• Korean Chemical Engineering Research
• /
• 제61권2호
• /
• pp.296-301
• /
• 2023

고온 운전이 가능한 고체산화물 연료전지의 최대의 장점은 내부개질을 통한 연료의 다양성에 있다. 하지만 기존의 Ni/SYZ전극은 탄소침적에 대한 단점을 가지고 있고, 이를 해결하기 위해 페로브스카이트 구조의 연료극 개발이 진행되었다. 본 연구에서는 페로브스카이트 대체 연료극의 낮은 전기전도도 및 촉매활성을 향상시키기 위해 rGO(reduced graphene oxide)를 Sr_0.92Y_0.08TiO₃(SYT)와 혼합하여 연료극에 대한 성능 평가를 진행하였다. Ni/YSZ(yttria stabilized zirconia)와 SYT에 1wt%rGO를 첨가하여 연료극을 합성하였다. 고온 산화조건에서 전극 제조 후 rGO의 유무 확인은 XPS 및 라만 분석을 통해 확인하였다. rGO/SYT 연료극은 rGO 대비 H₂에서 3배, CH₄에서 6배의 매우 큰 성능 향상을 보여주었다.

• 한국세라믹학회지
• /
• 제43권11호
• /
• pp.715-723
• /
• 2006

Perovskite oxide materials are very important for the electronics industry, because they exhibit promising properties. With an interest in the obvious applications, significant effort has been invested in the growth of highly crystalline epitaxial perovskite oxide thin films in our laboratory. And the desired structure of films was formed to achieve excellent properties. $Y_1Ba_2Cu_3O_{7-x}$ (YBCO) superconducting thin films were simultaneously deposited on both sides of 3 inch wafer by inverted cylindrical sputtering. Values of microwave surface resistance R$_2$ (75 K, 145 GHz, 0 T) smaller than 100 m$\Omega$ were reached over the whole area of YBCO thin films by pre-seeded a self-template layer. For implementation of voltage tunable high-quality varactor, A tri-layer structured SrTiO$_3$ (STO) thin films with different tetragonal distortion degree was prepared in order to simultaneously achieve a large relative capacitance change and a small dielectric loss. Highly a-axis textured $Ba_{0.65}Sr_{0.35}TiO_3$ (BST65/35) thin films was grown on Pt/Ti/SiO$_2$/Si substrate for monolithic bolometers by introducing $Ba_{0.65}Sr_{0.35}RuO_3$ (BSR65/35) thin films as buffer layer. With the buffer layer, the leakage current density of BST65/35 thin films were greatly reduced, and the pyroelectric coefficient of $7.6\times10_{-7}$ C $cm^{-2}$ $K^{-1}$ was achieved at 6 V/$\mu$m bias and room temperature.

• 한국재료학회지
• /
• 제33권11호
• /
• pp.475-481
• /
• 2023

Recently, the electron transport layer (ETL) has become one of the key components for high-performance perovskite solar cell (PSC). This study is motivated by the nonreproducible performance of ETL made of spin coated SnO₂ applied to a PSC. We made a comparative study between tin oxide deposited by atomic layer deposition (ALD) or spin coating to be used as an ETL in N-I-P PSC. 15 nm-thick Tin oxide thin films were deposited by ALD using tetrakisdimethylanmiotin (TDMASn) and using reactant ozone at 120 ℃. PSC using ALD SnO₂ as ETL showed a maximum efficiency of 18.97 %, and PSC using spin coated SnO₂ showed a maximum efficiency of 18.46 %. This is because the short circuit current (Jsc) of PSC using the ALD SnO₂ layer was 0.75 mA/cm² higher than that of the spin coated SnO₂. This result can be attributed to the fact that the electron transfer distance from the perovskite is constant due to the thickness uniformity of ALD SnO₂. Therefore ALD SnO₂ is a candidate as a ETL for use in PSC vacuum deposition.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.469.2-469.2
• /
• 2014

All-solid-state solar cell based on Chloride doped organometallic halide perovskite, (CH3NH3)PbIxCl3-x, has achieved a highly power conversion efficiency (PCE) to over 15% [1] and further improvements are expected up to 20% [2]. In this way, solar cells using novel light absorbing perovskite material are actively being studied as a next generation solar cells. However, making solution-process require high temperature up to $500^{\circ}C$ to form compact hole blocking layer and sinter the mesoporous oxide scaffold layer. Because of this high temperature process, fabrication of flexible solar cells on plastic substrate is still troubleshooting. In this study, we fabricated highly efficient flexible perovskite solar cells with PCE in excess of 11%. Atomic layer deposition (ALD) is used to deposit dense $TiO_2$ as hole blocking layer on ITO/PEN substrate. The all fabrication process is done at low temperature below $150^{\circ}C$. This work shows that one of the important blueprint for commercial use of perovskite solar cells.

• 한국전기전자재료학회논문지
• /
• 제34권1호
• /
• pp.73-77
• /
• 2021

Inorganic-organic hybrid perovskite solar cells have demonstrated considerable improvements, reaching 25.5% of certified power conversion efficiency in 2020 from 3.8% in 2009. In normal structured perovskite solar cells, TiO2 electron-transporting materials require heat treatment process at a high temperature over 450℃ to induce crystallinity. Inverted perovskite solar cells have also been studied to exclude the additional thermal process by using [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as a non-oxide electron-transporting layer. However, the drawback of the PCBM layer is a charge accumulation at the interface between PCBM and a metal electrode. The impact of bathocuproin (BCP) buffer layer on photovoltaic performance has been investigated herein to solve the problem of PCBM. 2-mM BCP-modified perovskite solar cells were observed to exhibit a maximum efficiency of 12.03% compared with BCP-free counterparts (5.82%) due to the suppression of the charge accumulation at the PCBM-Au interface and the resulting reduction of the charge recombination between perovskite and the PCBM layer.

• 한국세라믹학회지
• /
• 제29권5호
• /
• pp.377-382
• /
• 1992

For the development of solid oxide fuel cell the joined interface formation between perovskite oxygen electrode and YSZ solid electrolyte is emphasized in the aspect of reducing the undisirable overpotential. The diffusion couple of LaMnO3 and YSZ was prepared by hot pressing at 130$0^{\circ}C$ in the flow of oxygen gas. The high temperature solid state reaction mechanism between LaMnO3 and YSZ is discussed on the basis of the cation composition profile through EDX analysis. The cation components in perovskite compound diffuse considerably into YSZ, while cations of YSZ diffuse little into perovskite.

• 한국세라믹학회지
• /
• 제47권1호
• /
• pp.47-53
• /
• 2010

Ceramics with perovskite-type structure are interesting functional materials for several energy conversion processes due to their flexible structure and a variety of properties. Prominent examples are electrode materials in fuel cells and batteries, thermoelectric converters, piezoelectrics, and photocatalysts. The very attractive physical-chemical properties of perovskite-type phases can be modified in a controlled way by changing the composition and crystallographic structure in tailor-made soft chemistry synthesis processes. Improved thermoelectric materials such as cobaltates with p-type conductivity and n-type manganates are developed by following theoretical predictions and tested to be applied in oxidic thermoelectric converters.

• Bulletin of the Korean Chemical Society
• /
• 제18권1호
• /
• pp.91-97
• /
• 1997

In the course of magnetic study on several perovskite-type oxides, A2Fe(Ⅲ)BO6 (A = Ca, Sr, Ba and B = Sb, Bi), we have observed a strong irreversibility in their dc-magnetizations. When the structural data and the Mossbauer spectra are considered, such an irreversibility is to be associated with some competitions between the nearest-neighbors (nn) and the next-nearest-neighbors (nnn) in their magnetic sublattices. Particularly, the Mossbauer spectra indicate that Sr2FeBiO6 of cubic perovskite-structure is apparently well ordered crystalline compound. Nontheless this antiferromagnet shows a magnetic property which resembles that of a spin-glass. The strong history dependence is observed below 91 K and the irreversible magnetic behavior is also observed from the measurement of hysteresis loops at 10 K after zero-field-cooled (zfc) and field-cooled (fc) processes. Considering the nn and the nnn superexchanges of almost same order in ordered perovskite, it is proposed that there exists a competition and cancellation of antiferromagnetic and ferromagnetic superexchange between the nearest-neighbors and the next-nearest-neighbors, thus introducing a certain degree of frustration.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2009년도 춘계학술발표대회
• /
• pp.56.1-56.1
• /
• 2009

The intermediate operating temperature of solid oxide fuel cells (IT-SOFCs) have achieved considerable importance in the area of power fabrication. This is because to improve materials compatibility, their long-term stability and cost saving potential. However, to conserve rational cell performance at reduced-temperature regime, cathode performance should be obtained without negotiating the internal resistance and the electrode kinetics of the cell. Recently, double perovskite structure cathodes have been studied with great attention as a potential material for IT-SOFCs. In this study, double-perovskite structured cathodes of $GdBaCoCuO_{5+\delta}$, $GdBaCo_{2/3}Cu_{2/3}Fe_{2/3}O_{5+\delta}$ compositions and $(1-x)GdBaCo_2O_{5+\delta}+xCe_{0.9}Gd_{0.1}O_{1.95}$ (x = 10, 20, 30 and 40 wt.%) composites were evaluated as the cathode for intermediate temperature solid oxide fuel cells(IT-SOFCs). Electrical conductivity of the cathodes were measured by DC 4-probe method, and the thermal expansion coefficient of each sample was measured up to $900^{\circ}C$ by a dilatometer study. Area specific resistances(ASR) of the $GdBaCo_{2/3}Cu_{2/3}Fe_{2/3}O_{5+\delta}$ cathode and 70 wt.% $GdBaCo_2O5+\delta$ + 30wt.% Ce0.9Gd0.1O1.95 composite cathode on CGO electrolyte substrate were analyzed using AC 3-probe impedance study. The obtained results demonstrate that double perovskite-based compositions are promising cathode materials for IT-SOFCs.

• 한국재료학회지
• /
• 제10권4호
• /
• pp.282-289
• /
• 2000

전자싸이클로트론공명-플라즈마 화학기상증착법으로 $PbTiO_3$박막을 증착하였다. $RuO_2$ 기판과 Pt 기판 위에 금속유기화합물 원료기체 유량 및 증착온도에 따라서 $PbTiO_3$박막의 증착특성을 연구하였다. $RuO_2$ 기판 위에서 Pt 기판에 비하여 Pb-oxide 분자의 잔류시간이 상대적으로 크고, 페로브스카이트 핵생성 밀도는 상대적으로 작으며, 단일한 페로브스카이트 상의 $PbTiO_3$ 박막을 얻을 수 있는 공정범위가 Pt 기판보다 좁았다. $PbTiO_3$ 박막 증착 전 Ti-oxide 씨앗층을 도입함으로써 $RuO_2$ 기판에서도 페로브스카이트 핵생성 밀도를 증가시켜 단일한 페로브스카이트 박막을 얻을 수 있는 공정범위가 확장되었다. $PbTiO_3$에서 Ti 성분을 Zr으로 일부 대체시킨 $Pb(Zr,Ti)O_3\;(PZT)$ 박막의 경우에도 Ti-oxide 씨앗층을 도입함으로써 넓은 공정범위에서 단일한 페로브스카이트 PZT 박막을 $RuO_2$기판 위에서도 제조할 수 있었다.