KR20120078952A - Organic solar cell containing lanthanide-doped up-conversion nanoparticles - Google Patents

Abstract

PURPOSE: An organic solar cell including energy upconversion nanoparticles with doped rare-earth ion is provided to form lots of photo charges by converting light of wavelength area from a near infrared ray to a visible ray. CONSTITUTION: A hole-transport layer or an active layer includes energy upconversion nanoparticles on a matrix. The energy upconversion nanoparticles are doped by rare-earth ion. The rare-earth ion includes reactive ion and Ln3+. The reactive ion is selected in a group composed of Er3+ and Tm3+. The Ln3+ is selected in a group composed of Yb3+, Nd3+, Dy3+ and sm3+.

Description

Organic Solar Cell containing Lanthanide-doped Up-conversion Nanoparticles

The present invention relates to an organic solar cell including the upward energy transfer nanoparticles doped with rare earth ions, and more specifically, to absorb the sunlight in the near infrared region by introducing the upward energy transfer nanoparticles into a hole transport layer or an active layer. The present invention relates to an organic solar cell capable of improving efficiency.

Organic solar cells have been studied to overcome the shortcomings of inorganic solar cells, which are difficult to spread in general households due to high manufacturing costs. In 1985, CW Tang of Eastman Kodak used a heterojunction structure of AM2, 75mW /, using CuPc and perylene tetracarboxylic acid derivatives as donor ( p- type) and acceptor ( n- type) materials, respectively. After presenting an organic solar cell having an energy conversion efficiency of 0.95% under the condition of cm ² , interest and research on organic solar cells have been amplified.

The core materials of the organic solar cell are organic materials having electron donor (D) and electron acceptor (A) characteristics. When the solar cell made of these organic molecules absorbs light, electrons and holes (excitation here) ) Is formed and the organic solar cell uses the principle that the charge is separated by moving to the donor-acceptor (DA) interface, the electron moves to the acceptor, and the hole moves to the donor to generate photocurrent.

Recently, the research direction of organic solar cells has been focused on developing high efficiency solar cells that lower the cost of power generation and improve the light conversion efficiency. Various methods have been developed to increase the efficiency of solar cells, but further efficiency increases are required for the commercialization of organic solar cells. However, many materials currently used in organic solar cells do not have a wavelength band capable of sufficiently absorbing the solar spectrum, so there is a limit to achieving high efficiency.

Accordingly, the present inventors have made a thorough effort to develop an organic solar cell that can overcome the above-mentioned limitations of the prior art, and thus have completed the present invention.

As a result, an object of the present invention is to introduce uplink energy-transfer nanoparticles doped with rare earth ions in the hole transport layer or active layer constituting the organic solar cell, absorbing sunlight in the near-infrared region and thus absorbing more photocharges than conventional electron donor materials. The present invention provides an organic solar cell having improved light conversion efficiency.

In the present invention to achieve the above object in the organic solar cell comprising a positive electrode, a hole transport layer, an active layer and a cathode, the hole transport layer or the active layer is characterized in that it comprises an upward energy transfer nanoparticle doped with rare earth ions in the matrix An organic solar cell is provided.

According to one embodiment of the organic solar cell according to the present invention, the rare earth ions are Er ³⁺ and Tm ^{3 +} activated ion selected from the group consisting of one member and the ^{3 +} Yb, Nd ^{+ 3,} Dy ^{+ 3,} and Sm ³⁺ It may include one selected from the group consisting of Ln ^{3 +} .

According to one embodiment of the organic solar cell according to the present invention, the activation ion may have a mole fraction of 1 to 5 with respect to the upward energy transfer nanoparticles.

According to an embodiment of the organic solar cell according to the present invention, the Ln ^{3 +} may have a mole fraction of 10 to 30 with respect to the upward energy transfer nanoparticles.

According to one embodiment of the organic solar cell according to the present invention, the matrix may be one selected from the group consisting of YF ₃ , NaYF ₄ , KY ₃ F ₁₀ , LuPO ₄ and YbPO ₄ .

According to one embodiment of the organic solar cell according to the present invention, the upward energy transfer nanoparticles doped with rare earth ions in the matrix may form a core-shell structure.

According to an embodiment of the organic solar cell according to the present invention, the rare earth ions of the core layer are one of the activated ions selected from the group consisting of Er ^{3 +} and Tm ^{3 +} and Yb ^{3 +} , Nd ³⁺ , Dy It may include Ln ^{3 +} is one selected from the group consisting of ^{3 +} and Sm ^{3 +} .

According to one embodiment of the organic solar cell according to the present invention, the rare earth ion of the shell (shell) layer is ^{3 +} Tm, Dy ^{+ 3} and 1 of the active ion species selected from the group consisting of Ho ^{3 +} and Yb ^3+, Nd ^{3 +,} Dy ^{3 +,} and one member selected from the group consisting of Sm ^{3 +} may include Ln ^{+ 3.}

According to one embodiment of the organic solar cell according to the present invention, the upward energy transfer nanoparticles are surrounded by crystals composed of one species selected from compounds represented by Formulas 1 to 6 to form a core-shell structure. Can be.

[Formula 1]

(In Formula 1, m and n are each an integer of 1 to 10.)

[Formula 2]

(P in Formula 2 is an integer of 1 to 10.)

(3)

(In Formula 3, q is an integer of 1 to 10.)

[Formula 4]

[Chemical Formula 5]

(In Formula 5, r and s are integers of 1 to 10.)

[Formula 6]

 (In Formula 6, R is a phenyl group or a C1-C5 alkylene group, R 'is a C1-C5 alkyl group.)

According to one embodiment of the organic solar cell according to the present invention, the upward energy transfer nanoparticles may be supported with gold (Au) or silver (Ag) on the surface.

According to one embodiment of the organic solar cell according to the present invention, the upward energy transfer nanoparticles are polyacrylic acid (PAA), polymethyl methacrylate (PMMA) and polyallylamine chloride (poly (allylamine) hydrochloride), PAH) may be coated with one selected from the group consisting of.

According to one embodiment of the organic solar cell according to the present invention, the upward energy transfer nanoparticles are made of a film (film) between the layer between the positive electrode and the hole transport layer, between the hole transport layer and the active layer, and between the active layer and the cathode layer It can be included in one layer.

The organic solar cell according to the present invention absorbs sunlight in the near infrared region by introducing upward energy transfer nanoparticles doped with rare earth ions in the active layer to form more photocharges than the donor material of the active layer. The conversion efficiency can be improved.

1 is a cross-sectional view showing the structure of a general organic solar cell.
2 is a cross-sectional view illustrating a structure of an organic solar cell including uplink energy transition nanoparticles in an active layer.
3 is a cross-sectional view illustrating a structure of an organic solar cell including uplink energy transition nanoparticles in a hole transport layer.
4 is an energy level diagram showing an upward energy conversion mechanism of the rare earth ion doped upward energy transfer nanoparticles.
5 and 6 are cross-sectional views showing the structure of the upward energy transfer nanoparticles constituting the core-shell structure.
FIG. 7 is a cross-sectional view illustrating a structure of upward energy transfer nanoparticles in which gold (Au) or silver (Ag) is supported on a surface thereof.
(A) and (b) of FIG. 8 are TEM photographs of the upward energy transfer nanoparticles prepared in Examples, (c) EDED analysis results of the upward energy transfer nanoparticles prepared in Examples, and (d) near infrared rays. Photographs of the upward energy transfer nanoparticles prepared in the examples in hexane solution under excitation of a laser.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. 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. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

The present invention provides an organic solar cell comprising an anode, a hole transport layer, an active layer, and an anode, wherein the hole transport layer or the active layer includes upward energy transfer nanoparticles doped with rare earth ions in a matrix. do.

1 is a cross-sectional view showing the structure of a general organic solar cell. Referring to FIG. 1, an organic solar cell includes a substrate, an anode, a hole transport layer, an active layer, and a cathode. In general, organic solar cells use indium tin oxide (ITO), which is a transparent electrode, as a cathode material, and aluminum (Al) or calcium (Ca), etc., as a cathode material.

An active layer is formed on the anode, and a hole transport layer is formed between the anode and the active layer. The hole transport layer improves adhesion between the anode and the active layer, serves to transfer charge, and may be a PEDOT (poly (3,4-ethylenedioxythiophene): PSS (poly (styrene sulfonate)) layer.

The active layer is a photoelectric conversion layer containing an organic material, and absorbs light to generate excitons. The organic active layer may be a donor / acceptor bilayer in which a donor layer and an acceptor layer are separated, or a bulk heterojunction (BHJ) layer in which a donor and an acceptor are mixed. The donor may be poly (3-hexylthiophene) (P3HT) as a polythiophene derivative, and the acceptor may be phenyl-C61-butyric acid methyl ester (PCBM) as a fullerene derivative.

The organic solar cell according to the present invention includes upward energy transfer nanoparticles doped with rare earth ions in the hole transport layer or the active layer. The upward energy transfer nanoparticles as rare earth ions in the matrix, has an active ion and doped structure Ln ^{+ 3.}

The active ions are Er ^{3 +,} and from the group consisting of Tm ^{3 +} can be used to selected one member active ion, the Ln ^{3 +} roneun from the group consisting of Yb ^{3 +,} Nd ^{3 +,} Dy ^{3 +} and Sm ^{3 +} One selected can be used.

The active ion has a mole fraction of from 1 to 5 with respect to the upward energy transfer nanoparticles, wherein Ln ^{+ 3} may have a mole fraction of 10 to 30 with respect to the upward energy transfer nanoparticles.

The matrix may be one selected from the group consisting of YF ₃ , NaYF ₄ , KY ₃ F ₁₀ , LuPO ₄ and YbPO ₄ .

Figure 4 shows the upward energy conversion mechanism of the rare earth ion doped upward energy transfer nanoparticles. The wavelength conversion principle of the uplink energy conversion nanoparticles will be described with reference to FIG. 2.

It is an exciting light (980nm) of the near-infrared light by a rare earth ion of Yb ^{+ 3} in the ² F _² F _^7/2 energy level by absorption of a photon (Photon) _5/2. The energy of excited Yb ^{3 +} is the neighboring Er ^{3 +} ion The transition is to occur is Er ^{+ 3} is here a ⁴ I _11/2 by absorbing a photon of Yb ^{+ 3.} The Er ^{3 + 4} I _11/2 into been here is the non-light-emitting transitions will take place in the ⁴ S _3/2 Again, absorbs a photon of Yb ^{3 + 4} F _9/2 and a transition occurs to the metastable excited state . After re Er ^{+ 3} is it occurs that the final transition to the ⁴ G _11/2 by absorbing a photon of Yb ^3+. When excited Yb ^{3 +} is a quasi-stable state via a non-emission metastasis of _{^{2 H 9/2, 2 H}} 11/2, 4 S 3 / the energy transfer to occur in ₂ and ⁴ F _9/2 been here Yb ^{3 +} We are each a metastable state _{^{(2 H 9/2 → 4}} I 15/2 (408nm), 2 H 11/2 → 4 I 15/2 (523nm), 4 S 3/2 → 4 I 15/2 (541nm ) and the _{^{4 F 9/2 → 4 I 15/}} 2 ( e is dropped to a stable state at 660nm)). As a result, the upward energy transfer nanoparticles can convert wavelengths by absorbing near-infrared light and emitting visible light.

When the above-mentioned energy conversion nanoparticles doped with rare earth ions capable of converting wavelengths are introduced into the active layer, the light in the near infrared wavelength region is converted into the visible wavelength region to absorb the sunlight in the near infrared region, which the donor material has not absorbed. It is possible to increase the photoelectric conversion efficiency of the organic solar cell by forming more photocharge than the conventional donor material.

The donor and acceptor polymers should be mixed well enough, and the donor and acceptor polymers should be located within about 10 nm of the distance where the excitons of the P3HT polymer formed by absorbing light can diffuse. The crystallinity of the polymer of the donor and acceptor materials upon charge separation affects the movement of holes to the anode and the movement of electrons to the cathode. Therefore, the introduction of the rare earth ion-doped upward energy transfer nanoparticles into the active layer affects the degree of crystallization between the donor and the acceptor material, which further activates the charge separation phenomenon, thereby improving the light conversion efficiency of the organic solar cell. Can be increased.

In addition, the upward energy transfer nanoparticles doped with the rare earth ions may be introduced into the hole transport layer as well as the active layer of the organic solar cell. When the upstream energy transfer nanoparticles are introduced into the hole transport layer, it may play a role of hole transport and wavelength conversion of near-infrared sunlight.

The upward energy transfer nanoparticles doped with rare earth ions in the matrix may form a core-shell structure. The core (core) layer of the rare earth ions are Er ^{3 +} ions and activation of one member selected from the group consisting of Tm ^{3+ + 3} and Yb, Nd ^{+ 3,} Dy ^{+ 3,} and one member selected from the group consisting of Sm ^{3 +} Ln includes a ^{3 +,} wherein the rare earth ion of the shell (shell) layer is Tm ^3+, Dy ^{3 + 3 +} 1 and Ho jong active ion and Yb ^{+ 3,} selected from the group consisting of Nd ^3+, Dy ³⁺ and a ^{3 +} Ln one member selected from the group consisting of Sm ^{3 +.} For the upstream energy nanoparticles in the core layer, we use activating ions that can convert wavelengths into light in the green region, and for the upstream energy nanoparticles in the shell layer, we use activating ions that can convert wavelength into light in the blue region. Can be improved. 5 shows the structure of the upstream energy transfer nanoparticles of the core-shell structure as described above.

The upstream energy transfer nanoparticles may form a core-shell structure by being surrounded by a crystal composed of one type selected from compounds represented by the following Chemical Formulas 1 to 6 through a sol-gel process to protect from the surrounding environment.

[Formula 1]

(In Formula 1, m and n are each an integer of 1 to 10.)

[Formula 2]

(P in Formula 2 is an integer of 1 to 10.)

(3)

(In Formula 3, q is an integer of 1 to 10.)

[Formula 4]

[Chemical Formula 5]

(In Formula 5, r and s are integers of 1 to 10.)

[Formula 6]

 (In Formula 6, R is a phenyl group or a C1-C5 alkylene group, R 'is a C1-C5 alkyl group.)

FIG. 6 shows the structure of the uplink energy transfer nanoparticles having a core-shell structure surrounded by a compound represented by Chemical Formula 6 through a sol-gel process.

In addition, the upward energy transfer nanoparticles may be supported with gold (Au) or silver (Ag) on the surface. Surface plasmons refer to the collective vibration of electrons on the surface of a metal film. The resulting surface plasmon waves are surface electromagnetic waves propagating along the interface between the metal and the dielectric, and the metal exhibiting the surface plasmon phenomenon is easy to emit pendulum by external stimuli such as gold, silver, copper, and aluminum, and has a negative dielectric constant. Metals are given and used. Among them, silver (Ag) showing the sharpest surface plasmon resonance peak and gold (Au) showing excellent surface stability are commonly used depending on the emission wavelength. Therefore, in the present invention, in order to maximize the surface plasmon resonance phenomenon by loading gold (Au) or silver (Ag) on the surface of the upward energy transfer nanoparticles, the upward energy transfer nanoparticles are surfaced with a multidentate ligand. After coating to impart hydrophilic properties, gold (Au) or silver (Ag) may be supported on the surface. The multidentate ligands used herein include polyacrylic acid (PAA), polymethyl methacrylate (PMMA) and polyallylamine hydrochloride (poly (allylamine hydrochloride, PAH)). 7 shows the structure of the upward energy transfer nanoparticles in which the surface was coated with a multidentate ligand and then supported with gold (Au) or silver (Ag) on the surface.

The upward energy transfer nanoparticles may be fabricated into a film and included in any one of the layers between the anode and the hole transport layer, the layers between the hole transport layer and the active layer, and between the layers of the active layer and the cathode.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, these Examples are only for illustrating the present invention, and the scope of the present invention will not be construed as being limited by these Examples.

Example : Rare earth ion Doped  Upward Energy Transfer Nanoparticle Fabrication

The reagents used to prepare the upstream energy transfer nanoparticles were all purchased from Sigma-Aldrich. YCl ₃ (0.8 mmol), YbCl ₃ (0.18 mmol) and ErCl ₃ (0.02 mmol) were added to a 50 mL three necked flask in a glove box, followed by 6 mL of oleic acid as a surfactant and octane as a solvent. 15 mL of decene (octadecene) was added to the reaction solution. Thereafter, the reaction solution was reacted by stirring at 160 ° C. for 1 hour under a nitrogen atmosphere. After the reaction, the heated flask was cooled to room temperature (25 ° C.), and methanol containing NaOH (2.5 mmol) and NH ₄ F (4 mmol) was slowly added thereto, followed by stirring at room temperature (25 ° C.) for 30 minutes. Thereafter, the reaction solution was heated to 100 ° C. to remove methanol, and then reacted at 300 ° C. for 1 hour under a nitrogen atmosphere. After the reaction was repeated three or more times to remove the solvent in a centrifuge using water and ethanol and dried for 24 hours in an oven at 60 ℃ NaYF ₄ : Yb, Er nanoparticles were prepared.

Figure 8 (a) and (b) is a photograph of NaYF ₄ : Yb, Er nanoparticles prepared in the above Example by TEM (Transmission Electron Microscope), (c) NaYF ₄ prepared in the above example: EDAX analysis results of Yb, Er nanoparticles and (d) show photographs of NaYF ₄ : Yb, Er nanoparticles prepared in the above example in hexane solution under excitation of near infrared laser. As shown in (d) of FIG. 8, the NaYF ₄ : Yb, Er nanoparticles prepared in the example were found to convert wavelength into light in the green region.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (12)

An organic solar cell comprising an anode, a hole transport layer, an active layer, and a cathode, wherein the hole transport layer or the active layer comprises upward energy transfer nanoparticles doped with rare earth ions in a matrix.
The method of claim 1,
The rare-earth ions comprises an Ln ^{3 +} selected one member from the group consisting of Er ^{3 +} and Tm ^{3 +} one member activating ions and ^{Yb 3 +, Nd 3 +,} Dy 3 + and Sm ^{3 +,} selected from the group consisting of An organic solar cell characterized by the above.
The method of claim 2,
The activation ion is an organic solar cell, characterized in that it has a mole fraction of 1 to 5 with respect to the upward energy transfer nanoparticles.
The method of claim 2,
The Ln ^{3 +} is an organic solar cell, characterized in that it has a mole fraction of 10 to 30 relative to the upward energy transfer nanoparticles.
The method of claim 1,
The matrix is an organic solar cell, characterized in that one selected from the group consisting of YF ₃ , NaYF ₄ , KY ₃ F ₁₀ , LuPO ₄ and YbPO ₄ .
The method of claim 1,
The upstream energy transfer nanoparticles doped with rare earth ions in the matrix form a core-shell structure.
The method according to claim 6,
The rare earth ions of the core layer are one of ions selected from the group consisting of Er ^{3 +} and Tm ^{3 +} , and Ln is one selected from the group consisting of Yb ^{3 +} , Nd ^{3 +} , Dy ^{3 +,} and Sm ^{3 +} . An organic solar cell comprising ^{3 +} .
The method according to claim 6,
Rare earth ions of the shell layer is a group consisting of one active ion selected from the group consisting of Tm ^{3 +} , Dy ^{3 +} and Ho ^{3 +} and Yb ^{3 +} , Nd ^{3 +} , Dy ^{3 +} and Sm ^{3 +} An organic solar cell comprising one or more selected from Ln ^{3 +} .
The method of claim 1,
The upward energy transfer nanoparticle is an organic solar cell, characterized by a core-shell structure surrounded by a crystal composed of one selected from the compounds represented by Formulas 1 to 6 below.
[Formula 1]

(In Formula 1, m and n are each an integer of 1 to 10.)
(2)

(P in Formula 2 is an integer of 1 to 10.)
(3)

(In Formula 3, q is an integer of 1 to 10.)
[Chemical Formula 4]

[Chemical Formula 5]

(In Formula 5, r and s are integers of 1 to 10.)
[Formula 6]

(In Formula 6, R is a phenyl group or a C1-C5 alkylene group, R 'is a C1-C5 alkyl group.)
The method of claim 1,
The upward energy transfer nanoparticles are organic solar cells, characterized in that the surface is supported with gold (Au) or silver (Ag).
The method of claim 10,
The upward energy transfer nanoparticles are coated with one selected from the group consisting of polyacrylic acid (PAA), polymethyl methacrylate (PMMA), and polyallylamine hydrochloride (PAH). Organic solar cell, characterized in that.
The method of claim 1,
The upward energy transfer nanoparticles are fabricated as a film to be included in any one of the layers between the positive electrode and the hole transport layer, between the hole transport layer and the active layer, and between the active layer and the cathode layer.

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