• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.591-591
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• 2012

본 연구는 Transparent conducting oxide (TCO, 산화물투명전극)를 이용한 박막태양전지 효율향상에 관한 것으로, 이중의 TCO층(Double-stacked TCO layer)의 효과적인 광학 및 전기적 설계에 관한 것이다. 기존 박막 태양전지에서는 투명전극 TCO layer로서, ITO (Indium-Tin-Oxide), FTO (Fluorine- Tin-Oxide), 및 AZO(Aluminum-doped Zinc Oxide) 등을 사용해 왔다. 각 TCO layer마다 장점이 있지만 단점 또한 존재한다. ITO의 경우 높은 전기적 특성을 가지는 반면 수소 플라즈마에 취약하고 기계적 강도에 취약해 ITO 단일층만으로 박막 태양전지에 적용하는 것에 제한을 받는다. 한편, AZO의 경우 전기적 특성도 우수할 뿐만 아니라 수소 플라즈마에도 내구성이 강한 장점이 있지만, 일함수가 p형 반도체보다 낮아 Schottky junction이 되어, 높은 전위장벽이 형성된다. 이는 정공의 이동을 방해하고, 정공의 축적이 일어나서 순방향 전압을 인가할 때 많은 전류의 감소를 가져온다. 또한, AZO와 p형 반도체 사이의 높은 직렬저항으로 인해 광전압(Voc, Open circuit voltage)와 충실률 (FF, Fill factor)가 떨어진다는 단점이 있다. 본 실험에서는 ITO/AZO 2중구조의 TCO층을 적용하여 상기의 문제점을 해결하고자 한다. 이중 구조 TCO층은 Magnetron sputter system을 이용하여, 단계적으로 증착되었다. 빛이 입사하는 유리에 ITO를 제1전도층으로 증착하였는데, ITO는 입사광의 투과도와 전기전도성이 우수하다. 제2전도층으로는 AZO층을 이용하였으며, 실리콘 반도체층과 접하게 된다. AZO는 실리콘 증착시 발생하는 수소 플라즈마에 안정적이고, 물리적 강도 또한 우수한 장점이 있다. 이중 구조층위에 실리콘 광흡수층(Si absorber)을 증착하였으며, pin 구조를 가진다. 기존, 단일막 TCO층과 2중구조 TCO층을 이용하여, 실리콘 박막 태양전지를 구성하였다. 이때, ITO/AZO의 2중구조를 적용하였을 때 태양 전지 특성이 크게 향상된 결과를 얻을 수가 있었다. 특히, 전류밀도의 경우 ITO, FTO, AZO 각각 14.5 mA/cm2, 11.2 mA/cm2, 8.18 mA/cm2를 나타낸 반면 ITO/AZO 2중구조의 경우 약 17mA/cm2 로 크게 향상 되었고, 태양전지 변환 효율도 각각 7.5%, 6.9%, 4%에서 ITO/AZO 2중 구조의 경우 8.05%로 크게 향상되었다. 본 발표에서는 2중구조 TCO를 이용한 현공정에 적용 가능한 박막태양전지 효율향상 기법에 대해 논의하고자 한다.

• ETRI Journal
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• v.27 no.5
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• pp.545-550
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• 2005

We have carried out the fabrications of a barrier layer on a polyethersulfon (PES) film and organic light emitting diode (OLED) based on a plastic substrate by means of atomic layer deposition (ALD). Simultaneous deposition of 30 nm $AlO_x$ film on both sides of the PES film gave a water vapor transition rate (WVTR) of $0.062 g/m^2/day (@38^{\circ}C,\;100%\;R.H.)$. Further, the double layer of 200 nm $SiN_x$ film deposited by plasma enhanced chemical vapor deposition (PECVD) and 20 nm $AlO_x$ film by ALD resulted in a WVTR value lower than the detection limit of MOCON. We have investigated the OLED encapsulation performance of the double layer using the OLED structure of ITO / MTDATA (20 nm) / NPD (40 nm) / AlQ (60 nm) / LiF (1 nm) / Al (75 nm) on a plastic substrate. The preliminary life time to reach 91% of the initial luminance $(1300 cd/m^2)$ was 260 hours for the OLED encapsulated with 100 nm of PECVD-deposited $SiN_x$ and 30 nm of ALD-deposited $AlO_x$.

• Journal of Information Display
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• v.5 no.3
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• pp.30-34
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• 2004

Fabrications of barrier layer on a polyethersulfon (PES) film and OLED based on a plastic substrate by atomic layer deposition (ALD) have been carried out. Simultaneous deposition of 30 nm of $AlO_x$ film on both sides of PES film gave film MOCON value of 0.0615 g/$m^2$/day (@38$^{\circ}C$, 100 % R.H.). Moreover, the double layer of 200 urn $SiN_x$ film deposited by PECVD and 20 nm of $AlO_x$ film by ALD resulted in the MOCON value lower than the detection limit of MOCON. The OLED encapsulation performance of the double layer have been investigated using the OLED structure of ITO/MTDATA(20 nm)/NPD(40 nm)/AlQ(60 nm)/LiF(1 nm)/Al(75 nm) based on the plastic substrate. Preliminary life time to 91 % of initial luminance (1300 cd/$m^2$) was 260 hours for the OLED encapsulated with 100 nm of PECVD deposited $SiN_x$/30 nm of ALD deposited $AlO_x$.

• Korean Journal of Materials Research
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• v.18 no.4
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• pp.199-203
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• 2008

High-efficiency phosphorescent organic light emitting diodes using TCTA-TAZ as a double host and $Ir(ppy)_3$ as a dopant were fabricated and their electro-luminescence properties were evaluated. The fabricated devices have the multi-layered organic structure of 2-TNATA/NPB/(TCTA-TAZ) : $Ir(ppy)_3$/BCP/SFC137 between an anode of ITO and a cathode of LiF/AL. In the device structure, 2-TNATA[4,4',4"-tris(2-naphthylphenyl-phenylamino)-triphenylamine] and NPB[N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine] were used as a hole injection layer and a hole transport layer, respectively. BCP [2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline] was introduced as a hole blocking layer and an electron transport layer, respectively. TCTA [4,4',4"-tris(N-carbazolyl)-triphenylamine] and TAZ [3-phenyl-4-(1-naphthyl)-5-phenyl-1,2,4-triazole] were sequentially deposited, forming a double host doped with $Ir(ppy)_3$ in the [TCTA-TAZ] : $Ir(ppy)_3$ region. Among devices with different thickness combinations of TCTA ($50\;{\AA}-200\;{\AA}$) and TAZ ($100\;{\AA}-250\;{\AA}$) within the confines of the total host thickness of $300\;{\AA}$ and an $Ir(ppy)_3$-doping concentration of 7%, the best electroluminescence characteristics were obtained in a device with $100\;{\AA}$-think TCTA and $200\;{\AA}$-thick TAZ. The $Ir(ppy)_3$ concentration in the doping range of 4%-10% in devices with an emissive layer of [TCTA ($100\;{\AA}$)-TAZ ($200\;{\AA}$)] : $Ir(ppy)_3$ gave rise to little difference in the luminance and current efficiency.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.791-793
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• 2009

We have developed novel small molecular materials for solution phosphorescent OLEDs having multilayered device structures. These novel materials are applied as an interlayer which is between a buffer layer (or hole injection layer) and an emitting layer to improve the luminance efficiency of solution green phosphorescent OLEDs. In order to form stable double layers by spincoating process, we take the advantage of solubility differences of interlayer materials and emitting materials. Using CIM3 as an interlayer, we have attained the best luminance efficiency, 36 cd/A at a given constant of 2000cd/$m^2$ in the structure of ITO/PEDOT:PSS/CIM3/CIM6:Ir(mppy)$_3$/BAlq/Alq$_3$/LiF/Al.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.116-119
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• 1997

In this paper A double-layer organic electroluminescent(EL) device was fabricated using a TPD(N,N'-dipheny] -N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4.4'-diamine: aromatic diamine), as a hole-transport material and tris (8-hydroxy quinolinate) aluminum(Alq$_3$) as a an emiting material and its performance characteristics were investigated. structure of devices is ITO/TPD/Alq$_3$/Al. we have fabricated hole transport layer of two types. Doping material of Hole Transport material is Poly(methyl methacrylate)(PMMA) and PEI(Poly-Ether-Imide). Carrier injection from the electrodes to the doped PMMA and PEI layer through the dopants and concomitant electroluminescence from Alq$_3$were observed. Green emission with luminance of 40cd/m$^2$was achieved at a drive voltage of 30V

• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.449-453
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• 1996

In order to improve EL performance, anthracene was doped into the 8-hydroxyquinoline-aluminum (Alq$^3$) light-emitting layer of organic double layered EL cells. The EL cells were fabricated on ITO glass substrates by vacuum deposition. Doping of anthracene to the light-emitting $Alq^3$layer was performed by means of co-evaporation. The doping concentration was changed in the range of 5 to 30 wt.%. It was confirmed that anthracene doping of appropriate concentration increased the available current density and brightness of the EL cells. Carrier mobility of the $Alq^3$ layer was measured by time of flight method. The influence of anthracene doping on the cell performance was discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.9
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• pp.750-754
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• 2011

In this research, the electric characteristic of organic light-emitting diodes(OLEDs) was studied depending on thickness of amorphous fluoropolymer(Teflon-AF) which is the material of hole injection layer to improve electric characteristic of OLEDs. Sample composition was fabricated in double layer. The basic structure was fabricated by ITO/tris(8-hydroxyquinoline) aluminum (Alq3)/Al and the 2 layer was fabricated by ITO/2,2-Bistrifluoromethyl-4,5-Difluoro-1,3-Dioxole(Teflon-AF)/tris(8-hydro xyquinoline) aluminum (Alq3)/Al. The experiment was carried with variation of thickness of Teflon-AF at 1.0, 2.0, 2.5, 3.0 nm. The result showed when Teflon-AF thickness was 2.5 nm, the electric and optical characteristic were well performed. Moreover, when it was compared with Teflon-AF without materials, it was improved 15.1 times more on luminance, 12.7 times more on luminous efficiency and 12.1 times more on external quantum efficiency. Therefore, OLEDs element with optimum hole injection layer reduced energy barrier and driving voltage, and confirmed that it improved efficiency widely.

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.652-656
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• 2004

A new luminescent polymer, poly{1,4-phenylene-1,2-ethenediyl-2'-[2"-(4'"-octyloxyphenyl)-(5"-yl)-1",3",4"-oxadiazole]-1,4-phenylene-1,2-ethenediyl-2,5-bis-dodecyloxy-1,4-phenylene-1,2-ethenediyl} (Oxd-PPV), was synthesized by the Heck coupling reaction. Electron withdrawing pendant, conjugated 1,3,4-oxadiazole (Oxd), is on the vinylene unit. The band gap of the polymer figured out from the UV-visible spectrum was 2.23 eV and the polymer film shows bright yellow emission maximum at 552 nm. The electroluminescence (EL) maximum of double layer structured device (ITO/PEDOT:PSS/Oxd-PPV/Al) appeared at 553 nm. Relative PL quantum yield of Oxd-PPV film is 3.6 times higher than that of MEH-PPV film. The HOMO and LUMO energy levels of Oxd-PPV figured out from the cyclic voltammogram and the UV-visible spectrum are -5.32 and -3.09 eV, respectively, so that more balanced hole and electron injection efficiency can be expected compared to MEH-PPV. A double layer EL of Oxd-PPV has an maximum efficiency of 0.15 cd/A and maximum brightness of 464 cd/$m^2$.

• Analytical Science and Technology
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• v.5 no.1
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• pp.135-142
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• 1992

Indium tin oxide(ITO) films coated on the window glass selectively transmit the solar energy and infrared. We call this system passive solar collectors. Selectively absorbing properties of sol gel dip coated ITO films were characterized by UV-VIS-NIR spectroscopy. The effects of heat treating temperature, time, atmosphere, substrate and barrier layers are concerned. Indium tin oxide films heat-treated at $500^{\circ}C$ in a reducing atmosphere show intrinsic properties. Efficiency of solar energy transmittance was enhanced by coating of $SiO_2-ZrO_2$ as an alkali ion barrier layer. Energy was saved by the double layers of $SiO_2-ZrO_2$ and ITO since solar energy is transmitted and heat generated inside(${\lambda}$ > 2700nm) is reflected.