• Rapid Communication in Photoscience
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• v.4 no.4
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• pp.79-81
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• 2015

The influence of the grain size of the $CH_3NH_3PbI_3$ on the solar cell performance is investigated by controlling the ratio between $CH_3NH_3I$ and $PbI_2$ precursors. As the concentration of the precursors increased from 1.0M to 2.0M, the $CH_3NH_3PbI_3$ grain size increased from ~100nm to ~400nm. The solar cell utilizing the $CH_3NH_3PbI_3$ with large grain size shows improved photocurrent compared to the solar cell utilizing $CH_3NH_3PbI_3$ with small grain size, which is ascribed to the reduced recombination at the boundaries of grains.

• Journal of the Korean Ceramic Society
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• v.30 no.9
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• pp.723-730
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• 1993

The mechanism of formation of perovskite phase and the dielectric properties of PZMN[Pb(Zn, Mg)1/3Nb2/3O3] ceramics were examined using two different types of the columbite precursors, (Mg, Zn)Nb2O6 (MZN) and MgNb2O6＋ZnNb2O6 (MN＋ZN). The formatin of perovskite phase in PbO＋MN＋ZN system is characterized by an initial rapid formation of Mg-rich perovskite phase, followed by a sluggish formation of Zn-rich perovskite phase. On the other hand, thepyrochlore/perovskite transformation in the PbO＋MZN system proceeded uniformly with a spatial homogeneity. The degree of diffuseness of the rhombohedral/cubic phase transitionis higher in the PbO＋MN＋ZN system than in the PbO＋MZN specimen, indicating a broadened compositional distributjion of the B-site catons (Nb+5, Zn+2, Mg+2) in the PbO＋MN＋ZN system.

• Journal of the Korean Ceramic Society
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• v.36 no.11
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• pp.1235-1242
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• 1999

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.4
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• pp.315-320
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• 2020

Methylammonium lead iodide (MAPbI₃) thin films were grown at low temperatures on glass substrates via 3-zone chemical vapor deposition. Lead iodide (PbI₂) and lead bis (dipivaloylmethanate) [Pb(dpm)₂] precursors were used as lead sources. Due to the high sublimation temperature (~400℃) of the PbI₂ precursor, a low substrate temperature could not be constantly maintained. Therefore, MAPbI₃ thin films degraded into the PbI₂ phase. In contrast, for the Pb(dpm)₂ precursor, a substrate temperature of ~120℃ was maintained because the sublimation temperature of Pb(dpm)₂ is as low as 130℃ at a high vapor pressure. As a result, high-quality MAPbI₃ thin films were successfully grown on glass substrates using Pb(dpm)₂. The rms (root-mean-square) roughness of MAPbI₃ thin films formed from Pb(dpm)₂ was as low as ~19.2 nm, while it was ~22.7 nm for those formed using PbI₂. The grain size of the films formed from Pb(dpm)₂ was as large as approximately 350 nm.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.541-549
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• 1994

The crystallization behavior and structural change of amorphous $PbTiO_{3}$ precursors prepared by coprecipitation method were investigated by XRD, Raman spectra, TEM, and RDF. The precursors were prepared at $45^{\circ}C$ and pH of 9 from a mixed solution of lead nitrate and titanium tetrachloride derived using $H_2O_2$ or $NH_4NO_3$ as an ion stabilizer. The activation energy and temperature for crystallization of the coprecipitate prepared using $NH_4NO_3$ as an ion stabilizer were lower than that derived from the solution containing $H_2O_2$ stabilizer. The amorphous coprecipitate transformed to transient phase and then to crystalline $PbTiO_{3}$. Average interatomic distances of amorphous states decreased with increasing heat-treatment temperature.

• Progress in Superconductivity
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• v.3 no.2
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• pp.198-212
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• 2002

The effects of reacted precursors on phase evolution, microstructure, $J_{c}$ and junctional characteristic of the inter-granular contacts were investigated in Ag-sheathed T1-1223 tapes prepared using three kinds of reacted precursors, and compared to those in the tape prepared using an unreacted precursor The precursors were prepared by heat-treating a mixture of Sr-Ba-Ca-Cu-O, $Tl_2$$O_3$, PbO and $Bi_2$$O_3$ powders at $805^{\circ}C$ (precursor I ), $840^{\circ}C$ (precursor II ) and $905^{\circ}C$(precursor III) for 20 min. Tl-1223 phase content, grain size and J\ulcorner in the tapes appeared to increase in an order of precursors I, II and III Compared to tapes prepared using an unreacted precursor, the tapes prewar ed using precursors II and III revealed reduced pore and impurity densities and an enhanced texture. Also characteristic of inter -granular contacts and fraction of strong-links were improved. The improved properties are attributed to enhanced densification resulting from using the reacted precursors.s.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.555-559
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• 1997

Lead scandium niobate $Pb(Sc_{1/2}Nb_{1/2})O_3$ powders were prepared by the sol-gel method using lead acetate, scandium acetate, and niobium isopropoxide as precursors. Crystallization behavior and phase formation were investigated for gel-derived powders. After the calcination at $700^{\circ}C$ for 1 hr, $Pb(Sc_{1/2}Nb_{1/2})O_3$ powder with the purity of 97% was formed and the average particle size of powder was below 0.2 $\mu \textrm{m}$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.552-555
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• 2008

The purpose of this study was to find a best condition of fabricating lead zirconate thin film by sol-gel method, especially to find mol ratio and post annealing temperature. Lead zirconate thin film was made by spin coating method. The ratios of Pb and Zr of precursors were 1:0.8, 1:1.0, and 1:1.2. Annealing temperature of films were $600^{\circ}C$, $700^{\circ}C$, and $800^{\circ}C$ for 1 minute. Crystal structure was observed from XRD and antiferroelectricity was observed from hysteresis curves. The optimum mol ratio of Pb:Zr is 1:0.8 and annealing temperature is $800^{\circ}C$.

• Korean Journal of Materials Research
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• v.31 no.1
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• pp.54-59
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• 2021

In this work, narrow-band green-emitting CsPbBr3 particles are embedded in commercialized glass composites by a facile dry process. By optimizing the method through sintering in glass frit (GF) composites including CsBr and PbBr2, used as precursors, the encapsulation of CsPbBr3 particles made them waterproof with green fluorescence. To improve the fluorescent properties by reducing aggregation of CsPbBr3, fumed silica (FS) is additionally used to help particles avoid bulking up in the glass matrix. The CsPbBr3 perovskite/glass composites are characterized using scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy (EDS) maps, which support the existence of CsPbBr3 particles in the glass matrix. The photoluminescence (PL) properties demonstrate that the emission spectrum peak, full width at half maximum (FWHM), and photoluminescence quantum yield (PLQY) values are 519 nm, 17 nm, and 17.7 %. We also confirm the water-resistant properties. To enhance water/moisture stability, the composite sample is put directly into water, with its PLQY monitored periodically under UV light.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.19-19
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• 2002

Perovskite-type titanate dielectrics have attracted much attention in memory devices such as DRAMs or FeRAMs due to their high dielectric constants. However, low volatility of the Ba, Sr, Pb or Zr precursors with only thd ligands has limitations in obtaining high quality thin films by liquid source metal organic chemical vapor deposition (LS-MOCVD) processes. To improve the volatility of these precursors, many attempts have been made such as adding polyether ligands to satisfy the coordinative saturation. We report the synthesis of new precursors Ba(thd)₂(tmeea) and Sr(thd)₂(tmeea), where tmeea = tris[2-(2-methoxyethoxy)ethyl]amino, and LS-MOCVD of barium strontium titanate (BSTO) thin films using these precursors. Due to increased basicity of amines compared with ethers, it is expected that the nitrogen-donor ligand will make a strong bond to a metal than an analogous oxygen-donor ligand, consequently improving the volatility and thermal behavior of these precursors. Thin films of BSTO were grown on Pt(111)/SiO₂/Si(100) substrates by LS-MOCVD using a cocktail source consisting of the conventional Ti precursor Ti(thd)₂(O/sup i/Pr), and these new Ba and Sr precursors. As-grown films were characterized by XPS, SEM, XRD, XRF, and C-V and I-V measurements. BSTO films grown at 420℃ were stoichiometric barium strontium titanate with very smooth surface morphology and their dielectric constants were found to be as targe as 450. Dependence of the composition, microstructure and the electrical properties of the BSTO films on the growth temperature, annealing temperature, working pressure, and the composition of the cocktail source will be discussed.