KR101400902B1 - Organic solar cell and manufacturing method of the same - Google Patents

Abstract

The present invention relates to an organic solar cell and a manufacturing method of the same, and more specifically, to: a solar cell which includes a quantum dot in which organic ligand with thiophene is substituted, an electron donor, and an electron carrier in a photoactive layer of an organic solar cell; and a manufacturing method of the same. The present invention provides the organic solar cell which comprises: a first electrode including a substrate, and a transparent conductive layer located on the substrate; a hole injection layer located on the first electrode; the photoactive layer located on the hole injection layer, and including the electron donor, the electron carrier, and the quantum dot wherein the surface is processed with the organic ligand denoted by chemical formula 1; and a second electrode located on the photoactive layer.

Description

[0001] The present invention relates to an organic solar cell and a manufacturing method thereof,

More particularly, the present invention relates to an organic solar cell including a quantum dot having an organic ligand substituted with thiophene in a photoactive layer of an organic solar cell, an electron donor and an electron acceptor, And a manufacturing method thereof.

Unlike other energy sources, solar cells, which are photoelectric conversion devices that convert sunlight into electrical energy, are infinite and environmentally friendly, and their importance is increasing with time. Conventionally, silicon monocrystalline or polycrystalline silicon solar cells have been widely used. However, since silicon solar cells have a high manufacturing cost and can not be applied to flexible substrates, recently, researches on polymer solar cells Is progressing actively.

That is, since the polymer solar cell can be manufactured by spin coating, inkjet printing, roll coating or doctor blade method, the manufacturing process is simple and the manufacturing cost is low, and it is possible to coat a large area and form a thin film at a low temperature And almost all kinds of substrates such as a glass substrate and a plastic substrate can be used.

In addition, various types of solar cells, such as curved surfaces and spherical surfaces, can be fabricated without restriction of substrate type, and they can be bent or folded, which is convenient to carry. Such advantage is convenient to be attached to a person's clothes, a bag, or attached to a portable electric or electronic product. The polymer blend film has high transparency to light, so it can be applied to a glass window of a building or a glass window of an automobile, so that the blend film can generate power while allowing the outside to be seen. Thus, the application range can be much higher than that of an opaque silicon solar cell.

However, despite these merits, polymer solar cells are not suitable for practical applications because of their low power conversion efficiency and low life span. In other words, the power conversion efficiency of polymer solar cells remained at about 1% by the end of the 1990s, but the performance started to improve greatly due to the improvement of the morphology of the polymer blend structure in the 2000s.

Generally, a polymer solar cell includes a thin film layer including a conjugated polymer or a conductive polymer and an electron acceptor having a semiconductor property between a first electrode and a second electrode.

Typical polymers used in these polymer solar cells are conductive polymers such as polythiophene or poly (p-phenylene vinylene) derivatives, and these conductive polymers act as electron donors. However, in general, the exciton binding energy of the conductive polymer is in the range of 0.1 to 1.0 eV, so that the heat energy at room temperature (for example, (About 0.025 eV), the probability of separation into free electrons and holes is low. Therefore, a solar cell using a thin film made of a conductive polymer membrane has a power conversion efficiency of 0.1% or less.

Therefore, a dual thin film of a conductive polymer and an electron acceptor may be used as a method for enhancing low free electron generation efficiency of a single thin film of a conductive polymer. However, in the polymer semiconductor, the diffusion distance of the excitons is very short, about 3 to 10 nm. Therefore, in the double-layer thin film layer of the conductive polymer-electron acceptor, only the thickness of the thin film layer (generally about 100 nm) Free charge is generated only in a narrow range of the charge generation efficiency.

Therefore, in order to increase the heterojunction interface of the conductive polymer-electron acceptor, a polymer solar cell including a blend layer in which a conductive polymer and an electron acceptor are mixed has been actively studied. In this case, the hetero-junction interface of the conductive polymer-electron acceptor is distributed throughout the thin film, so free charge generation occurs effectively throughout the thin film.

Organic solar cells with such a bulk heterojunction structure are energy sources capable of large-scale and high-efficiency operation at low cost. Polymer solar cells including a conductive polymer and an electron acceptor have been actively studied for increasing the heterojunction interface of the conductive polymer-electron acceptor. In this case, the hetero-junction interface of the conductive polymer-electron acceptor is distributed throughout the thin film, so free charge generation occurs effectively throughout the thin film.

The most commonly studied structure is a blend of P3HT and PCBM with poly (3-hexylthiophene) (P3HT) as an electron donor and PCBM ([6,6] -phenyl-C ₆₁ butyric acid methyl ester) Is used as the photoactive layer. However, due to the limited light absorption band of P3HT and PCBM (PH3T> 1.9 eV), the efficiency range was limited.

Recently, research on adding semiconductor nanoparticles (quantum dots) having a wide light absorption range such as CdSe, PbS and CuInS ₂ has been started to improve the properties of the photoactive layer. The quantum dots have a wide absorption spectrum, can adjust the absorption band by adjusting the size, and are advantageous in terms of light stability and charge mobility. However, in most cases, P3HT-based organic solar cells with quantum dots exhibit low photoelectric conversion efficiency. It is considered that this is because the quantum dots added to the organic solar cell are not uniformly distributed, and they act to interfere with charge transfer and extraction while aggregating in the polymer photoactive layer. The cause of such coagulation is attributed to the quantum dot dispersion characteristics in the organic polymer photoactive layer depending on the organic ligands surrounding the quantum dots.

In Non-Patent Document 1, when the surface of CdSe nanoparticles is treated with hexanoic acid, agglomeration occurs between the particles, and when the solar cell is mixed with P3HT, the efficiency is only about 2% There was a problem.

Non-Patent Document 2 shows that even when CdSe is mixed with a mixed layer of PFT (poly (9,9-n-dihexyl-2,7-fluorenyleneevinylene-alt-2,5-thienylenevinylene) And there was a problem indicating that CdSe is agglomerated severely.

Accordingly, the inventors of the present invention have been studying a method of dispersing quantum dots in a polymer photoactive layer in consideration of the problems that the quantum dots of the conventional methods are not uniformly dispersed in the polymer photoactive layer and cohere, And the dispersibility of the quantum dots is improved by substituting the organic ligands with the organic ligands.

Improved efficiency of hybrid solar cells based on non-ligand-exchanged CdSE quantum dots and poly (3-hexylthiophene), Applied Physics Letters, 96, pp 013304, Y.zhou et al The effects of CdSe incorporation into bulk heterojunction solar cells, Journal of Materials Chemistry, vol. 20, pp. 4845 (2010), J.N. De Freitas et al

An object of the present invention is to provide an organic solar cell having improved photoelectric energy conversion efficiency by introducing a quantum dot surface-treated with a new organic ligand into an organic solar cell.

Still another object of the present invention is to provide a method for manufacturing an organic solar cell comprising a quantum dot having a surface substituted with an organic ligand containing thiophene, a photoactive layer of a solar cell by mixing P3HT and PCBM, .

A first electrode including a transparent conductive layer disposed on the substrate; a hole injection layer disposed on the first electrode; and an electron donor, an electron acceptor, and a hole injection layer disposed on the hole injection layer, And a second electrode located on the photoactive layer, wherein the photoactive layer comprises a quantum dot surface-treated with an organic ligand represented by the following formula

(Wherein R ¹ , R ² , R ³ And R ⁴ is one member independently selected from _{-SH, -NH 2, -COOH, H} , straight or branched chain alkyl, and the group consisting of C ₁ -AR ⁵ _-6, wherein, A is C _{1 -} a straight or branched alkylene of _6, R ⁵ is -SH, and -NH ₂ or -COOH, wherein R ^1, R ^2, R ³ And R ⁴ Is one or more of one type of compound selected from the group consisting of -SH, -NH _2, -COOH, and -AR ^5.).

The present invention also provides a method of manufacturing a semiconductor device, comprising the steps of: (1) forming a hole injection layer on a substrate on which a transparent conductive layer is formed; (Step 2) of forming a photoactive layer by applying a precursor solution for preparing a photoactive layer containing an electron donor, an electron acceptor and a quantum dot surface-treated with an organic ligand represented by the following formula 1 onto the hole injection layer and drying the solution; And forming a second electrode on the photoactive layer (step 3).

According to the organic solar cell of the present invention, an organic ligand including thiophene is added to a photoactive layer of a solar cell made of P3HT and PCBM and dispersed evenly to provide a quantum dot-containing solar cell improved in efficiency of the solar cell up to 3.4% .

Further, according to the method of manufacturing an organic solar cell according to the present invention, aggregation phenomenon between quantum dots, which is a conventional problem, is suppressed and quantum dots doped with thiophene are uniformly dispersed in the solution of the photoactive layer, The short-circuit current value can be increased linearly.

1 (a) and 1 (b) are transmission electron microscope (TEM) images showing the shape of quantum dots substituted with 2-thiophenecarboxylic acid.
Figure 2 is a graph showing the absorption spectra of quantum dots surface-substituted with various organic ligands.
FIGS. 3 (a) to 3 (d) are TEM images showing quantum dots surface-substituted with various organic ligands distributed in the photoactive layer.
4 is a graph showing the photocurrent density-voltage (JV) curves of organic solar cells according to the quantum dot solution addition amounts according to Examples 1 to 5 and Comparative Example 1 of the present invention.
FIG. 5 is a graph showing a photocurrent density-voltage (JV) curve of an organic solar cell when the addition amount of the quantum dot solution in which oleic acid is substituted according to Comparative Example 2 is 0.1 ml.
FIG. 6 is a graph showing the photocurrent density-voltage (JV) curve of an organic solar cell when the amount of the pyridine substituted quantum dot solution added is 0.1 ml according to Comparative Example 3. FIG.

The present invention provides an organic electroluminescent display device comprising a substrate, a first electrode disposed on the substrate and including a transparent conductive layer, a hole injection layer disposed on the first electrode, and an electron donor, an electron acceptor, And a second electrode disposed on the photoactive layer, wherein the photoactive layer comprises a quantum dot surface-treated with an organic ligand,

&Quot; Formula 1 "

(Wherein R ¹ , R ² , R ³ And R ⁴ are each independently selected from _{-SH, -NH 2, -COOH, H} , and one member selected from straight-chain or branched alkyl group consisting of C ₁ -AR ⁵ _-6, wherein, A is C _1- a straight or branched alkylene of _6, R ⁵ is -SH, and -NH ₂ or -COOH, wherein R ^1, R ^2, one or more of the R ³ and R ⁴ is -SH, -NH _2, -COOH and - AR < ⁵ >).

In the organic solar cell according to the present invention, the substrate is not particularly limited as long as it has transparency, and may be a transparent inorganic substrate such as quartz and glass, or a transparent inorganic substrate such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC) , Polypropylene (PP), polyimide (PI), polyethylene sulfonate (PES), polyoxymethylene (POM), an acrylonitrile styrene copolymer and an acrylonitrile-butadiene- And a transparent plastic substrate.

The substrate preferably has a transmittance of at least 70% or more, preferably 80% or more at a visible light wavelength of about 400 to 750 nm.

In the organic solar cell according to the present invention, the transparent conductive layer is preferably indium tin oxide.

In the organic solar cell according to an embodiment of the present invention, the first electrode includes a material having high transparency since light passing through the substrate reaches the photoactive layer, and it is preferable that the first electrode has a high A conductive material having a work function and a low resistance is preferable. Therefore, specific examples of the transparent conductive layer included in the first electrode is indium tin oxide (ITO), gold, silver, Florin a tin oxide (FTO) _{doped, ZnO-Ga 2 O 3,} ZnO-Al 2 O 3, SnO ₂ -Sb ₂ O ₃ , and the like, but are not limited thereto.

The first electrode may be deposited on a substrate by thermal vapor deposition, electron beam deposition, RF (Radio Frequency) or magnetron sputtering, chemical vapor deposition or the like.

A hole injection layer is formed on the substrate on which the first electrode is formed.

The hole injection layer is preferably made of a material including PEDOT (poly (3,4-ethylenedioxythiophene), PSS (poly (styrenesulfonate)).

PEDOT (poly (3,4-ethylenedioxythiophene) and PSS (poly (styrenesulfonate)) have a structure in which PEDOT is a p-conjugated conductive polymer and PSS is doped as an acceptor. The doped structure is referred to as PEDOT / PSS.

PEDOT / PSS has an ethylenedioxy group in the form of a ring in the structure of theophene and has excellent stability against air and heat. (760 nm to 780 nm or 1.6 eV to 1.7 eV) lower than that of thiophene due to the electron donating effect by the ethylenedioxy group substituted at the 3,4-positions, and discoloration is caused by the oxidation / reduction potential difference In the oxidation state, the absorption band exists in the infrared region, and transparency can be ensured.

At the same time, PSS can exist as a stable dispersion in water as a PEDOT / PSS complex because its anionic nature serves as a dispersant for water. As a result, it is possible to apply a general wet coating to form a thin film, thereby making it possible to produce a uniform film.

As the hole injection layer, an inorganic thin film such as MoO ₃ , NiO, or V ₂ O ₃ may be used in addition to PEDOT / PSS.

A photoactive layer is located above the hole injection layer.

In the case of the organic solar cell according to the present invention, the photoactive layer preferably comprises a p-type conductive polymer material including p-electrons as an electron donor and fullerene or a derivative thereof as an electron acceptor Electron donor-electron acceptor mixed layer.

Specific examples of the electron donor include, but are not limited to, P3HT (poly (3-hexylthiophene)).

In addition to P3HT,

Poly (2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylenevinylene] (MEH-PPV, phenylenevinylene]),

Poly [1,4 (2-methoxy-5-dimethyloctyloxy) phenylenevinylene]) (OC1C10-PPV,

Poly (2-methoxy-5- (3'7'dimethylocty) -1, 4-phenylenevinylene] (MDMO-PPV, 4-phenylenevinylene]),

Poly [N-9 "-heptadecanyl-2,7-carbazolate-5,5- (4'7'-di-2-thinyl-2 ', 1', 3'- benzothiadiazole)] (PCDTBT, poly [N-9 "-heptadecanyl-2,7-carbazole-

5,5- (4 ', 7'-di-2-thienyl-2', 1 ', 3'-benzothiadiazole)],

Di [4, 8-bis [(2-ethylhexyl)] oxy] benzo [1,2- - [(2-ethylhexyl) carbonyl] Tino [3,4-b] thiophene-pyridyl]] (PTB7, poly [[ 4,8-bis [(2-ethylhexyl) oxy] benzo [1,2- b [4,5- b ] dithiophene-2,6-diyl] [3-fluoro-2 - [(2- ethylhexyl) carbonyl] thieno [3,4- b ] thiophenediyl]

Synthesis of poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [2,1- b; 3,4- b '] dithiophene) , 1,3-benzothiadiazole)] (PCPDTBT, poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [ dithiophene) -tallow-4,7- (2,1,3-benzothiadiazole)]),

(2,2- b: 2 ', 3'-d] cyclohexane-aldehyde-4,7 (2,1-bipyridyl) , 3-benzothiadiazole)] (PSBTBT, Poly [2,6- (4,4'-bis (2-ethylhexyl) dithieno [3,2-b: 2 ', 3'- -4,7 (2,1,3-benzothiadiazole)]),

Ammonium perfluorooctanoic acid-3 (APFO-3) and

Poly [4,7-dithiophene-2-yl-benzo (1,2,5) thiadiazole-alt-dihexyl-9H-fluorene] (PFTBT, benzo (1,2,5) thiadiazole-alt-dihexyl-9H-fluorene]).

The photoactive layer preferably comprises a mixture of P3HT as an electron donor and a fullerene derivative PCBM ([6,6] -phenyl-C ₆₁ butyric acid methyl ester) as an electron acceptor, 1: 1.1 is preferable.

The photoactive layer includes an electron donor, an electron acceptor, and a quantum dot surface-treated with an organic ligand represented by the following formula (1). When the light is absorbed, the photoactive layer forms an exciton, and excitons are separated into electrons and holes, and the electrons and holes move to the first electrode and the second electrode, respectively,

&Quot; Formula 1 "

(Wherein R ¹ , R ² , R ³ And R ⁴ is one member independently selected from _{-SH, -NH 2, -COOH, H} , straight or branched chain alkyl, and the group consisting of C ₁ -AR ⁵ _-6, wherein, A is C _{1 -} a straight or branched alkylene of _6, R ⁵ is -SH, and -NH ₂ or -COOH, wherein R ^1, R ^2, R ³ And R ⁴ Is one or more of one type of compound selected from the group consisting of -SH, -NH _2, -COOH, and -AR ^5.).

In more detail, the electron donor used in the present invention absorbs light to form excitons (electron and hole pairs) in an excited state. The exciton thus formed is diffused in an arbitrary direction and is separated into electrons and holes while meeting the interface of the electron acceptor.

In this case, the electron donor should have a good optical absorption spectrum, a very strong light absorption, and excellent electrical properties such as charge mobility.

On the other hand, the electron acceptor preferably includes fullerene or a derivative thereof. As the electron acceptor, fullerene (C ₆₀ ) itself or PCBM designed to dissolve C ₆₀ in an organic solvent can be used.

In addition to PCBM, PC70BM ([6,6] -phenyl-C ₇₀ butyric acid methyl ester) and ICBA (indene-C 60 bisadduct) materials are also available.

At this time, it is preferable that the electron acceptor should have a low light absorption in the visible light region and at the same time, satisfy the condition that the electron affinity must be higher than that of the electron donor.

Therefore, the electrons are moved toward the electron acceptor having a high electron affinity, and the holes remain on the electron donor side to separate into the respective charge states.

They are moved to each electrode by the difference of the internal electric field formed by the difference in work function and the accumulated electric charge, and are finally collected in the form of current through the external circuit. This phenomenon is called photovoltaic effect.

However, as described above, P3HT used as an electron donor has a limited light absorption band. Accordingly, the present invention provides a quantum dot surface-treated with an organic ligand represented by Formula 1 as a method for expanding the light absorption band of P3HT.

The organic ligand represented by Formula 1 may be selected from the group consisting of 2-thiopheneacetic acid, 2-thiophene carboxylic acid, 2,5-thiophenedicarboxylic acid ). ≪ / RTI >

It is preferable that one kind selected from the group consisting of 2-thiopheneacetic acid, 2-thiophene carboxylic acid and 2,5-thiophenedicarboxylic acid is all (2-thiopheneacetic acid, 2-thiophenecarboxylic acid (2-thiophene carboxylic acid, 2-thiophenecarboxylic acid, and the like) thiophene carboxylic acid, 2,5-thiophenedicarboxylic acid, and the quantum dots connected to the organic ligand including thiophene may have a uniform distribution. .

The organic ligand has a functional group capable of binding with the quantum dots. When the length of the carbon chain including the organic ligand is long, there is a problem that the flow of electrons or holes trapped in the quantum dots is not free, Examples of the organic ligand used in the present invention include 2-thiopheneacetic acid, 2-thiophene carboxylic acid and 2,5-thiophenedicarboxylic acid. And the like.

The molar ratio of the quantum dot to the organic ligand is preferably 1: 0.5 to 1: 4.

If the molar ratio between the quantum dots and the organic ligand is less than 1: 0.5, the rate of substitution of the surface ligands for each quantum dot is lowered and it is difficult to improve the efficiency of the produced solar cell. If the molar ratio between the quantum dots and the organic ligand is 1: The effect of adding quantum dots to the photoactive layer of the solar cell is reduced by half.

In addition, the quantum dot has a broad light absorption spectrum, can control the light absorption band by adjusting the size, and is advantageous in terms of light stability and charge mobility.

Wherein the quantum dot is at least one selected from the group consisting of a II-VI chalcogenide compound, an I-III-VI compound, a Group IV element quantum dot, a III-V compound, PbSe, PbTe and PbS Is preferably an organic solar cell.

In this case, in the II-VI chalcogenide compound, the group II is one kind selected from the group consisting of Cd or Zn, the group VI is S, Se, and Te. In the group I-III-VI compound, Or Ag, a Group III element is In or Ga, a Group VI element is one selected from the group consisting of S, Se and Te, a Group IV element in the Group IV quantum dot is one selected from the group consisting of Si, Ge and Sn, In the III-V group compound, Group III element is In or Ga, and Group V is one kind selected from the group consisting of P, As and Sb.

When the electron donor constituting the photoactive layer is P3HT and the quantum dot surface-substituted with an organic ligand is a CdSe quantum dot surface-substituted with 2-thiophenecarboxylic acid, P3HT (poly (3-hexylthiophene) It is preferable that the mass ratio of the CdSe quantum dot surface-substituted with an openecarboxylic acid is mixed in a ratio of 1: 0.1 to 1: 1.

As can be seen from Experimental Example 4, if the mass ratio of the quantum dots of Pdc and Pdc with the organic ligands is less than 0.1, the effect of doping quantum dots is insufficient. If the mass ratio of quantum dots is more than 1, .

A second electrode is formed on the photoactive layer.

More specifically, the second electrode may be a multi-layer structure in which a buffer layer is formed of a material such as LiF or LiO ₂ , and the following materials are deposited thereon. Materials that may be included include low work function materials, specifically metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, aluminum, silver, tin and lead or their alloys But the present invention is not limited thereto.

The second electrode preferably includes a LiF layer and an Al layer sequentially from the photoactive layer.

The present invention further provides a method of manufacturing a solar cell including the quantum dot.

The method of manufacturing an organic solar cell according to the present invention includes the steps of: (1) forming a hole injection layer on a substrate on which a transparent conductive layer is formed; (2) a step of forming an electron donor, an electron acceptor and an organic ligand surface- (Step 2) of forming a photoactive layer by applying a precursor solution for forming a photoactive layer containing a quantum dot on the hole injection layer and drying the resultant, and forming a second electrode on the photoactive layer (step 3).

Hereinafter, a method of manufacturing the organic solar battery of the present invention will be described in detail.

Step 1 according to the present invention is a step of forming a hole injection layer on a substrate on which a transparent conductive layer is formed. More specifically, a substrate on which a transparent conductive layer is formed is spin-coated or slit coated A wet process, or a dry process such as deposition to form the hole injection layer.

As described above, PEDOT / PSS [(poly 3,4-ethylenedioxythiophene) / (poly styrenesulfonate)] material can be used as the hole injection layer.

Step 2 according to the present invention is a method for forming a photoactive layer by applying a precursor solution for preparing a photoactive layer containing an electron donor, an electron acceptor and a quantum dot surface-treated with an organic ligand represented by the above-mentioned formula 1 onto the hole injection layer, A step of preparing a solution in which a substance such as P3HT used as an electron donor and fullerene or a derivative thereof used as an electron acceptor are mixed and a quantum dot surface-treated with an organic ligand represented by the above formula (1) is dispersed A solution is separately prepared, the two solutions are mixed and maintained at a predetermined temperature or higher to synthesize a precursor solution for preparing a photoactive layer, and then the solution is coated on the hole injection layer and dried at a temperature of 100-200 ° C.

Examples of the electron donor include poly (3-hexylthiophene) (P3HT, poly (3-hexylthiophene)

Poly (2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylenevinylene] (MEH-PPV, phenylenevinylene]),

Poly [1,4 (2-methoxy-5-dimethyloctyloxy) phenylenevinylene]) (OC1C10-PPV,

Poly (2-methoxy-5- (3'7'dimethylocty) -1, 4-phenylenevinylene] (MDMO-PPV, 4-phenylenevinylene]),

Poly [N-9 "-heptadecanyl-2,7-carbazolate-5,5- (4'7'-di-2-thinyl-2 ', 1', 3'- benzothiadiazole)] (PCDTBT, poly [N-9 "-heptadecanyl-2,7-carbazole-

5,5- (4 ', 7'-di-2-thienyl-2', 1 ', 3'-benzothiadiazole)],

Di [4, 8-bis [(2-ethylhexyl)] oxy] benzo [1,2- - [(2-ethylhexyl) carbonyl] Tino [3,4-b] thiophene-pyridyl]] (PTB7, poly [[ 4,8-bis [(2-ethylhexyl) oxy] benzo [1,2- b [4,5- b ] dithiophene-2,6-diyl] [3-fluoro-2 - [(2- ethylhexyl) carbonyl] thieno [3,4- b ] thiophenediyl]

Synthesis of poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [2,1- b; 3,4- b '] dithiophene) , 1,3-benzothiadiazole)] (PCPDTBT, poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [ dithiophene) -tallow-4,7- (2,1,3-benzothiadiazole)]),

(2,2- b: 2 ', 3'-d] cyclohexane-aldehyde-4,7 (2,1-bipyridyl) , 3-benzothiadiazole)] (PSBTBT, Poly [2,6- (4,4'-bis (2-ethylhexyl) dithieno [3,2-b: 2 ', 3'- -4,7 (2,1,3-benzothiadiazole)]),

Ammonium perfluorooctanoic acid-3 (APFO-3) and

Poly [4,7-dithiophene-2-yl-benzo (1,2,5) thiadiazole-alt-dihexyl-9H-fluorene] (PFTBT, benzo (1,2,5) thiadiazole-alt-dihexyl-9H-fluorene]).

The electron acceptor preferably includes fullerene or a derivative thereof. As the electron acceptor, fullerene (C ₆₀ ) itself or PCBM designed to dissolve C ₆₀ in an organic solvent can be used.

In addition to PCBM, PC70BM ([6,6] -phenyl-C ₇₀ butyric acid methyl ester) and ICBA (indene-C 60 bisadduct) materials are also available.

In a conventional organic solar cell made of a photoactive layer (for example, a mixed layer of P3HT and fullerene or a derivative thereof), heat treatment is generally performed at a temperature of about 150 ° C (420 K) in order to increase the charge mobility of the photoactive layer . Due to this heat treatment, the fullerene or its derivative molecules diffuse in the blend layer of P3HT and fullerene or its derivatives, resulting in phase separation of fullerene or a group of its derivatives to form fullerene or its derivative cluster and P3HT crystallite ), And the electron mobility increases through the fullerene or its derivative cluster, and the hole mobility also increases with the P3HT crystal.

Wherein the organic ligand is selected from the group consisting of 2-thiopheneacetic acid, 2-thiophene carboxylic acid, and 2,5-thiophenedicarboxylic acid. It is preferable to use at least one species.

It is preferable that one kind selected from the group consisting of 2-thiopheneacetic acid, 2-thiophene carboxylic acid and 2,5-thiophenedicarboxylic acid is all (2-thiopheneacetic acid, 2-thiophenecarboxylic acid (2-thiophene carboxylic acid, 2-thiophenecarboxylic acid, and the like) thiophene carboxylic acid, 2,5-thiophenedicarboxylic acid, and the quantum dots connected to the organic ligand including thiophene may have a uniform distribution. .

The organic ligand has a functional group capable of binding with the quantum dots. When the length of the carbon chain including the organic ligand is long, there is a problem that the flow of electrons or holes trapped in the quantum dots is not free, Examples of the organic ligand used in the present invention include 2-thiopheneacetic acid, 2-thiophene carboxylic acid and 2,5-thiophenedicarboxylic acid. And the like.

In the method of manufacturing an organic solar cell, the quantum dots include a group II-VI chalcogenide compound, an group III-VI compound, a group IV element quantum dot, a group III-V compound, PbSe, PbTe, and PbS. And at least one selected from the group consisting of

In this case, in the II-VI chalcogenide compound, the group II is one kind selected from the group consisting of Cd or Zn, the group VI is S, Se, and Te. In the group I-III-VI compound, Or Ag, a Group III element is In or Ga, a Group VI element is one selected from the group consisting of S, Se and Te, a Group IV element in the Group IV quantum dot is one selected from the group consisting of Si, Ge and Sn, In the III-V group compound, Group III element is In or Ga, and Group V is one kind selected from the group consisting of P, As and Sb.

In the step 2, when the electron donor is P3HT and the quantum dot surface-substituted with the organic ligand is a CdSe quantum dot surface-substituted with 2-thiophenecarboxylic acid, P3HT (poly (3-hexylthiophene)) and 2-thiophene It is preferable that the mass ratio of the CdSe quantum dot substituted with the carboxylic acid is 1: 0.1 to 1: 1.

As can be seen from Experimental Example 4, if the mass ratio of the quantum dots of Pdc and Pdc with the organic ligands is less than 0.1, the effect of doping quantum dots is insufficient. If the mass ratio of quantum dots is more than 1, .

The solution containing the quantum dots is prepared by the following process.

The quantum dot surface-treated with the organic ligand represented by Formula 1 may be prepared by a) dispersing a quantum dot surface-treated with oleic acid in an organic solvent (Step 2-1), and b) A step (2-2) of adding an organic ligand, and (c) a step (2-3) of introducing a polar solvent into the quantum dot dispersion solution to which the organic ligand is added to precipitate quantum dots and vacuum drying .

Hereinafter, the surface treatment method of the quantum dot of the present invention will be described in detail.

Step 2-1 according to the present invention is a step of dispersing quantum dots surface-treated with oleic acid in an organic solvent. More specifically, quantum dots surface-treated with oleic acid, which can be mass-synthesized from vegetable oil, are dissolved in toluene, chloroform and hexane To at least one organic solvent selected from the group consisting of

Step 2-2 according to the present invention is a step of adding the organic ligand represented by Formula 1 to the quantum dot dispersion solution, and more specifically, a step of adding an organic ligand represented by Formula 1 to a solution in which quantum dots stabilized with oleic acid are dispersed, .

As described above, when the surface of the quantum dots is replaced with an organic ligand containing thiophene, a homogeneous surface free from agglomeration can be obtained in a precursor solution for the production of a photoactive layer containing an electron donor and an electron acceptor.

In step 2-2, it is preferable to add an organic ligand such that the molar ratio of the quantum dot to the organic ligand is 1: 0.5 to 1: 4. If the molar ratio between the quantum dots and the organic ligand is less than 1: 0.5, the rate of substitution of the surface ligands for each quantum dot is lowered and it is difficult to improve the efficiency of the produced solar cell. If the molar ratio between the quantum dots and the organic ligand is 1: The effect of adding quantum dots to the photoactive layer of the solar cell is reduced by half.

Step 2-3 according to the present invention is a step of introducing a polar solvent into the quantum dot dispersion solution to which the organic ligand is added to precipitate the quantum dots and vacuum drying the organic quantum dots. More specifically, the organic ligands include thiophene, A polar solvent such as methanol or acetone is introduced into the quantum dots, and the quantum dots are precipitated and vacuum dried.

As described above, when the organic ligand is substituted with the organic ligand represented by Formula 1, a quantum dot having a uniform shape is obtained.

Step 3 according to the present invention is a step of forming a second electrode on the photoactive layer. More specifically, a buffer layer is formed of a material such as LiF or LiO ₂ , and then a photoelectric conversion layer is formed by thermal vapor deposition, electron beam evaporation, RF or magnetron Sputtering, chemical vapor deposition or the like to form a metal layer.

The second electrode according to the present invention is preferably a double layer in which LiF is coated on the photoactive layer by spin coating or the like and then the Al layer is coated.

According to another aspect of the present invention, there is provided a method of manufacturing a light emitting device, including: forming a first electrode on a substrate, a first electrode including a transparent conductive layer on the substrate, a hole injection layer disposed on the first electrode, A photoactive layer including an electron donor, an electron acceptor, and a quantum dot surface-treated with an organic ligand represented by Formula 1, and a second electrode disposed on the photoactive layer.

The organic solar cell according to the present invention includes an electron donor, an electron acceptor and a quantum dot surface-treated with an organic ligand represented by the above-mentioned formula (1) in the photoactive layer, thereby uniformly dispersing the quantum dot surface- It is possible to improve the efficiency of the solar cell.

Actually, organic solar cells manufactured by the above method have a solar cell efficiency of 3.4% or more.

Hereinafter, preferred embodiments and experimental examples according to the present invention will be described in detail with reference to the accompanying drawings. It is to be understood, however, that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. .

<Examples>

(Example 1) Production of organic solar cell 1

Step 1: A step of forming a hole injection layer on a substrate on which a transparent conductive layer is formed

PEODT and PSS were applied by spin coating at 1000 rpm for 30 seconds on a glass plate on which ITO was formed as a transparent conductive layer. Then, the substrate was dried at 150 ° C for 30 minutes under atmospheric pressure to form a hole injection layer.

Step 2: applying a precursor solution for preparing a photoactive layer containing an electron donor, an electron acceptor and a quantum dot surface-treated with an organic ligand represented by the following formula (1) onto the hole injection layer and drying to form a photoactive layer

30 mg of P3HT and 24 mg of PCBM were dissolved in 1.8 ml of 1,2-dichlorobenzene at a concentration of 30 mg / ml.

The CdSe quantum dot surface-treated with oleic acid was dispersed in toluene. 50 mg of 2-thiophenecarboxylic acid was added to 50 ml of the quantum dot dispersion solution so that the ratio of the quantum dots and the organic ligand was 1: 3 at a molar ratio. After stirring at room temperature for 24 hours, acetone was introduced to precipitate the quantum dots. The precipitate, which was centrifuged and dried, was dried in vacuo.

30 mg of CdSe quantum dot surface-substituted with 2-thiophenecarboxylic acid was dissolved in 1 ml of 1,2-dichlorobenzene to a concentration of 30 mg / ml to prepare a quantum dot solution. 0.8 ml of this solution and 1.8 ml of the P3HT: PCBM solution were mixed and stirred while maintaining the temperature at 40 to 60 ° C to synthesize a precursor solution for preparing a photoactive layer.

The precursor solution for the preparation of the photoactive layer was coated on the hole injection layer prepared in step 1 by spin coating at 700 rpm for 30 seconds and then dried at 150 캜 for 30 minutes under atmospheric pressure to form a photoactive layer.

Step 3: forming a second electrode on top of the photoactive layer

An organic solar cell was fabricated by depositing a LiF layer and an Al layer on the photoactive layer formed in step 2 with a thermal evaporator (Infovin) to have a thickness of 1 nm and 100 nm, respectively.

(Example 2) Production of organic solar cell 2

An organic solar cell was prepared in the same manner as in Example 1, except that 0.5 ml of the quantum dot solution was mixed in Step 2 of Example 1, and a precursor solution for preparing a photoactive layer was synthesized.

(Examples 3 to 5) Preparation of organic solar cell 3 to 5

Except that 0.1 ml (Example 3), 0.3 ml (Example 4) and 1 ml (Example 5) of a quantum dot solution were mixed in Step 2 of Example 1, and a precursor solution for the preparation of a photoactive layer was synthesized An organic solar cell was prepared in the same manner as in Example 1.

(Comparative Example 1)

An organic solar cell was prepared in the same manner as in Example 1, except that the precursor solution for the preparation of the photoactive layer was synthesized without mixing the quantum dot solution in Step 2 of Example 1 above.

(Comparative Example 2)

A quantum dot solution was prepared by dissolving 30 mg of CdSe quantum dot surface-substituted with oleic acid in 1 ml of 1,2-dichlorobenzene at a concentration of 30 mg / ml in step 2 of Example 1 above. An organic solar cell was prepared in the same manner as in Example 1, except that 0.1 ml of the quantum dot solution and 1.8 ml of the mixed solution of P3HT and PCBM were mixed to prepare a precursor solution for preparing a photoactive layer.

(Comparative Example 3)

A quantum dot solution was prepared by dissolving 30 mg of CdSe quantum dot surface-substituted with pyridine in Step 2 of Example 1 at a concentration of 30 mg / ml in 1 ml of 1,2-dichlorobenzene. An organic solar cell was prepared in the same manner as in Example 1, except that 0.1 ml of the quantum dot solution and 1.8 ml of the mixed solution of P3HT and PCBM were mixed to prepare a precursor solution for preparing a photoactive layer.

<Experimental Example>

(Experimental Example 1) Confirmation of shape of CdSe quantum dot surface-substituted with 2-thiophenecarboxylic acid

The following experiment was conducted to confirm the shape of the CdSe quantum dot surface-substituted with 2-thiophenecarboxylic acid.

The CdSe quantum dot surface-treated with oleic acid was dispersed in toluene, and 2-thiophenecarboxylic acid (organic ligand) was added to the quantum dot dispersion solution so that the ratio of the quantum dots and the surface ligands was 1: 3 by molar ratio. After stirring at room temperature for 1 hour to 24 hours, a polar solvent such as methanol or acetone was introduced to precipitate quantum dots, followed by drying in vacuum.

1 (a) and 1 (b) are transmission electron microscope (TEM) images showing the shape of quantum dots substituted with 2-thiophenecarboxylic acid.

1 (a) and 1 (b), it is confirmed that the quantum dots substituted with 2-thiophenecarboxylic acid are synthesized into a shape in which four columns having a diameter of 4.6 nm and a length of about 11.6 nm are uniformly arranged .

(Experimental Example 2) Analysis of absorbance characteristics

The following experiments were carried out to investigate the absorbance characteristics of quantum dots substituted with various organic ligands.

30 mg of the CdSe quantum dot surface-substituted according to Step 2 in Example 1 (2-thiophenecarboxylic acid), Comparative Example 2 (oleic acid) and Comparative Example 3 (pyridine) was added to 1 ml of 1,2- / Ml, the absorbance characteristics were analyzed using a spectrometer (Agilent technology, Cary 5000). The results are shown in FIG.

Figure 2 is a graph showing the absorption spectra of quantum dots surface-substituted with various organic ligands.

According to FIG. 2, it can be seen that the long wavelength spectrum occurs due to the severe agglomeration between the quantum dots and pyridine surface-substituted quantum dots.

When pyridine is substituted, the absorption spectrum of the quantum dots spreads as a result of aggregation between the quantum dots.

According to Fig. 2, when the surface was substituted with 2-thiophenecarboxylic acid, no change in absorption spectrum was observed due to agglomeration. From this, it can be seen that when the 2-thiophenecarboxylic acid is used for surface substitution, it is uniformly dispersed in 1,2-dichlorobenzene. Thus, In the case of the quantum dot, the efficiency of the solar cell can be improved by being uniformly dispersed in the photoactive layer.

If the aggregation of particles such as pyridine occurs, the absorption spectrum of the quantum dots will spread, and the aggregation of particles will have a bad effect on the homogeneous and fine phase separation between polymer and fullerene important in bulk heterojunction type organic solar cells The efficiency of the solar cell is deteriorated as a whole.

(Experimental Example 3) Confirmation of quantum dot distribution in a precursor solution for producing a photoactive layer

The following experiment was conducted to confirm the distribution of quantum dots in the precursor solution for photoactive layer production.

In order to determine whether the quantum dots are uniformly distributed in the photoactive layer prepared according to Step 2 of Example 1, Comparative Examples 2 and 3, a pattern of each quantum dot was observed with a transmission electron microscope (TEM).

FIGS. 3 (a) to 3 (d) are TEM images showing quantum dots surface-substituted with various organic ligands distributed in the photoactive layer.

FIG. 3 (a) is a TEM photograph showing a state where quantum dots substituted with oleic acid are dispersed in the photoactive layer according to Comparative Example 2, and FIG. 3 (b) FIGS. 3 (c) and 3 (d) are TEM images showing the state where quantum dots substituted with 2-thiophenecarboxylic acid according to Example 1 are distributed in the photoactive layer. FIG.

3 (a) to (d), it can be confirmed that only quantum dots substituted with 2-thiophenecarboxylic acid among various organic ligands are uniformly dispersed in the photoactive layer. Thus, It was confirmed that the quantum dots substituted with the pentacarboxylic acid are quantum dots that can be uniformly distributed in the photoactive layer of the organic solar battery.

(Experimental Example 4) Experiment for Measuring Efficiency of Organic Solar Cell 1

The following experiment was conducted to confirm the efficiency of an organic solar cell including quantum dots substituted with 2-thiophenecarboxylic acid according to Examples 1 to 5 and Comparative Example 1 of the present invention.

The efficiency of the solar cell was measured using a solar simulator (Newport, 9600000) emitting light of 100 mW / cm 2 under the condition of AM 1.5. The efficiency of the solar cell is calculated according to Equation (1).

Photocurrent density-voltage (J-V) characteristics were measured using a Keithley 2400 source meter and corrected for photocurrent using a reference solar cell (Bunkoh-keiki BS 520).

Quantity of solution of quantum dot solution (ml) Short-circuit current (J _sc ) (mA / cm 2) Open Voltage (V _oc ) (V) FF (fill factor) efficiency(%) 0 (Comparative Example 1) 8.2 0.57 0.61 2.85 0.1 (Example 3) 8.44 0.56 0.62 2.93 0.3 (Example 4) 8.85 0.53 0.6 2.81 0.5 (Example 2) 9.6 0.5 0.61 2.93 0.8 (Example 1) 9.83 0.53 0.64 3.33 1 (Example 5) 8.29 0.56 0.53 2.46

According to Table 1, when the 2-thiophenecarboxylic acid was added to the solar cell, the efficiency was improved up to 3.33% by the addition of the 2-thiophenecarboxylic acid.

In particular, the short circuit current (Jsc) value is gradually increased from 8.2 mA / cm 2 to 9.83 mA / cm 2 at maximum depending on the quantum dot addition amount.

4 is a graph showing the photocurrent density-voltage (J-V) curves of organic solar cells according to the quantum dot solution addition amounts according to Examples 1 to 5 and Comparative Example 1 of the present invention.

According to Table 1 and FIG. 4, it can be confirmed that the addition of 0.8 mg of the quantum dot solution containing 2-thiophenecarboxylic acid per 1 mole of P3HT contributes to the improvement of the short-circuit current value, The efficiency of the organic solar cell can be improved up to 3.33% by adding a quantum dot solution containing an acid. Thus, it can be confirmed that the organic solar cell manufactured according to Example 1 of the present invention is a highly efficient cell.

In FIG. 4, the quantum dot solution has a concentration of 30 mg / ml. As mentioned above, P3HT and PCBM are also dissolved at a concentration of 30 mg / ml. Therefore, the ratio of P3HT: PCBM: CdSe = 1: 0.8: x indicates the volume ratio of the used solution, and the ratio is the mass ratio of each solute, regardless of the solute.

(Experimental Example 5) Experiment for Measuring the Efficiency of Organic Solar Cell 2

In order to confirm the efficiency of the organic solar cell including the quantum dot substituted with oleic acid according to Comparative Example 2 of the present invention, the following experiment was conducted.

The efficiency of the solar cell was measured in the same manner as in Experimental Example 4 for a solution in which 0.1 ml of a quantum dot solution containing oleic acid was added according to Comparative Example 2. [

FIG. 5 is a graph showing the photocurrent density-voltage (J-V) curve of an organic solar cell when the addition amount of the quantum dot solution in which oleic acid is substituted according to Comparative Example 2 is 0.1 ml.

It can be seen from FIG. 5 that the efficiency of the solar cell is drastically reduced to 0.35%, indicating that the efficiency of the solar cell including the quantum dot surface-substituted with oleic acid is reduced.

(Experimental Example 6) Experiment 3 for the efficiency measurement of organic solar cell

The following experiment was conducted to confirm the efficiency of an organic solar cell including pyridine-substituted quantum dots according to Comparative Example 3 of the present invention.

The efficiency of the solar cell was measured in the same manner as in Experimental Example 4 with respect to the solution in which 0.1 ml of the quantum dot solution containing pyridine was added according to Comparative Example 3.

 FIG. 6 is a graph showing a photocurrent density-voltage (J-V) curve of an organic solar cell when the amount of the pyridine substituted quantum dot solution is 0.1 ml according to Comparative Example 3. FIG.

6, it can be seen that the V _oc (open-circuit voltage) is 0.52 V, the FF is 0.49, the J _sc (short circuit current) is 6.68 mA / cm 2 and the solar energy efficiency is 1.68% The efficiency of the organic solar cell including the quantum dot is reduced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Several variations are possible.

Claims (17)

Board;
A first electrode located on the substrate and including a transparent conductive layer;
A hole injection layer disposed on the first electrode;
A photoactive layer disposed on the hole injection layer and including a quantum dot surface-treated with an electron donor, an electron acceptor, and an organic ligand represented by the following Formula 1, and having a tetrapod form; And
And a second electrode disposed on the photoactive layer and including a LiF layer and an Al layer in order from the photoactive layer, wherein the mass ratio of the electron donor to the quantum dot is 1: 0.1 to 1: 0.8. Solar cell:
&Quot; Formula 1 &quot;

Wherein R ¹ , R ² , R ³ and R ⁴ are each independently selected from the group consisting of -SH, -NH ₂ , -COOH, H, C _1-6 straight-chain or branched alkyl and -AR ⁵ One,
Herein, A is C _1-6 linear or branched alkylene,
R ⁵ is -SH, -NH ₂ or -COOH,
At least one of R ¹ , R ² , R ³ and R ⁴ is
-SH, -NH ₂ , -COOH and -AR ⁵ ). The method according to claim 1,
Wherein the transparent conductive layer is made of indium tin oxide (ITO). The method according to claim 1,
Wherein the hole injection layer is one selected from the group consisting of PEDOT (poly (3,4-ethylenedioxythiophene)) / PSS (poly (styrenesulfonate)), MoO ₃ , NiO and V ₂ O ₃ Organic solar cell. The method according to claim 1,
The electron donor may be selected from the group consisting of poly (3-hexylthiophene) (P3HT, Poly (3-hexylthiophene)
Poly (2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylenevinylene] (MEH-PPV, phenylenevinylene]),
Poly [1,4 (2-methoxy-5-dimethyloctyloxy) phenylenevinylene]) (OC1C10-PPV,
Poly (2-methoxy-5- (3'7'dimethylocty) -1, 4-phenylenevinylene] (MDMO-PPV, 4-phenylenevinylene]),
Poly [N-9 "-heptadecanyl-2,7-carbazolate-5,5- (4'7'-di-2-thinyl-2 ', 1', 3'- benzothiadiazole)] (PCDTBT, poly [N-9 "-heptadecanyl-2,7-carbazole-
5,5- (4 ', 7'-di-2-thienyl-2', 1 ', 3'-benzothiadiazole)],
Di [4, 8-bis [(2-ethylhexyl)] oxy] benzo [1,2- - [(2-ethylhexyl) carbonyl] Tino [3,4-b] thiophene-pyridyl]] (PTB7, poly [[ 4,8-bis [(2-ethylhexyl) oxy] benzo [1,2- b [4,5- b ] dithiophene-2,6-diyl] [3-fluoro-2 - [(2- ethylhexyl) carbonyl] thieno [3,4- b ] thiophenediyl]
Synthesis of poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [2,1- b; 3,4- b '] dithiophene) , 1,3-benzothiadiazole)] (PCPDTBT, poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [ dithiophene) -tallow-4,7- (2,1,3-benzothiadiazole)]),
(2,2- b: 2 ', 3'-d] cyclohexane-aldehyde-4,7 (2,1-bipyridyl) , 3-benzothiadiazole)] (PSBTBT, Poly [2,6- (4,4'-bis (2-ethylhexyl) dithieno [3,2-b: 2 ', 3'- -4,7 (2,1,3-benzothiadiazole)]),
Ammonium perfluorooctanoic acid-3 (APFO-3) and
Poly [4,7-dithiophene-2-yl-benzo (1,2,5) thiadiazole-alt-dihexyl-9H-fluorene] (PFTBT, benzo (1,2,5) thiadiazole-alt-dihexyl-9H-fluorene]). The method according to claim 1,
The organic ligand
At least one selected from the group consisting of 2-thiopheneacetic acid, 2-thiophene carboxylic acid and 2,5-thiophenedicarboxylic acid. Organic solar cell. The method according to claim 1,
Wherein the mole ratio of the quantum dot to the organic ligand is 1: 0.5 to 1: 4. The method according to claim 1,
Wherein the quantum dot is at least one selected from the group consisting of a II-VI chalcogenide compound, an I-III-VI compound, a Group IV element quantum dot, a III-V compound, PbSe, PbTe and PbS An organic solar cell;
(In the above-mentioned II-VI chalcogenide compounds, Group II is one kind selected from the group consisting of Cd or Zn, Group V is S, Se and Te,
In the above-mentioned Group I-III-VI compounds, Group I is one kind selected from the group consisting of Cu or Ag, Group III is In or Ga, Group VI is S, Se and Te,
Group IV elements in the Group IV quantum dots are one species selected from the group consisting of Si, Ge and Sn,
In the group III-V compound, Group III element is In or Ga, and Group V is one selected from the group consisting of P, As and Sb. delete delete Forming a hole injection layer on the substrate on which the transparent conductive layer is formed (step 1);
A quantum dot surface-treated with an electron donor, an electron acceptor and an organic ligand represented by the following formula (1), wherein the mass ratio of the electron donor and the quantum dot is 1: 0.1 to 1: 0.8 Applying a precursor solution onto the hole injection layer and drying to form a photoactive layer (step 2); And
And forming a second electrode on the photoactive layer in order from the photoactive layer to the LiF layer and the Al layer (step 3). The method of claim 1,
&Quot; Formula 1 &quot;

Wherein R ¹ , R ² , R ³ and R ⁴ are each independently selected from the group consisting of -SH, -NH ₂ , -COOH, H, C _1-6 straight-chain or branched alkyl and -AR ⁵ One,
Herein, A is C _1-6 linear or branched alkylene,
R ⁵ is -SH, -NH ₂ or -COOH,
At least one of R ¹ , R ² , R ³ and R ⁴ is
-SH, -NH ₂ , -COOH and -AR ⁵ ). 11. The method of claim 10,
The electron donor may be selected from the group consisting of poly (3-hexylthiophene) (P3HT, Poly (3-hexylthiophene)
Poly (2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylenevinylene] (MEH-PPV, phenylenevinylene]),
Poly [1,4 (2-methoxy-5-dimethyloctyloxy) phenylenevinylene]) (OC1C10-PPV,
Poly (2-methoxy-5- (3'7'dimethylocty) -1, 4-phenylenevinylene] (MDMO-PPV, 4-phenylenevinylene]),
Poly [N-9 "-heptadecanyl-2,7-carbazolate-5,5- (4'7'-di-2-thinyl-2 ', 1', 3'- benzothiadiazole)] (PCDTBT, poly [N-9 "-heptadecanyl-2,7-carbazole-
5,5- (4 ', 7'-di-2-thienyl-2', 1 ', 3'-benzothiadiazole)],
Di [4, 8-bis [(2-ethylhexyl)] oxy] benzo [1,2- - [(2-ethylhexyl) carbonyl] Tino [3,4-b] thiophene-pyridyl]] (PTB7, poly [[ 4,8-bis [(2-ethylhexyl) oxy] benzo [1,2- b [4,5- b ] dithiophene-2,6-diyl] [3-fluoro-2 - [(2- ethylhexyl) carbonyl] thieno [3,4- b ] thiophenediyl]
Synthesis of poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [2,1- b; 3,4- b '] dithiophene) , 1,3-benzothiadiazole)] (PCPDTBT, poly [2,6- (4,4-bis- (2-ethylhexyl) -4H-cyclopenta [ dithiophene) -tallow-4,7- (2,1,3-benzothiadiazole)]),
(2,2- b: 2 ', 3'-d] cyclohexane-aldehyde-4,7 (2,1-bipyridyl) , 3-benzothiadiazole)] (PSBTBT, Poly [2,6- (4,4'-bis (2-ethylhexyl) dithieno [3,2-b: 2 ', 3'- -4,7 (2,1,3-benzothiadiazole)]),
Ammonium perfluorooctanoic acid-3 (APFO-3) and
Poly [4,7-dithiophene-2-yl-benzo (1,2,5) thiadiazole-alt-dihexyl-9H-fluorene] (PFTBT, benzo (1,2,5) thiadiazole-alt-dihexyl-9H-fluorene]). 11. The method of claim 10,
The organic ligand
At least one member selected from the group consisting of 2-thiopheneacetic acid, 2-thiophene carboxylic acid, and 2,5-thiophenedicarboxylic acid Wherein the organic solar cell is a solar cell. 11. The method of claim 10,
Wherein the quantum dot is at least one selected from the group consisting of a II-VI chalcogenide compound, an I-III-VI compound, a Group IV element quantum dot, a III-V compound, PbSe, PbTe and PbS : &Lt; tb &gt;&lt; SEP &gt;
(In the above-mentioned II-VI chalcogenide compounds, Group II is one kind selected from the group consisting of Cd or Zn, Group V is S, Se and Te,
In the above-mentioned Group I-III-VI compounds, Group I is one kind selected from the group consisting of Cu or Ag, Group III is In or Ga, Group VI is S, Se and Te,
Group IV elements in the Group IV quantum dots are one species selected from the group consisting of Si, Ge and Sn,
In the group III-V compound, Group III element is In or Ga, and Group V is one selected from the group consisting of P, As and Sb.
delete 11. The method of claim 10,
The quantum dot surface-treated with the organic ligand
a) dispersing the quantum dot surface-treated with oleic acid in an organic solvent (step 2-1);
b) adding an organic ligand represented by the following formula (1) to the quantum dot dispersion solution (step 2-2); And
(c) introducing a polar solvent into the quantum dot dispersion solution to which the organic ligand is added to precipitate quantum dots and vacuum drying the organic quantum dots; and (2-3)
&Quot; Formula 1 &quot;

(Wherein R ¹ , R ² , R ³ And R ⁴ is one member independently selected from _{-SH, -NH 2, -COOH, H} , straight or branched chain alkyl, and the group consisting of ⁵ -AR C _{1 -6,}
Herein, A is a straight or branched alkylene having _{1 to 6} carbon atoms,
R ⁵ is -SH, -NH ₂ or -COOH,
The R ¹ , R ² , R ³ And R ⁴ One or more of
-SH, -NH ₂ , -COOH and -AR ⁵ ). 16. The method of claim 15,
Wherein the step 2-2 is a step of adding an organic ligand so that a molar ratio of the quantum dot to the organic ligand is 1: 0.5 to 1: 4. 11. A process for the preparation of a compound according to claim 10,
Board;
A first electrode located on the substrate and including a transparent conductive layer;
A hole injection layer disposed on the first electrode;
A quantum dot disposed on the hole injection layer and being in the form of an electron donor, an electron acceptor and an organic ligand represented by Chemical Formula 1 and being in the form of a tetrapod, wherein the mass ratio of the electron donor and the quantum dot is 1: 1: 0.8 photoactive layer; And
And a second electrode located on the photoactive layer and including a LiF layer and an Al layer sequentially from the photoactive layer.

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