KR20230046938A - SnO2 ELECTRON TRANSPORT MATERIAL AND OPTOELECTRONIC DEVICE USING THEREOF - Google Patents

Abstract

An electron transport layer according to one embodiment of the present disclosure includes a SnO_2 layer and SnO_2 doped with Zn on the SnO_2 layer. The provided SnO_2 electron transport layer has high efficiency and high durability.

Description

SnO2 electron transport layer and optical device using it {SnO2 ELECTRON TRANSPORT MATERIAL AND OPTOELECTRONIC DEVICE USING THEREOF}

The present disclosure relates to a SnO ₂ electron transport layer and an optical device using the same.

The need to develop environmentally friendly and sustainable energy technologies that can respond to climate change is increasing. Optical devices include both photoelectric conversion devices and electro-optical conversion devices, and a solar cell, one of the photoelectric conversion devices, is attracting attention as a sustainable energy technology as a solution that can actively respond to future energy demand. A solar cell is the most basic unit of photovoltaic power generation and a semiconductor device that converts solar energy into electrical energy, and uses a photovoltaic effect.

However, since today's solar cell technology is not efficient enough to replace future energy demand, technological innovation beyond the current technology level is required. Accordingly, technologies based on innovative materials such as dye-sensitized solar cells, organic solar cells, quantum dot solar cells, and perovskite solar cells (PSC) have been developed as next-generation solar cells.

Among them, perovskite solar cells have taken off as one axis of thin-film solar cells to replace conventional silicon solar cells. A perovskite solar cell including a hole transporting material, a light absorbing material, and an electron transporting material exhibits a remarkably high photovoltaic effect by using the perovskite material as a light absorbing material.

However, perovskite solar cells have many limitations because they have instability to light, heat, and humidity. For example, since SnO ₂ as an electron transport layer is coated with a thin layer, uniform and dense coating is difficult, resulting in a problem in terms of long-term stability.

Embodiments disclosed herein provide a SnO ₂ electron transport layer having high efficiency and high durability.

Embodiments disclosed herein provide a perovskite optical device having high efficiency and high durability.

Embodiments disclosed herein improve physical properties of the SnO ₂ electron transport layer by using the SnO ₂ electron transport layer having a Bi-Layer structure.

Embodiments disclosed in this specification provide a perovskite optical device including a SnO ₂ electron transport layer having an efficiency equivalent to that of a glass device even when applied to a flexible device.

An electron transport layer according to an embodiment of the present disclosure includes a SnO ₂ layer and a SnO ₂ layer doped with Zn on the SnO ₂ layer.

According to one embodiment of the present disclosure, the SnO ₂ layer and the Zn-doped SnO ₂ layer have a bi-layer structure.

According to one embodiment of the present disclosure, the electron transport layer is formed on the ITO electrode.

According to an embodiment of the present disclosure, the electron transport layer can be used for both flexible devices and glass devices.

According to one embodiment of the present disclosure, the electron transport layer is manufactured by a low-temperature process.

According to one embodiment of the present disclosure, the SnO ₂ layer doped with Zn is composed of nano rods.

An optical device according to an embodiment of the present disclosure includes an electron transport layer according to the above-described embodiment.

According to various embodiments of the present disclosure, a SnO ₂ electron transport layer having high efficiency and high durability is provided.

According to various embodiments of the present disclosure, a perovskite optical device having high efficiency and high durability is provided.

According to various embodiments of the present disclosure, the physical properties of the SnO ₂ electron transport layer are improved by using the SnO ₂ electron transport layer having a Bi-Layer structure.

According to various embodiments of the present disclosure, even when applied to a flexible device, a perovskite optical device including a SnO ₂ electron transport layer having an efficiency equivalent to that of a glass device is provided.

Effects of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Embodiments of the present disclosure will be described with reference to the accompanying drawings described below, wherein like reference numbers indicate like elements, but are not limited thereto.
1A and 1B are views showing an electron transport layer (single layer) formed on ITO according to the prior art.
2a and 2b are views illustrating an electron transport layer (bi-layer) formed on ITO according to an embodiment of the present disclosure.
3 to 6 correspond to single layer and bi-layer data graphs measured in glass devices.
7 corresponds to a data graph of a bi-layer measured in a flexible device.

Terms used in this disclosure will be briefly described, and the disclosed embodiments will be described in detail. The terms used in this specification have been selected from general terms that are currently widely used as much as possible while considering the functions in the present disclosure, but they may vary according to the intention of a person skilled in the related field, a precedent, or the emergence of new technologies. In addition, in a specific case, there is also a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the invention. Therefore, the terms used in the present disclosure should be defined based on the meaning of the terms and the general content of the present disclosure, not simply the names of the terms.

In this disclosure, expressions in the singular number include plural expressions unless the context clearly dictates that they are singular. Also, plural expressions include singular expressions unless the context clearly specifies that they are plural.

In the present disclosure, when a part includes a certain component, this means that it may further include other components without excluding other components unless otherwise stated.

Reference to “A and/or B” in this disclosure means A, or B, or A and B.

As used in this disclosure, the term "about" and the like is intended to encompass tolerances when tolerances exist.

In the present disclosure, the term “at least one” included in the Markush-type expression means including one or more selected from the group consisting of elements described in the Markush-type expression.

In the present disclosure, “perovskite” or “PE” means a material having a perovskite crystal structure, and may have various perovskite crystal structures in addition to the crystal structure of ABX ₃ .

In the present disclosure, "optical device" is used to include both photoelectric conversion devices and electro-optical conversion devices. For example, the optical device includes, but is not limited to, a solar cell, a light emitting diode (LED), a photodetector, an X-ray detector, and a laser.

In the present disclosure, the term "halide", "halogen", "halogenide" or "halo" refers to a material or composition in which a halogen atom belonging to group 17 of the periodic table is included in the form of a functional group, for example, chlorine. , bromine, fluorine or iodine compounds.

In the present disclosure, the term "layer" means a layer form having a thickness. A layer may correspond to porous or non-porous. Porosity means having porosity. The layer as a whole may have a bulk form or correspond to a single crystal thin film, but is not limited thereto.

In the present disclosure, when a member is said to be located “on” another member, this includes not only the case where a member is in contact with another member, but also the case where another member exists between the two members unless otherwise stated. do.

In the present disclosure, when simply described as efficiency without any additional explanation, the efficiency means power conversion efficiency (PCE).

In the present disclosure, double layer is used as the same meaning as bi-layer, and double layer and bi-layer may mean a double layer.

In the present disclosure, a glass element means an element comprising a glass substrate.

Hereinafter, specific details for the implementation of the present disclosure will be described in detail with reference to the accompanying drawings. However, in the following description, if there is a risk of unnecessarily obscuring the gist of the present disclosure, detailed descriptions of well-known functions or configurations will be omitted.

Advantages and features of the disclosed embodiments, and methods of achieving them, will become apparent with reference to the following embodiments in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below and may be implemented in various different forms, but only the present embodiments make the present disclosure complete, and the present disclosure does not extend the scope of the invention to those skilled in the art. It is provided only for complete information.

In the accompanying drawings, identical or corresponding elements are given the same reference numerals. In addition, in the description of the following embodiments, overlapping descriptions of the same or corresponding components may be omitted. However, omission of a description of a component does not intend that such a component is not included in an embodiment.

An optical device according to an embodiment of the present disclosure includes a first electrode, a first charge transport layer formed on the first electrode, a perovskite layer formed on the first charge transport layer, and a second charge transport layer formed on the perovskite layer. , and a second electrode formed on the second charge transport layer.

For example, when an optical device is used in an n-i-p solar cell, the photonic device may have a structure in which a first electrode, an electron transport layer, a perovskite layer, a hole transport layer, and a second electrode are sequentially stacked. Alternatively, when the optical device corresponds to a solar cell having a p-i-n structure, the solar cell may have a structure in which a first electrode, a hole transport layer, a perovskite layer, an electron transport layer, and a second electrode are sequentially stacked.

For example, the optical device may have a planar structure, a Bi-Layer structure, or a Meso-Superstructure structure. Depending on the structure of the optical device, the shape of the electrode, the charge transport layer, and the perovskite layer may be modified.

The electrode includes a first electrode and/or a second electrode, and may be an anode or a cathode. An electrode may be an anode or cathode. When the first electrode is an anode, the second electrode may be a cathode. For example, the electrode may be a conductive oxide such as indium-tin oxide (ITO), indium zinc oxide (IZO), or fluorine-doped tin oxide (FTO). Alternatively, the electrode may be silver (Ag), gold (Au), magnesium (Mg), aluminum (Al), platinum (Pt), tungsten (W), copper (Cu), molybdenum (Mo), nickel (Ni), palladium (Pd), chromium (Cr), calcium (Ca), samarium (Sm) and lithium (Li), and combinations thereof. Alternatively, the electrode is placed on a flexible and transparent material such as plastic such as PET (polyethylene terephthalate), PEN (polyethylene naphthelate), PP (polyperopylene), PI (polyimide), PC (polycarbornate), PS (polystylene), POM (polyoxyethylene), etc. A conductive material may be doped.

The electrode may correspond to a material commonly used as an electrode material for a front electrode or a rear electrode in an optical device. The electrode may be a material selected from one or more of gold, silver, platinum, palladium, copper, aluminum, carbon, cobalt sulfide, copper sulfide, nickel oxide, and composites thereof, but is not limited thereto. For example, the electrode is any one selected from fluorine-doped tin oxide (FTO), indium-doped tin oxide (ITO), ZnO, CNT (carbon nanotube), and graphene, or the like. It may correspond to two or more inorganic conductive electrodes or organic conductive electrodes such as PEDOT:PSS, but is not limited thereto.

As the charge transport layer, an electron transport layer (ETL) or a hole transport layer (HTL) may be formed on the first electrode. When the first charge transport layer is an electron transport layer, the second charge transport layer may correspond to a hole transport layer. Alternatively, when the first charge transport layer is a hole transport layer, the second charge transport layer may correspond to an electron transport layer.

The electron transport layer may correspond to a semiconductor including “n-type material”. "n-type material" means an electron transport material. The electron transport material can be a single electron transport compound or elemental material or a mixture of two or more electron transport compounds or elemental materials. The electron transport compound or elemental material may be undoped or doped with one or more dopant elements.

For example, the electron transport layer may be an electron conductive organic material layer or an electron conductive inorganic material layer. The electron conductive organic material may be an organic material used as an n-type semiconductor in a typical organic solar cell. For example, electron-conducting organics are fullerenes (C60, C70, C74, C76, C78, C82, C95) and PCBM ([6,6]-phenyl-C61butyric acid methyl ester). and fulleren-derivatives including C71-PCBM, C84-PCBM, PC70BM ([6,6]-phenyl C70-butyric acid methyl ester), PBI (polybenzimidazole), PTCBI (3,4,9, 10-perylenetetracarboxylic bisbenzimidazole), F4-TCNQ (tetra urorotetracyanoquinodimethane), or a mixture thereof, but is not limited thereto.

The electron-conductive inorganic material may be an electron-conductive metal oxide used for electron transfer in a conventional quantum dot-based solar cell, dye-sensitized solar cell, or perovskite-based solar cell. In one embodiment, the electron-conductive metal oxide may be an n-type metal oxide semiconductor. For example, n-type metal oxide semiconductors include Ti oxide, Zn oxide, In oxide, Sn oxide, W oxide, Nb oxide, Mo oxide, Mg oxide, Ba oxide, Zr oxide, Sr oxide, Yr oxide, La oxide, V It may be one or more materials selected from oxides, Al oxides, Y oxides, Sc oxides, Sm oxides, Ga oxides, In oxides, and SrTi oxides, mixtures thereof, or composites thereof, but is not limited thereto.

The electron transport layer may be a dense layer (dense membrane) or a porous layer (porous membrane). The dense electron transport layer may be the aforementioned electron conductive organic film or electron conductive inorganic dense film. The electron transport layer of the porous film may be a porous film made of the above-described electron conductive inorganic particles.

An electron transport layer according to an embodiment of the present disclosure will be described later.

The hole transport layer may correspond to a semiconductor including “p-type material”. "p-type material" means a hole transporting material. The hole transport material can be a single hole transport compound or elemental material or a mixture of two or more hole transport compounds or elemental materials. The hole transport compound or elemental material may be undoped or doped with one or more dopant elements. The hole transport material may be an organic hole transport material, an inorganic hole transport material, or a combination thereof.

The hole transport layer may be prepared by a solution process. The hole transport layer may be a thin film of organic hole transport material. The hole transport layer thin film may have a thickness of 10 nm to 500 nm, but is not limited thereto.

The hole transport material may correspond to an organic hole transport material, specifically, a monomolecular or polymer organic hole transport material (hole conductive organic material). As a high-molecular organic hole transport material, one or two or more materials selected from thiophene-based, para-phenylene-vinylene-based, carbazole-based, and triphenylamine-based materials may be included.

Monomolecular to low molecular weight organic hole transport materials include pentacene, coumarin 6, 3- (2-benzothiazolyl) -7- (diethylamino) coumarin), zinc phthalocyanine (ZnPC), copper phthalocyanine (CuPC), TiOPC (titanium oxide phthalocyanine), Spiro-MeOTAD (2,2',7,7'-tetrakis (N,N-p-dimethoxyphenylamino)-9,9'-spirobifluorene), F16CuPC (copper (II) 1,2,3, 4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro29H,31H-phthalocyanine), SubPc (boron subphthalocyanine chloride) and N3 (cis-di(thiocyanato)-bis (2,2'-bipyridyl-4,4'-dicarboxylic acid)-ruthenium (II)), but includes one or more materials selected from, but is not limited thereto.

Polymer organic hole transport materials are P3HT (poly[3-hexylthiophene]), MDMO-PPV (poly[2-methoxy-5-(3',7'-dimethyloctyloxyl)]-1,4-phenylene vinylene), MEH- PPV (poly[2-methoxy-5-(2''-ethylhexyloxy)-p-phenylene vinylene]), P3OT (poly(3-octyl thiophene)), POT (poly(octyl thiophene)), P3DT (poly(3 -decyl thiophene)), P3DDT (poly(3-dodecyl thiophene), PPV (poly(p-phenylene vinylene)), TFB (poly(9,9'-dioctylfluorene-co-N-(4-butylphenyl)diphenyl amine) , Polyaniline, SpiroMeOTAD ([2,2′,7,7′-tetrkis(N,N-di-p-methoxyphenyl amine)-9,9′-spirobi fluorine]), PCPDTBT (Poly[2,1,3- benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl-4H- cyclopenta [2,1-b:3,4- b']dithiophene-2,6-diyl]], Si-PCPDTBT(poly [(4,4′′-bis(2-ethylhexyl)dithieno[3,2-b:2′′,3′′-d]silole)- 2,6-diyl-alt-(2,1,3- benzothiadiazole)-4,7-diyl]), PBDTTPD(poly((4,8-diethylhexyloxyl) benzo([1,2- b:4,5-b']dithiophene)-2,6-diyl)-alt- ((5-octylthieno[3,4-c]pyrrole-4,6-dione)-1,3-diyl)), PFDTBT(poly[2,7-(9-(2-ethylhexyl)-9-hexyl- fluorene)-alt-5,5-(4', 7, -di-2-thienyl-2',1', 3'-benzothiadiazole)]), PFO-DBT(poly[2,7-.9,9 -(dioctyl-fluorene)-alt-5,5-(4',7'-di-2-.thienyl-2', 1', 3'- benzothiadiazole)]), PSiFDTBT(poly[(2,7- dioctylsilafluorene)-2,7diyl-alt-(4,7-bis(2-thienyl)-2,1,3-benzothiadiazole)-5,5′-diyl]), PSBTBT(poly[(4,4′′- bis(2-ethylhexyl)dithieno[3,2-b:2′',3′'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl ]), PCDTBT (Poly [[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5 -thiophenediyl]), PFB(poly(9,9′′-dioctylfluorene-co-bis(N,N′′-(4,butylphenyl))bis(N,N′′-phenyl-1,4-phenylene)diamine ), F8BT (poly(9,9′′-dioctylfluorene-co-benzothiadiazole), PEDOT (poly(3,4-ethylenedioxythiophene)), PEDOT:PSS (poly(3,4- ethylenedioxythiophene) poly(styrenesulfonate)), PTAA (poly(triarylamine)), Poly(4-butylphenyldiphenyl-amine), PIF8-TAA (poly-indenofluoren-8-triarylamine), and copolymers thereof, but may include one or more selected materials, but are not limited thereto. no.

The electron transport layer or the hole transport layer may correspond to or include a buffer layer. The surface of the electron transport layer or hole transport layer may be modified using doping. The electron transport layer or hole transport layer is formed on one side of the electrode through spin coating, dip coating, inkjet printing, gravure printing, spray coating, bar coating, gravure coating, brush painting, thermal evaporation, sputtering, E-Beam, screen printing, blade process, etc. It can be formed by being applied to or coated in the form of a film.

A method of generating an electron transport layer according to an embodiment of the present disclosure will be described later.

The perovskite layer may be formed to directly contact the first electrode. Alternatively, the perovskite layer may be formed to directly contact the electron transport layer or the hole transport layer. The perovskite layer contains perovskite.

The perovskite layer may be formed through various processes including a vapor deposition process or a solution process. The perovskite layer may be formed using a vapor deposition process. The vapor deposition process may correspond to a process of depositing a material on a surface of a target object (eg, a substrate) by supplying a material in a vaporized state or a plasma state into a vacuum chamber. The perovskite layer may be formed through a coating process in a solution process. Coating processes include spin coating, bar coating, nozzle printing, spray coating, slot die coating, gravure printing, inkjet printing, screen printing, electrohydrodynamic jet printing, electrospray, and combinations thereof It may be selected from the group consisting of, but is not limited thereto.

For example, perovskite may contain monovalent organic cations, divalent metal cations and halide anions. In one embodiment, the perovskite of the present invention may satisfy the following formula.

[Formula 1]

AMX ₃

In Formula 1, A is a monovalent cation and may correspond to an organic ammonium ion, an amidinium group ion, or a combination of an organic ammonium ion and an amidinium group ion.

For example, an organic cation as A may have the formula (R ₁ R ₂ R ₃ R ₄ N) ⁺ . In this case, R ₁ to R ₄ may correspond to hydrogen, unsubstituted or substituted C1-C20 alkyl, or unsubstituted or substituted aryl.

For example, an organic cation as A may have the formula (R ₅ NH ₃ ) ⁺ , where R ₅ may correspond to hydrogen or substituted or unsubstituted C1-C20 alkyl.

For example, an organic cation as A has the formula (R ₆ R ₇ N=CH-NR ₈ R ₉ ) ⁺ , in which case R ₆ to R ₉ may correspond to hydrogen, methyl, or ethyl.

In addition, A is a monovalent metal ion and may correspond to an alkali metal ion.

For example, the monovalent metal ion as A may correspond to Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , or Cs ⁺ ion.

In addition, A may correspond to a combination of a monovalent organic cation and a monovalent metal ion.

For example, A may correspond to a form in which a monovalent metal ion is doped with a monovalent organic cation. The monovalent metal ion, which is the doped metal ion, may include an alkali metal ion, and the alkali metal ion may be one or two or more selected from Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , and Cs ⁺ ions.

M may be a divalent metal ion. For example, M is Cu ²⁺ , Ni ²⁺ , Co ²⁺ , Fe ²⁺ , Mn ²⁺ , Cr ²⁺ , Pd ²⁺ , Cd ²⁺ , Ge ²⁺ , Sn ²⁺ , Pb ²⁺ and Yb ² metal cations selected from the group consisting of ⁺ and combinations thereof, but are not limited thereto.

X may correspond to a halogen ion. For example, the halogen ion includes, but is not limited to, a halogen ion selected from the group consisting of I ^- , Br ^- , F ^- , Cl ^- and combinations thereof.

For example, the perovskite may be any one or a mixture of two or more selected from CH ₃ NH ₃ PbI ₃ (methylammonium lead iodide, MAPbI ₃ ) and CH(NH ₂ ) ₂ PbI ₃ (formamidinium lead iodide, FAPbI ₃ ).

Hereinafter, an electron transport layer according to an embodiment of the present disclosure will be described in more detail.

1A and 1B are views showing an electron transport layer (single layer) formed on ITO according to the prior art. An SnO ₂ layer may be formed on the transparent electrode (ITO) using a low-temperature process of about 300° C., about 250° C., about 200° C., or about 150° C. or less to form the electron transport layer. However, long-term stability has been a problem because it is difficult to form a uniform and dense electron transport layer because the thickness of the formed layer is thin. An image taken of the surface of the SnO ₂ layer formed of a single layer is shown in FIG. 1A, and it can be seen that the layer is thin and not dense. A side view of the electron transport layer is shown in a conceptual diagram in FIG. 1B.

2a and 2b are views illustrating an electron transport layer (bi-layer) formed on ITO according to an embodiment of the present disclosure. An image taken of the surface of the electron transport layer formed as a bi-layer is shown in FIG. 2A, and it can be seen that the layer is thick and relatively dense. A side view of the electron transport layer is shown in a conceptual diagram in FIG. 2B.

According to one embodiment of the present disclosure, a SnO ₂ layer is formed on ITO. The thickness of the SnO ₂ layer may correspond to about 30 nm, and may be formed using spin coating (400 rpm/30 s) in the case of a unit device.

Then, a Zn-doped SnO ₂ (Zn:SnO ₂ ) layer is coated on the SnO ₂ layer. The Zn:SnO ₂ layer may be composed of nano-sized rods. The thickness of the Zn:SnO ₂ layer may correspond to about 20 to 30 nm, and may be formed using spin coating (4000 rpm/30 s).

The SnO ₂ layer and the SnO ₂ :Zn layer are formed in contact with each other to have a bi-layer structure. Through the bi-layer structure, it is possible to solve the problem of the conventional single-layer SnO ₂ electron transport layer, which has a thin layer thickness and is not dense. In particular, by forming a Zn:SnO ₂ layer composed of nanorods on the SnO ₂ layer, a more dense and uniformly thick multi-layered SnO ₂ electron transport layer can be formed. The nanorods may have a diameter of about 2.5 nm and a length of about 6 to 7 nm.

In order to confirm the performance difference according to the structure of the SnO ₂ electron transport layer, a performance comparison between a single layer and a bi-layer structure was performed based on the glass element, and the results are shown in FIGS. 3 to 6 .

Single layer (glass element): ITO / SnO ₂ / Perovskite (FAPbI ₃ ) _0.95 (MAPbBr ₃ ) _0.05 / Spiro / Au

Double layer (glass element): ITO / SnO ₂ / Zn:SnO ₂ / Perovskite (FAPbI ₃ ) _0.95 (MAPbBr ₃ ) _0.05 / Spiro / Au

As a result of device characteristics confirmation through TPV and TPC, the multi-layer structure has overall improved solar cell parameters than the single-layer structure and has an increased efficiency of 1% or more. In addition, it can be confirmed that the multi-layer structure maintains the light stability at 90% level for 500 hours even in long-term stability.

Furthermore, the multi-layer structure applied to the flexible element showed an efficiency equivalent to the performance shown when applied to the glass element (see FIG. 7).

Double layer (flexible device): ITO (PEN) / SnO ₂ / Zn:SnO ₂ / Perovskite (FAPbI ₃ ) _0.95 (MAPbBr ₃ ) _0.05 / Spiro / BABr / Au

The measurement data shown in FIGS. 3 to 7 were measured using the following method.

1) Current-voltage characteristics: using an artificial solar device (ORIEL class A solar simulator, Newport, model 91195A) and a source-meter (source-meter, Kethley, model 2420), JSC) and fill factor (FF) were measured.

2) Photoelectric Conversion Efficiency (PCE, η): A light source of 280 to 2500 nm wavelength for a perovskite optical device manufactured under a constant temperature and humidity condition of 1,000 W/m 2 and a temperature of 85 ° C and a humidity of 85% was exposed to measure the PCE value.

3) Charge transfer characteristics of the hole transport layer according to additives: The charge transfer characteristics were measured by current-voltage characteristics.

The preferred embodiments of the present invention described above have been disclosed for illustrative purposes, and those skilled in the art with ordinary knowledge of the present invention will be able to make various modifications, changes and additions within the spirit and scope of the present invention, and such modifications, changes and additions should be regarded as falling within the scope of the claims.

Those skilled in the art to which the present invention pertains can make various substitutions, modifications, and changes without departing from the technical spirit of the present invention. is not limited by

Claims (7)

As an electron transport layer,
SnO ₂ layer; and
SnO ₂ layer doped with Zn on the SnO ₂ layer
Including, electron transport layer.
According to claim 1,
The SnO ₂ layer and the Zn-doped SnO ₂ layer have a bi-layer structure, the electron transport layer.
According to claim 1,
The electron transport layer is formed on the ITO electrode, the electron transport layer.
According to claim 1,
The electron transport layer can be used for both flexible devices and glass devices.
According to claim 1,
The electron transport layer can be produced by a low-temperature process, the electron transport layer.
According to claim 1,
The Zn-doped SnO ₂ layer is composed of nanorods, an electron transport layer.
An optical device comprising the electron transport layer according to any one of claims 1 to 6.

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