• 한국결정학회:학술대회논문집
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• 한국결정학회 2000년도 추계 학술연구발표회
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• pp.28-28
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• 2000

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.163.1-163.1
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• 2016

Lead halide perovskites CH3NH3PbX3 (X=Cl, Br, I) have received great interest in the past few years because of their excellent photoelectronic properties as well as their low-cost solution process. Their theoretical efficiency limit of the solar cell devices was predicted around 31% by a detailed balance model for the reason that exceptional light-harvesting and superior carrier transport properties. Additionally, these excellent properties contribute to the applications of optoelectronic devices such as LASERs, LEDs, and photodetectors. Since these devices are mainly using perovskite thin film, one of the most important factor to decide the efficiency of these applications is the quality of the film. Even though, optoelectrical devices are composed of polycrystalline thin film in general, not a single crystalline form which has longer carrier diffusion length and lower trap density. For these reasons, monodomain perovskite thin films have potential to elicit an optimized device efficiency. In this study, we analyzed the crystallography of the in-plane aligned perovskite thin film by X-ray diffraction (XRD) and selected area electron diffraction (SAED). Also the basic optic properties of perovskites were checked using scanning electron microscopy (SEM) and UV-Vis spectrum. From this work, the perovskite which is aligned in all directions both of out-of-plane and in-plane was fabricated and analyzed.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 하계학술연구발표회 및 한.일 공동심포지엄
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• pp.150-151
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• 2003

In the past years, a giant magnetoresistance (GMR) effect found in perovskite-like structured materials has attracted considerable attention among scientists and manufacturers, since, a practical point of view, the capacity of producing magnetic and sensing sensors. In a stream of this interest, further efforts to understand the underlying mechanism that leads to the GMR effect relative to the correlation between transport and magnetic properties, have been extensively devoted. In these cases, spin-glass-like behaviors are ascribed to the frustration of random competing exchange interactions, namely the ferromagnetic double-exchange interaction between Co$\^$3+/ (or Mn$\^$3+/) and Co$\^$4+/(or Mn$\^$4+/) and the antiferromagnetic one like spins. Noticeably, the distinction of spin-glass region from cluster-glass one, involved in the remarkable changes in transport and magnetic properties at a critical value of doping concentration, was observed. Magnetic anomalies in zero-field-cooled (ZFC) magnetization as well as ac magnetic susceptibility below Curie temperature T$\sub$c/ and the charge/orbital fluctuation were also realized. In this work, we present a study of magnetic properties of a deficient manganese perovskites system of La$\sub$0.6/Sr$\sub$x/MnTi$\sub$y/O$_3$, and particularly provide its new magnetic phase diagram.

• The Korean Journal of Ceramics
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• 제6권3호
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• pp.309-314
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• 2000

In the present study, preliminary experimental results of the change in the properties of perovskite-type oxides caused by the $^{18}O$- exchange have been reported. Two systems were selected for the exchange, (1) $ATiO_3$(A=Ca,Sr,Ba) and (2) manganese perovskite. The dielectric properties of isotope-exchanged $SrTi^{18}O_3$showed a drastic change from a quantum paraelectricity below 3K to ferroelectric-like behavior with a peak at 23K and an enhanced dielectric constant, 35000 at the peak. On the contrary, the $T_c$ for $BaTiO_3$was found to increase by 0.9K. The observed isotope shift of $T_c$ as well as $T_co$ for the manganese perovskites is correlated with the key parameters controlling the lattice such as $Mn^{3+}$ content, average ionic radius of the A-site cation <$r_A$> ad A-site ionic disorder $\sigma^2$.

• Current Optics and Photonics
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• 제2권6호
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• pp.514-518
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• 2018

Carrier diffusion length in the light-sensitive material is one of the key elements in improving the light-current conversion efficiency of solar-cell devices. In this paper, we measured the carrier diffusion length in lead-halide perovskite ($MAPbI_3$) and mixed lead-halide ($MAPbI_{3-x}Cl_x$) perovskite devices using scanning photocurrent microscopy (SPCM). The SPCM signal decreased as we moved the focused laser spot away from the metal contact. By fitting the data with a simple exponential curve, we extracted the carrier diffusion length of each perovskite film. Importantly, the diffusion length of the mixed-halide perovskite was higher than that of the halide perovskite film by a factor of 3 to 6; this is consistent with the general expectation that the carrier mobility will be higher in the case of the mixed lead-halide perovskites. Finally, the diffusion length was investigated as a function of applied bias for both samples, and analyzed successfully in terms of the drift-diffusion model.

• 한국표면공학회지
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• 제52권1호
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• pp.6-15
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• 2019

Metal-halide perovskite (MHP) solar cell is a promising candidate for next-generation flexible devices and the BIPV (Building-integrated photovoltaics) because it can exhibit high power conversion efficiencies over 23%, good bendability and low processing cost. However, MHP solar cells are commonly fabricated by the spin coating that is not a reliable method to produce large-scale commercial solar cells. A shear coating can be one of the potential candidates for the large-scale deposition method of MHP films. In this work, the influences of the process parameters such as solvents of precursor solution, substrate temperature, concentrations of precursor solution, and annealing time on the thin film growth of MHP were investigated for the shear coating process. This study presents the possibility of the shear coating process for large-scaled perovskite film fabrication and reveals the role of process condition in the thin film growth of perovskites.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 somma/kms meeting
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• pp.193-193
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• 2003

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2003년도 somma/kms meeting
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• pp.339-339
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• 2003

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.168.1-168.1
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• 2007

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2008년도 Asian Magnetics Conference
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• pp.105.1-105.1
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• 2008