CN114085362A

CN114085362A - Preparation method and application technical field of polymer donor material containing multi-element aromatic ring thieno-thiophene diketone

Info

Publication number: CN114085362A
Application number: CN202111471800.8A
Authority: CN
Inventors: 孙艳明; 叶灵龙
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2021-12-06
Filing date: 2021-12-06
Publication date: 2022-02-25
Anticipated expiration: 2041-12-06
Also published as: CN114085362B

Abstract

The invention provides a preparation method and application of a polymer donor material containing multi-element aromatic ring thiophene diketone, wherein the polymer provided by the invention is a polymer with a structure shown in a formula (I), and experiments show that the polymer provided by the invention can obtain higher photoelectric conversion efficiency which can reach 15.04% when being used as an active layer component of a photoelectric conversion device.

Description

Preparation method and application technical field of polymer donor material containing multi-element aromatic ring thieno-thiophene diketone

Technical Field

The invention relates to the field of solar cells, in particular to a polymer based on multi-element aromatic thienothiophene diketone and a preparation method and application thereof.

Background

Energy is a material basis and guarantee for the development of human society. With the rapid development of science and technology, the human demand for energy is increasing year by year. At present, the main energy acquisition way is still fossil energy, but the energy is increasingly exhausted, and obvious environmental pollution is caused. Solar energy is an inexhaustible clean energy and is widely concerned by scientific workers, factories and enterprises in various countries.

Scientists have produced various solar cells based on the photovoltaic effect. Among them, organic solar cells (OPVs) have the outstanding advantages of light weight, low cost, and the ability to be fabricated into flexible large-area devices. Through continuous efforts of researchers, the photoelectric conversion efficiency of a single photovoltaic cell based on a polymer exceeds 18%, and the single photovoltaic cell based on the polymer has excellent performance in the field of indoor photovoltaics and has great commercial application potential.

Most important in organic solar cells are photoactive layers. The most excellent photoactive layer system is now a polymer donor/small molecule acceptor. In recent years, the structure of a high-performance small molecule acceptor is discovered, so that the photoelectric conversion efficiency of the organic solar cell is rapidly improved, and the development of a polymer donor material is slow. Obviously, the donor material and the acceptor material are equally important, and the development of the donor material is not slow to obtain a higher-performance organic solar cell.

The existing excellent polymer donor material mainly comprises a benzodithiophene derivative and a benzodithiophene diketone derivative, wherein the benzodithiophene derivative and the benzodithiophene diketone derivative bring proper energy level and good self-assembly effect due to a unique planar electron-withdrawing structure, and are one of the most excellent electron-deficient units in the donor polymer material. Therefore, it is of great importance to develop more polymer donor materials in a preferred form, which can improve the photoelectric conversion efficiency of solar cells.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a polymer based on a poly-aromatic thienothiophene dione, and a preparation method and an application thereof.

The invention provides a polymer containing a multi-element aromatic ring thiophene diketone, which is a polymer with a formula (I):

wherein, R is_1-1And R_1-2Independently selected from oxygen, sulfur, selenium, amino, carbonyl, sulfuryl, sulfoxide, vinyl and imino,

the R is_2-1、R_2-2、R_3-1、R_3-2Independently selected from hydrogen, bromine, iodine, sulfuryl, sulfoxide, ester group, carbonyl, trifluoromethyl, C1-C30,

ar is₁Selected from unsubstituted or substituted ethenylene, unsubstituted or substituted ethynylene, unsubstituted or substituted monocyclic arylene, unsubstituted or substituted bicyclic arylene, unsubstituted or substituted tricyclic arylene, unsubstituted or substituted monocyclic heteroarylene, unsubstituted or substituted bicyclic heteroarylene, or unsubstituted or substituted tricyclic heteroarylene;

ar is₂Selected from unsubstituted or substituted fluorenes, carbazoles, dibenzofurans, silafluorenes, benzophosphinindoles, dibenzothiophenes, germanofluorenes, stannofluorenes;

n is a natural number between 5 and 1000, preferably between 10 and 100.

Preferably, said R is_2-1、R_2-2、R_3-1、R_3-2Independently selected from hydrogen or C5-C20 alkyl, chlorine, bromine, iodine, C1-C20 sulfuryl, C1-C20 sulfoxide, C2-C20 ester, C1-C20 carbonyl, trifluoromethyl or C2-C20 alkynyl.

Preferably, the heteroatoms in the monocyclic heteroarylene, bicyclic heteroarylene and tricyclic heteroarylene are nitrogen, sulfur or oxygen.

Preferably, the substituent of the substituted ethenylene group, the substituted ethynylene group, the substituted monocyclic arylene group, the substituted bicyclic arylene group, the substituted three-ring arylene group, the substituted monocyclic heteroarylene group, the substituted bicyclic heteroarylene group and the substituted three-ring heteroarylene group is a substituted or unsubstituted aryl group of C6-C30, a substituted or unsubstituted arylalkyl group of C6-C60, an alkyl group of C1-C20, an alkoxy group of C1-C20, an ester sulfone group, a fluoroalkyl group, a fluorinated heterocyclic group, an ethenylene group, an ethynylene group, a monocyclic arylene group, a bicyclic arylene group, an arylene group containing three rings, a monocyclic heteroarylene group, a bicyclic heteroarylene group or a heteroaromatic group containing three rings.

Preferably, Ar is Ar₁Selected from the following structures:

wherein R is hydrogen, C1-C20 alkyl, C1-C20 alkoxy, C6-C30 aryl substituted by C1-C20 alkyl, C6-C60 arylalkyl substituted by Cl-C30 alkyl, ester group, sulfone group, fluoroalkyl group, fluoro heterocyclic group, ethenylene, ethynylene, monocyclic arylene, bicyclic arylene, arylene containing three rings, monocyclic heteroarylene, bicyclic heteroarylene or heteroarylene containing three rings;

x is an oxygen group element, preferably S;

y is a carbon group element.

Preferably, Ar is₂Selected from the following structures:

wherein, R is₄、R₅、R₆、R₇、R₈、R₉Independently selected from hydrogen or C5-C20 alkyl, C2-C20 ester group of chlorine, C1-C20 carbonyl and trifluoromethyl.

Z is selected from carbon group, nitrogen group and oxygen group.

The invention also relates to a semiconductor composition comprising the polymer having the formula (I) described above.

The invention also relates to a photoelectric conversion device, wherein the active layer material in the photoelectric conversion device is the polymer with the formula (I).

Compared with the prior art, the polymer based on the poly-aromatic fused thiophene dione is a polymer with a structure shown in a formula (I), and experiments show that the polymer provided by the invention can obtain higher photoelectric conversion efficiency which is as high as 15.04% when being used as an active layer component of a photoelectric conversion device.

Drawings

FIG. 1 is a UV-VIS absorption spectrum of polymer P1 prepared in example 5 in chloroform solution and film;

FIG. 2 is a J-V plot of a photovoltaic device made from polymer P1;

fig. 3 is a EQE curve of polymer P1 as the active layer.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only illustrative and are not intended to limit the present invention.

Generally, the number average molecular weight of the polymer of the present invention is 1000 to 1,000,000, the preferred number average molecular weight is 3000 to 500,000, and the further preferred number average molecular weight is 20,000 to 200,000. It is understood that the molecular weight can be varied to optimize polymer properties. For example, lower molecular weights ensure solubility, while higher molecular weights ensure good film forming properties.

The invention provides a preparation method of a polymer, which synthesizes a compound shown in formula (I) through monomer formula (II) and monomer formula (III),

wherein W is selected from I, Br or Cl, and V is selected from a boronic acid group, a boronic ester group, a zinc halide group, or a trialkyltin group;

the boronic acid group is selected from the group including, but not limited to: 1,3, 2-dioxaborane-2-yl, 4,5, 5-tetramethyl-1, 2, 3-dioxaborolan-2-yl or 5, 5-dimethyl-1, 3, 2-dioxaborane-2-yl;

the magnesium halide group is selected from the group including, but not limited to: magnesium chloride, bromide or iodide; the zinc halide group is preferably: zinc chloride or bromide;

the trialkyltin group is selected from the group including, but not limited to: trimethyltin, triethyltin or tributyltin.

If a polycondensation reaction is carried out between a dimagnesium haloaromatic compound and an aromatic dihalide, the polymerization reaction is a typical "McCullough" process as reported by McCullough and Lowe [ chem. In the McCullough method, tetrahydrofuran and toluene are used as common solvents, and a mixed solvent of tetrahydrofuran and toluene may be used. Some catalysts containing Pd or Ni, such as [1, 3-bis (diphenylphosphino) propane ] dichloronickel (ii) and tetrakis (triphenylphosphine) palladium (0), can be used as catalysts for the reaction, and the molar ratio between the catalyst and the starting material is 10% to 0.1%. The reaction is typically carried out at a temperature of about 10 ℃ to the reflux temperature of the solvent. The polymerization reaction may be carried out for 10 minutes to 72 hours for different reactivity of the reactants. The dimagnesium haloarene used in this reaction can be prepared from the Grignard displacement reaction [ Macromolecules,2001,34,4324-4333] as reported by Loewe and McCullough, or from the reaction between an arene dihalide and magnesium. In some embodiments, the aromatic dihalide and dimagnesium haloaromatic hydrocarbon used in the "McCullough process" with the polymer of the present invention are aromatic dibromides and dimagnesium bromoaromatic hydrocarbons.

If a polycondensation reaction is carried out between a di-zinc haloaromatic compound and an aromatic dihalide, the polymerization reaction is typically the "Rieke process" as reported by Chen and Rieke [ synth. met,1993,60,175 ]. In this process, tetrahydrofuran is generally used as a solvent, [1, 2-bis (diphenylphosphino) ethane ] nickel (ii) dichloride, which can be used as a catalyst for the reaction and is generally carried out at about 10 ℃ to the reflux temperature of the solvent, at a molar ratio of the catalyst to the starting materials of 10% to 0.1%. Depending on the reactivity of the reactants, the polymerization may be carried out for 10 minutes to 72 hours, in a preferred embodiment, the aromatic dihalides and zinc bis-haloarylenes used in the "Rieke process" with the polymers of the invention are aromatic dibromides and zinc bis-chloroarenes.

If polycondensation is carried out between an aromatic diboronic acid compound or an aromatic diboronate compound and an aromatic dihalide, the polymerization is a typical "Suzuki reaction" as reported by Miyaura and Suzuki [ ChemRev.1995,95,2457-2483 ]. In this process, solvents including but not limited to many types of solvents such as tetrahydrofuran and toluene, some catalysts containing Pd such as tetrakis (triphenylphosphine) palladium (0) may be used as the catalyst for the reaction, and the molar ratio between the catalyst and the starting material is 10% to 0.1%. The reaction is typically carried out at a temperature of about 10 ℃ to the reflux temperature of the solvent. The polymerization reaction may be carried out for 10 minutes to 72 hours for different reactivity of the reactants. In some embodiments, the arene dihalide used in the polymer "Suzuki reaction" for some embodiments of the present invention is an arene diiodide, an arene dihalide, or an arene dichloride.

If the polycondensation reaction is carried out between a trialkyltinylarene compound and an arene dihalide, the polymerization reaction is a typical "Stille reaction" as reported by John k. Stille and Luping Yu [ angelw. chem. int. ed.1986,25, 508-; chem. rev.2011,111,1493-1528], in the method, the solvent includes but is not limited to many types of solvents of tetrahydrofuran, N-dimethylformamide, toluene and chlorobenzene, and a mixed solvent such as a mixed solvent of tetrahydrofuran and toluene, a mixed solvent of toluene and N, N-dimethylformamide may be sometimes used but is not limited to a mixture of these two mixed solvents. Some catalysts containing Pd such as tetrakis (triphenylphosphine) palladium (0), palladium chloride, palladium acetate and/or (dibenzylideneacetone) palladium (0) may be used as catalysts for the reaction, and the molar ratio between the catalyst and the starting material is 10% to 0.1%. The reaction is generally carried out at a temperature of between 10 and 200 ℃. The polymerization time is from 10 minutes to 72 hours. In some embodiments, the arene dihalide used in the polymer "Stille reaction" used in some embodiments of the present invention is arene diiodide, arene dihalide, or arene dichloride and bistrimethylstannic arene.

Definition and naming: unless otherwise indicated, the invention is not limited to specific starting materials, reagents or reaction conditions, but may be varied. The term "alkyl" as used herein refers to a branched or unbranched saturated alkyl group typically, but not necessarily, containing 1 to 30 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-octyl, isooctyl, decyl, and the like; and cycloalkyl groups such as cyclopentyl, cyclohexyl, and the like.

"arylene" has its usual meaning. The term "heteroarylene" as used herein refers to an aromatic ring of 5 or 6 atoms containing one or more "heteroatoms" (i.e., atoms other than carbon, such as nitrogen, oxygen, sulfur, silicon, selenium, phosphorus). The term "N-containing heteroarylene" as used herein refers to a heteroarylene group in which one or more "heteroatoms" as defined above is nitrogen. The "fused" rings share the same bond, and the "connected" rings are connected by a single bond.

The term "substituted" as in "substituted arylene", "substituted heteroarylene", and the like, refers to moieties in which at least one hydrogen atom bonded to a carbon or heteroatom is replaced with one or more non-hydrogen substituents, which may include, but are not limited to, alkyl or aryl groups, and functional groups such as halogen, hydroxy, alkylthio, alkoxy, aryloxy, alkylcarbonyl, acyloxy, nitro, nitrile, and the like.

In general, the polymer of the present invention is selected to be combined with an admixture, and the two may be mixed in any ratio, e.g., a mass ratio of polymer to admixture of 1:1.5, etc. The admixture is typically a compound selected such that when an excitation source comprising light or voltage is applied to the combination, charge transfer and/or energy transfer occurs between the admixture and the polymer. For example, the admixture may be a fullerene, such as: c₆₀Or C₇₀Or some substituted fullerene derivatives, such as PCBM ([6, 6)]-phenyl radical C₆₁Methyl butyrate) and indene-containing fullerenes. Polymers according to some embodiments of the invention are particularly useful as photovoltaic materials in photovoltaic devices such as photodetector devices, solar cell devices, and the like.

The present invention also protects a photovoltaic device (including a solar cell device) generally comprising a hole-collecting layer, an electron-collecting layer, and a layer of photovoltaic material between the hole-collecting layer and the electron-collecting layer; the photovoltaic material layer at least comprises the polymer or semiconductor composition provided by the invention. Additional layers, prototypes, or substrates may or may not be present in the photovoltaic device.

In describing embodiments of the invention, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. It is to be understood that each specific element includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

The practice of the present invention may employ conventional techniques of polymer chemistry within the skill of the art. In the following examples, efforts are made to ensure accuracy with respect to numbers used (including amounts), temperature, reaction time, etc.), but some experimental errors and deviations should be accounted for. The temperatures used in the following examples are expressed in degrees Celsius and the pressures are at or near atmospheric. All solvents, reagents were commercially available and all reactions were carried out under nitrogen atmosphere. All reagents were obtained commercially unless otherwise indicated.

Example 1: synthesis of intermediate 2

Potassium tert-butoxide (2.7g,24.1mmol,4eq) was added in portions to a solution of fluorene (1.0g, 6.0mmol) and bromo-n-octane (3.5g,18.1mmol,3eq) in tetrahydrofuran (15mL) at 0 deg.C; after the addition, stirring at room temperature for 1 hour; adding 20mL of water for quenching, extracting an organic phase by using dichloromethane, washing by water to remove impurities, drying the organic phase by using anhydrous sodium sulfate, filtering and concentrating; petroleum ether is used as an eluent, and the crude product is eluted by a silica gel column to obtain colorless liquid, namely an intermediate 2; intermediate 2 was obtained in 2.0g, 85% yield;¹h NMR analysis was consistent with literature.

Example 2: synthesis of intermediate 3

Aluminum trichloride (1.5g,11.3mmol,4.4eq) was added in portions to a solution of intermediate 2(1.0g,2.6mmol) and compound C1(0.94g,2.6mmol,1eq) in dichloromethane (20 mL) at 0 ℃; after the addition, stirring at room temperature for 3 hours; adding 20mL of ice water for quenching, extracting an organic phase by using dichloromethane, washing with water to remove impurities, drying the organic phase by using anhydrous sodium sulfate, filtering and concentrating; petroleum ether and dichloromethane are used as eluent, and the crude product is eluted by a silica gel column to obtain light yellow liquid, namely an intermediate 3; intermediate 2 was obtained in 0.5g, yield 28%;

the structure confirmation data is as follows:¹H NMR(400MHz,CDCl₃)δ8.59(s,1H),8.29(s, 1H),7.90-7.88(d,1H),7.44–7.40(m,3H),2.14–1.96(m,4H), 1.25–0.96(m,12H),0.81–0.78(t,6H)。

example 3: synthesis of intermediate 4

Intermediate 3(0.50g,0.73mmol), tributyltin-based thiophene (0.25g,1.8 mmol,2.4eq), Pd under inert atmosphere₂(dba)₃(25mg) and P (o-tol)₃(50mg) was added to 15mL of toluene and stirred at 80 ℃ for 6 hours; cooling to room temperature, removing the solvent, and eluting with petroleum ether and dichloromethane as eluent through a silica gel column to obtain a yellow solid, namely an intermediate 4; intermediate 4 was obtained in 0.45g, yield 90%;

the structure confirmation data is as follows:¹H NMR(400MHz,CDCl₃)δ8.62(s,1H),8.30(s, 1H),7.88-7.86(m,3H),7.58–7.57(m,2H),7.43–7.40(m,3H),7.19 –7.17(m,2H),2.14–1.96(m,4H),1.25–0.96(m,12H),0.81–0.77 (t,6H)。

example 4: synthesis of intermediate M1

N-bromosuccinimide (NBS) (0.52g,2.9mmol,5eq) was added to a 40mL mixed solution of N, N-Dimethylformamide (DMF) and dichloromethane of intermediate 4(0.40g,0.58mmol) under dark conditions; stirring at 40 deg.C overnight; extracting the organic phase with dichloromethane, washing with water to remove impurities, drying the organic phase with anhydrous sodium sulfate, filtering and concentrating; eluting with petroleum ether and dichloromethane as eluent through silica gel column to obtain orange solid intermediate M1; intermediate M2 was obtained at 0.35g, 71% yield;

the structure confirmation data is as follows:¹H NMR(400MHz,CDCl₃)δ8.62(s,1H),8.32(s, 1H),7.89-7.87(m,1H),7.58–7.56(m,2H),7.45–7.40(m,3H),7.14 –7.12(m,2H),2.14–1.99(m,4H),1.25–0.96(m,12H),0.81–0.77 (t,6H)。

example 5: synthesis of Polymer P1

Under an inert atmosphere, compound M1(84.9mg,0.10mmol), compound M2(94.1g,0.10 mmol) and Pd (PPh)₃)₄(1.2mg) was added to a mixed solvent of 4mL of toluene and 1mL of DMF; stirring at 110 ℃ until more viscous, about 45 minutes; the mixture was poured into 30mL of methanol and the filtrate was removed; dissolving the filter residue with 30mL of chloroform, and eluting with chloroform as eluent through a silica gel column to obtain a black solid, namely a polymer P1; polymer P1 was obtained in 82mg, 63% yield. Molecular weight by GPC (1,2,4-trichlorobenzene,150 ℃ C.) with Mw 203.7kDa and PDI 6.17.

Example 6

Physical characterization of conjugated polymer organic solar cell donor material based on multi-element aromatic ring-thiophene diketone unit and manufacturing and performance test of solar cell device

¹The H NMR spectra were measured by a Bruker AV-400 instrument, the UV-Vis absorption spectra by a Shimadzu UV-2700 UV-Vis absorption spectrometer and the cyclic voltammetry measurements by a CHI660E electrochemical workstation.

The conjugated polymer organic solar cell device based on the poly aromatic thienothiophene dione unit adopts a forward structure, and the structure is Glass/ITO/PEDOT, PSS/active layer/PNDIT-F3N/Ag. The material of the photoactive layer is a conjugated polymer donor material and a Y6 non-fullerene acceptor material, and the blending weight ratio of the materials is 1: 1.2.

Example 7

Photophysical, electrochemical and solar cell device performance of polymer P1

The ultraviolet-visible absorption spectrum of the polymer P1 in chloroform solution and film is shown in FIG. 1. The specific details are tabulated in table 1.

TABLE 1 optical absorption data for Polymer P1

The maximum absorption position of the polymer P1 in the solution is 590nm, and the initial absorption position is 682 nm. When the polymer P1 was spin-coated into a film, its maximum absorption and initial absorption were 588nm and 685nm, respectively. The polymer P1 is shown to have an enhanced aggregation state between molecular chains after film formation. From the position of the initial absorption of the polymer film according to the formula

The optical band gap of the obtained polymer P1 was 1.81 eV.

The solar cell device performance data for polymer P1 is summarized in table 2.

The J-V curve of the photovoltaic device with the P1 and Y6 mixed at a ratio of 1:1.2(w/w, 6.1mg/mL) and 0.5% CN added using chloroform as the solvent is shown in FIG. 3. Under this condition, the short-circuit current density of the device was 24.08mA/cm²The open circuit voltage is 0.86V, the filling factor is 72.5 percent, and the energy conversion efficiency is 15.04 percent.

The EQE curve of the active layer with the P1 and Y6 mixed at a ratio of 1:1.2(w/w, 6.1mg/mL), 0.5% CN added and chloroform as solvent is shown in FIG. 3. The EQE test range shown in the figure is 300-1000nm, and the EQE value is more than 70% in the range of about 500-850 nm.

TABLE 2 solar cell device Performance data for Polymer P1

While the scope of the invention has been described in connection with the preferred embodiments, it is not to be restricted by the embodiments but only by the appended claims. In light of the present inventive concept, those skilled in the art will recognize that certain changes may be made in the embodiments of the invention to which the invention pertains without departing from the spirit and scope of the claims.

Claims

1. A polymer comprising a polyvalent aromatic thienothiophenedione, said polymer being a polymer having the formula i:

wherein, R is_1-1And R_1-2Independently selected from oxygen, sulfur, selenium, amino, carbonyl, sulfone, sulfoxide, vinyl and imino,

ar is₂Selected from unsubstituted or substituted fluorenes, carbazoles, dibenzofurans, silafluorenes, benzophosphoindoles, dibenzothiophenes, germanidesFluorene, tin heterofluorene;

n is a natural number between 5 and 1000, preferably between 10 and 100.

2. The polymer of claim 1, further characterized in that R is_2-1、R_2-2、R_3-1、R_3-2Independently selected from hydrogen or C5-C20 alkyl, chlorine, bromine, iodine, C1-C20 sulfuryl, C1-C20 sulfoxide, C2-C20 ester, C1-C20 carbonyl, trifluoromethyl or C2-C20 alkynyl.

3. The polymer of claim 1, further characterized in that the heteroatoms in the monocyclic heteroarylene, bicyclic heteroarylene, and tricyclic heteroarylene are nitrogen, sulfur, or oxygen.

4. The polymer of claim 1 further characterized in that the substituents of said substituted vinylene, substituted ethynylene, substituted monocyclic arylene, substituted bicyclic arylene, substituted tricyclic arylene, substituted monocyclic heteroarylene, substituted bicyclic heteroarylene, and substituted tricyclic heteroarylene are substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C60 arylalkyl, C1-C20 alkyl, C1-C20 alkoxy, ester sulfone, fluoroalkyl, fluoroheterocyclyl, vinylene, ethynylene, monocyclic arylene, bicyclic arylene, tricyclic arylene, monocyclic heteroarylene, bicyclic heteroarylene, or tricyclic heteroarylene.

5. The polymer of claim 1, further characterized by the Ar₁Selected from the following structures:

wherein R is hydrogen, C1-C20 alkyl, C1-C20 alkoxy, C1-C20 alkyl-substituted aryl of C6-C30, Cl-C30 alkyl-substituted arylalkyl of C6-C60, ester group, sulfone group, fluoroalkyl group, fluoro heterocyclic group, ethenylene group, ethynylene group, monocyclic arylene group, bicyclic arylene group, arylene group containing three rings, monocyclic heteroarylene group, bicyclic heteroarylene group or heteroarylene group containing three rings;

x is an oxygen group element, preferably S;

y is a carbon group element.

6. The polymer of claim 1, further characterized by the Ar₂Selected from the following structures:

Z is selected from carbon group, nitrogen group and oxygen group.

7. A semiconducting composition comprising a polymer of formula I as claimed in any one of claims 1 to 6.

8. A photoelectric conversion device, wherein an active layer material in the photoelectric conversion device is the polymer having the formula I according to any one of claims 1 to 6.