TWI826020B - Copolymers, active layers and organic photovoltaic components - Google Patents

Abstract

A copolymer as an electron acceptor material, an active layer and an organic photovoltaic element containing the copolymer. The copolymer has a wide absorption wavelength distribution and high absorptivity in the ultraviolet-visible light region. Therefore, the copolymer can be used as an electron acceptor material to increase photocurrent density, making the copolymer electron acceptor material have excellent photoelectric conversion properties. .

Description

Copolymers, active layers and organic photovoltaic components

The present invention relates to a copolymer that can be used as an electron acceptor material, an active layer and an organic photovoltaic element containing the copolymer. In particular, it relates to a random copolymer and an active layer containing the random copolymer. layers and organic photovoltaic components.

With the evolution of the times, the consumption of energy resources such as coal, oil, natural gas and nuclear energy is increasing day by day, and the energy crisis has also emerged. Therefore, solar power generation has been developed. Solar power generation is a renewable and environmentally friendly power generation method that can reduce environmental pollution. The first generation of solar cells is mainly based on silicon crystal (silicon based) solar cells, which have high photoelectric conversion rates. The second-generation solar cell is a thin-film cadmium telluride (CdTe) solar cell, but the toxicity of its raw materials and the production process cause great pollution to the environment. As a result, the third generation of organic solar cells was born, including dye-sensitized solar cells (DSSC), nanocrystalline cells or organic photovoltaic elements (OPV). Compared with inorganic materials that require vacuum process coating, organic photovoltaic components can be made using dip coating, spin coating, slit coating, screen printing, inkjet printing, etc. It is easier to achieve low-cost and mass production economic benefits. Among them, the new generation of organic photovoltaic devices uses electron acceptor materials and electron donor materials (polymers) as active layer (light absorption layer) materials during production. The new generation of organic photovoltaic components has several advantages: (1) light weight and low production cost; (2) flexible; (3) device structure highly designable; (4) suitable for liquid phase processes and can Large area wet coating.

Although organic photovoltaic components have many advantages, most of the current developments in electron acceptor materials are based on fullerene derivatives (such as PC ₆₀ BM and PC ₇₀ BM). However, the fullerene derivatives themselves have the following shortcomings : Easy to dimerize under light, easy to crystallize when heated, weak absorption in visible light region, difficult to modify and purify structure, expensive, etc. Therefore, in recent years, various circles have actively developed non-fullerene electron acceptor materials in order to achieve higher performance. As far as is currently known, compared to non-fullerene electron acceptor materials in the form of organic small molecules, polymer-type electron acceptor materials usually have good mechanical properties, film-forming properties and thermal stability. Therefore, the development of using polymer-type electron acceptor materials as the active layer of organic photovoltaic elements to improve the power conversion efficiency (PCE) of organic photovoltaic elements has become a key research direction of scientists in recent times. For example, Chinese patent publication numbers CN113174032A (Document 1) and CN113024780A (Document 2).

When making the active layer of an organic photovoltaic element, it is also necessary to consider the type of solvent that can dissolve the polymer-type electron acceptor material, its solubility, and its stability after standing. Whether precipitation will occur, and the impact of the formed active layer solution on film-forming properties and PCE when forming the active layer, etc. However, Document 1 does not discuss the above issues, and does not disclose the type of solvent used in the active layer. In addition, based on environmental protection issues, non-chlorine (refers to chlorine-free) solvents are the first choice when choosing solvents. Moreover, even if non-chlorine solvents are used, the solubility and whether the active layer solution will survive after standing should be taken into consideration. Precipitates are produced, especially active layer solutions without precipitates are preferred. Although Document 2 mentions that non-chlorine solvents such as toluene can be used as the active layer solvent, in the embodiment, chloroform containing chlorine is still used as the solvent, and the highest PCE is only 12.6%. In fact, when the solvent of the active layer in Document 2 is changed to a non-chlorine solvent such as xylene, the experimental results can be found that the active layer solution has precipitates of polymeric electron acceptor materials attached to the wall of the container (this (Comparative examples will be discussed later and illustrated with pictures). Therefore, when the solvent of the active layer is changed to a non-chlorine solvent such as xylene, the precipitates will cause poor film formation or form defects when forming the active layer. This brings the PCE below 12.6%.

One of the factors that led to the discussion of the above-mentioned problem in Document 2 is that the polymer-type electron acceptor material in Document 2 is a homopolymer. Since the homopolymer has good crystallinity, its solubility will be low, which causes When dissolving homopolymers, it is necessary to use non-environmentally friendly chlorine-containing solvents such as chloroform to achieve higher solubility. When using non-chlorine solvents such as xylene, although it is claimed that it can dissolve homopolymers, the above-mentioned precipitation It is easy for objects to appear, thus making the film formation of the active layer poor or forming defects.

Therefore, it is necessary to develop a polymer structure that can be dissolved using relatively environmentally friendly chlorine-free solvents (such as toluene, xylene) as active layer materials, so that the active layer solution will not produce precipitates, and fullerene derivatives. Active layers with good electron transport properties and organic photovoltaic components with high PCE, such as higher than 16%, have become current research targets.

In view of the problems of existing organic photovoltaic elements, the present invention provides a copolymer that can be used as an electron acceptor material, which can be used as an active layer of an organic photovoltaic element in combination with an electron donor material. In particular, the present invention provides a random copolymer, which is composed of at least two repeating units arranged in a random manner in the main chain of the random copolymer. The two repeating units are different from each other, so the crystallinity is reduced so that This random copolymer can be dissolved using relatively environmentally friendly chlorine-free solvents (such as toluene, xylene). In addition, the active layer also has good electron transport properties of fullerene derivatives. Unexpectedly, the copolymer of the present invention has a wide absorption wavelength distribution and high absorbance in the ultraviolet-visible light region, so it can improve the absorption in the visible light region and increase the photocurrent density, thereby enabling the organic photovoltaic element to have excellent photoelectric conversion characteristics. And has good power conversion efficiency (PCE).

Therefore, the first object of the present invention is to provide a copolymer. Unless specifically indicated as a random copolymer, the copolymers referred to in the present invention should be understood as random copolymers. Either a random copolymer or a block copolymer. Preferably, the copolymer referred to in the present invention is a random copolymer.

其中，

係為第一重複單元結構；

係為第二重複單元結構； 該第一重複單元結構與該第二重複單元結構係不相同；a與b皆為莫耳分率的實數，且0<a<1，0<b<1，並a與b的和為1；π¹及π²係各自獨立地為芳香環基或雜芳香環基，π¹及π²彼此間可為相同或不相同；SMA²係為稠環(FUSED RING)結構的基團或非稠環(NON FUSED RING)結構的基團； SMA¹為

； C¹與C²係各自獨立地為

、

、

、

、

或

C¹與C²彼此間可為相同或不相同； X為O、S、Se、-NR⁵-或

；R¹與R²係各自獨立地為C₁~C₃₀烷基、C₁~C₃₀烷氧基、C₁~C₃₀烷基芳基或C₁~C₃₀烷基雜芳基，R¹與R²彼此間可為相同或不相同；R³與R⁴係各自獨立地為未經取代或經R⁰取代的C₁~C₃₀烷基、C₁~C₃₀烷氧基、C₁~C₃₀烷基芳基、C₁~C₃₀烷基雜芳基、C₁~C₃₀烷氧基芳基或C₁~C₃₀烷氧基雜芳基，R³與R⁴彼此間可為相同或不相同；R⁰為C₁~C₃₀烷氧基、C₁~C₃₀烷基芳基、C₁~C₃₀烷基雜芳基、C₁~C₃₀烷氧基芳基或C₁~C₃₀烷氧基雜芳基；R⁵為C₁~C₃₀烷基或C₁~C₃₀烷氧基；R⁶與R⁷係各自獨立地為H、F、Cl、R⁸、-CN、-OR⁹、-SR¹⁰、-C(=O)OR¹¹、芳基或雜芳基，R⁶與R⁷彼此間可為相同或不相同；R⁸至R¹¹分別為未經取代或經至少一R¹²取代的C₄~C₃₀直鏈、支鏈或環狀烷基、未經取代或經至少一R¹²取代的C₄~C₃₀烯基、或未經取代或經至少一R¹²取代的C₄~C₃₀炔基，R¹²為鹵素或-CN； EG為

、

、

、

或

； Z¹至Z³係各自獨立地為H、F、Cl、Br、R⁸、-CN、-OR⁹、-SR¹⁰-或C(=O)OR¹¹，Z¹至Z³彼此間可為相同或不相同。 Therefore, the copolymer of the present invention includes the structure represented by the following chemical formula (I):

in,

The system is the first repeating unit structure;

is a second repeating unit structure; the first repeating unit structure and the second repeating unit structure are different; a and b are both real numbers of mole fraction, and 0<a<1, 0<b<1, And the sum of a and b is 1; π ¹ and π ² are each independently an aromatic ring group or a heteroaromatic ring group, and π ¹ and π ² can be the same or different from each other; SMA ² is a fused ring (FUSED RING) structure group or non-fused ring (NON FUSED RING) structure group; SMA ¹ is

; C ¹ and C ² systems are independently

,

,

,

,

or

C ¹ and C ² may be the same or different from each other; X is O, S, Se, -NR ⁵ - or

; R ¹ and R ² are each independently a C ₁ ~ C ₃₀ alkyl group, a C ₁ ~ C ₃₀ alkoxy group, a C ₁ ~ C ₃₀ alkyl aryl group or a C ₁ ~ C ₃₀ alkyl heteroaryl group, R ¹ and R ² may be the same or different from each other; R ³ and R ⁴ are each independently an unsubstituted or R ⁰ substituted C ₁ ~ C ₃₀ alkyl group, C ₁ ~ C ₃₀ alkoxy group, C ₁ ~ C ₃₀ alkylaryl, C ₁ ~ C ₃₀ alkyl heteroaryl, C ₁ ~ C ₃₀ alkoxy aryl or C ₁ ~ C ₃₀ alkoxy heteroaryl, R ³ and R ⁴ are mutually exclusive They can be the same or different; R ⁰ is C ₁ ~ C ₃₀ alkoxy group, C ₁ ~ C ₃₀ alkylaryl group, C ₁ ~ C ₃₀ alkyl heteroaryl group, C ₁ ~ C ₃₀ alkoxy aryl group Or C ₁ ~ C ₃₀ alkoxy heteroaryl; R ⁵ is C ₁ ~ C ₃₀ alkyl or C ₁ ~ C ₃₀ alkoxy; R ⁶ and R ⁷ are each independently H, F, Cl, R ⁸ , -CN, -OR ⁹ , -SR ¹⁰ , -C(=O)OR ¹¹ , aryl or heteroaryl, R ⁶ and R ⁷ may be the same or different from each other; R ⁸ to R ¹¹ are respectively C ₄ ~ C ³⁰ linear, branched or cyclic alkyl that is unsubstituted or substituted with at least one R 12, C ₄ ~ C ₃₀ alkenyl _that is unsubstituted or substituted with at least one R ¹² , or unsubstituted Or C ₄ ~ C ₃₀ alkynyl substituted by at least one R ¹² , R ¹² is halogen or -CN; EG is

,

,

,

or

; Z ¹ to Z ³ are each independently H, F, Cl, Br, R ⁸ , -CN, -OR ⁹ , -SR ¹⁰ - or C(=O)OR ¹¹ , Z ¹ to Z ³ can be mutually exclusive be the same or different.

In particular, the "alkylaryl", "alkylheteroaryl", "alkoxyaryl" and "alkoxyheteroaryl" mentioned in the present invention refer to "alkyl "Substituted aryl", "alkyl-substituted heteroaryl", "alkoxy-substituted aryl", "alkoxy-substituted heteroaryl". In addition, the preceding carbon number refers to the carbon number of the alkyl group, for example, C ₁ ~ C ₃₀ alkylaryl refers to an aryl group substituted by C ₁ ~ C ₃₀ alkyl, C ₁ ~ C ₃₀ alkyl heteroaryl The base refers to the heteroaryl group substituted by C ₁ ~ C ₃₀ alkyl group, the C ₁ ~ C ₃₀ alkoxy aryl group refers to the aryl group substituted by C ₁ ~ C ₃₀ alkoxy group, C ₁ ~ C ₃₀ Alkoxyheteroaryl refers to a heteroaryl group substituted by a C ₁ to C ₃₀ alkoxy group. The aforementioned "small molecule group" refers to "the residue (Residue) of a compound that is not a polymer or an oligomer". In addition, in the present invention, "Z ¹ to Z ³ " refers to "Z ¹ , Z ² and Z ³ ", and the "R ⁸ to R ¹¹ " refers to "R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ ", and the rest are analogized without going into details. Moreover, it can be known from the structure of the above-mentioned EG group that the EG group is an electron-withdrawing group.

Preferably, SMA ² is a group of this fused ring structure.

Preferably, the group of the fused ring structure is a five-membered fused ring derivative group, a seven-membered fused ring derivative group or a nine-membered fused ring derivative group.

，該七元稠環衍生物基團為

或

，該九元稠環衍生物基團為

，U為NQ²³、C(Q²⁴)₂或 Si(Q²⁵)₂，Q¹至Q²²係各自獨立地為H、C₁~C₃₀烷基、C₁~C₃₀烷氧基、C₁~C₃₀烷基芳基或C₁~C₃₀烷基雜芳基，Q²³至Q²⁵係各自獨立 地為H、C₁~C₃₀烷基或C₁~C₃₀烷氧基；Q¹至Q⁶彼此間可為相同或不相同、Q⁷至Q¹²彼此間可為相同或不相同、Q¹³至Q¹⁶彼此間可為相同或不相同、及/或Q¹⁷至Q²²彼此間可為相同或不相同。 Preferably, the five-membered fused ring derivative group is

, the seven-membered fused ring derivative group is

or

, the nine-membered fused ring derivative group is

, U is NQ ²³ , C(Q ²⁴ ) ₂ or Si(Q ²⁵ ) ₂ , Q ¹ to Q ²² are each independently H, C ₁ to C ₃₀ alkyl, C ₁ to C ₃₀ alkoxy, C ₁ ~ C ₃₀ alkylaryl or C ₁ ~ C ₃₀ alkyl heteroaryl, Q ²³ to Q ²⁵ are each independently H, C ₁ ~ C ₃₀ alkyl or C ₁ ~ C ₃₀ alkoxy; Q ¹ to Q ⁶ can be the same or different from each other, Q ⁷ to Q ¹² can be the same or different from each other, Q ¹³ to Q ¹⁶ can be the same or different from each other, and/or Q ¹⁷ to Q ²² can be the same as or different from each other. can be the same or different.

或

，R¹³為2-乙基己基(2-ethylhexyl)，R¹⁴ 為2-己基癸基(2-hexyldecyl)。 Preferably, the group of the non-fused ring structure is

or

, R ¹³ is 2-ethylhexyl, and R ¹⁴ is 2-hexyldecyl.

Specifically, based on the above examples of the group of the condensed ring structure and the group of the non-condensed ring structure, the group of the condensed ring structure refers to the group connecting its left and right ends in the structure of SMA ² Multiple carbocyclic rings and/or multiple heterocyclic rings on the main chain of each electron-withdrawing group (EG group) are connected by shared ring edges, that is, the main chain of SMA ² is all fused ring phase. A connected fully fused ring structure; in contrast, the non-fused ring structure refers to the presence of at least one single bond on the main chain of the other electron-withdrawing group (EG group) connecting its left and ^right ends in the structure of SMA 2 Multiple other carbocyclic rings and/or multiple other heterocyclic rings are connected, that is, the main chain of SMA ² is a non-fully fused ring structure in which not all are connected by fused rings.

、

、

、

、

或

，V為S、O或Se，R¹⁷至R¹⁸定義與前述R⁶定義 相同且R¹⁷與R¹⁸彼此間可為相同或不相同，n為0~12之整數。 Preferably, π ¹ and π ² are each independently

,

,

,

,

or

, V is S, O or Se, R ¹⁷ to R ¹⁸ have the same definition as the aforementioned R ⁶ and R ¹⁷ and R ¹⁸ may be the same or different from each other, n is an integer from 0 to 12.

Therefore, the second object of the present invention is to provide an active layer containing the aforementioned copolymer.

Preferably, the active layer includes an electron donor material and an electron acceptor material, and the electron acceptor material includes the aforementioned copolymer.

Preferably, the electron acceptor material further includes a fullerene derivative, that is, the electron acceptor material includes the copolymer and the fullerene derivative, and the fullerene derivative is PC ₆₀ BM or PC ₇₀ BM. .

Therefore, the third object of the present invention is to provide an organic photovoltaic element including the aforementioned copolymer and/or the active layer.

Preferably, the organic photovoltaic element includes a substrate, a first electrode laminated on the substrate, an electron transport layer laminated on the first electrode, a laminated There is an active layer above the electron transport layer, a hole transport layer laminated above the active layer, and a second electrode laminated above the hole transport layer, and the active layer includes the copolymer.

Preferably, the organic photovoltaic element includes a substrate, a first electrode laminated on the substrate, a hole transport layer laminated on the first electrode, an active layer laminated on the hole transport layer, An electron transport layer is laminated on the active layer, and a second electrode is laminated on the electron transport layer, and the active layer includes the copolymer.

The effect of the present invention is: because the copolymer of the present invention as an electron acceptor material contains a strong electron-pulling group [SMA ¹ ] and another strong electron-pulling group [SMA ² ] in the main chain, through different The chemical structure is used to increase the absorption wavelength distribution in the ultraviolet-visible light region, and the energy level and solubility are adjusted through the conjugated group [π]. Especially when the copolymer is a random copolymer and/or SMA ² is a polyvalent fused ring derivative group, the crystallinity and/or polarity of the copolymer are reduced, so it can be used with relatively environmentally friendly chlorine-free solvents (such as toluene, dibenzoic acid). toluene) dissolved. Appropriate addition of the copolymer of the present invention to the active layer can improve the energy level matching between the electron donor material and the electron acceptor material. Therefore, when the copolymer of the present invention is used as an electron acceptor material, the wide absorption wavelength in the ultraviolet-visible light region and the high absorbance are used to increase the photocurrent density, thereby improving the energy conversion efficiency of the organic photovoltaic element.

70:Substrate

80: first electrode

90: Organic semiconductor layer

91:Electron transport layer

92:Active layer

93: Hole transport layer

100:Second electrode

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, wherein: Figure 1 is a spectrum chart illustrating the ultraviolet-visible light of copolymers 1 to 3 and polymers 1 to 2 in solution. Absorption spectrum; Figure 2 is a spectrum chart illustrating the UV-visible light absorption spectrum of copolymers 1~3 and polymers 1~2 formed into films in the solid state; Figure 3 is the solubility of polymers 1~2 and copolymers in xylene Photographic diagram; Figure 4 is a cross-sectional schematic diagram illustrating the first structure of the organic photovoltaic element of the present invention; Figure 5 is a cross-sectional schematic diagram illustrating the second structure of the organic photovoltaic element of the present invention; and Figure 6 is a graph respectively. The voltage-current density of the organic photovoltaic elements of Comparative Examples 1 to 3 and Application Examples 1 to 3 will be described.

<Preparation of copolymers 1~3>.

Preparation Example 1: Preparation of copolymer 1.

Preparation of compound 3:

First add compound 1 (5g, 6.7mmol) to dimethylformamide (DMF, 40mL), then add potassium carbonate (5.5g, 40mmol) and compound 2 (11g, 27mmol), heat to 80°C, and react 3 hours. Then, lower the temperature and add heptane and water for extraction. The organic layer is first dried over anhydrous magnesium sulfate and concentrated to remove the solvent. Finally, after solid precipitation with heptane and isopropyl alcohol, a brown solid compound 3 (5.8 g, yield: 67%) was obtained.

Preparation of compound 4:

First, dissolve compound 3 (5.5g, 4.2mmol) in 1,2-dichloroethane (55mL) and add anhydrous dimethylformamide (19mL, 252mmol). Under an ice bath, slowly drop in chloroform. Phosphorus (12mL, 126mmol). Then, the temperature was raised to reflux and stirred for 2 hours. After the reaction is completed, dichloromethane is added for extraction. The organic layer is dried over anhydrous magnesium sulfate, filtered, and concentrated to dryness with a gyroconcentrator. Finally, after purification by silica gel column chromatography (methylene chloride: n-heptane = 2:1 as eluant) and vacuum drying, an orange liquid compound 4 (3.8 g, yield: 67%) was obtained.

Preparation of compound 6:

First, compound 4 (3.8g, 0.28mmol) and compound 5 (2.1g, 8.5mmol) were added to chloroform (38mL), then pyridine (0.3mL) was slowly added dropwise, and the reaction was carried out under nitrogen protection for 3 hours. After the reaction is completed, cool and concentrate to dryness with a rotary concentrator. Then, the solid was first precipitated with methanol, and then purified by silica gel column chromatography (chloroform as the eluent) and dried under vacuum to obtain a dark purple solid as compound 6 (4.9 g, yield: 93%).

Preparation of compound 8:

First, compound 7 (1.5g, 1.56mmol) and compound 5 (1.27g, 4.67mmol) were added to chloroform (15mL), then pyridine (py, 0.1mL) was slowly added dropwise, and the reaction was carried out under nitrogen protection for 3 hours. After the reaction is completed, cool and concentrate to dryness with a rotary concentrator. Then, the solid was first precipitated with methanol, and then purified by silica gel column chromatography (chloroform was used as the eluant) and dried under vacuum to obtain a dark purple solid, which was compound 8 (2.1 g, yield: 90%).

Preparation of copolymer 1:

Compound 6 (186mmol), compound 8 (79.7mmol), compound 13 (265mmol), tris(2-furyl)phosphine [(o-toly) ₃ P] (42.5mmol), tris(dibenzylidene) were mixed under nitrogen. Acetone) dipalladium [Pd ₂ (dba) ₃ ] (10.6 mmol) was put into a 50 mL reaction bottle. Next, 12 mL of anhydrous chlorobenzene (PhCl) was added, and the mixture was stirred at 130° C. for 3 hours. After cooling the reaction to room temperature, the contents of the reaction bottle were poured into methanol to precipitate a solid. The precipitate was collected by filtration, and the solid was subjected to Soxhlet extraction with methanol, acetone and chloroform in sequence. Finally, the chloroform residual liquid was poured into methanol to precipitate again, and the precipitate was collected by filtration and dried under vacuum to obtain copolymer 1.

Preparation Example 2: Preparation of copolymer 2.

Preparation of compound 10:

First, compound 9 (2g, 1.85mmol) and compound 5 (1.51g, 5.56mmol) were added to chloroform (20mL), then pyridine (0.2mL) was slowly added dropwise, and the reaction was carried out under nitrogen protection for 3 hours. After the reaction is completed, cool and concentrate to dryness with a rotary concentrator. Then, the solid was first precipitated with methanol, and then purified by silica gel column chromatography (chloroform as the eluent) and dried under vacuum to obtain a dark purple solid as compound 8 (2.6 g, yield: 88%).

Preparation of copolymer 2:

Compound 6 (1.86mmol), compound 10 (79.7mmol), compound 13 (265mmol), tris(2-furyl)phosphine [(o-toly) ₃ P] (42.5mmol), tris(diethylene) were added under nitrogen. Benzyl acetone) dipalladium [Pd ₂ (dba) ₃ ] (10.6 mmol) was put into a 50 mL reaction bottle. Next, 21 mL of anhydrous chlorobenzene (PhCl) was added, and the mixture was stirred at 130° C. for 3 hours. After cooling the reaction to room temperature, the contents of the reaction bottle were poured into methanol to precipitate a solid. The precipitate was collected by filtration, and the solid was subjected to Soxhlet extraction with methanol, acetone and chloroform in sequence. Finally, the chloroform residue was poured into methanol to precipitate again, and the precipitate was collected by filtration and dried under vacuum to obtain copolymer 2 .

Preparation Example 3: Preparation of copolymer 3.

Preparation of compound 12:

First, compound 11 (2g, 1.36mmol) and compound 5 (1.12g, 4.1mmol) were added to chloroform (20mL), then pyridine (0.2mL) was slowly added dropwise, and the reaction was carried out under nitrogen protection for 3 hours. After the reaction is completed, cool and concentrate to dryness with a rotary concentrator. Then, the solid was first precipitated with methanol, and then purified by silica gel column chromatography (chloroform as the eluant) and dried under vacuum to obtain a dark purple solid as compound 12 (2.4 g, yield: 90%).

Preparation of copolymer 3:

Compound 6 (1.86mmol), compound 12 (79.7mmol), compound 13 (265mmol), tris(2-furyl)phosphine [(o-toly) ₃ P] (42.5mmol), tris(diethylene) were added under nitrogen. Benzyl acetone) dipalladium [Pd ₂ (dba) ₃ ] (10.6 mmol) was put into a 50 mL reaction bottle. Next, 21 mL of anhydrous chlorobenzene (PhCl) was added, and the mixture was stirred at 130° C. for 3 hours. After cooling the reaction to room temperature, the contents of the reaction bottle were poured into methanol to precipitate a solid. The precipitate was collected by filtration, and the solid was subjected to Soxhlet extraction with methanol, acetone and chloroform in sequence. Finally, the chloroform residue was poured into methanol to precipitate again, and the precipitate was collected by filtration and dried under vacuum to obtain copolymer 3 .

<Polymers 1 and 2 used in the comparative examples described below are provided>.

Polymer 1 contains repeating units as shown below and Polymer 1 is a homopolymer:

Polymer 2 contains repeating units as shown below and Polymer 2 is a homopolymer:

<Ultraviolet-visible (UV-Vis) absorption spectrum>.

First of all, Figure 1 is the UV-visible light absorption spectrum measured by an instrument after dissolving copolymers 1~3 and polymer 1~2 in chloroform; Figure 2 is respectively the UV-visible light absorption spectrum of copolymers 1~3 and polymer. After dissolving substances 1~2 in chloroform, coating them on a transparent glass slide and drying to form a solid film, the ultraviolet-visible light absorption spectrum was measured by the instrument.

Referring to the spectra of Figures 1 and 2, copolymers 1~3 have a broad absorption wavelength distribution in the ultraviolet-visible region; and, compared to polymers 1~2, copolymers 1~3 have 3 has high absorption in the ultraviolet-visible light region, so the aforementioned copolymer can be used as an electron acceptor material with a wide absorption wavelength distribution.

<Solubility in chlorine-free solvents>.

Figure 3 shows how 10 mg of polymers 1~2 and copolymer 3 were placed in glass containers, 1 ml of chlorine-free solvent xylene was added, heated to 100°C, stirred for 3 hours, and finally returned to room temperature. result. Obviously, the left and middle glass containers containing polymers 1 and 2 respectively have sediments, indicating that polymers 1 and 2 are insoluble in xylene or have low solubility; in contrast, the right glass container containing copolymer 3 does not. The precipitate shows that copolymer 3 is soluble in xylene with high solubility.

<Structure of Organic Optoelectronic Devices>

The organic optoelectronic components of the present invention include, but are not limited to, organic light-emitting diodes, organic thin film transistors, organic photovoltaic components (OPV) and organic photodetectors. , OPD), the present invention takes organic photovoltaic elements (OPV) as an example.

Figure 4 is a cross-sectional view of the first structure of the organic photovoltaic element used in the present invention. The organic photovoltaic element includes a substrate 70, a first electrode 80 stacked on the substrate 70, an organic semiconductor layer 90 stacked on the first electrode 80, and a second electrode stacked on the organic semiconductor layer 90. 100. The organic semiconductor layer 90 includes an electron transport layer 91 stacked above the first electrode 80 , an active layer 92 stacked above the electron transport layer 91 , and a hole transport layer stacked above the active layer 92 93. Therefore, the second electrode 100 is stacked on the hole transport layer 93 .

Figure 5 is a cross-sectional view of the second structure of the organic photovoltaic element used in the present invention. The organic photovoltaic element includes a substrate 70, a first electrode 80 stacked on the substrate 70, an organic semiconductor layer 90 stacked on the first electrode 80, and a second electrode stacked on the organic semiconductor layer 90. 100. The organic semiconductor layer 90 includes a hole transport layer 93 stacked above the first electrode 80 , an active layer 92 stacked above the hole transport layer 93 , and an electron transport layer 92 stacked above the active layer 92 . Layer 91. Therefore, the second electrode 100 is stacked on the electron transport layer 91 .

For convenience of explanation and understanding, the following is an implementation using the structure of the organic photovoltaic element in FIG. 4 as an application example.

<Comparative Examples 1 to 3 and Application Examples 1 to 3>.

Preparation of organic photovoltaic elements (OPV).

The organic photovoltaics of Comparative Examples 1 to 3 and Application Examples 1 to 3 were prepared based on the active layer materials (electron donor materials and electron acceptor materials) of the organic photovoltaic elements listed in Table 1 below, and the following methods for preparing organic photovoltaic elements. element.

The electron donor material used in Comparative Examples 1 to 3 and Application Examples 1 to 3 is polymer 4, which contains repeating units as shown below. Polymer 4 is a homopolymer:

(PC₆₀BM)。 The electron acceptor materials used in Comparative Examples 1 to 3 and Application Examples 1 to 3 include Compound 14 and Compound 15:

(PC ₆₀ BM).

The following is a method for preparing organic photovoltaic elements.

Before preparing organic photovoltaic components, the patterned ITO glass substrate (12Ω/□) was cleaned sequentially in an ultrasonic vibration tank using detergent, deionized water, acetone, and isopropyl alcohol for 10 minutes. After the ITO glass substrate is cleaned by ultrasonic vibration, the surface is treated in a UV-ozone cleaning machine for 30 minutes. Among them, the glass substrate is the aforementioned substrate 70, and the ITO is the aforementioned first electrode 80, which is also the anode in the structure of Figure 3.

The zinc acetate [Zn(OAc) ₂ ] solution is spin-coated on the ITO glass substrate, and baked at 170° C. for 30 minutes to form a ZnO layer (zinc oxide layer), which is the aforementioned electron transport layer 91 .

Polymer 4 listed in Comparative Example 1 in Table 1 was used as an electron donor material, and was combined with a non-fullerene electron acceptor material (Compound 14), a fullerene electron acceptor material (fullerene-derived compound 15) in a weight ratio of 1:1.2:0.2, and then use o-xylene as the solvent to prepare an active layer solution. Compared with Comparative Example 1, Comparative Examples 2 and 3 added polymers 1 and 2 respectively. The weight ratio of polymer 4: compound 14: compound 15: polymer 1 or polymer 2 is 1:1.2:0.2:0.1 .

According to the application examples 1 to 3 in Table 1, copolymer 4 is used as an electron donor material, and is combined with a non-fullerene electron acceptor material (compound 14), copolymer 1 or 2 or 3, and fullerene After the electron acceptor material of ene (compound 15) was mixed in a weight ratio of 1:1.1:0.1:0.2, o-xylene was used as the solvent to prepare an active layer solution.

Next, the active layer solution is spin-coated on the aforementioned ZnO layer (electron transport layer 91), and baked under nitrogen at 120°C for 10 minutes to form the aforementioned active layer on the ZnO layer (electron transport layer 91). 92. Then, it is sent into a vacuum chamber, and molybdenum trioxide (MoO ₃ ) metal oxide (about 10 nm) is heated and deposited to form the aforementioned hole transport layer 93 on the active layer 92 . Then, Ag metal (about 100 nm) is heated and deposited as the aforementioned second electrode 100, which is also the cathode in the structure of FIG. 4.

<Electrical Analysis of Organic Photovoltaic Elements>

The measurement area of the organic photovoltaic element is defined as 0.04cm ² through the metal mask. Keithley 2400 is used as the power supply, controlled by the Lab-View program, and the electrical properties of the components are measured under the illumination of AM1.5G simulated sunlight (SAN-EI XES-40S3) with an illumination of 100mW/ ^cm2 , and recorded with a computer program. , the voltage-current curves obtained by the organic photovoltaic elements of Comparative Examples 1 to 3 and Application Examples 1 to 3 are shown in Figure 6 respectively.

<Analysis of energy conversion efficiency (PCE) of organic photovoltaic components>

In Table 2, Voc represents open voltage, Jsc represents short-circuit current, FF represents fill factor, and PCE represents energy conversion efficiency. The open circuit voltage and short circuit current are the intercepts of the voltage-current density curve on the X-axis and Y-axis respectively. When these two values increase, the efficiency of the organic photovoltaic element is better improved. In addition, the fill factor is the area that can be plotted within the curve divided by the product of the short-circuit current and the open-circuit voltage. When the three values of open circuit voltage, short circuit current and fill factor are divided by the irradiated light, the energy conversion efficiency can be obtained, and the higher value of the energy conversion efficiency is better. From the results in Table 2, it can be found that the energy conversion efficiency PCE of Comparative Example 1 is 15.7%, the PCE of Comparative Examples 2 and 3 is only 10.6% and 10.7% respectively, and the organic photovoltaic cells of Application Examples 1 to 3 all exceed 16%. Energy conversion efficiency. Therefore, adding the copolymer of the present invention to the electron acceptor material can amplify the visible light absorption distribution and increase the absorbance of the active layer, thereby increasing the photocurrent density. At the same time, it can effectively adjust the energy level and achieve a slight voltage gain. In addition, in Application Examples 1 to 3, the energy conversion efficiency of the organic photovoltaic element prepared by adding Copolymer 1 and Copolymer 3 to the electron acceptor material is PCE=16.4%, which is the optimal value.

Therefore, it can be seen from the above results that the copolymer of the present invention has wider visible light absorption characteristics and high absorption. Therefore, the copolymer of the present invention can be appropriately added to the active layer formula to increase the photocurrent density, and at the same time improve the copolymer donor material, Matching of energy levels between non-fullerene electron acceptor materials and fullerene electron acceptor materials. The slight gain in voltage and increase in current density effectively improve the power conversion efficiency (PCE) of organic photovoltaic cells.

However, the above are only examples of the present invention, and should not be used to limit the scope of the present invention. All simple equivalent changes and modifications made based on the patent scope of the present invention and the content of the patent specification are still within the scope of the present invention. Within the scope covered by the patent of this invention.

Claims (12)

A copolymer containing repeating units represented by the following chemical formula (I):

in,

The system is the first repeating unit structure;

is a second repeating unit structure; the first repeating unit structure and the second repeating unit structure are different; a and b are both real numbers of mole fraction, and 0<a<1, 0<b<1, And the sum of a and b is 1; π ¹ and π ² are each independently a heteroaromatic ring group; SMA ² is a group with a condensed ring structure, and the group with the condensed ring structure refers to the structure of SMA ² Multiple carbocyclic rings and/or multiple heterocyclic rings on the main chain connecting the electron-withdrawing groups at each of its left and right ends are connected by shared ring edges; SMA ¹ is

; C ¹ and C ² are independently

,

or

X is S; R ¹ and R ² are each independently a C ₁ ~ C ₃₀ alkyl group, a C ₁ ~ C ₃₀ alkoxy group, an aryl group substituted by a C ₁ ~ C ₃₀ alkyl group, or a C ₁ ~ C ₃₀ alkyl group. Alkyl-substituted heteroaryl; R ³ and R ⁴ are each independently unsubstituted or R ⁰ substituted C ₁ ~ C ₃₀ alkyl, C ₁ ~ C ₃₀ alkoxy, C ₁ ~ C ₃₀ Alkyl-substituted aryl, C ₁ to C ₃₀ alkyl-substituted heteroaryl, C ₁ to C ₃₀ alkoxy-substituted aryl or C ₁ to C ₃₀ alkoxy-substituted heteroaryl; R ⁰ is a C ₁ ~ C ₃₀ alkoxy group, an aryl group substituted by a C ₁ ~ C ₃₀ alkyl group, a heteroaryl group substituted by a C ₁ ~ C ₃₀ alkyl group, or a C ₁ ~ C ₃₀ alkoxy group substituted Aryl or heteroaryl substituted by C ₁ ~ C ₃₀ alkoxy; EG is

,

,

,

or

; Z ¹ to Z ³ are each independently H, F, Cl, Br, R ⁸ , -CN, -OR ⁹ , -SR ¹⁰ - or C(=O)OR ¹¹ ; R ⁸ to R ¹¹ are not respectively C ₄ ~ C ³⁰ linear, branched or cyclic alkyl group substituted or _substituted with at least one R 12, C ₄ ~ C ₃₀ alkenyl group unsubstituted or substituted with at least one R ¹² , or unsubstituted or C ₄ ~ C ₃₀ alkynyl group substituted by at least one R ¹² , R ¹² is halogen or -CN. The copolymer according to claim 1, wherein SMA ² is a group with a fused ring structure. The copolymer according to claim 2, wherein the group of the fused ring structure is a five-membered fused ring derivative group, a seven-membered fused ring derivative group or a nine-membered fused ring derivative group. The copolymer according to claim 3, wherein the five-membered fused ring derivative group is

, the seven-membered fused ring derivative group is

or

, the nine-membered fused ring derivative group is

, U is NQ ²³ , C(Q ²⁴ ) ₂ or Si(Q ²⁵ ) ₂ , Q ¹ to Q ²² are each independently H, C ₁ ~ C ₃₀ alkyl, C ₁ ~ C ₃₀ alkoxy, Aryl group substituted by C ₁ ~ C ₃₀ alkyl group or heteroaryl group substituted by C ₁ ~ C ₃₀ alkyl group, Q ²³ to Q ²⁵ are each independently H, C ₁ ~ C ₃₀ alkyl group or C ₁ ~ C ₃₀ alkoxy group. The copolymer according to claim 1, wherein π ¹ and π ² are each independently

,

,

,

,

or

, V is S, O or Se, the definitions of R ¹⁷ to R ¹⁸ are the same as the definition of R ⁶ mentioned above, and n is an integer from 0 to 12. An active layer includes the copolymer described in claim 1. The active layer of claim 6, wherein the active layer includes an electron donor material and an electron acceptor material, and the electron acceptor material includes the copolymer. The active layer as claimed in claim 7, wherein the electron acceptor material further contains a fullerene derivative. The active layer of claim 8, wherein the electron acceptor material further includes a fullerene derivative, and the fullerene derivative is PC ₆₀ BM or PC ₇₀ BM. An organic photovoltaic element comprising the copolymer described in claim 1. The organic photovoltaic element according to claim 10, wherein the organic photovoltaic element includes a substrate, a first electrode laminated on the substrate, an electron transport layer laminated on the first electrode, an electron transport layer laminated on the electron There is an active layer above the transport layer, a hole transport layer laminated above the active layer, and a second electrode laminated above the hole transport layer, and the active layer includes the copolymer. The organic photovoltaic element according to claim 10, wherein the organic photovoltaic element includes a substrate, a first electrode laminated on the substrate, a hole transport layer laminated on the first electrode, and a hole transport layer laminated on the first electrode. There is an active layer above the hole transport layer, an electron transport layer laminated above the active layer, and a second electrode laminated above the electron transport layer, and the active layer includes the copolymer.