV curves were 2.57, 3.48, and 3.31 μs, respectively. Compared to Comparative Example 1, the additive-treated organic solar cells exhibited a faster charge extraction process and a longer charge carrier lifetime, particularly Example 1, which is consistent with J SC Consistent with the improvement of FF. J SC With light intensity (P) light The measurements were used to investigate the effect of TTz-Pt on the charge recombination mechanism of organic solar cells. SC With P light The relationship between J is described as follows: SC ∝P light α ( Figure 10 The α values ​​for Comparative Example 1, Example 1, and Example 6 were 0.96, 0.97, and 0.96, respectively, indicating weak bimolecular recombination in all three organic solar cells. Furthermore, by measuring the Vo in the organic solar cells... OC As P light Functions are used to study trap-assisted composition. For example... Figure 11As shown, the n value of Example 1 is 1.01, which is less than 1.16 in Comparative Example 1 and 1.05 in Example 6, indicating that trap-assisted recombination was suppressed in Example 1. The charge transport behavior of the active layer with and without additive treatment was revealed using photo-induced charge carrier extraction (photo-CELIV) under linearly increasing voltage. Figure 12 As shown, the carrier mobilities of Comparative Example 1, Example 1, and Example 6 are 1.61 × 10⁻⁶, respectively. -4 2.22×10 -4 and 2.05×10 -4 cm 2 V -1 s -1 The improved charge transport properties can explain the enhanced J in Example 1. SC And FF value.

[0091] The extended exciton diffusion length allows more excitons to diffuse to the D / A interface, offering great potential for fabricating high-efficiency thick-film organic solar cells. The longest exciton diffusion length, 38.3 nm, was obtained in Example 1 through TPV experiments. Figure 13-14 This is greater than the exciton diffusion length of Comparative Example 1 (18.3 nm) and Example 6 (23.7 nm). Therefore, the 300 nm thick film in Example 2 exhibits a higher PCE of 18.63%, compared to Comparative Example 1 (17.23%) and Example 6 (17.71%).

[0092] To investigate the versatility of TTz-Pt in improving the photovoltaic performance of thin-film and thick-film devices, representative active layer systems, including PM6:L8-BO and D18:L8-BO:IDIC, were applied, as shown in Table 3. The structural formula of the active layer system is as follows:

[0093]

[0094] In Example 4, a power conversion efficiency of 20.12% was achieved. Thanks to the superior thickness insensitivity of the TTz-Pt additive treatment, Example 5 achieved a power conversion efficiency of 18.84%, which is higher than that of existing 300 nm thick organic solar cells. These results demonstrate that by introducing an organometallic platinum complex (TTz-Pt) as a solid additive, a simple and universal method can be developed to extend the exciton diffusion length and achieve the fabrication of high-efficiency thick-film organic solar cells.

[0095] Table 2. Photovoltaic parameters of D18-Cl:L8-BO OSCs with different active layer thicknesses under different additive treatments

[0096]

[0097] Table 3. OSC photovoltaic parameters of various active layers processed with different additives

[0098]

[0099] This embodiment also discloses an organometal palladium complex with the following structural formula:

[0100]

[0101] Specific preparation methods include:

[0102] Step 1: Under nitrogen protection, 2-bromothiazole, 2-(tributyltinyl)thiophene, and a catalytic amount of tetra(triphenylphosphine)palladium were added to a flask. Anhydrous toluene was then added, and the reaction mixture was stirred at 110°C for 24 hours. After cooling, the mixture was poured into ultrapure water and extracted with dichloromethane. The organic layer was dried over anhydrous MgSO4. The solvent was removed by vacuum evaporation, and the crude product was purified by silica gel column chromatography to give compound 2-(thiophene-2-yl)thiazole (TTz).

[0103] Step 2: Add the aqueous solution of potassium tetrachloropalladate to the acetic acid solution of TTz and reflux under nitrogen. Filter off the precipitate solid of Pd(II)-dichlorobridged dimer, wash with acetic acid and ethanol, and dry under vacuum. Reflux the dimer and sodium acetylacetonate in acetone, remove the solvent under reduced pressure, and purify the complex by silica gel chromatography to obtain the organometallic platinum complex TTz-Pd.

[0104] Furthermore, other coordination metals (II) Cu, Fe, Ni, Co, and Zn can also align planarly with surrounding ligands to form planar structures, thereby achieving properties similar to TTz-Pt. This planar structure endows these complexes with specific stereochemical properties during chemical reactions, which is crucial in many optoelectronic processes. Therefore, metal complexes formed by other coordination metals can achieve excellent performance in thick-film organic solar cells.

[0105] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its scope and spirit, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. An organometallic complex characterized in that, The structural formula of the organic metal complex is: ; The metal X is selected from any one of Pt and Pd. The R unit is selected from any one of straight-chain or branched alkyl with 1-3 carbon atoms.

2. Process for the preparation of organometallic complexes, characterized in that, The preparation method of the organic metal complex of claim 1 comprises: Step 1: under nitrogen protection, 2-bromothiazole, 2-(tributylstannyl)thiophene or (thieno[3,2-b]thiophen-2-yl)tributyltin and a catalytic amount of tetrakis(triphenylphosphine)palladium are added into a flask; anhydrous toluene is added, and the reaction mixture is stirred at 110°C for 24 hours; after cooling, the mixture is poured into ultrapure water and extracted with dichloromethane; the organic layer is dried over anhydrous MgSO4; the solvent is removed by evaporation under reduced pressure, and the crude product is purified by silica gel column chromatography to obtain compound 2-(thiophen-2-yl)thiazole or 2-(thieno[3,2-b]thiophen-2-yl)thiazole; Step 2: an aqueous solution of K2XCl4 is added to the acetic acid solution of 2-(thiophen-2-yl)thiazole or 2-(thieno[3,2-b]thiophen-2-yl)thiazole obtained in step 1, wherein X is any one of Pt and Pd, and heated under reflux with nitrogen; the dimer is filtered, washed with acetic acid and ethanol, and dried under vacuum; the dimer and sodium acetylacetonate are heated under reflux in acetone, the solvent is removed under reduced pressure, and the complex is purified by silica gel chromatography to obtain the organic metal complex.

3. Use of the organic metal complex of claim 1 in the preparation of an organic solar cell.

4. Use according to claim 3, characterized in that, The preparation method of the organic solar cell comprises: Step 1: an ITO-coated glass substrate is cleaned by ultrasonic wave in detergent, deionized water, acetone and isopropanol, and dried with nitrogen; Step 2: the glass substrate obtained in step 1 is subjected to oxygen plasma treatment, PEDOT:PSS is spin-coated on the glass substrate, and the substrate is transferred to a nitrogen-filled glove box after drying; Step 3: an active layer with the addition of the organic metal complex is spin-coated on the substrate obtained in step 2, and heat annealing treatment is performed; Step 4: PDINN solution is spin-coated on the substrate obtained in step 3, and a top electrode is formed by evaporating 100 nanometers of Ag.

5. Use according to claim 4, characterized in that, The addition amount of the organic metal complex in step 3 is 1.5%-4.5% of the weight of the donor.

6. Use according to claim 4, characterized in that, The active layer is specifically one of D18-Cl:L8-BO, PM6:L8-BO, D18:L8-BO:IDIC.

7. Use according to claim 4, characterized in that, The thickness of the active layer is 100-300 nanometers.

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