KR102091798B1 - Organic solar cell including of metal nanostructures having regular configuration, and method of preparing the same - Google Patents

Abstract

It relates to an organic solar cell comprising a metal nanostructure having a regular arrangement, and a method of manufacturing the organic solar cell.

Description

An organic solar cell including a metal nanostructure having a regular arrangement, and a manufacturing method therefor {ORGANIC SOLAR CELL INCLUDING OF METAL NANOSTRUCTURES HAVING REGULAR CONFIGURATION, AND METHOD OF PREPARING THE SAME}

The present application relates to an organic solar cell including a metal nanostructure having a regular arrangement, and a method for manufacturing the organic solar cell.

Over the past few decades, organic photovoltaic devices have attracted great attention due to the advantages of low device manufacturing cost, flexibility, and light-weight properties. For useful applications, it has been greatly demanded that the following conditions (conditions) will be met in organic photovoltaic cells: 1) Mixing of semiconductor polymers with higher light absorption coefficients for the development of indoor photovoltaic systems; 2) the use of lightweight materials to increase portability; 3) increase of cell space to obtain higher efficiency; And 4) reduction in device production price. The development of efficient active layers, especially p-type donor polymers, has been a major issue since the active layers mainly affect the overall arrangement and performance of the device. Recently, poly [4,8-bis [(2-ethylhexyl) oxy] benzo [1,2-b: 4,5-bA] dithiophene-2,6-diyl] [3-fluoro-2 -[(2-ethylhexyl) carbonyl] thieno [3,4-b] -thiophendiyl] (poly [4,8-bis [(2-ethylhexyl) oxy] benzo [1,2-b Low bandgap photoactivity such as: 4,5-bA] dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl) carbonyl] thieno [3,4-b] -thiophenediyl], PTB7) Materials have attracted great attention as a result of their ability to absorb a wider range of solar light and the resulting higher photovoltaic performance. However, it has been reported that the external quantum efficiency (EQE) of a device containing low bandgap photoactive materials remains relatively low, which necessitates the use of three-component materials.

In this regard, the effect of surface plasmon resonance (SPR) exhibited by metal nanoparticles (MNPs) has emerged as one of the most powerful approaches. In numerous studies, plasmonic enhancement of organic photovoltaic cells (OPVs) has been achieved based on improved light absorption and scattering effects by controlling the size, shape, and composition of metal nanostructures. In addition, spectral overlap between the SPR band of the MNPs and the absorption range of the photoactive polymers led to an increase in EQE values as well as photocurrent density, which leads to an improvement in power conversion efficiency (PCE). The highest efficiency of plasmonic OPV devices was reported up to ˜10% based on PTB7: PC ₇₀ BM photoactive layers, and an overall improvement of ˜20% was obtained for plasmon-free control devices. However, the performance of plasmonic cells reported so far is still reportedly low compared to the highest efficiencies of 11-12% obtained from OPV devices with specially designed polymer systems or tandem configurations. .

In addition, the enhancement of PCE induced by the plasmonic effect has usually been limited to a level of less than 20%, so the development of new and unexpected plasmonic nanostructures following a mechanism that reasonably supports the plasmonic enhancement effect is It is important. In many cases, MNP colloids were dispersed in a charge transport layer or active layer in OPVs. However, the use of MNPs has several technical problems to be overcome: 1) aggregation between MNPs in the hole transport layer or the active layer; 2) difficulty in synthesizing uniform nanoparticles; 3) unregulated spatial arrangement of MNPs; 4) Reduction of near-fields generated from MNPs in the charge transport layer as they interfere with contact between MNPs and active materials, and 5) negatives such as exciton quenching or charge recombination Direct contact between MNPs and active substances that can cause an effect. In light of the above mentioned background technologies and issues, increasing interest has been focused on the development of periodic metal nanostructures (PMNs) using controlled size, shape, and distance between particles and spatial arrangement. . The PMNs provide a stronger plasmonic effect than MNPs due to the availability of hot spots in the nanogap, as well as scatter and confine more incident light in the device.

To fabricate PMNs, several techniques have been widely studied, including nano imprinting, electron beam lithography, and laser interference lithography (LIL). In particular, LIL is well known for its simple process, which can form perfectly desired patterns in a large area, and has advantages over other nanolithography techniques for the following reasons: 1) Low cost but high throughput (high- throughput); 2) non-contamination on the surface; 3) Large area production up to hundreds of mm scale; 4) Easy adjustment of patterns with different periods, sizes, and shapes on the nanoscale. Thus, the combination of OPVs and PMNs produced by the LIL process is a useful approach and ideal platform to understand the mechanism of the plasmonic effect and obtain a marked improvement in PCE based on the fine-tuned optical properties of PMNs. Can be

Here, we describe the fabrication of the most efficient plasmonic OPV device integrated with plasmonic metal nano dot (MND) patterns using LIL where the SPR band matches absorption of the photoactive layers. In particular, the plasmonic OPV battery showed the best PCE reported to date, and showed a 45% increase in PCE (7.18% to 10.42%) compared to the reference cell. Thus, a well-designed protocol for plasmonic OPV devices has been proposed using improved optical engineering methods. In this regard, Korean Patent Registration No. 10-1187630 discloses an optoelectronic device containing a nanostructure, an organic solar cell, and a method of manufacturing the same.

The present application provides an organic solar cell including a metal nanostructure having a regular arrangement, and a method for manufacturing the organic solar cell.

However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The first aspect of the present application includes a transparent electrode layer formed on a substrate; A buffer layer formed on the transparent electrode layer and including a plurality of metal nanostructures; An active layer formed on the buffer layer; And an upper solar cell formed on the active layer, wherein the plurality of metal nanostructures are included in the buffer layer as a regularly arranged two-dimensional single-layer structure.

The second aspect of the present application includes forming a transparent electrode layer on the substrate; Forming a buffer layer including a plurality of metal nanostructures on the transparent electrode layer; Forming an active layer on the buffer layer; And forming an upper electrode on the active layer, wherein the plurality of metal nanostructures are included in the buffer layer as a regularly arranged two-dimensional single layer structure. A method of manufacturing a battery is provided.

According to one embodiment of the present application, a plurality of metal nanostructures in the buffer layer may be regularly arranged as a two-dimensional single layer structure using laser interference lithography. Due to the regular two-dimensional single-layer structure, the photovoltaic density-voltage characteristic and the EQE value of the organic solar cell are significantly increased, and thus the PCE value can be significantly increased.

According to one embodiment of the present application, due to the regular two-dimensional monolayer structure of the plurality of metal nanostructures, light of a wide wavelength band may be absorbed, and narrow and high absorbance may be exhibited in a desired region of a specific wavelength.

1 is, in one embodiment of the present application, a schematic diagram showing an organic solar cell in three dimensions.
2 is a cross-sectional view showing a cross-section of an organic solar cell in one embodiment of the present application.
3 is, in one embodiment of the present application, a process diagram showing the production process of PMNs.
4A is a graph showing pitch size and hole size as a function of an angle of incidence between a Lloyd`s mirror image and a substrate in an LIL system in one embodiment of the present application.
4B to 4E are SEM images of hole patterns prepared at different angles of 5 °, 10 °, 20 °, and 40 °, respectively, in one embodiment of the present application.
5A is a graph showing pitch size and dot size as a function of an angle of incidence between a Lloyd`s mirror image and a substrate in an LIL system in one embodiment of the present application.
5B to 5E are SEM images of PMNs prepared at different angles of 5 °, 10 °, 20 °, and 40 °, respectively, in one embodiment of the present application.
6A is a graph showing absorption spectra of PMNs having different sizes in one embodiment of the present application.
6B is a linear graph showing the relationship between the pitch and the SPR band position of the PMNs in one embodiment of the present application.
7A is a graph showing JV characteristics of an OPV device including AgNDs and an OPV device not including AgNDs (comparative example) under AM 1.5 G, 100 mW / cm ² light irradiation, in one embodiment of the present application. .
7B is a graph showing EQE spectra in one embodiment of the present application.
FIG. 7C is a graph showing the degree of EQE enhancement and the absorbance of AgNDs in OPV devices with or without AgNDs in one embodiment of the present application.
Figure 8 (a), in one embodiment of the present application, shows the electric field density distribution of the OPV device does not include and / or AgNDs.
FIG. 8 (b) shows light absorption profiles of an OPV device that does not include and / or does not include AgNDs in one embodiment of the present application.
8 (c) is a graph showing calculated absorption spectrum profiles of an OPV device that does not include and / or does not include AgNDs, in one embodiment herein.
9A is an AFM image of PMN arrays fabricated on an ITO / glass substrate, in one embodiment of the present application.
FIG. 9 (b) is a graph showing a topographic height profile of PMN arrays fabricated on an ITO / glass substrate in one embodiment of the present application.
9C is a current map of PMN fabricated on an ITO / glass substrate under a 0.5 V bias condition, in one embodiment of the present application.
9D is a graph showing the current level of PMNs prepared on an ITO / glass substrate in one embodiment of the present application.
10 is, in one embodiment of the present application, a photograph and a schematic diagram of an experimental setup of the LIL process.
11 is a schematic diagram showing the principle of a pattern using LIL in one embodiment of the present application.
12 (a) is, in one embodiment of the present application, a current map of AgND on an ITO / glass substrate.
12 (b) is a graph showing I-V characteristics obtained at a measurement point under a bias voltage in one embodiment of the present application.

Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present application pertains may easily practice. However, the present application may be implemented in various different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present application in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

Throughout this specification, when a part is "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another element in between. do.

Throughout this specification, when a member is said to be “on” another member, this includes not only the case where one member abuts another member, but also the case where another member exists between the two members.

Throughout the present specification, when a part “includes” a certain component, it means that the component may further include other components, not to exclude other components, unless specifically stated to the contrary. The terms "about", "substantially", and the like, as used throughout this specification, are used in or at a value close to that value when manufacturing and material tolerances specific to the stated meaning are given, and are understood herein. To aid, accurate or absolute figures are used to prevent unconscionable abusers from unduly using the disclosed disclosure. The term "~ (to) step" or "step of ~" as used throughout this specification does not mean "step for".

Throughout the present specification, the term “combination of these” included in the expression of the marki form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the marki form, wherein the component It means to include one or more selected from the group consisting of.

The first aspect of the present application includes a transparent electrode layer formed on a substrate; A buffer layer formed on the transparent electrode layer and including a plurality of metal nanostructures; An active layer formed on the buffer layer; And an upper solar cell formed on the active layer, wherein the plurality of metal nanostructures are included in the buffer layer as a regularly arranged two-dimensional single-layer structure. 1 and 2 are each a schematic diagram showing the organic solar cell in three dimensions and a cross-sectional view showing a cross section of the organic solar cell.

In one embodiment of the present application, as shown in FIGS. 1 and 2, after the transparent electrode layer 120 is laminated on the substrate 110, a regular two-dimensional single layer structure on the transparent electrode layer using laser interference lithography It forms a plurality of metal nanostructures 130 arranged as. Thereafter, a buffer layer 140 is coated on the plurality of metal nanostructures, and an active layer 150 is coated on the buffer layer. Finally, the organic solar cell 101 can be completed by depositing the upper electrode 160 on the active layer.

In one embodiment of the present application, the substrate may include a transparent substrate and a transparent flexible substrate, and may include a substrate selected from the group consisting of glass, transparent plastic, and combinations thereof, but is not limited thereto. It does not work.

In one embodiment of the present application, the transparent electrode layer is indium tin oxide (ITO), silver (Ag), copper (Cu), titanium (Ti), gold (Au), graphene (Graphene), poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) [poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate), PEDOT: PSS], and materials selected from the group consisting of combinations thereof It may be to include, but is not limited thereto.

In one embodiment of the present application, the metal nanostructure may include metal selected from the group consisting of gold, silver, platinum, copper, aluminum, and combinations thereof, but is not limited thereto.

In one embodiment of the present application, the shape of the metal nanostructure includes a shape selected from the group consisting of nanodots, nanoholes, nanoparticles, nanorods, nanohexahedrons, nanopillars, nanorings, and combinations thereof. It may be, but is not limited to this.

In one embodiment of the present application, the height of the metal nanostructure may be about 30 nm to about 70 nm, but is not limited thereto.

In one embodiment of the present application, the size of the metal nanostructure may be about 50 nm to about 1,000 nm. For example, the size of the metal nanostructure is about 50 nm to about 1,000 nm, about 100 nm to about 1,000 nm, about 200 nm to about 1,000 nm, about 300 nm to about 1,000 nm, about 400 nm to about 1,000 nm , About 500 nm to about 1,000 nm, about 600 nm to about 1,000 nm, about 700 nm to about 1,000 nm, about 800 nm to about 1,000 nm, about 900 nm to about 1,000 nm, about 50 nm to about 900 nm, about 50 nm to about 800 nm, about 50 nm to about 700 nm, about 50 nm to about 600 nm, about 50 nm to about 500 nm, about 50 nm to about 400 nm, about 50 nm to about 300 nm, about 50 nm To about 200 nm, or about 50 nm to about 100 nm. The smaller the size of the metal nanostructure, the higher the current density of the OPV device including the metal nanostructure.

In one embodiment of the present application, the pitch between the plurality of metal nanostructures may be 100 nm to 2,000 nm. For example, the pitch between the metal nanostructures is about 100 nm to about 2,000 nm, about 300 nm to about 2,000 nm, about 500 nm to about 2,000 nm, about 700 nm to about 2,000 nm, about 900 nm to about 2,000 nm , About 1,100 nm to about 2,000 nm, about 1,300 nm to about 2,000 nm, about 1,500 nm to about 2,000 nm, about 1,700 nm to about 2,000 nm, about 1,900 nm to about 2,000 nm, about 100 nm to about 1,900 nm, about 100 nm to about 1,700 nm, about 100 nm to about 1,500 nm, about 100 nm to about 1,300 nm, about 100 nm to about 1,100 nm, about 100 nm to about 900 nm, about 100 nm to about 700 nm, about 100 nm To about 500 nm, or about 100 nm to about 300 nm. The pitch between the metal nanostructures means the length between the metal nanostructures and the metal nanostructures, and the size of the metal nanostructures means the diameter of the nanostructures. The pitch and size can be adjusted by changing the incident angle of the laser. The pitch may decrease as the incident angle of the laser increases, and as the pitch decreases, the current density of the OPV device including the metal nanostructure may increase.

In one embodiment of the present application, the ratio of the size and pitch of the plurality of metal nanostructures may be about 1: 1 to 30. For example, the ratio of the size and pitch of the plurality of metal nanostructures is about 1: 1 to 30, about 1: 5 to 30, about 1:10 to 30, about 1:15 to 30, and about 1:20 to 30, or about 1:25 to 30.

In one embodiment of the present application, when the active layer includes an organic photoactive material, the light absorption band of the organic solar cell is about 400 nm to about 700 nm, and the wavelength band is limited, but the buffer layer has the regular two-dimensional dimension. As the plurality of metal nanostructures arranged as a single-layer structure is additionally introduced, diffraction occurs more, so that the light absorption band of the organic solar cell may be extended to about 400 nm to about 1,200 nm (visible light and infrared range). For example, the light absorption band is about 400 nm to about 1,200 nm, about 500 nm to about 1,200 nm, about 600 nm to about 1,200 nm, about 700 nm to about 1,200 nm, about 800 nm to about 1,200 nm, about 900 nm to about 1,200 nm, about 1,000 nm to about 1,200 nm, about 1,100 nm to about 1,200 nm, about 400 nm to about 1,100 nm, about 400 nm to about 1,000 nm, about 400 nm to about 900 nm, about 400 nm To about 800 nm, about 400 nm to about 700 nm, about 400 nm to about 600 nm, or about 400 nm to about 500 nm.

In one embodiment of the present application, the plasmonic effect in the organic solar cell may be improved by introducing a plurality of metal nanostructures arranged as the regular two-dimensional monolayer structure. Stronger plasmonic due to the availability of hot spots in the nanogap of the PMNs by adjusting the size, shape, and distance between the particles and the spatial arrangement of a plurality of uniform and regularly controlled metal nanostructures This is because it not only provides an effect, but also allows scatter and confine more incident light in the device.

In one embodiment of the present application, the organic solar cell includes a buffer layer and an active layer between the transparent electrode layer and the upper electrode on the substrate, the buffer layer is made of a polymer compound, etc., and the active layer is made of a material for photoelectric conversion However, it is not limited thereto.

In one embodiment of the present application, the buffer layer is poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) [poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate), PEDOT: PSS] , Poly (styrenesulfonate) (PSS), nickel oxide (NiO), vanadium oxide (V ₂ O ₃ ), spiro-MeOTAD [2,2 ', 7,7'-tetrakis (N, Np-dimethoxy-phenylamino) -9,9'-spirobifluorene], and combinations thereof, but may include a material selected from the group, but is not limited thereto.

In one embodiment of the present application, the active layer is 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] thiophendiyl]]: [6,6] -phenyl C ₇₀ Butyric acid methyl-ester (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]]: [6,6] -phenyl C ₇₀ butyric acid methyl-ester PTB7: PC ₇₀ BM), poly [N-9 "- Heptadecanyl-2,7-carbazolealt-5,5- (4 ', 7'-di-2-thienyl-2', 1 ', 3'-benzothiadiazole)]: [6, 6] -phenyl C ₇₀ butyric acid methyl-ester [poly [N-9 "-heptadecanyl-2,7-carbazolealt-5,5- (4 ', 7'-di-2-thienyl-2', 1 ', 3'-benzothiadiazole)]: [6,6] -phenyl C ₇₀ butyric acid methyl-ester, PCDTBT: PC ₇₀ BM], 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] Thiophendyl]]: Inden-C ₆₀ Bis adduct (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]]: indene-C ₆₀ bisadduct, PTB7: ICBA), poly (3-hexylthiophene): [6,6] -phenyl C ₆₀ buty Poly (3-hexyl thiophene): [6,6] -phenyl C ₆₀ butyric acid methyl-ester, P3HT: PC ₆₀ BM), perovskite material, and combinations thereof It may be to include a material selected from the group consisting, but is not limited thereto.

The second aspect of the present application includes forming a transparent electrode layer on the substrate; Forming a buffer layer including a plurality of metal nanostructures on the transparent electrode layer; Forming an active layer on the buffer layer; And forming an upper electrode on the active layer, wherein the plurality of metal nanostructures are included in the buffer layer as a regularly arranged two-dimensional single layer structure. A method of manufacturing a battery is provided. The detailed description of parts overlapping with the first aspect of the present application is omitted, but the description of the first aspect of the present application may be equally applied even if the description is omitted in the second aspect.

In one embodiment of the present application, referring to the process diagram showing the manufacturing process of PMNs in FIG. 3, spin coating the adhesive layer on the substrate and then spin coating the photoresist on the adhesive layer. For the laser interference lithography process, the laser beam is irradiated on the prepared film while changing the incident angle. The pitch and size of the hole patterns on the photoresist can be adjusted by changing the incident angle of the laser beam. The PMNs can be prepared by depositing a nano-thick metal on the photoresist and then removing the photoresist according to a lift-off process.

In one embodiment of the present application, the size of the metal nanostructure may be about 50 nm to about 1,000 nm. For example, the size of the metal nanostructure is about 50 nm to about 1,000 nm, about 100 nm to about 1,000 nm, about 200 nm to about 1,000 nm, about 300 nm to about 1,000 nm, about 400 nm to about 1,000 nm , About 500 nm to about 1,000 nm, about 600 nm to about 1,000 nm, about 700 nm to about 1,000 nm, about 800 nm to about 1,000 nm, about 900 nm to about 1,000 nm, about 50 nm to about 900 nm, about 50 nm to about 800 nm, about 50 nm to about 700 nm, about 50 nm to about 600 nm, about 50 nm to about 500 nm, about 50 nm to about 400 nm, about 50 nm to about 300 nm, about 50 nm To about 200 nm, or about 50 nm to about 100 nm. The smaller the size of the metal nanostructure, the higher the current density of the OPV device including the metal nanostructure.

In one embodiment of the present application, the pitch between the plurality of metal nanostructures may be 100 nm to 2,000 nm. For example, the pitch between the metal nanostructures is about 100 nm to about 2,000 nm, about 300 nm to about 2,000 nm, about 500 nm to about 2,000 nm, about 700 nm to about 2,000 nm, about 900 nm to about 2,000 nm , About 1,100 nm to about 2,000 nm, about 1,300 nm to about 2,000 nm, about 1,500 nm to about 2,000 nm, about 1,700 nm to about 2,000 nm, about 1,900 nm to about 2,000 nm, about 100 nm to about 1,900 nm, about 100 nm to about 1,700 nm, about 100 nm to about 1,500 nm, about 100 nm to about 1,300 nm, about 100 nm to about 1,100 nm, about 100 nm to about 900 nm, about 100 nm to about 700 nm, about 100 nm To about 500 nm, or about 100 nm to about 300 nm. As the pitch decreases, the current density of the OPV device including the metal nanostructure may increase.

In one embodiment of the present application, the ratio of the size and pitch of the plurality of metal nanostructures may be about 1: 1 to 30. For example, the ratio of the size and pitch of the plurality of metal nanostructures is about 1: 1 to 30, about 1: 5 to 30, about 1:10 to 30, about 1:15 to 30, and about 1:20 to 30, or about 1:25 to 30.

In one embodiment of the present application, forming a buffer layer including the plurality of metal nanostructures includes: forming an adhesive layer on the transparent electrode layer; Forming a photoresist layer on the adhesive layer; Forming a regular one-dimensional porous photoresist hole pattern by irradiating a one-dimensional laser interference pattern to the photoresist layer using laser interference lithography; Depositing a metal on the photoresist hole pattern; And removing the photoresist layer by firing treatment to form a two-dimensional monolayer structure in which a plurality of metal nanostructures are regularly arranged, but is not limited thereto.

In one embodiment of the present application, the pitch and size of the regular one-dimensional porous photoresist hole pattern may be adjusted according to the incident angle of the irradiated laser, but is not limited thereto.

In one embodiment of the present application, the incident angle of the irradiated laser may be about 5 ° to about 45 °, but is not limited thereto. For example, the incident angle of the irradiated laser is about 5 ° to about 45 °, about 10 ° to about 45 °, about 15 ° to about 45 °, about 20 ° to about 45 °, about 25 ° to about 45 ° , About 30 ° to about 45 °, about 35 ° to about 45 °, about 40 ° to about 45 °, about 5 ° to about 40 °, about 5 ° to about 35 °, about 5 ° to about 30 °, about It may be 5 ° to about 25 °, about 5 ° to about 20 °, about 5 ° to about 15 °, or about 5 ° to about 10 °, but is not limited thereto.

Hereinafter, the present application will be described in more detail by using examples, but the following examples are only illustrative to aid understanding of the present application, and the contents of the present application are not limited to the following examples.

[Example]

1. Manufacturing PMN

The ITO substrates were washed continuously with acetone, methanol, and deionized water for 30 minutes by ultra-sonication, and then dried in an oven at a temperature of 120 ° C. for 10 minutes. The overall manufacturing process of nano dot (ND) patterning is schematically illustrated in FIG. 3. The adhesion layer (HMDS: PGMEA = 1: 4) was spin-coated on the ITO substrate at 4000 rpm for 40 seconds before being dried at a temperature of 100 ° C for 90 seconds. Thereafter, a photoresist (AR-N4240 mixed with a 1: 1 ratio of Thinner AR 300-12) was spin coated on the adhesive layer for 40 seconds at 4000 rpm and dried for 90 seconds at a temperature of 180 ° C. For the LIL process, films were placed on a Lloyd's mirror and exposed to a laser source flowing through the spatial filter shown in FIG. 10. A frequency-doubled argon-ion laser of 257 nm wavelength was used and the exposure power to the sample was 0.12 mW / cm ² . The power of the laser system was controlled by an optical power / energy meter (Newport 1936-C). The diameter and focal length of the initial laser beam were approximately 0.15 mm and 3.4 mm, respectively. The distance between the spatial filter and the samples was approximately 1.2 m while the exposure time was set to 133 seconds. The pitch and size of the hole patterns could be adjusted by changing the incident angle of the laser beam on the PR films from 5 ° to 40 °. Finally, 50 nm thick silver (Ag) was thermally deposited under vacuum, following the life-off step of PR using acetone.

2. Organic solar cell manufacturing

First, the PEDOT: PSS solution was spin coated on AgNDs / ITO substrates prepared in advance at 3000 rpm for 30 seconds, after which the films were annealed for 30 seconds at a temperature of 110 ° C. in a glove box. Thereafter, for the active layer deposition, PTB7: PC ₇₀ BM with a mass ratio of 1: 1.5 was mixed with 1 mL of chlorobenzene: 1,8-diiodooctane (97: 3 volume ratio) solvent and spin coated at 1000 rpm for 40 seconds. . The films were held in the glove box for 30 minutes without any annealing process. Finally, 1 nm LiF and 100 nm Al were thermally deposited as top electrodes. A comparative example device without AgNDs was prepared following this method using an ITO substrate without AgNDs covered.

3. Characteristics

Ag hole and dot arrays were observed using FE-SEM (S-4800, Hitachi Ltd.). The optical characteristic, the optical extinction spectrum, was measured using an ultraviolet-visible-NIR spectrometer (Cary 5000, Varian Technology). The photovoltaic performance was measured with a solar simulator (Polaronix K3000, McScience) under AM 1.5 condition with 100 mW / cm ² intensity. EQE was measured with an IPCE measurement system (PEC-S20, HS technology) to analyze the incident photon-to-current efficiency. Conductive atomic force microscopy (c-AFM) was performed to confirm the surface and electrical properties of AgND (Nanoscope multimode AFM, Bruker).

4. FDTD simulation

Plasmonic near-field distribution of AgND arrays embedded in the PEDOT: PSS layer was simulated using Lumerical Solution software. The simulation domain condition was used for periodic boundary conditions for the x-axis and y-axis and a perfectly matched layer (PML) condition for the z-axis. All mesh sizes were setup as 0.5 nm for a close design. Optical constants of Ag were obtained from Palik with a spectral range from 300 nm to 800 nm. In addition, a plane wave source was used to calculate the absorption density derived from the electric field and AgNDs. The present inventors considered z as a light incident direction and x as a polarity direction. Absorption and dispersion were measured by a total-field (incident field and scattered field) power monitor and a dispersion-field power monitor.

5. Result Analysis

In the LIL process, the incident angle and the wavelength of the laser beam determine the pitch and size of the PMN arrays according to Equation 1 below.

<Equation 1>

In the above equation, P denotes the periodicity, λ denotes the wavelength of the laser, and θ denotes the angle of incidence of the Lloyd`s mirror onto the specimen. A detailed illustration of laser interference is also shown in FIG. 11. Here, λ of the laser source was fixed at 257 nm, and θ was adjusted as 5 °, 10 °, 15 °, 20 °, 25 °, 30 °, 35 °, and 40 °.

<Table 1>

As summarized in Table 1 and FIG. 4 (a), the values of the pitch and the individual hole sizes decreased as θ increased, and as the structure and optical properties of PMNs changed the incident angle of the laser beam, This indicates that it can be easily adjusted in an easy way. Representative SEM images of hole arrays prior to the lift-off process of PR prepared at θ of 5 °, 10 °, 20 °, and 40 ° are shown in FIGS. 4B-4E. By the silver deposition and lift-off process, periodic MNDs with different sizes were obtained. The size scale of the MNDs was plotted as a function of angle in FIG. 5 (a), and a series of MNDs SEM images are shown in FIGS. 5 (b) to 5 (e), respectively. As with the periodicity, the size of the MNDs was systematically controlled in a uniform manner over a large surface area. The measured diameter of the MNDs was somewhat smaller than the diameter of the holes of the MNDs because the edges of the holes were not completely filled by silver (Ag) during the thermal deposition process.

Absorbance spectra of MND arrays on an ITO-coated glass substrate were obtained by UV-vis spectroscopy shown in Fig. 6 (a). Localized surface plasmon resonance (LSPR) peaks were observed at 573 nm, 729 nm, 1001 nm, and 1278 nm for 91 nm, 202 nm, 350 nm, and 624 nm dot sizes, respectively. The plot corresponding to LSPR λ _max compared to the period shown in FIG. 6B shows the characteristic LSPR bands of each ND array, and the measured λ _max represents a red shift as the period increases. The absorbance λ _max is suitable for a linear equation with high accuracy (R ² = 0.968).

The comparative device was made under the same conditions except for the inclusion of AgNDs. In FIG. 7A, the photocurrent density-voltage of the four types of AgNDs (when the LIL angles in Table 1 above are 5 °, 10 °, 20 °, and 40 °, respectively) and the AgVs-free OPV device (comparative device) (JV) properties are shown under AM 1.5 G illuminations. All the AgND-based devices showed better performance than the comparative device, and the best OPV device performance was obtained from a device comprising AgNDs with the smallest LIL angle (Table 1 above is 40 °). Intuitively, this result can be regarded as the result of an improved photocurrent density in the absorption band that best matches the absorption band of the photoactive layer. We further investigated the enhancement mechanism in the following section. Representative photovoltaic parameters when the LIL angle of Table 1 is 40 ° are summarized in Table 2 below.

<Table 2>

When PMNs are embedded into the HTL of OPV devices, the values of the fill factor (FF) and open circuit voltage (V _oc ) remain almost unchanged compared to the device including the comparative example PEDOT: PSS HTL. During, a significant increase in short circuit current density (J _sc ) values was observed, reflecting that the improvement in PCE is directly related to the increased J _sc values. The highest efficiency was obtained from devices containing PMNs of 91 nm size with ˜0.73 VV _OC , ˜23.35 mA / cm ² J _SC , ˜0.61 FF, and ˜10.42 (up to 10.55%) PCE. The J _sc and PCE values were increased to 40.7% and 45.1%, respectively, compared to the comparative device without PMNs. These results represent the greatest degree of performance improvement due to the plasmonic effect in plasmonic organic photovoltaic devices based on single-junction cells with the highest PCE.

However, the transmittance of the ITO substrate containing PMNs was lower than that of the ITO substrate without PMNs, and the J _sc value, light absorption, and dispersion were higher in the device. In that regard, the significant improvement in J _sc value after incorporation of plasmonic AgNDs was influenced by the electrical properties of the plasmonic nanostructures, since photocurrent enhancement could also be derived from increased number or mobility of charge carriers. Was. The EQE spectra of devices with respective ND and pitch sizes of 91 nm and 202 nm are shown in FIG. 7B compared to the comparative device. The wavelength-independent EQE enhancement in the range of 460 nm to 760 nm shown in FIG. 7C reflects the possibility that AgNDs will act as modifiers that define electrical properties in the device. In addition, it was confirmed that the absorption spectrum of AgNDs produced under the condition of 40 ° laser incident light was very consistent with the increase of the EQE spectrum. Broadband enhanced EQE can affect the increase in current density by Equation 2 below:

<Equation 2>

On the other hand, the reduced EQE in a relatively narrow range of 390 nm to 450 nm can be seen as a result of self-absorption of AgNDs.

To confirm the plasmonic effect of AgNDs, such as near field and absorption enhancement, an FDTD simulation was performed. In FIG. 8 (a), the distribution of electric field density was calculated on a device that does not contain / or contain PMNs under the optimal arrangement of AgNDs embedded in ITO and PEDOT: PSS (left and right, respectively). A strong electric field was generated and observed to be distributed around AgNDs. Fig. 8 (b) shows the light absorption profiles of OPV devices that do not contain and / or contain AgNDs under excitation with a wavelength of 550 nm light irradiation (left and right, respectively). In the PTB7: PCBM layer, stronger absorption was observed when AgND arrays were introduced into the device compared to the device without AgND, leading to a significant increase in J _sc and PCE values as shown in FIGS. 7A-7C. In particular, the absorption density was higher in the vicinity of AgNDs functioning as hot spots. Based on the above results, absorption spectra in the PTB7: PCBM active layer were also calculated and plotted in Figure 8 (c). The absorbance profile is consistent with the EQE results, which clearly reflects that the increase in J _sc and PCE values is due to the plasmonic properties of AgND in the device.

To further investigate the role of plasmonic AgNDs, the present inventors measured the electrical performance of AgNDs using a conductive atomic force microscope (c-AFM). 9 (a) and 9 (b), AFM images of PMN arrays fabricated on ITO / glass substrates and topographical height profiles along the red line are shown. One was able to observe the average height of AgNDs measured around 50 nm. 9 (c) shows the current flow profile in the AgNDs and ITO under 0.5 V bias conditions, in which the overflowed currents through the AgNDs were confirmed. Current levels at the AgNDs and ITO surfaces along the blue line in the current map are shown in Figure 9 (d), and a significantly increased current level was observed at the AgNDs. In addition, as shown in FIG. 12, while the ITO showed a gradually increased current flow, the currents in the AgNDs increased rapidly when the bias voltage was slightly greater than 0 V. The results obtained from c-AFM studies clearly demonstrate that the plasmonic MNDs play a role as a current path and enable a current flow.

The above description of the present application is for illustrative purposes, and those skilled in the art to which the present application pertains will understand that it is possible to easily modify to other specific forms without changing the technical spirit or essential features of the present application. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present application is indicated by the claims, which will be described later, rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be interpreted to be included in the scope of the present application.

101: organic solar cell
110: description
120: transparent electrode layer
130: metal nanostructure
140: buffer layer
150: active layer
160: upper electrode

Claims (10)

A transparent electrode layer formed on the substrate;
A buffer layer formed on the transparent electrode layer and including a plurality of metal nanostructures;
An active layer formed on the buffer layer; And
Upper electrode formed on the active layer
An organic solar cell comprising:
The plurality of metal nanostructures are two-dimensional single-layer structures arranged regularly and are included in the buffer layer.
As the plurality of metal nanostructures regularly arranged as the two-dimensional single-layer structure is introduced, the light absorption band of the organic solar cell is expanded within the range of visible light and infrared light, thereby improving the plasmonic effect in the organic solar cell. And
The size of the pitch between the plurality of metal nanostructures is 150 nm to 1,300 nm,
The ratio of the size and pitch of the plurality of metal nanostructures is 1: 1 to 30,
By adjusting the size of the pitch between the plurality of metal nanostructures regularly arranged as the two-dimensional single-layer structure, the current density of the organic solar cell is increased,
Organic solar cells.
According to claim 1,
The size of the metal nanostructure is 50 nm to 700 nm, an organic solar cell.
delete delete Forming a transparent electrode layer on the substrate;
Forming a buffer layer including a plurality of metal nanostructures on the transparent electrode layer;
Forming an active layer on the buffer layer; And
Forming an upper electrode on the active layer
A method of manufacturing an organic solar cell comprising:
The plurality of metal nanostructures are two-dimensional single-layer structures arranged regularly and are included in the buffer layer.
As the plurality of metal nanostructures regularly arranged as the two-dimensional single-layer structure is introduced, the light absorption band of the organic solar cell is expanded within the range of visible light and infrared light, thereby improving the plasmonic effect in the organic solar cell. And
Forming a buffer layer including the plurality of metal nanostructures,
Forming an adhesive layer on the transparent electrode layer;
Forming a photoresist layer on the adhesive layer;
Forming a regular one-dimensional porous photoresist hole pattern by irradiating a one-dimensional laser interference pattern to the photoresist layer using laser interference lithography;
Depositing a metal on the photoresist hole pattern; And
Forming a two-dimensional single layer structure in which a plurality of metal nanostructures are regularly arranged by removing the photoresist layer by firing treatment
It includes,
The size of the pitch between the plurality of metal nanostructures is 150 nm to 1,300 nm,
The ratio of the size and pitch of the plurality of metal nanostructures is 1: 1 to 30,
By adjusting the size of the pitch between the plurality of metal nanostructures regularly arranged as the two-dimensional single-layer structure, the current density of the organic solar cell is increased,
Method of manufacturing an organic solar cell.
The method of claim 5,
The size of the metal nanostructure is 50 nm to 700 nm, the method of manufacturing an organic solar cell.
delete delete delete The method of claim 5,
The pitch and size of the regular one-dimensional porous photoresist hole pattern is adjusted according to the incident angle of the irradiated laser, a method of manufacturing an organic solar cell.

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