KR101821971B1 - Electron accepting polymer of formed random terpolymer, producing method of the same and inverted type polymer solar cells comprising the same - Google Patents

Abstract

The present invention relates to an electron accepting polymer in a form of a random terpolymer, and to a method producing the same and a polymer solar cell comprising the same. The present invention provides an electron accepting polymer including a terpolymer to enhance energy conversion efficiency, and specifically, energy efficiencies of all-PSCs have increased to be a state: P1 : 2.5% < P2 : 2.73% < P3 : 2.87% < P4 : 3.21% < P5 : 3.60%.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron acceptor polymer in the form of a random terpolymer, a method for producing the same, and an inverse type polymer solar cell including the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron acceptor polymer in the form of a random terpolymer, a process for producing the same, and an inverted polymer solar cell comprising the same. The present invention relates to an electron acceptor polymer in the form of a terpolymer, a method for producing the same, and an antiferroelectric polymer solar cell comprising the same.

Organic solar cells have been attracting attention as an alternative energy source for the past decade and have been studied for power conversion efficiency (PCE) of bulk heterojunction (BHJ) solar cells, which consists of electron donor polymers and fullerene derivatives ) Was improved by more than 10%. Although the fullerene derivative has excellent properties as an electron acceptor because of its high electron affinity and high electron mobility, fullerene, which is a widely used phenyl-C61 butyric acid methyl ester, has a high synthesis cost and low It is not an ideal receptor substance because of problems such as light absorption. In addition, due to the crystalline nature of the fullerene, fullerene-based organic solar cells have low flexibility and stretchability.

Recently, all-polymer solar cells (all-PSCs) composed of a blend of conjugated electron donor polymer / electron acceptor polymers have been found to be as diverse as fullerene-based organic solar cells It has a lot of advantages because of its advantages. These various advantages have (1) ease of controlling the energy level of the electron acceptor polymer, (2) simultaneous light absorption of the electron donor polymer and the electron acceptor polymer, and (3) excellent mechanical / thermal properties. In particular, an electron acceptor polymer based on naphthalenediimide (NDI) has a very flat planar structure, excellent electron mobility, and excellent mixing with an electron donor polymer, thereby being able to replace the fullerene. However, n- type electron acceptor polymer may have a very low electron mobility than that of the fullerene, the packing arrangement of the n- type electron acceptor thin film polymer in the short-circuit current (short-circuit current, J _SC) of the all-PSCs And careful control is required to improve the fill factor (FF) value. The use of terpolymers comprising three different monomers in the polymer backbone is an efficient approach to modify the physical / photoelectric properties of donor-acceptor type conjugated polymers. The crystallinity of the conjugated polymer and the packing structure in the thin film can be controlled by the use of a terpolymer, which plays an important role in improving the electron mobility of the electron acceptor polymer and in manufacturing high performance all-PSCs. The introduction of selenophene into the terpolymer significantly improves the intramolecular interactions and the selenophene is preferred to the quinoidal structure rather than the aromatic structure, orbital overlap) can occur, leading to a highly ordered polymer structure. Therefore, the presence of selenophene in the π-conjugated basic skeleton can facilitate the charge transfer between the chains, which can have an advantage in charge mobility. For example, in a tertiary copolymer based on diketopyrrolopyrrole, the composition ratio of thiophene (T) and selenophene (S) changes the crystallinity of the terpolymer, And has optimum conditions between crystallinity and solubility as well as conversion efficiency. Recently, Jenekhe's group (non-patent document 1) reports all-PSCs based on NDI-selenophene, which has an energy conversion efficiency of 7.7%. Although the use of selenophen units in all-PSCs reveals its potential, the effects of binding of selenophen units in the n-type polymer in relation to structural, electrical, and photoelectrochemical properties to date have not been clearly established .

 Jenekhe, S. A. et. Al., Adv. Mater. 27, 4578-4584 (2015)  Hou, J. et. Al., Adv. Mater. 27, 6046-6054 (2015)  Zhan, X. et. Al., Polym. Chem. 6, 5254-5263 (2015)  Seferos, D. S. et. Al., J. Polym. Sci. A Polym. Chem. 52, 3337-3345 (2014)  Jenekhe, S. A. et. Al., Chem. Commun. 50, 10801-10804 (2014)

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide an electron acceptor polymer in the form of a terpolymer, which is formed at a different composition ratio, to provide an electron acceptor polymer in the form of a random terpolymer, And a method of manufacturing the same, and an inverted polymer solar cell including the same.

In order to achieve the above object, there is provided an electron acceptor polymer represented by the following formula (1).

[Chemical Formula 1]

X represents an equivalent of 0, 0.2, 0.5, 0.8, 1.

The present invention provides a method for producing an electron acceptor polymer represented by the following formula (1), comprising the steps of:

(T), 2,5-bis (trimethylstannyl) -selenophene (S) were added to a microwave glass bottle and stirred with a magnetic stirrer to prepare a first mixture (S1);

Pd ₂ (dba) ₃ , P ( o- toluyl) ₃ and anhydrous toluene and N, N-dimethylformamide (DMF) were added to the first mixture, A step (S2) of producing a second mixture by a stille coupling reaction;

Cooling the second mixture at room temperature and precipitating in alcohol (S3);

(S4) extracting and purifying the second mixture precipitated in the alcohol with an organic solvent; And

And drying the purified second mixture in vacuum (S5).

[Chemical Formula 1]

Here, x represents an equivalent of 0, 0.2, 0.5, 0.8, 1.

The present invention relates to a semiconductor device comprising a substrate, a lower electrode formed on the substrate, a ZnO layer formed on the lower electrode, an active layer formed on the ZnO layer and including an electron acceptor polymer represented by Formula 1, ₃ layers, and an upper electrode formed on the MoO ₃ layer.

The electron acceptor polymer in the form of a random terpolymer according to the present invention, the process for producing the same, and the antireflection polymer solar cell comprising the electron acceptor polymer according to the present invention can provide the electron acceptor polymer in the form of a terpolymer, .

1 (a) to 1 (e) show the hydrogen nuclear magnetic resonance spectra ( ¹ H NMR spectra, 300 MHz, 0-dichlorobenzene-d ₄ ) of the terpolymers P1 to P5 having various composition ratios according to an embodiment of the present invention , CDCl _3, 100 ° C).
2 (a) is an ultraviolet-visible light absorption spectrum of ternary copolymers P1 to P5 having various composition ratios diluted in a chloroform solution according to the present invention, and FIG. 2 (b) And ultraviolet-visible light absorption spectra of the terpolymers (P1 to P5).
3 is a graph showing a result of measurement using cyclic voltammograms (CV) on films of various kinds of terpolymers (P1 to P5) according to an embodiment of the present invention.
4 is a graph showing a comparison of energy level diagrams of PTB7 and terpolymers (P1 to P5) having various composition ratios according to an embodiment of the present invention.
FIG. 5 is a GIXD pattern image of pure films of various composition ratios of terpolymers (P1 to P5) according to an embodiment of the present invention. (a) P (NDI2HD-T 100), (b) P (NDI2HD-T 80 S 20), (c) P (NDI2HD-T 50 S 50), (d) P (NDI2HD-T 20 S 80), (e) P (NDI2HD- _S100 )
6 (a) is an in-plane line-cut graph of a 2D GIXD image of pure films of terpolymers (P1 to P5) of various composition ratios according to an embodiment of the present invention, and Fig. 6 (b) 3 is an out-of-plane line-cut graph of a 2D GIXD image of a pure film of terpolymers (P1 to P5) of various composition ratios according to an embodiment.
FIG. 7 (a) is a JV curve graph of BHJ-type all-PSCs based on PTB7 of a terpolymer (P1 to P5) having various composition ratios according to an embodiment of the present invention, FIG. 7 (c) is a graph showing the EQE spectra of BHJ-type all-PSCs based on PTB7 based on terpolymers (P1 to P5) having various composition ratios according to an embodiment of the present invention. Graphs showing the tendency of Jsc and PCE according to the content of selenophene in the terpolymer.
FIG. 8 is an ultraviolet-visible light absorption spectrum of a terpolymer (P1 to P5) film having various composition ratios according to an embodiment of the present invention blended with PTB7 under the conditions of an optimized device.
FIG. 9 is a space-charge-limited JV curve graph of the three-way copolymers P1 to P5 of various composition ratios according to an embodiment of the present invention in the dark room.
10 shows height images of a blend containing PTB7 in terpolymers (P1 to P5) of various composition ratios according to an embodiment of the present invention (scale bar is 1 m). The root mean square roughness of the tri-copolymer (P1 to P5) films of various composition ratios according to an embodiment of the present invention is (a) 0.61 nm (P1), (b) 0.68 nm (P2) c) 0.79 nm (P3), (d) 0.69 nm (P4), and (e) 0.88 nm (P5).

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.

The term " step "or" step of ~ " used throughout the specification does not mean "step for. Throughout this specification, the terms "A and / or B" mean "A or B, or A and B ".

Throughout this specification, the term "combination thereof" included in the expression of the machine form means one or more combinations or combinations selected from the group consisting of the constituents described in the expression of the machine form, And the like.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to inform.

The electron acceptor polymer in the form of a random terpolymer according to the present invention provides an electron acceptor polymer represented by the following formula (1).

[Chemical Formula 1]

X represents an equivalent of 0, 0.2, 0.5, 0.8, 1.

The electron acceptor polymers include electron-deficient NDI 2H units and electron-rich 2,5-bis (trimethylstannyl) -thiophene (T) and 2,5-bis (trimethylstannyl) -selenophene ), And the composition ratio of 2,5-bis (trimethylstannyl) -thiophene (T) and 2,5-bis (trimethylstannyl) -selenophene (S) are differently formed in the basic skeleton of NDI2HD to form P (NDI2HD- _{T 100) (P1), P} (NDI2HD-T 80 -S 20) (P2), P (NDI2HD-T 50 -S 50) (P3), P (NDI2HD-T 20 -S 80) (P4), and P (NDI2HD-S1 ₀₀ ) (P5) electron acceptor polymer.

In addition, as the composition ratio of 2,5-bis (trimethylstannyl) -selenophene (S) increases in the basic skeleton of NDI2HD, the crystallinity of terpolymers improves, and as a result of the improvement of the crystallinity, And charge transfer between molecules is improved.

In addition, the electron acceptor polymer is included in an active layer of an inversion-type polymer solar cell to improve energy conversion efficiency.

The present invention relates to a process for the preparation of a compound of formula

Formula 2 (NDI2HD), Formula 3 (2,5-Bis (trimethylstannyl) -thiophene, T), and general formula 4 (2,5-bis (trimethylstannyl) -selenophene, S) as a starting material by the NDI2HD: T _X: a composition ratio of _1-X S in a microwave vial, and the step (S1) for stirring the mixture to prepare a 1 by the magnetic stirrer, wherein the Pd ₂ (dba) to 1 mixture of _3, P (o -tolyl) _3, and (S2) adding anhydrous toluene and anhydrous N, N-dimethylformamide (DMF) into a microwave reactor and performing a Stille coupling reaction to prepare a second mixture, (S3) of cooling the mixture at room temperature and precipitating the alcohol in the alcohol; and a step (S3) of precipitating the second mixture precipitated in the alcohol, using Soxhlet extraction method, with methanol, hexane, acetone and chloroform Extracting and purifying the purified second mixture (S4) and drying the purified second mixture in a vacuum W provides a method for producing an electron acceptor polymer represented by the general formula (1).

X represents an equivalent of 0, 0.2, 0.5, 0.8, 1.

[Reaction Scheme 1]

As shown in Reaction Scheme 1, the electron acceptor polymer was synthesized by the reaction of 2,5-bis (trimethylstannyl) -thiophene (T) with 2,5-bis (trimethylstannyl) -selenophene depending on the composition ratio of the (S) P (NDI2HD-T 100) (P1), P (NDI2HD-T 80 -S 20) (P2), P (NDI2HD-T 50 -S 50) (P3), P (NDI2HD- T ₂₀ -S ₈₀ ) (P4), and P (NDI2HD- _S100 ) (P5) electron acceptor polymer. The electron acceptor polymer is precipitated in chloroform and then extracted with Soxhlet extraction method using organic solvents such as methanol, hexane, acetone, and chloroform.

The weight-average molecular weight (Mw), the number-average molecular weight (Mn), and the polydispersity index (PDI) of the P1 to P5 electron acceptor polymers were measured using o- Benzene was measured with SEC at 80 DEG C, and the results are summarized in Table 1 below. The weight average molecular weight (Mw) of the P1 to P5 electron acceptor polymers is 112 to 160 kg / mol and the number-average molecular weight (Mn) is 53 to 74 kg / mol. The polydispersity index (PDI) is 2.1 to 2.4.

Polymers Mn
(kg / mol ) ^a Mw
(kg / mol ) ^a PDI
(Mw / Mn) ^a P ( NDI2HD -T ₁₀₀ )
(P1) 54 114 2.10 P ( NDI2HD -T ₈₀ -S ₂₀ )
(P2) 74 154 2.08 P ( NDI2HD -T ₅₀ -S ₅₀ )
(P3) 53 112 2.10 P ( NDI2HD -T ₂₀ -S ₈₀ )
(P4) 69 147 2.13 P ( NDI2HD -S ₁₀₀ )
(P5) 67 160 2.40

a: SEC measured value corrected to polystyrene standard value.

To determine the actual composition ratio between 2,5-bis (trimethylstannyl) -thiophene (T) and 2,5-bis (trimethylstannyl) -selenophene (S) in the electron acceptor polymer, ( ¹ H NMR spectroscopy), and elemental analysis (EA) was summarized in Table 2 below. &Lt; tb &gt;&lt; TABLE &gt; The ratio of the actual T / S in the electron acceptor polymer is confirmed by comparing peaks corresponding to T (7.56 ppm) and S (7.74 ppm) (see FIGS. 1 (a) to (e)). Further, the ratio of T / S from the elemental component analysis in the above-mentioned ternary copolymer of P2 to P4 is confirmed by comparing the ratio of carbon atoms to sulfur atoms. From the NMR and EA analyzes, the ratio of the actual T / S of the electron acceptor polymer of the present invention is summarized in Table 3 below.

Polymers C H N S P ( NDI2HD -T ₁₀₀ )
(P1) Measured 66.84 7.50 1.93 13.41 Calculated 66.92 7.54 2.05 14.10 P ( NDI2HD -T ₈₀ -S ₂₀ )
(P2) Measured 67.11 7.33 1.91 14.71 Calculated 67.52 7.02 1.87 17.17 P ( NDI2HD -T ₅₀ -S ₅₀ )
(P3) Measured 67.93 7.22 1.75 16.46 Calculated 67.52 7.02 1.87 17.17 P ( NDI2HD -T ₂₀ -S ₈₀ )
(P4) Measured 68.12 7.06 1.69 17.56 Calculated 67.52 7.02 1.87 17.17 P ( NDI2HD -S ₁₀₀ )
(P5) Measured 67.58 6.79 1.67 18.96 Calculated 67.85 6.81 1.72 19.69

Polymers Feed ratio
(T: S) Actual ratio
(NMR) Actual ratio
( EA ) P ( NDI2HD -T ₈₀ -S ₂₀ )
(P2) 4: 1 4.05: 1 3.32: 1 P ( NDI2HD -T ₅₀ -S ₅₀ )
(P3) 1: 1 1.03: 1 1: 1.07 P ( NDI2HD -T ₂₀ -S ₈₀ )
(P4) 1: 4 1: 3.83 1: 4.34

material

NDI2HD (4,9-Dibromo-2,7-bis (2-hexyldecyl) benzo [lnn] [3,8] -phenanthroline-1,3,6,8-tetraone, 4,9- 7-bis (2-hexyldecyl) benzo [lmn] [3,8] -phenanthroline-1,3,6,8-tetraone) was purchased from Suzhou, Jiangsu, , 5-Bis (trimethylstannyl) -thiophene and 2,5-bis (trimethylstannyl) -selenophene (2,5-bis (trimethylstannyl) Average molecular weight (Mn) = 14 kg / m &lt; 2 &gt;) was used according to the method described in Non-Patent Document 6 (Kim, BJ et al., Chem. Mater. 26, 6963-6970 mol, weight-average molecular weight (Mw) = 28 kg / mol and polydispersity index (PDI) = 1.94) were purchased from 1 material (Dorval, Quebec, Canada). 1 Materials Inc. Other chemicals were purchased from Sigma-Aldrich and used without further purification.

Analytical instrument

Using CDCl ₃ or o-dichlorobenzene-d ₄ solvent to measure the hydrogen nuclear magnetic resonance spectra ⁽¹ H NMR spectra) the liquid phase The synthesized polymers Mn, Mw, and PDI were analyzed using a Waters 1515 isocratic HPLC pump and temperature control module, and a SEC (Size Exclusion Chromatography) with a Waters 2414 refractive index detector, using a 300 MHz nuclear magnetic resonance spectrometer (Bruker) ) System. The ultraviolet-visible light absorption spectrum was measured with a UV-1800 spectrophotometer (Shimadzu Scientific Instruments) using polystyrene standards (flow rate: 1 mL / min) with o- dichlorobenzene as eluent at 80 deg. (10 ^-6 M) diluted at room temperature and a solid state film. Cyclic voltammetry (CV) was measured using a CHI 600C electrochemical analyzer at 0.1 M Bu ₄ NPF ₆ The platinum disk working electrode, platinum counter electrode, and silver wire pseudo-reference electrode in anhydrous acetonitrile containing tetrabutylammonium hexafluorophosphate (tetrabutylammonium hexafluorophosphate) were measured at a scan rate of 50 mV / s and GIXS was measured at the Pohang Accelerator Laboratory , And the GIXS sample was prepared by spin coating on a silicon substrate, and an X-ray having a wavelength of 1.1179 Å was measured at a wavelength of ~ 0.12 ° Was measured GIXS sample a square, AFM was measured with a Veeco Dimension 3100 instrument in tapping mode.

Polymer synthesis using stille coupling reaction

A random tertiary copolymer polymer having various composition ratios was synthesized by the following polymerization procedure using a stille reaction under microwave irradiation. The detailed copolymerization process is as follows.

2,5-bis (trimethylstannyl) -thiophene and 2,5-bis (trimethylstannyl) -selenophene were weighed and put into a high-frequency glass bottle, followed by stirring with a magnetic stirrer. _{And, Pd 2 (dba) 3 (} (dibenzylideneacetone) dipalladium, ( dibenzylideneacetone the dene) dipalladium), 2 mol% and _{P (o -tolyl) 3 ((} tri (o-tolyl) phosphine, tree (o- tolyl ) 8 mol% is further added, and the mixture is continuously stirred in a sealed state. Anhydrous toluene and anhydrous N, N-dimethylformamide (DMF) are added. The mixture was degassed for 30 minutes using argon gas. The glass bottle was placed in a microwave reactor, stirred at 150 DEG C for 3 hours, and cooled at room temperature to obtain a polymer. ml methanol and 5 ml hydrochloric acid, and the mixture was stirred for 2 hours. After the completion of the stirring, the polymer was subjected to Soxhlet extraction using methanol, hexane, acetone, and chloroform sequentially Extracted and purified. The chloroform Polymers of standing was concentrated under reduced pressure while precipitation in methanol. Finally, the polymer was dried in vacuo for 24 hours.

&Lt; Example 1 > P (NDI2HD-T ₁₀₀ ) Polymerization of (P1)

A P1 polymer was synthesized by the above synthesis method using a mixture of NDI 2HD (1.0 eq.) And 2,5-bis (trimethylstannyl) thiophene (1.0 eq., T) in a mixture of toluene and DMF. Element P1 The results are as follows.

SEC (size exclusion chromatography, chloroform fraction): Mn = 54 k, Mw = 114 k, PDI = 2.10.

Analysis calculated: C, 75.33%; H, 9.10%; N, 3.51%; S, 4.02%.

Actual value: C, 74.68%; H, 8.97%; N, 3.42%; S, 4.00%.

&Lt; Example 2 > P (NDI2HD-T ₈₀ S ₂₀ ) Polymerization of (P2)

A mixture of NDI 2HD (1.0 eq.), 2,5-bis (trimethylstannyl) thiophene (0.8 eq., T) and 2,5-bis (trimethylstannyl) selenophene (0.2 eq., S) in a mixture of toluene and DMF P2 polymer was synthesized by the same synthesis method, and the element composition of the P2 polymer was analyzed as follows.

SEC (size exclusion chromatography, chloroform fraction): Mn = 74 k, Mw = 154 k, PDI = 2.08.

Analysis calculated: C, 74.61%; H, 8.82%; N, 3.48%; S, 3.19%.

Actual value: C, 74.12%; H, 8.85%; N, 3.34%; S, 3.04%.

&Lt; Example 3 > P (NDI2HD-T ₅₀ S ₅₀ ) Polymerization of (P3)

A mixture of NDI 2HD (1.0 eq.), 2,5-bis (trimethylstannyl) thiophene (0.5 eq., T) and 2,5-bis (trimethylstannyl) selenophene (0.5 eq., S) in a mixture of toluene and DMF The P3 polymer was synthesized by the same synthetic method, and the elemental composition of the P3 polymer was analyzed as follows.

SEC (size exclusion chromatography, chloroform fraction): Mn = 53 k, Mw = 112 k, PDI = 2.10.

Analysis calculated: C, 73.27%; H, 8.73%; N, 3.42%; S, 1.96%.

Actual value: C, 73.72%; H, 8.74%; N, 3.38%; S, 1.90%.

&Lt; Example 4 > P (NDI2HD-T ₂₀ S ₈₀ ) Polymerization of (P4)

A mixture of NDI 2HD (1.0 eq.), 2,5-bis (trimethylstannyl) thiophene (0.2 eq., T) and 2,5-bis (trimethylstannyl) selenophene (0.8 eq., S) in a mixture of toluene and DMF The P4 polymer was synthesized by the same synthetic method, and the elemental composition of the P4 polymer was analyzed as follows.

SEC (size exclusion chromatography, chloroform fraction): Mn = 69 k, Mw = 147 k, PDI = 2.13.

Analysis calculated: C, 72.09%; H, 8.52%; N, 3.36%; S, 0.77%.

Actual value: C, 73.04%; H, 8.64%; N, 3.32%; S, 0.73%.

&Lt; Example 5 > P (NDI2HD-S ₁₀₀ ) Polymerization of (P5)

A mixture of NDI 2HD (1.0 eq.) And 2,5-bis (trimethylstannyl) selenophene (1.0 eq., S) in a mixture of toluene and DMF was synthesized by the synthesis method described above. Elemental composition analysis of the P5 polymer The results are as follows.

SEC (size exclusion chromatography, chloroform fraction): Mn = 67 k, Mw = 160 k, PDI = 2.40.

Analysis calculated: C, 71.15%; H, 8.60%; N, 3.32%; S, 0.00%.

Actual value: C, 71.82%; H, 8.52%; N, 3.30%; S, 0.00%.

< Example  6> Fabrication of Inverted Type All-Polymer Solar Cells and Measurements

The present invention relates to a semiconductor device comprising a substrate, a lower electrode formed on the substrate, a ZnO layer formed on the lower electrode, an active layer formed on the ZnO layer and including an electron acceptor polymer represented by Formula 1, ₃ layers, and an upper electrode formed on the MoO ₃ layer. As an example of the above antireflection polymer solar cell, an ITO / ZnO / active layer / MoO ₃ / Ag structure antireflection polymer solar cell was manufactured and the solar cell efficiency was tested.

The glass substrate on which the ITO was formed was washed with acetone, water and isopropyl alcohol through ultrasonic treatment, and the washed substrate was placed in an oven and dried at 80 ° C for 20 minutes. ITO formed on the glass substrate was a ZnO layer Lt; RTI ID = 0.0 &gt; UV-ozone &lt; / RTI &gt;

ZnO solution was prepared using a sol-gel process, and 1 g of zinc acetate dihydrate (Zn (O2CCH3) 2 (H2O) 2, 99.9%) and 0.28 g of ethanolamine (HOCH2CH2NH2, 99.5% Ethoxyethanol (CH3OCH2CH2OH > 99.8%) for 24 hours or longer and dissolved. The ZnO solution was spin-coated on the ITO at a rate of 3,000 rpm for 40 seconds to form a ZnO layer. The ZnO layer was heated at 200 ° C in an air atmosphere for 10 minutes, and the device formed up to the ZnO layer was maintained in a nitrogen atmosphere To the glove box.

The electron acceptor polymers of P1 to P5 prepared in Examples 1 to 5 for forming the active layer were prepared by using a chloroform solvent and 1, 8-diiodooctane (DIO) A blend was made with an electron donor polymer. The PTB7 is a poly [[4,8-bis [(2-ethylhexyl) oxy] benzo [1,2-b: 4,5-b '] dithiophene-2,6- (2-ethylhexyl) carbonyl] thieno [3,4-b] thiophenediyl]] (poly [[4,8- ] Thiophene-2.6-diyl] [3-fluoro-2 - [(2-ethylhexyl) carbonyl] thiophene [3,4-b] thiophendiyl]]). PTB7: The optimized donor (D): acceptor (A) ratio of P1 to P5 is 1.3: 1 w / w, and the electron acceptor polymers of P1 to P5 and the donor of PTB7 electron donor The total concentration (D + A) was equal to 12 mg / mL (containing 1 volume% DIO additive). The blending solution was stirred on a hot plate at 45 ° C for 1 hour before spin coating on ITO / ZnO substrate, and then spin-coated on ITO / ZnO substrate at 3,000 rpm for 40 seconds. The substrate formed up to the active layer was placed in a deposition chamber, and MoO ₃ of thickness 10 nm and Ag of 120 nm were sequentially thermally deposited under high vacuum (less than 10 ^-6 Torr) for one hour or more. The active layer was formed with an area of 0.09 cm ² as measured by an optical microscope. The current density-voltage (JV) of the ITO / ZnO / active layer / MoO ₃ / Ag structure antireflective polymer solar cell was measured under the atmospheric condition under the imitation AM 1.5G light (100 mWcm ^-2 , Peccell: PEC-L01) Respectively. The imitation solar system meets the Class AAB and the intensity of the imitation sun is corrected by using a standard silicon reference cell with a KG-5 visible light color filter. The current density-voltage characteristics were recorded using a Keithley 2400 SMU instrument.

< Experimental Example  1> Optical and electrochemical properties

As shown in FIG. 2, in the diluted chloroform solution and thin foil, the optical properties of the terpolymers (P1 to P5) having various composition ratios according to one embodiment of the present invention are shown. In the solid state thin film, the terpolymers (P1 to P5) show similar absorption spectra in the region of 300 to 700 nm. As shown in Table 1, the maximum absorption peak (? _Max ) was red-shifted as the composition ratio of selenophene increased (P1? P5). However, the peak of the electron oscillation due to the pre-aggregation of the polymer in the solution state started to appear from the terpolymer P3, and the intensity of the peak of the electron oscillation was significantly increased in the terpolymers P4 and P5. This confirms that the binding of the selenophene unit improves the intramolecular assembly of the ternary copolymer. In addition, the optical energy bandgap (E _g ^opt ) based on the start of light absorption for the terpolymers P1 to P5 was measured to be 1.84, 1.83, 1.79, 1.77, and 1.73 eV, respectively. 3, the lowest energy Unoccupied Molecular Orbital (LUMO) energy level of the terpolymers P1 to P5 is a ferrocene / ferrocenium (Fc / Fc ⁺ ) redox pair (CV) using a redox couple (4.80 eV lower than the vacuum level) as an external standard and the highest level occupied molecular orbital of the terpolymers P1 to P5 Occupied Molecular Orbital (HOMO) energy level was calculated by adding or subtracting the value of the optical energy band gap (E _g ^opt ) from the LUMO energy level determined by the CV (see Table 4). The LUMO energy levels of the terpolymers P1 to P5 were close to about 3.8 eV, but the HOMO energy levels of the terpolymers P1 to P5 gradually increased as the composition ratio of selenophene was increased (see FIG. 4 ).

HOMO energy levels: - 5.68 eV (P1) <-5.63 eV (P2) <- 5.61 eV (P3) <- 5.53 eV (P4) <- 5.51 eV (P5).

Polymers lambda max
Film (nm) ^a HOMO
(eV) ^b LUMO
(eV) ^c E _g ^opt
(eV) ^d P ( NDI2HD -T ₁₀₀ )
(P1) 343,599 - 5.68 - 3.84 1.84 P ( NDI2HD -T ₈₀ -S ₂₀ )
(P2) 346,607 - 5.63 - 3.80 1.83 P ( NDI2HD -T ₅₀ -S ₅₀ )
(P3) 349,609 - 5.61 - 3.82 1.79 P ( NDI2HD -T ₂₀ -S ₈₀ )
(P4) 355,620 - 5.53 - 3.76 1.77 P ( NDI2HD -S ₁₀₀ )
(P5) 357,627 - 5.51 - 3.78 1.73

a: ultraviolet-visible light absorption spectrum measurement

b: the HOMO energy level is calculated by adding or subtracting the value of the optical energy band gap (E _g ^opt ) from the LUMO energy level determined by CV

c: The LUMO energy level is measured by a cyclic voltammetry (CV)

d: The optical energy band gap (E _g ^opt ) is calculated based on the start of light absorption for the terpolymers P1 to P5

< Experimental Example  2> Structural properties of pristine films

As shown in FIG. 5, the pure films of the terpolymers P1 to P5 having various composition ratios according to an embodiment of the present invention show the effect of the selenophene unit and the microstructure thereof in the crystalline behavior by GIXS X-ray scattering). In addition, the pure films of the terpolymers (P1 to P5) having various composition ratios according to an embodiment of the present invention were spin-coated with a chloroform solution and measured under the same conditions without any additional treatment process. FIG. 6 is a graph illustrating the in-plane, q _xy and out-of-plane, q-plane images of the pure film of the three-way copolymers P1 to P5 of various composition ratios according to an embodiment of the present invention. _z ) shows the line cut. As shown in the following Table 5, the terpolymers (P1 to P5) show reflection peaks from (100) crystal planes in a plane direction having lamellar spacings (d ¹⁰⁰ ) of 2.21 to 2.24 nm. Further, in the basic skeleton of the NDI2HD polymer, reflection peaks from (001) crystal planes caused by repeating NDI units are observed in the terpolymers (P1 to P5). The reflection peak from the (010) crystal face corresponding to? -Π stacking in the out-of-plane direction decreases from 0.415 nm (P1) to 0.405 nm (P5) as the composition ratio of selenophene increases. The decrease in the reflection peak from the (010) crystal face is due to the fact that the orbital overlap of the electron orbital function occurs well in the intramolecular chain. The π-π stacking is very pronounced in the out-of-plane direction, which plays an important role in efficient charge exchange between the electrodes of all-PSCs. In addition, the increase in the composition ratio of the selenophenes is such that (200) reflection peak and (300) reflection peak start appearing as higher-order reflection peaks in the in-plane direction and out-plane direction, . The correlation lengths of lamellar (L _C ) of the terpolymers (P1 to P5) in the pure film were calculated from the full width at half maximum (FWHM) of the scattering peak using the Scherrer equation See Table 2). The value of L _C ¹⁰⁰ of the terpolymer (P1 ~ P5) is gradually increased to 9.63 nm (P1) <9.86 nm (P2) <13.14 nm (P3) <13.77 nm (P4), and 15.39 nm (P5) , Confirming that a high content of selenophene can be produced with a more advanced crystal structure. In addition, the preferred quinone form from the selenophenes can inhibit chain rotation in the basic framework of the NDI2HD polymer and can control high molecular interactions.

Thus, the P5 can be remarkably observed in the represented values (h00) and (00l) reflection peak and the large correlation length (correlation lengths, L _C). The correlation length of the π-π stacking in the terpolymers (P1 to P5) is 1.52 nm (P1) <1.55 nm (P2) <1.59 nm (P3) <1.61 nm (P4) Respectively.

Polymers d ¹⁰⁰  (nm) ^a L _c ¹⁰⁰  (nm) ^b d ⁰¹⁰  (nm) ^c L _c ⁰¹⁰  (nm) ^d P ( NDI2HD -T ₁₀₀ )
(P1) 2.24 9.63 0.415 1.52 P ( NDI2HD -T ₈₀ -S ₂₀ )
(P2) 2.23 9.86 0.411 1.55 P ( NDI2HD -T ₅₀ -S ₅₀ )
(P3) 2.22 13.14 0.408 1.59 P ( NDI2HD -T ₂₀ -S ₈₀ )
(P4) 2.12 13.77 0.405 1.61 P ( NDI2HD -S ₁₀₀ )
(P5) 2.22 15.39 0.405 1.66

a: domain of the lamella space

b: Lamellar correlation length

c: Ternary copolymers (P1 to P5) calculated from in-plane and out-plane 2D GIXS The pi-pi stacking values of pure films

d: ternary copolymers (P1 to P5) calculated using the Scherrer equation. π-π stacking crystals of pure films

< Experimental Example  3> Photovoltaic and Electrical Properties Photovoltaic  and electrical properties)

In order to understand the correlation between the structural characteristics of the terpolymer and the performance of a solar cell (photovoltaic cell), the present invention provides an all-terpolymer based on terpolymers (P1 to P5) having various composition ratios according to an embodiment of the present invention, PSCs devices were fabricated. The solar cell element is formed of an inverted structure of ITO / ZnO / active layer / MoO ₃ / Ag, and the active layer includes a terpolymer (P1 to P5) as an electron acceptor polymer and PTB7 as an electron donor polymer. The optimum donor / acceptor blend ratio in the active layer is 1.3 (donor): 1 (acceptor) w / w and 1% by volume of 1,8-diiodooctane (DIO) And the thickness of the active layer is about 100 nm. 7 (a) shows a JV curve graph of BHJ (bulk heterojunction) all-PSCs based on PTB7 based on terpolymers (P1 to P5) of various composition ratios according to an embodiment of the present invention Table 6 summarizes the characteristics of the solar cell of the present invention. The all-PSCs device based on the terpolymers P1 to P5 having various composition ratios according to the embodiment of the present invention has an open circuit voltage V (V) because the LUMO energy levels of the terpolymers P1 to P5 are similar, _OC ) values were measured to be 0.79 V similarly. However, the energy conversion efficiency (PCE) of the all-PSCs increased to P1 (2.50%) <P2 (2.73%) <P3 (2.87%) <P4 (3.21%) <P5 (3.60%). The dramatic improvement of the PCE is that the short circuit current density J _sc is 6.64 mA cm ^-2 (P1) <7.02 mA cm ^-2 (P2) <7.41 mA cm ^-2 (FIG. ⁷ P3) < 7.88 (P4) < 8.99 mA cm ^-2 (P5). As shown in FIG. 7 (b) and Table 7, the all-PSCs based on the ternary copolymers P1 to P5 having various composition ratios according to an embodiment of the present invention exhibit external quantum efficiency external quantum efficiencies (EQEs) were measured. The value of the short circuit current density (J _sc ) for all-PSCs was constant as shown in the EQE spectrum. As the composition ratio of selenophene of the terpolymer increased, the EQE value was improved in the range of 500 to 700 nm. For example, the EQE value is improved by 35% in the 620 nm region (P1: 36.7%? P5: 49.4%). The increase in the EQE value is due to a change in electrical properties such as charge exchange and transition in the active layer rather than light absorption. As shown in FIG. 8, the difference in ultraviolet-visible light spectra of the all-PSCs based on the ternary copolymers P1 to P5 having various composition ratios according to an embodiment of the present invention It is because there is not.

In order to understand the tendency of the PCE and J _sc , an electron only space-charge-limited current (SCLC) device was fabricated with a pure terpolymer (see FIG. 9). The electron-only space-charge-limited current (SCLC) device consists of ITO / ZnO / pure terpolymer (P1 to P5) / LiF / Al. As the composition ratio of selenophene increases, the electron mobility (μ _e ) in the SCLC device becomes 7.79 × 10 ^-6 cm ² V ^-1 s ^-1 (P1) <8.85 × 10 ^-6 cm ² V ^-1 s ^{-1 P2) <1.91 × 10 -5 cm} 2 V -1 s -1 (P3) <1.99 × 10 -5 cm 2 V was increased to ^-1 s ^-1 (P4), P5 is the highest value of the electron mobility (μ ^{_{e = 1.91 × 10 -5 cm 2}} V -1 s - 1) had. The increased electric mobility is attributed to the intermolecular attractive force of selenium (Se) atoms and the improvement in stiffness (inhibition of chain rotation) in the basic skeleton of NDI2HD polymer confirmed by GIXS measurement. In addition, the increased electron mobility has a PCE improvement in the all-PSCs device based on the ternary copolymers P1 to P5 of various composition ratios according to an embodiment of the present invention, J _{sc of} PSCs It is one of the important reasons to improve the value.

Polymers ^a PCE
( % ) ^b V _OC
(V) J _SC
(mA cm ^-2 ) FF μ _e
( cm2 V - 1 s - One) ^c P1 2.50 (2.39) 0.792 6.64 0.48 7.79 X 10 ^-6 P2 2.73 (2.63) 0.794 7.02 0.49 8.85 X 10 ^-6 P3 2.87 (2.75) 0.785 7.41 0.49 1.91 X 10 ^-5 P4 3.21 (3.07) 0.793 7.88 0.51 1.99 X 10 ^-5 P5 3.60 (3.52) 0.791 8.99 0.51 2.21 X 10 ^-5

FF: fill factor, PCE: power conversion efficiency, SCLC: space-charge-limited current,

a: The blend ratio is 1.3 (donor): 1 (acceptor) w / w, and the blend contains 1 vol% of 1,8-diiodooctane (DIO) as an additive. Polymer solar cells are formed with an inverted structure of ITO / ZnO / active layer / MoO ₃ / Ag.

b: The values in parentheses indicate the average value of PCE measured by manufacturing six or more solar cells including P1 ~ P5 polymer

c: The electron mobility is measured by the SCLC method with a film of pure terpolymer

Polymers ^a PCE
( % ) ^b V _OC
(V) J _SC
(mA cm ^-2 ) FF Cal J _SC ^b
(mA cm ^-2 ) P1 2.39 ± 0.08 0.781 ± 0.008 6.36 ± 0.13 0.48 ± 0.01 6.36 P2 2.63 ± 0.08 0.785 ± 0.005 6.89 ± 0.16 0.49 ± 0.01 6.75 P3 2.75 + 0.08 0.783 ± 0.002 7.27 ± 0.08 0.48 ± 0.01 7.08 P4 3.07 ± 0.09 0.782 ± 0.006 7.99 ± 0.19 0.49 ± 0.01 7.58 P5 3.52 + - 0.10 0.789 ± 0.004 8.86 ± 0.17 0.50 0.02 8.58

a: The blend ratio is 1.3 (donor): 1 (acceptor) w / w, and the blend contains 1 vol% of 1,8-diiodooctane (DIO) as an additive. Polymer solar cells are formed with an inverted structure of ITO / ZnO / active layer / MoO ₃ / Ag. The values in the table are the average values of PCE measured by manufacturing six or more solar cells including P1 ~ P5 polymer

b: Jsc value calculated by EQE measurement

Experimental Example 4 Measurement of Blend Morphology by AFM

The effect of the selenophene composition ratio on the active layer blend was analyzed by atomic force microscopy (AFM). Since the exciton diffusion length to the semiconductor polymer is within a few nanometers, the polymer blend in the active layer must phase-separate between the donor and the acceptor of the polymer on a scale of several tens of nanometers. As shown in FIG. 10, the blend film containing PTB7 in the terpolymers (P1 to P5) having various composition ratios according to an embodiment of the present invention has a root mean square roughness in the range of 0.61 to 0.88 nm I have. In addition, the microstructure which has a multi-continuous and homogeneously phase separated with a scale of several tens of nanometers was observed in all the blend films containing PTB7 in the terpolymers (P1 to P5), which leads to efficient charge separation. Also, while maintaining a well mixed phase, the AFM image shows that the composition ratio of the various selenophenes in the terpolymer affects the shape of the fine fibers in the blend. In particular, P5 films show very fine structure of fine fibers, which is confirmed by GIXS results. Therefore, the P5 film having the highest composition ratio of selenophenes can produce all-PSCs having a high PCE value due to high electron mobility through a well-developed microfiber structure. In addition, the polymer-patting structure and arrangement at the polymer donor / acceptor interface is influenced by the binding of selenophene in the basic skeleton of PNDI2HD, which makes an important contribution to photovoltaic performance. Therefore, the present invention can explain the packing structure and arrangement of the terpolymer at the interface between the polymer donor and the acceptor.

A new series of P (NDI2HD-T-S) terpolymers (P1-P5) with different T / S composition ratios have been successfully synthesized. The crystallinity of the terpolymer was systematically adjusted according to the T / S composition ratio. The ternary copolymer according to one embodiment of the present invention has improved optical, electrochemical, electrical and photoelectric properties depending on the T / S composition ratio. The introduction of a high content of selenophene resulted in a strong crystallinity (large LC value and a more developed microfiber structure) of the terpolymer, which markedly enhanced electron mobility. Also, when the high content of selenophenes is combined, the energy conversion efficiency is remarkably increased from 2.50% (P1) to 3.60% (P5).

Therefore, the present invention is very important for the ternary copolymer approach to control the intramolecular assembly of polymers, and the ternary copolymers promoted electron mobility. In addition, the present invention can provide guidelines for the production of n-type polymeric receptors for high performance all-PSC.

The present invention has been described with reference to the preferred embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

Claims (7)

delete delete 1. A method for producing an electron acceptor polymer represented by the following formula (1), comprising the steps of:
(T), 2,5-bis (trimethylstannyl) -selenophene (S) were added to a microwave glass bottle and stirred with a magnetic stirrer to prepare a first mixture (S1);
Pd ₂ (dba) ₃ , P ( o- toluyl) ₃ and anhydrous toluene and N, N-dimethylformamide (DMF) were added to the first mixture, A step (S2) of producing a second mixture by a stille coupling reaction;
Cooling the second mixture at room temperature and precipitating in alcohol (S3);
(S4) extracting and purifying the second mixture precipitated in the alcohol with an organic solvent; And
And drying the purified second mixture in vacuum (S5).
[Chemical Formula 1]

Here, x represents an equivalent of 0, 0.2, 0.5, 0.8, 1.
The method of claim 3,
Wherein the electron acceptor polymer forms? -Π stacking.
delete delete delete

Images