• Journal of the Korean institute of surface engineering
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• v.30 no.4
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• pp.255-261
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• 1997

Thin film batteries can be used as a micro power source for electronic in which minute power is needed. In this study, lithium phosphorous oxynitride(LIPON) thin films were deposited as an eletrolyte for lithium ion batteries using RF magentron sputtering of lithium phosphate in N2. Ti was also added into the LIPON films as a second network former to enhance the ioinc conductivity of the films. The optimum conditions for LIPON film deposition were sought and the electrolyte with the conductivity of $2.5 \times 10^{-6}$S/cm was obtained at the condition of RF power 4.4 W/$\textrm{cm}^2$, process pressure 10 mtorr and pure nitrogen ambience. Furthermore, the conductivity of LIPON films was increased from $2.5 \times 10^{-6}$S/cm to $8.6 \times 10^{-6}$S/cm by the doping of 2.4at.% Ti. It was also found that by adding Ti to LIPON films, Li content was increased and nitrogen content that reported having the cross-linking effect on LIPON films was also increased as confirmed XPS.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.193-193
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• 2013

실리콘 박막 태양전지는 광 흡수층에서 형성된 정공과 전자를 효과적으로 분리하기 위해 p형과 n형으로 도핑된 층을 형성하는 p-i-n구조를 갖게 된다. 이러한 도핑 층을 형성하기 위해 B2H6와 PH3와 같은 독성 가스를 사용하기 때문에, 공정 안정성과 환경적인 이슈가 대두된다. 또한 도핑은 추가적으로 실리콘 박막 태양전지의 안정화 효율을 지속적으로 저하시키는 요인이 된다. 이러한 문제점을 개선하기 위하여, 창층으로 MoO3, V2O5, WO3 등과 같이 높은 일함수를 갖는 전이금속 산화물을 사용하고, 광 흡수층으로 i-Si:H을, 후면 전극으로 낮은 일함수를 나타내는 LiF/Al을 사용하였다. 전이금속 산화물과 LiF/Al의 큰 일함수 차이에 의해서 흡수층인 i-Si:H 에서 생성된 캐리어들은 효과적으로 분리되고 수집이 된다. 금속 산화물은 스퍼터링 공정에 의하여 이루어졌으며, 스퍼터링 공정조건에 따라 산화도가 조절되며, 이러한 산화도에 따라 태양전지의 셀 특성이 결정된다. 도핑 층이 없는 새로운 형태의 실리콘 박막 태양전지는 기존 비정질 실리콘 박막 태양전지에 비해 높은 안정화 효율을 나타내며, 이는 도핑 층이 없기 때문에 기존 실리콘 박막 태양전지의 열화현상에 따른 효율저하가 발생하지 않는 장점을 지내고 있다.

• Korean Journal of Materials Research
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• v.29 no.3
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• pp.150-154
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• 2019

This study investigates the effect of MnO2 and CuO as acceptor additives on the microstructure and piezoelectric properties of $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$, which has a rhombohedral-tetragonal phase boundary composition. $MnO_2$ and CuO-added $0.96(K_{0.5}Na_{0.5})_{0.95}Li_{0.05}Nb_{0.93}Sb_{0.07}O_3-0.04BaZrO_3$ ceramics sintered at a relatively low temperature of $1020^{\circ}C$ show a pure perovskite phase with no secondary phase. As the addition of $MnO_2$ and CuO increases, the sintered density and grain size of the resulting ceramics increases. Due to the difference in the amount of oxygen vacancies produced by B-site substitution, Cu ion doping is more effective for uniform grain growth than Mn ion doping. The formation of oxygen vacancies due to B-site substitution of Cu or Mn ions results in a hardening effect via ferroelectric domain pinning, leading to a reduction in the piezoelectric charge coefficient and improvement of the mechanical quality factor. For the same amount of additive, the addition of CuO is more advantageous for obtaining a high mechanical quality factor than the addition of $MnO_2$.

• Korean Journal of Materials Research
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• v.32 no.4
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• pp.210-215
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• 2022

Extensive research is being carried out on Ni-rich Li(Ni_xCo_yMn_1-x-y)O₂ (NCM) due to the growing demand for electric vehicles and reduced cost. In particular, Ni-rich Li(Ni_xCo_yMn_1-x-y-zAl_z)O₂ (NCMA) is attracting great attention as a promising candidate for the rapid development of Co-free but electrochemically more stable cathodes. Al, an inactive element in the structure, helps to improve structural stability and is also used as a doping element to improve cycle capability in Ni-rich NCM. In this study, NCMA was successfully synthesized with the desired composition by direct coprecipitation. Boron and tin were also used as dopants to improve the battery performance. Macro- and microstructures in the cathodes were examined by microscopy and X-ray diffraction. While Sn was not successfully doped into NCMA, boron could be doped into NCMA, leading to changes in its physicochemical properties. NCMA doped with boron revealed substantially improved electrochemical properties in terms of capacity retention and rate capability compared to the undoped NCMA.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.224-224
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• 2016

Many researchers have been tried to improve the performance of the phosphorescent organic light-emitting diode(PHOLED) by controlling of the dopant profile in the emission layer. In this work, as shown in Fig. 1 insert, a typical red PHOLED device which has the structure of ITO/NPB(50nm)/CBP(30nm)/TPBi(10nm)/Alq3(20nm)/LiF(0.8nm)/Al(100nm) is fabricated with a 5nm thick doping section in the emission layer. The doping section is formed by co-deposition of CBP and Ir(btp)2acac with a doping concentration of 8%, and it's location(x) is changed from HTL/EML interface to EML/HBL in 5nm steps. The current efficiency versus current density of the devices are shown in Fig. 1. By changing the location of doping section, as shown in Fig. 1 and 2, at x=5nm, the efficiency shows the maximum of 3.1 cd/A at 0.5 mA/cm2 and it is slightly decreased when the section is closed to HTL and slightly increased when the section is closed to HBL. If the doping section is closed to HTL(NPB) the excitons can be quenched easily to NPB's triplet state energy level(2.5eV) which is relatively lower than that of CBP(2.6eV). Because there is a hole accumulation at EML/HBL interface the efficiency can be increased slightly when the section is closed to HBL. Even the thickness of the doping section is only 5nm,. the maximum efficiency of 3.1 cd/A with x=5 is closed to that of the homogeneously doped device, 3.3 cd/A, because the diffusion length of the excitons is relatively long. As a result, we confirm that the current efficiency of the PHOLED can be improved by the doping profile optimization such as partially, not homogeneously, doped EML structure.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.30 no.5
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• pp.194-199
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• 2020

By controlling the composition of the metal-oxide nanosheet having a two-dimensional layered crystal structure, material properties and application can be extended. In this study, the composition of the nanosheet could be expanded from pure composition to doping composition by successfully synthesizing the TiO₂ nanosheet doped with Nb. Specifically, the doping composition was designed when synthesizing the layered metal oxide as a starting material (K_0.8Ti_1.73-xNb_xLi_0.27O₄, x = 0, 0.03, 0.07) and chemical exfoliation was performed. By doing this, it was possible to obtain the Nb-doped TiO_y ultrathin nanosheet. The size of the nano sheet was 2 ㎛ or less based on the long length in the x-y direction, and the thickness was about 1 nm. Nb-doping was confirmed by XRD and SEM-EDS analysis.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1416-1418
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• 2005

A new DCM derivative containing a phenothiazine moiety, 4-(dicyanomethylene)-2-t-butyl-6-(9-ethylphenothiazine-2- enyl)-4H-pyran (DCPTZ), has been synthesized as an orange-red fluorescent dye molecule for organic lightemitting diodes (OLEDs). EL devices with the structure of $ITO/PEDOT-PSS/{\alpha}-NPD/Alq_3:DCPTZ/Alq_3/LiF/Al$ have been fabricated with changing the doping concentration of the DCPTZ. Maximum EL spectra of the devices ranged from $580{\sim}620$ nm depending on the doping concentration of the dye molecule. An EL device with 0.5 % doping concentration showed CIE coordinate (0.51, 0.47) at luminance of 100 $cd/m^2$. White light-emitting devices with the structure of $ITO/PEDOT-PSS/{\alpha}-NPD/{\alpha}-NPD:DCPTZ/DPVBi/Alq_3/$ LiF/Al have been also fabricated. The thickness of blue light-emitting 1,4-bis(2,2- diphenylvinyl)benzene (DPVBi) layer was changed to obtain a white light-emission. A white light-emission from the device was observed when the thickness of the DPVBi layer became thicker than 10 nm.

• Journal of the Korean Electrochemical Society
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• v.17 no.3
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• pp.149-155
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• 2014

In this study, a positive-electrode material in a lithium secondary battery $Li[Ni_{0.575}Co_{0.1}Mn_{0.325}]O_2$ was synthesized as precursor by co-precipitation. Cathode material was synthesized by adding iron. The synthesized cathode material was analyzed by scanning electron microscope and x-ray diffraction. The analysis of x-ray diffraction showed that the a-axis and c-axis is increased by doping iron. And $I_{(003)}/I_{(104)}$ is increased and $I_{(006)}+I_{(102)}/I_{(101)}$ is decreased. Through this result, it was confirmed that the structural stability is improved. And impedance measurements show that the charge transfer resistance ($R_{ct}$) is lowered by doping iron. Consequently, electrochemical properties are improved by doping iron. In particular, the cycle characteristics are improved at a high temperature condition (328 K). Structural stabilities are contributing to the cycle properties.

• Journal of the Korean Ceramic Society
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• v.38 no.2
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• pp.112-116
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• 2001

고상반응법에 의한 제조한 ZnGa$_2$O$_4$형광체에 Li 및 Tm 원소를 도핑함에 따른 발광특성을 조사하였다. 254nm 여기 하에서, 환원 처리된 ZnGa$_2$O$_4$형광체는 245nm에서 흡수피크와 380nm에서 발광피크를 나타내며, 이는 스피넬 구조에서 Ga$^{3+}$ 이온의 $^4$T$_2$$\longrightarrow$$^4$A$_2$천이에 기인한다. ZnGa$_2$O$_4$형광체에 있어서 Li 및 Tm을 도핑했을 경우가 도핑하지 않은 시료에 비해 발광강도 및 색순도가 개선되었으며, Li 및 Tm을 각각 0.1 mol, 0.01 mol 첨가했을 때 가장 우수한 발광강도 및 색순도 특성을 보였다.

• Journal of the Korean Ceramic Society
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• v.56 no.2
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• pp.111-129
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• 2019

Recently, all-solid-state batteries (ASSBs) have attracted increasing interest owing to their higher energy density and safety. As the core material of ASSBs, the characteristics of the solid electrolyte largely determine the performance of the battery. Thus far, a variety of inorganic solid electrolytes have been studied, including the NASICON-type, LISICON-type, perovskite-type, garnet-type, glassy solid electrolyte, and so on. The garnet Li₇La₃Zr₂O₁₂ (LLZO) solid electrolyte is one of the most promising candidates because of its excellent comprehensively electrochemical performance. Both, experiments and theoretical calculations, show that cubic LLZO has high room-temperature ionic conductivity and good chemical stability while contacting with the lithium anode and most of the cathode materials. In this paper, the crystal structure, Li-ion transport mechanism, preparation method, and element doping of LLZO are introduced in detail based on the research progress in recent years. Then, the development prospects and challenges of LLZO as applied to ASSBs are discussed.