KR20090115579A - Method for manufacturing a transparent conducting oxides for organic semiconductor device having increased work function - Google Patents

Method for manufacturing a transparent conducting oxides for organic semiconductor device having increased work function Download PDF

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KR20090115579A
KR20090115579A KR1020080041501A KR20080041501A KR20090115579A KR 20090115579 A KR20090115579 A KR 20090115579A KR 1020080041501 A KR1020080041501 A KR 1020080041501A KR 20080041501 A KR20080041501 A KR 20080041501A KR 20090115579 A KR20090115579 A KR 20090115579A
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transparent electrode
work function
organic semiconductor
semiconductor device
assembled monolayer
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KR100977152B1 (en
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윤영수
지승현
김수호
박훈
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건국대학교 산학협력단
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Abstract

PURPOSE: A method for manufacturing a transparent electrode of an organic semiconductor device with an increased work function is provided to improve characteristic of a device by lowering a hole injection barrier of an organic semiconductor device. CONSTITUTION: A self assembled monolayer forming compound is naturally evaporated or heated under the room temperature and the atmosphere. A self assembled monolayer is formed in a transparent conducting oxide by evaporating the self assembled monolayer forming compound for a constant time. The self assembled monolayer forming compound is evaporated for 1 to 3 minutes. The self assembled monolayer forming layer is chloromethyl trichlorosilane. The ITO(Indium Tin Oxide), ZITO(Zinc Indium Tin Oxides), ZnO, or FTO(Fluorine Tin Oxide) are sued as the transparent electrode.

Description

증가된 일함수를 가지는 유기반도체 소자의 투명전극의 제조방법 {Method for manufacturing a transparent conducting oxides for organic semiconductor device having increased work function}Method for manufacturing a transparent conducting oxides for organic semiconductor device having increased work function

본 발명은 유기반도체 소자의 투명전극의 제조방법 및 그 소자에 관한 것으로서, 더욱 상세하게는 일함수가 증가된 투명전극의 제조방법 및 그 방법으로 제작된 투명전극을 포함하는 유기반도체 소자에 관한 것이다.The present invention relates to a method for manufacturing a transparent electrode of an organic semiconductor device and a device thereof, and more particularly, to a method for manufacturing a transparent electrode with increased work function and an organic semiconductor device including a transparent electrode manufactured by the method. .

전계 발광 (Electro-luminescence: EL)은 임의의 형광체가 전기장의 인가 하에서 빛을 발하는 현상이고, 이러한 현상을 이용하는 소자가 EL 소자이다. 이러한 유기 EL 소자의 구조에서, 유기 화합물을 이용한 발광 물질로 이루어진 유기층은 2개의 전극사이에 배치된다. 상기 유기층의 배열은 정공 주입층, 정공 수송층, 정공 저지층 (L.S. Hung, C. W. Tang, and M. G. Manson, Appl. Phys. Lett. 70, 152, 1997), 발광층, 전자 수송층, 전자 주입층의 다층구조로 이루어진다. 상기 2개의 전극 사이에 삽입된 다층 구조는 통상의 기판 상에 형성된다. 유기 EL 소자는 발광층에 도달한 주입된 전자와 정공이 재결합할 때 발생되는 빛을 이용하는 것으로서, 따라서, 10V 미만의 낮은 전압을 이용한 고휘도 발광과 빠른 응답 속도가 가능하 다.Electro-luminescence (EL) is a phenomenon in which any phosphor emits light under application of an electric field, and an element using this phenomenon is an EL element. In the structure of such an organic EL element, an organic layer made of a light emitting material using an organic compound is disposed between two electrodes. The organic layer may be arranged in a multi-layered structure including a hole injection layer, a hole transport layer, a hole blocking layer (LS Hung, CW Tang, and MG Manson, Appl. Phys. Lett. 70, 152, 1997), a light emitting layer, an electron transport layer, and an electron injection layer. Is made of. The multilayer structure inserted between the two electrodes is formed on a conventional substrate. The organic EL device uses light generated when the injected electrons and holes that have reached the light emitting layer recombine. Thus, high luminance light emission using a low voltage of less than 10V and fast response speed are possible.

상기와 같은 유기 EL 소자는 구동전압이 낮을수록 디스플레이에의 응용에 유리한데, 낮은 구동전압에서 작동이 가능하기 위해서는 이 전압에서 적절한 양의 전자와 정공의 주입이 가능하여야 한다 (X. Zhou, at al., Appl. Phys. Lett. 78, 410, 1999).The lower the driving voltage is, the more advantageous the application to the display. In order to operate at a lower driving voltage, an appropriate amount of electrons and holes must be injected at this voltage (X. Zhou, at al., Appl. Phys. Lett. 78, 410, 1999).

유기물을 이용하는 유기 전계 발광소자의 경우 높은 전압이 가해질 경우 전자나 정공이 가지게 되는 높은 에너지 때문에 약한 분자 구조를 갖는 유기 발광층이 손상되어 소자 특성이 저하되고, 수명 또한 저하되게 된다. 따라서 낮은 전압에서 충분한 수의 정공과 전자의 주입이 가능하게 하는 것이 매우 중요하다.In the case of an organic EL device using an organic material, when the high voltage is applied, the organic light emitting layer having a weak molecular structure is damaged due to the high energy of electrons or holes, resulting in deterioration of device characteristics and lifetime. Therefore, it is very important to be able to inject a sufficient number of holes and electrons at low voltage.

정공의 주입을 쉽게 하기 위해서는 양전극의 일함수와 정공 주입층의 HOMO (Highest Occupied Molecular Orbital) 레벨 사이의 에너지 차이가 작도록 만들어 주어야 한다. 그 에너지 차이를 정공 주입 장벽 (Hole injection barrier)이라 한다.In order to facilitate the injection of holes, the energy difference between the work function of the positive electrode and the highest Occupied Molecular Orbital (HOMO) level of the hole injection layer should be made small. The energy difference is called the hole injection barrier.

한편, ITO (Indium Tin Oxide, In2O3-SnO2) 박막은 가시광 영역에서의 높은 투과율을 가지며 전기전도도가 우수하여 다양한 평판표시소자와 태양전지 등의 전자소자 분야에서 투명전극으로 광범위하게 사용되고 있다. 특히, 차세대 디스플레이로서 인식되고 있는 OLED (Organic Light Emitting Diodes) 및 OTFT (Organic Tin Film Transistor) 소자의 전극으로 ITO 박막이 대부분 사용되고 있다.On the other hand, ITO (Indium Tin Oxide, In 2 O 3 -SnO 2 ) thin film has high transmittance in the visible light region and has excellent electrical conductivity, so it is widely used as a transparent electrode in various flat panel display devices and electronic devices such as solar cells. have. In particular, ITO thin films are mostly used as electrodes of OLED (Organic Light Emitting Diodes) and OTFT (Organic Tin Film Transistor) devices, which are recognized as next-generation displays.

그러나, ITO 투명전극으로부터 OLED의 홀주입층 또는 유기반도체에 정공을 주입할 경우, 상기에서 언급한 바와 같이 ITO와 유기반도체 사이에 큰 에너지 장벽이 존재하기 때문에 ITO의 일함수를 홀주입층 또는 유기반도체를 구성하는 유기화합물의 일함수 이상으로 증가시켜 ITO (+(양극))와 유기반도체 사이의 에너지 장벽을 감소시키는 것이 중요하다. 이 에너지 장벽을 줄이기 위해서는 전극인 ITO와 유기반도체에 사용될 수 있는 유기화합물이 갖는 이온화 포텐셜의 차이를 줄일 필요가 있다. 현재 OLED에서 사용되고 있는 정공 수송층과 OTFT에서 사용되고 있는 유기반도체의 일함수는 5.1 ~ 5.4eV이다. 따라서 ITO의 일함수가 4.5 ~ 4.6eV임을 감안하면, ITO를 사용하는 전극과 유기 반도체 사이에는 매우 큰 에너지 장벽이 존재하게 되는 문제점이 있다.However, when holes are injected into the hole injection layer or organic semiconductor of the OLED from the ITO transparent electrode, the work function of the ITO is changed to the hole injection layer or the organic semiconductor because there is a large energy barrier between the ITO and the organic semiconductor as mentioned above. It is important to reduce the energy barrier between ITO (+ (anode)) and the organic semiconductor by increasing it beyond the work function of the organic compounds constituting the semiconductor. In order to reduce this energy barrier, it is necessary to reduce the difference between the ionization potential of the organic compound that can be used for the electrode ITO and the organic semiconductor. The work function of the hole transport layer currently used in OLED and the organic semiconductor used in OTFT is 5.1 to 5.4 eV. Therefore, considering that the work function of ITO is 4.5 to 4.6 eV, there is a problem that a very large energy barrier exists between the electrode using ITO and the organic semiconductor.

따라서, 상기 문제점을 해결하기 위해 ITO 대신 일함수가 큰 다른 물질들을 사용하고 있지만, 광투과도, 공정의 편의성 및 가격 등의 문제점으로 인해 아직까지 ITO를 대체할 일함수 높은 투명전극은 개발되지 못하고 있는 실정이다. 또한, 건식 (UV, 산소플라즈마) 방법을 이용한 표면개질을 통한 일함수의 증가에 대한 연구가 진행되고 있는데, 예를 들면, 일정한 O2 가스분위기에서 ITO를 증착하여 박막을 형성한 후 유기 발광소자의 양전극으로 사용하는 산소 플라즈마 (F. Steuber, at al., Appl. Phys. Lett. 74, 3558, 1999)와 UV 램프 (K. Sugiyama, at al., J. Appl. Phys. 87, 295, 2000)를 사용하여 기 형성된 ITO층의 표면 처리를 하는 방법들이 이용되고 있다. 그러나, 이러한 처리를 거치면 양전극으로 사용되는 ITO의 일함수가 증가되어 정공주입 장벽을 낮출 수는 있으나 그 일함수 증가의 폭이 작아 기대이상의 효과를 거둘 수가 없으며, 진공장비 등의 고가의 장비를 사용해야 하는 단점을 가지고 있다. Therefore, in order to solve the above problems, other materials having a large work function are used instead of ITO. However, transparent electrodes having a high work function have not been developed due to problems such as light transmittance, process convenience, and price. It is true. In addition, studies on the increase of the work function through surface modification using a dry (UV, oxygen plasma) method, for example, organic light emitting device after forming a thin film by depositing ITO in a constant O 2 gas atmosphere Oxygen plasma (F. Steuber, at al., Appl. Phys. Lett. 74, 3558, 1999) and UV lamp (K. Sugiyama, at al., J. Appl. Phys. 87, 295, 2000) are used to surface-treat the pre-formed ITO layer. However, this treatment increases the work function of the ITO used as the positive electrode, which can lower the hole injection barrier. However, the increase of the work function is so small that it cannot achieve the expected effect, and expensive equipment such as vacuum equipment should be used. It has a disadvantage.

한편, 해외에서는 자가조립단층 (Self Assembled Monolayer; SAM)형 표면개질을 이용하여 금속 등의 일함수를 증가시키는 연구가 진행되고 있다. SAM형 표면개질은 자가조립단층을 이루는 물질을 이용하여 고체의 표면에 자가조립단층을 형성하는 것이다. SAM은 고체의 표면에 강하게 흡착되며, 열적, 화학적 안정도 및 물리적 강도가 매우 우수하고, SAM의 형성이 용이하여 나노테크놀러지 (nanotechnology)에 널리 이용되고 있다. 또한, 다른 방법들에 비해 공정의 단순함은 물론 대면적의 용이함을 가지고 있으며, SAM에 의한 표면개질은 기판의 표면에 물리적, 화학적 손상을 주지 않고 표면의 특성을 변화시킬 수 있는 장점을 가지고 있다. On the other hand, overseas studies are being conducted to increase the work function of metals by using a self-assembled monolayer (SAM) type surface modification. SAM type surface modification is to form a self-assembled monolayer on the surface of the solid by using the material of the self-assembled monolayer. SAM is strongly adsorbed on the surface of a solid, has excellent thermal, chemical stability and physical strength, and is easy to form SAM, and is widely used in nanotechnology. In addition, compared to other methods, the process has the simplicity and ease of large area, and the surface modification by SAM has the advantage of changing the characteristics of the surface without causing physical and chemical damage to the surface of the substrate.

그러나, 아직 SAM형 표면개질에 대한 연구가 활발하게 이루어지지 않고 있으며, 상용화의 보고도 없는 실정이다. 또한, 해외 연구에서 보고된 SAM에 의한 투명전극의 일함수의 증가는 약 0.3eV에 불과하여 유기반도체와의 옴 (ohmic) 접촉의 가능성을 제시하지는 못하고 있는 실정이다 (J. Mater., Chem., 10, pp169-173, 2000).However, research on SAM type surface modification has not been actively conducted, and there are no reports of commercialization. In addition, the increase in the work function of the transparent electrode by SAM reported in overseas studies is only about 0.3 eV, which does not suggest the possibility of ohmic contact with the organic semiconductor (J. Mater., Chem. , 10, pp 169-173, 2000).

이에 본 발명자들은 상기 종래기술의 문제점들을 해결하기 위하여, 연구를 거듭한 결과 증발법을 이용하여 투명전극의 표면에 SAM을 형성시킴에 의해 광투과도의 변화없이 일함수를 탁월하게 증가시킬 수 있음을 확인함으로써, 본 발명을 완성하였다.In order to solve the problems of the prior art, the present inventors have repeatedly studied that the work function can be excellently increased without changing the light transmittance by forming a SAM on the surface of the transparent electrode using an evaporation method. By confirming, the present invention was completed.

결국 본 발명의 목적은 증가된 일함수를 가지는 유기반도체 소자의 투명전극의 제조방법을 제공하는 것이다.After all, an object of the present invention is to provide a method for manufacturing a transparent electrode of an organic semiconductor device having an increased work function.

본 발명의 다른 목적은 상기 제조방법에 의해 제작되는 투명전극을 포함하는 유기반도체 소자를 제공하는데 있다.Another object of the present invention to provide an organic semiconductor device comprising a transparent electrode produced by the manufacturing method.

상기 목적을 달성하기 위하여, 본 발명은 유기반도체 소자의 투명전극을 형성하는 방법에 있어서, 실온, 대기압 하에서 자연증발하거나 또는 열에 의해 가열된 자가조립단층 (Self Assembled Monolayer; SAM) 형성 화합물을 일정시간 동안 증발시켜 투명전극에 자가조립단층 (SAM)을 형성시키는 것을 특징으로 하는 증가된 일함수를 가지는 유기반도체 소자의 투명전극의 제조방법을 제공한다.In order to achieve the above object, the present invention provides a method for forming a transparent electrode of an organic semiconductor device, the self-assembled monolayer (SAM) forming compound that is naturally evaporated or heated by heat at room temperature, atmospheric pressure for a predetermined time It provides a method of manufacturing a transparent electrode of an organic semiconductor device having an increased work function characterized in that the evaporation during the formation of a self-assembled monolayer (SAM) on the transparent electrode.

본 발명에 있어서, 상기 자가조립단층 형성 화합물은 1 ~ 5분간, 바람직하게는 1 ~ 3분간 증발시키는 것을 특징으로 할 수 있다.In the present invention, the self-assembled monolayer forming compound may be evaporated for 1 to 5 minutes, preferably 1 to 3 minutes.

본 발명에 있어서, 상기 투명전극으로는 ITO (Indium Tin Oxide), ZITO (Zinc Indium Tin Oxides), GITO (Gallium Indium Tin Oxides), ZnO 또는 FTO (Fluorine Tin Oxide)가 사용되는 것을 특징으로 할 수 있으며, 바람직하게는 ITO가 사용되는 것을 특징으로 할 수 있다.In the present invention, the transparent electrode may be characterized in that ITO (Indium Tin Oxide), ZITO (Zinc Indium Tin Oxides), GITO (Gallium Indium Tin Oxides), ZnO or FTO (Fluorine Tin Oxide) is used. Preferably, ITO may be used.

본 발명에 있어서, 상기 자가조립단층 (SAM) 형성 화합물은 트리클로로실란 계열 (RSiCl4)로 이루어진 군으로부터 선택되는 것을 특징으로 할 수 있으며, 바람직하게는 클로로메틸 트리클로로실란 (chloromethyl trichlorosilane)인 것을 특징으로 할 수 있다.In the present invention, the self-assembled monolayer (SAM) forming compound may be selected from the group consisting of trichlorosilane series (RSiCl 4 ), preferably chloromethyl trichlorosilane (chloromethyl trichlorosilane) It can be characterized.

본 발명은 상기 제조방법에 의해 제작되어 일함수가 증가된 투명전극을 포함하는 유기 반도체 소자를 제공한다.The present invention provides an organic semiconductor device including the transparent electrode manufactured by the above manufacturing method and the work function is increased.

본 발명에 따른 유기반도체 소자의 투명전극의 제조방법은 광투과도의 변화없이 일함수가 현저하게 증가된 투명전극을 제작할 수 있도록 함으로써, 유기반도체 소자의 정공주입 장벽을 낮추어 소자의 특성을 개선할 수 있다. 또한, 증발법을 이용한 단순한 제조공정으로 인하여 비용절감 및 생산성 향상을 도모할 수 있다.In the method of manufacturing a transparent electrode of an organic semiconductor device according to the present invention, it is possible to manufacture a transparent electrode with a significantly increased work function without a change in light transmittance, thereby lowering the hole injection barrier of the organic semiconductor device, thereby improving the characteristics of the device. have. In addition, cost reduction and productivity improvement can be achieved due to a simple manufacturing process using an evaporation method.

이하, 본 발명을 상세히 설명하면 다음과 같다.Hereinafter, the present invention will be described in detail.

본 발명은 증가된 일함수를 가지는 유기반도체 소자의 투명전극의 제조방법 및 그 방법으로 제작된 투명전극을 포함하는 유기반도체 소자에 관한 것이다.The present invention relates to a method for manufacturing a transparent electrode of an organic semiconductor device having an increased work function and to an organic semiconductor device including a transparent electrode manufactured by the method.

도 1은 본 발명의 증가된 일함수를 가지는 유기반도체 소자의 투명전극의 제조방법을 개략적으로 나타낸 실험도로서, 본 발명은 유기반도체 소자의 투명전극을 형성하는 방법에 있어서, 투명전극의 박막을 과산화수소, 암모니아 및 물의 혼합용액에 담그어 투명전극의 표면에 염기화를 유도한 후, 자연증발하거나 또는 열에 의해 가열된 자가조립단층 (Self Assembled Monolayer; SAM) 형성 화합물을 일정시간 동안 증발시켜 상기 염기화된 투명전극에 SAM을 형성시키는 것을 포함하여 구성되는 것을 특징으로 한다.1 is an experimental view schematically showing a method for manufacturing a transparent electrode of an organic semiconductor device having an increased work function of the present invention, the present invention is a method of forming a transparent electrode of an organic semiconductor device, a thin film of a transparent electrode After immersing in a mixed solution of hydrogen peroxide, ammonia and water to induce basification on the surface of the transparent electrode, the self-assembly monolayer (SAM) -forming compound formed by evaporation or heating by evaporation is evaporated for a predetermined time. And forming a SAM on the transparent electrode.

상기 투명전극의 표면에 자가조립단층 (Self Assembled Monolayer; SAM) 형성 화합물이 잘 형성될 수 있도록 전극의 표면에 OH기를 형성시켜주는 단계로, 과산화수소, 암모니아 및 물을 3:3:5의 비율로 혼합한 혼합용액에 투명전극의 박막을 5 ~ 20분, 바람직하게는 5 ~ 10분 동안 담그어 염기화를 유도하는 것을 특징으로 한다. A step of forming an OH group on the surface of the electrode to form a self-assembled monolayer (SAM) -forming compound on the surface of the transparent electrode, hydrogen peroxide, ammonia and water in a 3: 3: 5 ratio The thin film of the transparent electrode is immersed in the mixed solution for 5 to 20 minutes, preferably 5 to 10 minutes, characterized in that induction of basicization.

상기 염기화가 유도된 투명전극의 표면을 개질하기 위하여 SAM을 형성시키는 단계는, 실온 및 대기압 상태에서 자연증발하는 SAM 형성 화합물 또는 열에 의해 가열된 SAM 형성 화합물을 1 ~ 5분, 바람직하게는 1 ~ 3분 동안 증발시켜 투명전극의 표면에 SAM을 형성시키고, 이 SAM의 형성에 의해 일함수 변화를 이끌어 내는 것을 특징으로 한다.The step of forming the SAM to modify the surface of the basic electrode is induced, 1 to 5 minutes, preferably 1 to 5 minutes to the SAM-forming compound that is spontaneously evaporated at room temperature and atmospheric pressure After evaporation for 3 minutes to form a SAM on the surface of the transparent electrode, by the formation of the SAM it is characterized in that the work function changes.

본 발명에서 사용가능한 SAM 형성 화합물은 트리클로로실란 계열 (RSiCl4)이며, 바람직하게는 클로로메틸 트리클로로실란을 사용할 수 있으나, 이에 의해 한정되지는 않는다. The SAM-forming compound usable in the present invention is trichlorosilane series (RSiCl 4 ), preferably chloromethyl trichlorosilane can be used, but is not limited thereto.

상기 투명전극 (Transparent Conducting Oxide; TCO)은 광투과성 투명 기판 위에 양전극으로 사용되는 것으로서, ITO (Indium Tin Oxide), ZITO (Zinc Indium Tin Oxides), GITO (Gallium Indium Tin Oxides), ZnO 또는 FTO (Fluorine Tin Oxide)가 사용되며, 바람직하게는 ITO가 사용될 수 있는데, 이를 제작하는 방법은 DC 혹은 RF 스터터링 (sputtering), 전자빔 (electron beam) 증착방법 등 공지의 방법이 이용될 수 있다.The transparent electrode (TCO) is used as a positive electrode on a transparent transparent substrate, ITO (Indium Tin Oxide), ZITO (Zinc Indium Tin Oxides), GITO (Gallium Indium Tin Oxides), ZnO or FTO (Fluorine) Tin Oxide) is used, and preferably ITO may be used, and a method of manufacturing the same may be a known method such as DC or RF sputtering and electron beam deposition.

상기와 같은 방법으로 제작한 ITO 투명전극의 경우 비저항이 ~10-4Ω㎝ 정도이고, 광 투과율은 가시광선 영역에서 90%이상이며 일함수 값은 4.5 ~ 4.6eV 정도이다. 상기와 같이 ITO의 일함수는 4.5 ~ 4.6eV이며, 유기반도체의 일함수는 5.1 ~ 5.4eV임으로 ITO 투명전극과 유기반도체 사이에 매우 큰 에너지 장벽이 존재하게 된다. 이 에너지 장벽은 유기반도체와 전극 사이의 정공주입이 원활하게 이루어 질 수 없도록 하며, 유기반도체 소자의 특성을 저하시키게 된다. 따라서, 투명전극과 유기반도체 사이에 정공의 주입이 원활하게 이루어질 수 있도록 투명전극의 일함수를 유기반도체 수준으로 증가시킬 필요성이 있다. In the case of the ITO transparent electrode manufactured by the above method, the specific resistance is about 10 −4 Ωcm, the light transmittance is 90% or more in the visible region, and the work function is about 4.5 to 4.6 eV. As described above, the work function of ITO is 4.5 to 4.6 eV, and the work function of the organic semiconductor is 5.1 to 5.4 eV, so that a very large energy barrier exists between the ITO transparent electrode and the organic semiconductor. This energy barrier prevents the hole injection between the organic semiconductor and the electrode to be performed smoothly, and deteriorates the characteristics of the organic semiconductor device. Therefore, there is a need to increase the work function of the transparent electrode to the level of the organic semiconductor so that holes can be smoothly injected between the transparent electrode and the organic semiconductor.

본 발명은 증발법을 이용한 간단한 공정에 의한 SAM의 형성으로 인해 투명전극의 일함수를 유기반도체의 수준으로 증가시킬 수 있다.The present invention can increase the work function of the transparent electrode to the level of the organic semiconductor due to the formation of SAM by a simple process using the evaporation method.

도 2는 본 발명의 방법에 의해 제작된 투명전극의 일함수를 나타낸 그래프로서, 도 2에 도시한 바와 같이, 본 발명에 의해 표면개질된 ITO 투명전극의 일함수는 5.2 ~ 5.3eV로서 표면개질되지 않은 ITO 투명전극 (4.55eV)에 비하여 월등히 증가된 일함수를 가진다. Figure 2 is a graph showing the work function of the transparent electrode produced by the method of the present invention, as shown in Figure 2, the work function of the surface-modified ITO transparent electrode by the present invention is 5.2 ~ 5.3eV surface modification It has a significantly increased work function compared to the ITO transparent electrode (4.55eV).

또한, 도 3은 본 발명의 방법에 의해 제작된 ITO 투명전극의 광투과도 변화를 나타낸 그래프로서, 도 3에 도시한 바와 같이, 본 발명에 의해 표면개질된 ITO 투명전극의 광투과도는 실험적 오차 범위 내에서 변하지 않아, 본 발명의 제조방법 은 전극의 표면에 물리적, 화학적 손상을 주지 않으면서 일함수를 개선할 수 있다.In addition, Figure 3 is a graph showing the change in the light transmittance of the ITO transparent electrode produced by the method of the present invention, as shown in Figure 3, the light transmittance of the surface-modified ITO transparent electrode by the present invention is an experimental error range Unchanged within, the manufacturing method of the present invention can improve the work function without causing physical and chemical damage to the surface of the electrode.

도 4는 본 발명의 방법에 의해 제작된 ITO 투명전극의 일함수 증가에 의한 전류특성을 평가한 것으로서, 도 4에 도시한 바와 같이, 일함수가 증가한 ITO 투명전극의 경우 홀주입 증가로 인해 같은 전압의 인가시 전류의 양이 많아지는 것을 관찰할 수 있다. 이는 투명전극의 일함수의 증가로 인해 유기반도체 소자의 정공주입 장벽이 감소하여 소자의 특성이 개선됨을 나타낸다.Figure 4 is an evaluation of the current characteristics by the increase in the work function of the ITO transparent electrode manufactured by the method of the present invention, as shown in Figure 4, in the case of the ITO transparent electrode with increased work function due to the increase in hole injection It can be observed that the amount of current increases when the voltage is applied. This indicates that the hole injection barrier of the organic semiconductor device is reduced due to the increase of the work function of the transparent electrode, thereby improving the device characteristics.

이하, 실시예에 의하여 본 발명을 더욱 상세히 설명하고자 한다.Hereinafter, the present invention will be described in more detail with reference to Examples.

단, 하기 실시예는 본 발명을 예시하는 것일 뿐, 본 발명의 내용이 하기 실시 예에 한정되는 것은 아니다. However, the following examples are merely to illustrate the invention, but the content of the present invention is not limited to the following examples.

실시예 1: 증가된 일함수를 가지는 ITO 투명전극의 제조Example 1 Fabrication of ITO Transparent Electrode with Increased Work Function

ITO 투명전극 표면의 이물질을 제거한 뒤, ITO 투명전극의 표면에 자가조립단층 (Self Assembled Monolayer; SAM) 형성 화합물이 잘 형성될 수 있도록 OH기를 만들어 주기 위하여 과산화수소, 암모니아 및 물이 3:3:5로 혼합된 용액에 ITO 박막을 10분 동안 담그어 주었다.After removing foreign substances on the surface of the ITO transparent electrode, hydrogen peroxide, ammonia, and water were added to the surface of the ITO transparent electrode to form an OH group to form a self-assembled monolayer (SAM) -forming compound. The ITO thin film was immersed in the mixed solution for 10 minutes.

상기 염기화된 ITO 투명전극에 자가조립단층을 형성하기 위해, 실온 및 대기압 상태에서 자연증발하는 자가조립단층 형성 화합물인 클로로메틸 트리크롤로실란 (chloromethyl trichlorosilane)을 밀폐된 공간에서 1 ~ 3분 동안 자연증발시켜 ITO 투명전극 표면에 자가조립단층을 형성시켜 증가된 일함수를 가지는 ITO 투명전 극을 제조하였다 (도 1 참조).In order to form a self-assembled monolayer on the basicized ITO transparent electrode, chloromethyl trichlorosilane, a self-assembled monolayer-forming compound that evaporates naturally at room temperature and atmospheric pressure, for 1 to 3 minutes in an enclosed space. By spontaneous evaporation to form a self-assembled monolayer on the surface of the ITO transparent electrode to prepare an ITO transparent electrode having an increased work function (see Figure 1).

실험예 1: 특성 분석Experimental Example 1: Characterization

상기 실시예 1의 ITO 투명전극의 일함수는 켈빈 탐침 (Kelvin probe)을 이용하여 측정하였으며, ITO 투명전극의 일함수 증가에 따른 유기소자의 전류향상 정도는 홀주입층인 NPB를 이용하여 전류특성을 평가함으로서 측정하였다. The work function of the ITO transparent electrode of Example 1 was measured using a Kelvin probe, and the current improvement of the organic device according to the increase of the work function of the ITO transparent electrode was performed using NPB, which is a hole injection layer. It was measured by evaluating.

그 결과는 도 2 내지 4에 나타내었으며, 도 2는 본 발명의 제조방법에 의해 제작된 ITO 투명전극의 일함수 증가를 나타내며, 도 3은 본 발명의 제조방법에 의해 제작된 ITO 투명전극의 광투과도 변화를 나타내고, 도 4는 ITO 투명전극의 일함수 증가에 따른 전류특성의 향상 정도를 나타낸다.The results are shown in Figures 2 to 4, Figure 2 shows the increase in the work function of the ITO transparent electrode produced by the manufacturing method of the present invention, Figure 3 is a light of the ITO transparent electrode produced by the manufacturing method of the present invention The change in transmittance is shown, and FIG. 4 shows the degree of improvement in current characteristics as the work function of the ITO transparent electrode increases.

도 2에 도시한 바와 같이, 표면개질되지 않은 ITO 투명전극의 일함수는 4.55eV이었으며, 본 발명의 SAM에 의해 표면개질된 ITO 투명전극의 일함수는 5.2 ~ 5.3eV임을 알 수 있었다. 상기한 바와 같이 ITO 투명전극의 일함수 증가는 유기반도체 및 OLED의 홀주입층이 5.1 ~ 5.4eV일 경우 ITO 투명전극과 유기층과의 에너지 장벽을 줄일 수 있으며, ITO 투명전극에서 유기층으로의 홀주입이 원활해질 수 있는 가능성을 제시할 수 있다. As shown in FIG. 2, the work function of the unmodified ITO transparent electrode was 4.55 eV, and the work function of the ITO transparent electrode surface-modified by the SAM of the present invention was 5.2 to 5.3 eV. As described above, the increase in the work function of the ITO transparent electrode can reduce the energy barrier between the ITO transparent electrode and the organic layer when the hole injection layer of the organic semiconductor and the OLED is 5.1 to 5.4 eV, and the hole injection from the ITO transparent electrode to the organic layer. This may suggest the possibility of smoothing.

또한, 도 3에 도시한 바와 같이, 본 발명에 의한 ITO 투명전극의 광투과도는 실험적 오차 범위 내에서 변하지 않아 투명전극으로서의 역할을 할 수 있음을 확인할 수 있었다.In addition, as shown in Figure 3, the optical transmittance of the ITO transparent electrode according to the present invention did not change within the experimental error range it could be confirmed that it can serve as a transparent electrode.

또한, 도 4에 도시한 바와 같이, 일함수가 증가된 ITO 투명전극의 경우, 홀 주입 증가로 인해 같은 전압의 인가시 전류의 양이 많아지는 것을 알 수 있었으며, 이는 ITO 투명전극의 일함수의 증가가 OLED 내부의 홀주입을 증가시켜 전류특성을 향상시킴을 확인할 수 있었다.In addition, as shown in FIG. 4, in the case of the ITO transparent electrode having the increased work function, it was found that the amount of current increases when the same voltage is applied due to the increase of the hole injection. It can be seen that the increase improves the current characteristics by increasing the hole injection inside the OLED.

도 1은 본 발명의 증가된 일함수를 가지는 유기반도체 소자의 투명전극의 제조방법을 개략적으로 도시한 실험도이다.1 is an experimental view schematically showing a method of manufacturing a transparent electrode of an organic semiconductor device having an increased work function of the present invention.

도 2는 본 발명의 제조방법에 의해 제작된 ITO 투명전극의 일함수 증가를 나타낸 그래프이다.Figure 2 is a graph showing the increase in the work function of the ITO transparent electrode produced by the manufacturing method of the present invention.

도 3은 본 발명의 제조방법에 의해 제작된 ITO 투명전극의 광투과도 변화를 나타낸 그래프이다.3 is a graph showing a change in light transmittance of the ITO transparent electrode produced by the manufacturing method of the present invention.

도 4는 본 발명의 제조방법에 의해 제작된 ITO 투명전극의 일함수 증가에 따른 전류특성을 나타낸 그래프이다.Figure 4 is a graph showing the current characteristics according to the increase in the work function of the ITO transparent electrode produced by the manufacturing method of the present invention.

Claims (5)

유기반도체 소자의 투명전극을 형성하는 방법에 있어서, In the method of forming a transparent electrode of an organic semiconductor device, 실온, 대기압 하에서 자연증발하거나 또는 열에 의해 가열된 자가조립단층 (Self Assembled Monolayer; SAM) 형성 화합물을 일정시간 동안 증발시켜 투명전극에 자가조립단층 (SAM)을 형성시키는 것을 특징으로 하는 증가된 일함수를 가지는 유기반도체 소자의 투명전극의 제조방법.Increased work function characterized by evaporation of self-assembled monolayer (SAM) forming compounds spontaneously evaporated at room temperature or atmospheric pressure or by heating to form self-assembled monolayers (SAM) on transparent electrodes. Method of manufacturing a transparent electrode of an organic semiconductor device having a. 제1항에 있어서, 상기 자가조립단층 (Self Assembled Monolayer; SAM) 형성 화합물은 1 ~ 3분간 증발시키는 것을 특징으로 하는 투명전극의 제조방법.The method of claim 1, wherein the self-assembled monolayer (SAM) -forming compound is evaporated for 1 to 3 minutes. 제1항에 있어서, 상기 투명전극으로는 ITO (Indium Tin Oxide), ZITO (Zinc Indium Tin Oxides), GITO (Gallium Indium Tin Oxides), ZnO 또는 FTO (Fluorine Tin Oxide)이 사용되는 것을 특징으로 하는 투명전극의 제조방법.The transparent electrode of claim 1, wherein indium tin oxide (ITO), zinc indium tin oxides (ZITO), gallium indium tin oxides (GITO), znO, or fluorine tin oxide (FTO) is used as the transparent electrode. Method for producing an electrode. 제1항에 있어서, 상기 자가조립단층 (SAM) 형성 화합물은 클로로메틸 트리클로로실란 (chloromethyl trichlorosilane)인 것을 특징으로 하는 투명전극의 제조 방법.The method of claim 1, wherein the self-assembled monolayer (SAM) forming compound is chloromethyl trichlorosilane. 제1항 내지 제4항 중 어느 한 항의 방법으로 제작되어 일함수가 증가된 투명전극을 포함하는 유기 반도체 소자.An organic semiconductor device comprising a transparent electrode manufactured by the method of any one of claims 1 to 4, the work function is increased.
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