KR20170114853A - photoactive layer for photovoltaic cell, photovoltaic cell including thereof, and manufacturing method thereof - Google Patents

Abstract

The photoactive layer for a solar cell of the present invention includes a first photoactive layer including a quantum dot, an intermediate layer disposed on the first photoactive layer and having a first metal oxide layer / a metal layer / a second metal oxide layer sequentially stacked, And a second photoactive layer including a conjugated polymer and a fullerene derivative so as to improve the interface characteristics and the degree of matching between the photoactive layers having different absorption bands, The efficiency can be improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoactive layer for a solar cell, a solar cell including the same, and a method of manufacturing the same,

The present invention relates to a solar cell, and more particularly, to a photoactive layer for a solar cell, a solar cell including the same, and a method of manufacturing the same.

Recently, as interest in alternative energy development has increased, much research has been done on solar cell development. A solar cell is a semiconductor device that converts light energy directly into electrical energy. It consists of two or more layers of semiconductor material that absorb light. In the solar cell, when a semiconductor diode forming a p-n junction is irradiated with light, a photon is absorbed to generate an electron / hole pair, and a potential difference is generated at a junction of two different materials.

Solar cells can be classified into inorganic solar cells or organic solar cells according to the material of the photoactive layer. Conventionally, most of the solar cells are monocrystalline or polycrystalline silicon solar cells. However, recently, unstable supply of silicon materials has intensified, and high cost problems have arisen due to unbalanced supply and demand, and a new solar cell is being developed to replace them.

On the other hand, a tandem solar cell has a structure in which two or more materials having different optical bandgaps are formed. The tandem solar cell includes a semiconductor layer (Top cell) including a material having a wide bandgap near the incident surface of light and a material having a relatively narrow bandgap at a portion far from the incident surface of the light And a structure in which a semiconductor layer (bottom up) is inserted.

As an alternative to such a solar cell, research has been conducted on an organic / inorganic composite tandem solar cell having a heterojunction structure in which an organic material and an inorganic material are mixed. The organic / inorganic hybrid tandem solar cell has the advantages of improving the photoelectric conversion efficiency and service life of the solar cell by complementing the disadvantages of the organic and inorganic materials.

However, the tandem solar cell efficiently absorbs the spectrum of sunlight by using the photoactive layer having a different absorption band, thereby improving the photoelectric conversion efficiency of the solar cell. However, it is difficult to improve the photoelectric conversion efficiency merely by merely combining the photoactive layer having different absorption bands. Therefore, there is an urgent need to develop a tandem solar cell capable of improving the photoelectric conversion efficiency of a solar cell by improving the interface characteristics and degree of matching between the photoactive layers having different absorption bands.

KR 2011-0036185 A

The present invention has been devised to solve the problems described above, and it is an object of the present invention to provide a photoactive layer for a solar cell capable of improving the photoelectric conversion efficiency of a solar cell by improving the interface characteristics and the degree of matching between the photoactive layers having different absorption bands, , A solar cell including the same, and a method of manufacturing a solar cell including the same.

In order to solve the above problems, the present invention provides a photoactive layer for a solar cell, comprising: a first photoactive layer including quantum dots; An intermediate layer disposed on the first photoactive layer and including a first metal oxide layer, a metal layer, and a second metal oxide layer sequentially stacked; And a second photoactive layer disposed on the intermediate layer and comprising a conjugated polymer and a fullerene derivative.

In one preferred embodiment of the present invention, the first photoactive layer and the second photoactive layer may be connected in series.

In one preferred embodiment of the present invention, the quantum dot may include at least one selected from the group consisting of PbS, PbSe, PbTe, CdS, CdSe, InP, InAs and CdTe.

In one preferred embodiment of the present invention, the quantum dot is PbS, and the PbS is a thioalkyl sulfanyl group, a tetra (alkyl) salt, an iodide ion, At least one selected from the group consisting of bromide ion and chloride ion may be bonded to the surface as a ligand.

In one preferred embodiment of the present invention, the conjugated polymer includes at least one member selected from the group consisting of one or other n-type polymers in the p-type polymer group including PTB7, P3HT and PCDTBT, , PC ₇₁ BM, C ₆₀ .

In a preferred embodiment of the present invention, the conjugated polymer may be PTB7 and the fullerene derivative may be PC ₇₁ BM.

In one preferred embodiment of the present invention, the weight ratio of the conjugated polymer to the fullerene derivative may be 1: 1-2.

In one preferred embodiment of the present invention, the thickness of the first photoactive layer is 60 to 100 nm, and the thickness of the second photoactive layer is 70 nm or more.

In one preferred embodiment of the present invention, the first metal oxide layer and the second metal oxide layer may have a thickness of 10 to 30 nm and the metal layer may have a thickness of 0.1 to 3.0 nm.

In one preferred embodiment of the present invention, the thickness of the metal layer may be 0.5 to 1.5 nm.

In a preferred embodiment of the present invention, the first metal oxide layer includes MoO _x , the metal layer includes Au, and the second metal oxide layer may include ZnO.

Another aspect of the present invention relates to a solar cell, comprising: a first electrode; A photoactive layer disposed on the first electrode for the quantum dot-organic material composite tandem solar cell of the present invention; And a second electrode disposed on the photoactive layer.

As a preferred embodiment of the present invention, an electron transport layer may be further disposed between the first electrode and the photoactive layer.

Another aspect of the present invention relates to a method of manufacturing a photoactive layer for a solar cell, comprising: forming a first photoactive layer including quantum dots; Forming an intermediate layer by sequentially laminating a first metal oxide layer, a metal layer, and a second metal oxide layer on the first photoactive layer; And forming a second photoactive layer including a conjugated polymer and a fullerene derivative on the intermediate layer.

In a preferred embodiment of the present invention, the first metal oxide layer includes MoOx, the metal layer includes Au, and the second metal oxide layer may include ZnO.

According to a preferred embodiment of the present invention, the forming the first photoactive layer may include: coating a solution containing a PbS quantum dot on the first electrode to form a PbS quantum dot layer; Immersing the PbS quantum dot layer in a ligand solution containing EDT (1,2-Ethanedithiol) solution and TBAI (tetrabutylammonium iodide) solution to bind the ligand on the surface of the PbS quantum dot layer; And washing the ligand bound PbS quantum dot layer.

In one preferred embodiment of the present invention, the concentration molar ratio of the EDT (1,2-Ethanedithiol) solution and the TBAI (tetrabutylammonium iodide) solution may be 1: 0.1-10.

As a preferred embodiment of the present invention, the step of forming the first photoactive layer, the step of forming the intermediate layer, and the step of forming the second photoactive layer may be performed by a spin coating method, a slit coating method a solution containing at least one selected from the group consisting of a coating, a drop casting, a dip casting, an ink jet, a printing, and an imprint Process. ≪ / RTI >

As a preferred embodiment of the present invention, the step of forming the first photoactive layer and the step of forming the second photoactive layer may be performed at a temperature of 20 to 30 캜 and a pressure of atmospheric pressure.

In one preferred embodiment of the present invention, the weight ratio of the conjugated polymer to the fullerene derivative may be 1: 1 to 2 in the step of forming the second photoactive layer.

Another aspect of the present invention provides a method for manufacturing a quantum dot-organic composite tandem solar cell. The method includes: preparing a first electrode; Forming an electron transport layer on the first electrode by a sol-gel process; Forming a photoactive layer on the electron transporting layer by the method for manufacturing a photoactive layer for a solar cell according to the present invention; And forming a second electrode on the photoactive layer.

According to the photoactive layer for a solar cell, the solar cell including the same, and the manufacturing method thereof according to the present invention, it is possible to improve the photoelectric conversion efficiency of the solar cell by improving the interface characteristics and the degree of matching between the photoactive layers having different absorption bands There is an effect.

1 is a schematic view (a) and a sectional SEM photograph (b) of a solar cell according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals designate like elements throughout the specification.

First, a photoactive layer for a solar cell according to an embodiment of the present invention will be described.

The photoactive layer for a solar cell according to an embodiment of the present invention includes a first photoactive layer, an intermediate layer disposed on the first photoactive layer, and a second photoactive layer disposed on the intermediate layer.

The first photoactive layer includes a quantum dot. The quantum dot may include at least one selected from the group consisting of PbS, PbSe, PbTe, CdS, CdSe, InP, InAs and CdTe. Also preferably, the quantum dot is PbS and the PbS may be a colloidal quantum dot. In the case of PbS, since the interface characteristics with the intermediate layer and the second photoactive material, which will be described later, are excellent, the photoelectric conversion efficiency can be further improved. When the PbS is a colloidal quantum dot, the quantum dots are uniform in size and electrical characteristics can be improved.

The PbS has a surface on which a thioalkyl sulfanyl group, a tetra (alkyl) salt, an iodide ion, a bromide ion, and a chloride ion ion) may be ligand-bonded. The alkyl group of thioalkylsulfanyl may be any one of C1 to C5, preferably C1 to C3, and more preferably C2. The alkyl group of the tetraalkylammonium salt may be any one of C1 to C5, preferably C4 to C5, and more preferably C4.

At this time, the PbS quantum dots include the thioalkyl sulfanyl group, the tetra (alkyl) salt, the iodide ion, the bromide ion, and the chloride ion ion may be contained on the surface in a molar ratio of 1: 0.1 to 10, and preferably in a molar ratio of 1: 0.2 to 3. When the functional group or salt is contained at the above-mentioned molar ratio, the short circuit current density, open voltage, performance index and power conversion efficiency in the solar cell including the same may be improved.

At this time, the PbS quantum dot may have an average particle diameter of 1 nm to 20 nm, preferably 2 nm to 8 nm. When the particle diameter of the PbS quantum dots is less than 1 nm, there is a problem that uniform preparation is difficult, and even when the PbS quantum dots exceed 20 nm, uniform production and dispersion are difficult.

The thickness of the first photoactive layer may be 60 to 100 nm. If the thickness of the photoactive layer is less than 60 nm, the light absorption may be limited, and if it exceeds 100 nm, the electron transport efficiency may be lowered.

Next, the intermediate layer is formed by stacking a first metal oxide layer, a metal layer, and a second metal oxide layer. The intermediate layer is disposed between the first photoactive layer and the second photoactive layer, which have different light absorption bands, to improve the interface characteristics and the degree of matching between the first photoactive layer and the second photoactive layer, Thereby improving the photoelectric conversion efficiency. In addition, the first photoactive layer and the second photoactive layer are electrically connected in series.

The first metal oxide layer serves to prevent impurities from diffusing from the first photoactive layer into a second photoactive layer, which will be described later. The first metal oxide layer may comprise MoO _x .

At this time, the thickness of the first metal oxide layer may be 10 to 30 nm, and more preferably 15 to 25 nm. When the thickness of the first metal oxide layer is less than 10 nm, the first metal oxide layer may have a small effect of preventing impurities from diffusing from the first photoactive layer into a second photoactive layer described later. When the thickness is more than 30 nm When applied to solar cells, lightening may be difficult.

The metal layer amplifies light of a specific wavelength between the first photoactive layer and the second photoactive layer to absorb light in a wide wavelength band, thereby improving the photoelectric conversion efficiency. The metal layer may comprise a highly reflective metal, and the highly reflective metal may comprise Au.

The thickness of the metal layer may be 0.1 to 3.0 nm, more preferably 0.5 to 1.5 nm. When the thickness of the metal layer is less than 0.1 nm or exceeds 3.0 nm, it may be difficult to make the light-weighting thin when applied to a solar cell.

The second metal oxide layer enhances transmission of light between the first photoactive layer and the second photoactive layer. The second metal oxide layer may include a metal oxide having a high permeability index, and may preferably include ZnO.

At this time, the thickness of the second metal oxide layer may be 10 to 30 nm, more preferably 15 to 25 nm. If the thickness of the second metal oxide layer is less than 10 nm, the effect of enhancing the transmission of light between the first photoactive layer and the second photoactive layer may be insignificant. If the thickness is more than 30 nm, .

Wherein the intermediate layer has an optical property improving property when applied to a solar cell when the first metal oxide layer contains MoO _x and the metal layer contains Au and the second metal oxide layer contains ZnO, Thereby balancing the improvement of the electrical characteristics.

The second photoactive layer may be an organic photoactive layer including an organic material. Accordingly, since the second photoactive layer absorbs light in a wavelength band different from that of the first photoactive layer including quantum dots, it can absorb light in a wide wavelength band when applied to a solar cell.

The second photoactive layer includes a conjugated polymer and a fullerene derivative. The conjugated polymer includes at least one selected from the group consisting of one or other n-type polymers in the p-type polymer group including PTB7, P3Ht and PCDTBT. The fullerene derivative includes PCBM, PC ₇₁ BM, C ₆₀ Lt; / RTI > Preferably, the conjugated polymer is PTB7, and the fullerene derivative may be PC ₇₁ BM. In this case, the interface between the first photoactive layer and the second photoactive layer may be more excellent.

The weight ratio of the conjugated polymer to the fullerene derivative may be 1: 1-2. If the weight ratio of the conjugated polymer to the fullerene derivative is less than 1: 1 or exceeds 1: 2, the photoelectric conversion efficiency of the second photoactive layer may be insignificant.

The thickness of the second photoactive layer may be 70 nm or more. When the thickness of the second photoactive layer is less than 70 nm, it may be difficult to make it light in application to a solar cell.

Hereinafter, the method of manufacturing the photoactive layer for a solar cell will be described.

A method of manufacturing a photoactive layer for a solar cell according to an embodiment of the present invention includes the steps of forming a first photoactive layer including quantum dots, forming a first metal oxide layer, a metal layer, and a second metal oxide layer Sequentially forming a second photoactive layer on the intermediate layer, the second photoactive layer including a conjugated polymer and a fullerene derivative.

The first photoactive layer may be formed on a substrate when applied to a solar cell. The quantum dot used in the step of forming the first photoactive layer is the same as the quantum dot included in the first photoactive layer described above, so that the above description will be referred to. The step of forming the first photoactive layer may be performed by a solution process. The solution process may be carried out by spin coating, slit coating, drop casting, dip casting, ink jet printing, printing, and imprinting. And imprint. The term " a "

When the quantum dot is PbS, the PbS particles are coated on the electrode by the solution process. Subsequently, the ligand can be bound on the surface of the PbS quantum dot-formed layer by immersion in a ligand solution containing EDT (1,2-Ethanedithiol) solution and TBAI (tetrabutylammonium iodide) solution. At this time, the concentration of EDT in the EDT solution may be 1 mM to 1 M, more preferably 5 mM to 15 mM. When the concentration of EDT is less than 1 mM, it is difficult to control the concentration accurately. When the concentration exceeds 1 M, it is difficult to remove residual EDT.

In addition, the concentration of TBAI in the TBAI solution may be 0.1 mM to 5 M, and more preferably 10 mM to 50 mM. When the concentration of the TBAI is less than 0.1 mM, it is difficult to control the concentration accurately, and when the concentration exceeds 5 M, it is difficult to remove the residual TBAI.

The concentration of the ligand solution containing EDT (1,2-Ethanedithiol) solution and TBAI (tetrabutylammonium iodide) solution is preferably 1 to 20 mM, more preferably 2 to 8 mM. The characteristics of the quantum dot semiconductor layer can be determined according to the concentration of the ligand solution even when the mixing ratio of the two kinds of solutions is maintained.

At this time, the ligand solution may contain EDT solution and TBAI solution in a molar ratio of 1: 0.1 to 10, more preferably 1: 3.5 to 4. The ligand solution can improve the short circuit current density, the open-circuit voltage, the performance index, and the power conversion efficiency in the solar cell including the EDT solution and the TBAI solution at the above-mentioned molar ratio.

Thereafter, the method may further include washing and drying the ligand-bound PbS.

Next, the step of forming the intermediate layer on the first photoactive layer may be performed by sequentially laminating the first metal oxide layer, the metal layer, and the second metal oxide layer. The first metal oxide layer, the metal layer, and the second metal oxide layer forming material used herein are the same as the first metal oxide layer, the metal layer, and the second metal oxide layer material described above, so that the above description will be referred to.

The step of forming the first metal oxide layer on the first photoactive layer may be performed by a solution process. The solution process may be carried out by spin coating, slit coating, drop casting, dip casting, ink jet printing, printing, and imprinting. And imprint. The term " a "

The forming of the metal layer on the first metal oxide layer may be performed by thermally depositing the metal layer material on the first metal oxide layer. At this time, the deposition temperature is 150 占 폚 or lower and can be performed for 1 minute to 30 minutes.

Next, the step of forming the second metal oxide layer on the metal layer may be performed by a solution process as in the first metal oxide layer forming step described above.

Through such a process, an intermediate layer in which a first metal oxide layer, a metal layer, and a second metal oxide layer are stacked in this order on the first photoactive layer can be formed.

Next, the step of forming the second photoactive layer on the intermediate layer will be described.

The material used for forming the second photoactive layer will be described in detail with reference to the description of the second photoactive layer. The second photoactive layer forming step may be performed by a solution process similar to the first photoactive layer forming step. The solution process may be carried out by spin coating, slit coating, drop casting, dip casting, ink jet printing, printing, and imprinting. And imprint. The term " a "

The step of forming the first photoactive layer and the step of forming the second photoactive layer may be performed at a temperature of 20 to 30 캜 and a pressure of atmospheric pressure as they are performed through a solution process. As the low temperature and atmospheric pressure processes are possible, the process is simplified. Further, it is possible to prevent the mechanical or electrical characteristics of the first photoactive layer or the second photoactive layer from being degraded by the high temperature and the high pressure during the formation of the first photoactive layer or the second photoactive layer.

A quantum dot-organic composite tandem solar cell according to another embodiment of the present invention will be described.

The solar cell includes a first electrode, a photoactive layer disposed on the first electrode, and a second electrode disposed on the photoactive layer.

The first electrode may be formed of one selected from the group consisting of indium tin oxide (ITO), fluorine doped tin oxide (FTO), aluminum doped zinc oxide (AZO), indium gallium zinc oxide (IGZO), glass, polyethylene terephthalate (PET), polyethylene naphthalate , And a polyimide, and may be an ITO substrate.

A detailed description of the photoactive layer will be made in reference to the above description.

At this time, an electron transfer layer may be further included between the first electrode and the photoactive layer. The electron transport layer may include at least one n-type semiconductor selected from the group consisting of ZnO, TiO ₂ , SnO ₂ , ITO and derivatives thereof, preferably ZnO.

Wherein the second electrode is selected from the group consisting of silver, gold, aluminum, copper, indium tin oxide (ITO), fluorine doped tin oxide (FTO), aluminum doped zinc oxide (AZO), and indium gallium zinc oxide And may be an electrode including at least one kind of silver, preferably a silver electrode.

A method of manufacturing a quantum dot-organic composite tandem solar cell according to another embodiment of the present invention will be described.

A method of fabricating a quantum dot-organic composite tandem solar cell according to an embodiment of the present invention includes the steps of preparing a first electrode, forming a photoactive layer on the first electrode, and forming a first electrode .

The first electrode uses the same material as the first electrode described above, so that the above description will be referred to. In addition, the step of forming the photoactive layer on the first electrode will be described with reference to the above description.

The method may further include forming an electron transport layer on the first electrode between the step of preparing the first electrode and the step of forming the photoactive layer. The step of forming the electron transport layer may be performed by a sol-gel process. When the electron transport layer is formed by the sol-gel process, the electron transfer effect can be further improved. Thus, the photoelectric conversion efficiency can be improved.

The second electrode material used in the step of forming the second electrode on the photoactive layer is the same as the second electrode, so that the above description will be referred to. The forming of the second electrode may be performed without limitation as long as it is a known technique for forming an electrode. For example, the second electrode may be formed using a shadow mask, but is not limited thereto.

1 is a schematic view (a) and a sectional SEM photograph (b) of a solar cell according to an embodiment of the present invention.

1, a solar cell according to an embodiment of the present invention includes a first photoactive layer (PbS-CQD) including quantum dots, an intermediate layer (MoO _x / Au / ZnO-np) 2 photoactive layer (PTB7-Th / PC ₇₁ BM) are stacked in a tandem shape. Also, referring to the SEM photograph, it can be seen that each layer is uniformly formed.

Hereinafter, exemplary embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are intended to aid understanding of the present invention, and the present invention is not limited by the following experimental examples.

≪ Preparation Example 1 - Preparation of a quantum dot solution >

PbO (0.94 g, 99.99%, Sigma-Aldrich) and oleic acid (1-octadecene, 20 mL, ODE, technical grade 90%, Sigma-Aldrich) dissolved and degassed at 100 & oleic acid, 3 mL, technical grade 90%, Sigma-Aldrich) was prepared.

Thereafter, the temperature was raised to 115 ° C., and sulfur formed by TMS2-S (360 ° L, synthetic grade hexamethyldisilathiane, Sigma-Aldrich) and ODE (10 mL) was rapidly injected under an atmosphere of N ₂ gas.

After 1-2 seconds, toluene (20 mL) was injected for thermal quenching. The mixed flask was then cooled in a bath to form colloidal PbS quantum dots.

Thereafter, the colloidal PbS quantum dots were purified and extracted with acetone, and then dispersed in toluene.

The colloidal PbS quantum dots were then mixed with methanol and washed twice or three times with a centrifuge. Thereafter, a drying process for evaporating methanol was carried out, and the dried colloidal PbS quantum dots were dissolved in octane at a concentration of 40 mg / mL to prepare a quantum dot layer forming solution.

≪ Preparation Example 1 - Production of solar cell >

The ZnO electron transport layer was coated on the ITO transparent electrode using a sol-gel process at a temperature of 150 DEG C or less for 20 minutes. Then, the quantum dot layer forming solution prepared in Preparation Example 1 was coated on the electron transport layer through a spin coating process. Then, the coated quantum dot layer was coated with tetrabutylammonium iodide (10 mg / mL) dissolved in methanol and 1,2-ethanedithiol dissolved in acetonitrile at a concentration of 2 mM , EDT, GC > 98%, Fluka) were sequentially subjected to ligand substitution of the colloidal PbS quantum dots to form a 85 nm thick first photoactive layer.

Thereafter, MoO _x and Au were sequentially deposited on the first photoactive layer at a pressure of 10 ^-6 Torr or less at a thickness of 20 nm and 1 nm, and then a solution (22 mg / cm 2) containing ZnO nanoparticles was formed on the Au layer. mL) was spin-coated (4000 RPM) and dried at room temperature to form a 20 nm thick ZnO layer. Thus, an intermediate layer laminated in the form of MoO _x / Au / ZnO was formed on the first photoactive layer.

Thereafter, PTB7 and PC ₇₁ BM at a concentration of 20 mg / mL were mixed at a weight ratio of 1: 1.5 to prepare an organic material mixture. Then, a spin-coating process was applied to the intermediate layer to form a second photoactive layer having a thickness of 95 nm.

Finally, an Ag electrode was thermally deposited on the second photoactive layer through a shadow mask on the second photoactive layer at a pressure of 10 ^-6 Torr or less. The immersed Ag electrode exhibited an active area of 7.1 mm ² .

≪ Production Examples 2 to 6 >

A solar cell was manufactured in the same manner as in Preparation Example 1 except that the thicknesses of the first photoactive layer and the second photoactive layer were changed as shown in Table 1 below.

≪ Comparative Production Examples 1 to 6 >

Except that an intermediate layer and a second photoactive layer were not formed, and a second electrode was formed on the first photoactive layer after the first photoactive layer alone was formed on the first electrode. Further, as shown in Table 1, the solar cell was manufactured with different thicknesses of the first photoactive layer.

≪ Comparative Production Examples 7 to 10 >

Except that the first photoactive layer and the intermediate layer were not formed, only the second photoactive layer was formed on the first electrode, and then the second electrode was formed on the second photoactive layer. Further, as shown in Table 1 below, a solar cell was manufactured with different thicknesses of the second photoactive layer.

EXPERIMENTAL EXAMPLE 1 Measurement of light conversion efficiency characteristics according to the composition and thickness of the photoactive layer [

The power conversion efficiency (PCE), the open circuit voltage (V _oc ), and the short-circuit current density of the solar cells prepared in the above-mentioned Production Examples 1 to 7 and Comparative Production Examples 1 to 10 current density, J _sc ) and fill factor (FF) were measured and are shown in Table 1 below.

division Laminated form The thickness (nm) of the first photoactive layer The thickness (nm) of the second photoactive layer PCE
(%) V _oc
(V) J _sc
(mA / cm ² ) FF Production Example 1 A / B / C 85 95 8.27 1.30 10.36 0.63 Production Example 2 A / B / C 60 95 6.55 1.30 7.32 0.69 Production Example 3 A / B / C 75 95 7.37 1.30 8.70 0.65 Production Example 4 A / B / C 100 95 7.43 1.29 9.09 0.64 Production Example 5 A / B / C 85 105 7.81 1.31 9.79 0.62 Production Example 6 A / B / C 85 80 7.49 1.28 8.82 0.66 Comparative Preparation Example 1 A 280 - 6.34 0.56 24.04 0.48 Comparative Production Example 2 A 220 - 5.85 0.54 21.23 0.51 Comparative Production Example 3 A 160 - 6.01 0.59 17.53 0.59 Comparative Production Example 4 A 100 - 4.90 0.55 15.00 0.59 Comparative Preparation Example 5 A 85 - 4.39 0.54 14.10 0.58 Comparative Preparation Example 6 A 75 - 4.22 0.57 12.38 0.60 Comparative Preparation Example 7 C - 105 7.82 0.79 16.44 0.60 Comparative Preparation Example 8 C - 95 8.33 0.79 17.20 0.62 Comparative Preparation Example 9 C - 80 8.61 0.80 16.90 0.64 Comparative Preparation Example 10 C - 60 8.87 0.79 16.88 0.66 A: the first photoactive layer
B: middle layer
C: Second photoactive layer

Referring to Table 1, as the solar cells of Production Examples 1 to 6 in which the first photoactive layer including quantum dots, the intermediate layer, and the second photoactive layer containing an organic material are laminated are improved in optical characteristics and electrical characteristics It can be seen that the photoelectric conversion efficiency characteristics are excellent.

On the other hand, in Comparative Production Examples 1 to 6 in which only the first photoactive layer was formed, the short circuit current density value was high, but the photoelectric conversion efficiency was lowered. Therefore, when only the first photoactive layer is formed, the electrical characteristics are improved but the optical characteristics are lowered, so that the photoelectric conversion efficiency is actually lowered.

Further, in Comparative Production Examples 7 to 10 in which the second photoactive layer was formed only, the photoelectric conversion efficiency values were similar to those of Production Examples 1 to 6, but the open circuit voltage value was lower.

As a result, it can be seen that the electric characteristics and the optical characteristics of the solar cell according to the embodiment of the present invention are improved in a balanced manner.

≪ Preparation Examples 7 to 8 &

A solar cell was manufactured in the same manner as in Production Example 1 except that the thickness of the Au layer in the intermediate layer was changed as shown in Table 1 below.

<Comparative Production Example 11>

A solar cell was manufactured in the same manner as in Production Example 1 except that an intermediate layer in the form of a stacked layer of MoO _x / ZnO was formed without forming an Au layer when the intermediate layer was formed .

EXPERIMENTAL EXAMPLE 2 Measurement of light conversion efficiency characteristics according to the thickness of the metal layer of the intermediate layer [

The power conversion efficiency (PCE), the open circuit voltage (Voc), the short-circuit current density (short-circuit current) of the solar cell manufactured in Examples 1, 7 and 8, density, Jsc) and fill factor (FF) were measured and shown in Table 2 below.

division Lamination type of intermediate layer Thickness of metal layer (nm) PCE (%) V _oc (V) J _sc (mA / cm ² ) FF Production Example 1 a / b / c One 8.27 1.30 10.36 0.63 Production Example 7 a / b / c 0.5 7.25 1.29 9.24 0.61 Production Example 8 a / b / c 2 7.28 1.26 8.85 0.66 Comparative Production Example 11 a / c 0 5.35 1.21 8.77 0.50 a: a first metal oxide layer
b: metal layer
c: a second metal oxide layer

Referring to Table 2, it can be seen that Examples 1, 7, and 8 in which a metal layer is formed on the intermediate layer have excellent electrical characteristics and optical characteristics as compared with Comparative Preparation Example 11 in which no metal layer is formed on the intermediate layer.

In particular, in the case of Production Example 1 in which the thickness of the metal layer is 1 nm, the electrical characteristics and the optical characteristics are the most excellent.

As a result, the solar cell according to an embodiment of the present invention includes a first photoactive layer including a quantum dot and an organic material, including an intermediate layer in which a first metal oxide, a metal layer, and a second metal oxide layer are stacked It is possible to improve the electrical and optical characteristics by improving the interface characteristics between the first and second photoactive layers.

<Comparative Production Example 12>

ZnO nanoparticles were spin-coated on the first electrode instead of the sol-gel process in the preparation of the ZnO electron transport layer, followed by drying to form a ZnO electron transport layer, A battery was produced.

&Lt; Experimental Example 2 - Measurement of light conversion efficiency characteristics by electron transport layer forming process >

The power conversion efficiency (PCE), the open circuit voltage (Voc), the short-circuit current density (Jsc), the fill factor (fill factor, FF) were measured and shown in Table 3 below.

division PCE (%) V _oc (V) J _sc (mA / cm ² ) FF Production Example 1 8.27 1.30 10.36 0.63 Comparative Preparation Example 12 7.64 1.30 9.24 0.64

Referring to Table 3, it can be seen that the photoelectric conversion effect of Preparation Example 1 using a sol-gel process is superior to that of Comparative Preparation Example 12 using a solution process in forming an electron transport layer.

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. It will be apparent to those skilled in the art that the present invention, Various modifications and variations are possible.

Claims (21)

A first photoactive layer comprising quantum dots;
An intermediate layer disposed on the first photoactive layer and including a first metal oxide layer, a metal layer, and a second metal oxide layer sequentially stacked; And
And a second photoactive layer disposed on the intermediate layer and comprising a conjugated polymer and a fullerene derivative. The method according to claim 1,
Wherein the first photoactive layer and the second photoactive layer are electrically connected in series. The method according to claim 1,
Wherein the quantum dot includes at least one selected from the group consisting of PbS, PbSe, PbTe, CdS, CdSe, InP, InAs, and CdTe. The method of claim 3,
Wherein the quantum dot is PbS and the PbS is selected from the group consisting of a thioalkyl sulfanyl group, a tetra (alkyl) salt, an iodide ion, a bromide ion, wherein at least one selected from the group consisting of chloride ions is bonded to the surface as a ligand. The method according to claim 1,
Wherein the conjugated polymer comprises at least one member selected from the group consisting of PTB7, P3Ht and PCDTBT, wherein the fullerene derivative is at least one member selected from the group consisting of PC ₇₁ BM, PC ₇₁ BM, and C ₆₀ , . 6. The method of claim 5,
Wherein the conjugated polymer is PTB7 and the fullerene derivative is PC ₇₁ BM. The method according to claim 1,
Wherein the weight ratio of the conjugated polymer to the fullerene derivative is 1: 1 to 2. The method according to claim 1,
Wherein the thickness of the first photoactive layer is 60 to 100 nm and the thickness of the second photoactive layer is 70 nm or more. The method according to claim 1,
Wherein the thickness of the first metal oxide layer and the second metal oxide layer is 10 to 30 nm and the thickness of the metal layer is 0.1 to 3.0 nm. 10. The method of claim 9,
Wherein the metal layer has a thickness of 0.5 to 1.5 nm. The method according to claim 1,
Wherein the first metal oxide layer comprises MoO _x , the metal layer comprises Au, and the second metal oxide layer comprises ZnO. A first electrode;
A photoactive layer for a quantum dot-organic material composite tandem solar cell according to any one of claims 1 to 12, which is disposed on the first electrode; And
And a second electrode disposed on the photoactive layer. 13. The method of claim 12,
Organic compound composite tandem solar cell further comprising an electron transport layer disposed between the first electrode and the photoactive layer. Forming a first photoactive layer comprising quantum dots;
Forming an intermediate layer by sequentially laminating a first metal oxide layer, a metal layer, and a second metal oxide layer on the first photoactive layer; And
And forming a second photoactive layer including a conjugated polymer and a fullerene derivative on the intermediate layer. 15. The method of claim 14,
Wherein the first metal oxide layer comprises MoOx, the metal layer comprises Au, and the second metal oxide layer comprises ZnO. 15. The method of claim 14,
Wherein forming the first photoactive layer comprises:
Forming a PbS quantum dot layer by coating a solution containing a PbS quantum dot on the first electrode;
Immersing the PbS quantum dot layer in a ligand solution containing EDT (1,2-Ethanedithiol) solution and TBAI (tetrabutylammonium iodide) solution to bind the ligand on the surface of the PbS quantum dot layer; And
And washing the ligand-bound PbS quantum dot layer. 17. The method of claim 16,
Wherein the concentration molar ratio of the EDT (1,2-Ethanedithiol) solution and the TBAI (tetrabutylammonium iodide) solution is 1: 0.1-10. 15. The method of claim 14,
The step of forming the first photoactive layer, the step of forming the intermediate layer, and the step of forming the second photoactive layer may be performed by spin coating, slit coating, drop casting A photoactive layer for a solar cell, which is carried out by a solution process comprising at least one member selected from the group consisting of a spin coating method, a dip casting method, an ink jet method, a printing method and an imprint method, &Lt; / RTI &gt; 15. The method of claim 14,
Wherein the step of forming the first photoactive layer and the step of forming the second photoactive layer are performed at a temperature of 20 to 30 캜 and a pressure of the atmospheric pressure. 15. The method of claim 14,
Wherein the weight ratio of the conjugated polymer to the fullerene derivative is 1: 1 to 2 in the step of forming the second photoactive layer. Preparing a first electrode;
Forming an electron transport layer on the first electrode by a sol-gel process;
Forming a photoactive layer on the electron transporting layer by the method of manufacturing a photoactive layer for a solar cell according to any one of claims 15 to 20; And
And forming a second electrode on the photoactive layer. The method of manufacturing a quantum dot-organic material composite tandem solar cell,

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