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Inorganic-organic Hybrid Halide Perovskite Solar Cells: Evolution and Issues
석상일 ( Sang Il Seok ) 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
The general formula AMX3 of inorganic-organic hybrid perovskite materials (A: organic cation, methylammonium (MA) or formamidinium (FA), M: metal, X: halide anion, Br, I) exhibits beneficial properties for high-performance photovoltaic systems such as a suitable band gap (1.5-1.4 eV), high absorption coefficient ( 10<sup>4</sup>-10<sup>5</sup> cm<sup>-1</sup>), low exciton binding energy (< 50 meV), and long charge-carrier diffusion length (~175 μm). In addition, these materials exhibit easy crystallization at low-temperature by solution processing, resulting in their low cost. Based on above distinct properties of perovskite materials, we have designed a new photovoltaic platform for efficient perovskite solar cells (PSCs). The performance have been remarkably increased to more than 22% by introducing a mediator to retard the rapid crystallization between organic cations and PbI2, and manipulate the chemical composition of the perovskites via solvent engineering, intramolecular exchange process, and defect engineering, making these routs attractive for attaining low-cost and high-performance devices. Although perovskite solar cells have improved efficiency in the short term, a variety of problems such as long-term stability, the use of nontoxic materials, and large-area modularization must be addressed for commercialization. In this presentation, I will introduce the presenters' work to improve the efficiency and long-term stability of PSCs and discuss future challenges.
TiO<sub>2</sub> 졸을 이용한 수중 Humic Acid의 광산화-화학적 산화법에 의한 부식산의 분해처리 기술에 관한 연구(I)-
석상일,안복엽,김미선,서태수,이동석,Seok, Sang Il,Ahn, Bok Yeop,Kim, Mi Sun,Suh, Tae Soo,Rhee, Dong Seok 대한환경공학회 2000 대한환경공학회지 Vol.22 No.6
가시광 영역에서 투명한 $TiO_2$ 졸을 이용하여 수중 humic acid의 광분해 특성을 고찰하였다. $TiO_2$ 졸은 $TiCl_4$ 용액의 가수분해 침전물인 $TiO(OH)_2$를 $H_2O_2$와 반응시켜 titanium peroxo solution (TPS)을 제조한 후, 이 용액을 온도와 시간의 함수로 열처리하여 제조하였다. Humic acid의 광분해를 위하여 사용된 졸의 적정 농도는 100ppm 전 후이었으며, photoluminescence(PL)를 이용하여 결정되었다. $TiO_2$ 졸의 humic acid에 대한 광촉매 효능은 TPS를 $100^{\circ}C$에서 12시간 이상 열처리한 졸을 이용할 때 가장 높았으며, 상용되고 있는 Degussa P25 보다 우수한 것으로 나타났다. 또한 상용의 분말로부터 유도된 현탁 반응은 처리수가 $TiO_2$로 인해 높은 탁도를 나타내는 반면, TPS로부터 유래한 졸은 거의 탁도를 나타내지 않고 높은 투명성을 보였다. The photo-oxidation of an aqueous humic acid solution using $TiO_2$ sols. which is transparent in visible range, was studied. The $TiO_2$ sols were prepared by a process wherein hydrogen peroxide was added to a gel of $TiO(OH)_2$ originated from hydrolysis of $TiCl_4$, and the resulting titanium peroxo solution(TPS) was heated. The concentration of $TiO_2$ used for photo-oxidation was about 100ppm, determined by comparing the photoluminescence(PL) intensity measured as a function of $TiO_2$ concentration. $TiO_2$ sols aged at $100^{\circ}C$ for more than 12h were found to exhibit a maximum rate in photocatalytic decomposition of humic acid. and the efficiency was better than that of Degussa P25. In addition, the resulting aqueous humic acid after photocatalytic decomposition with sols had an excellent transmittance of visible light, while that treated with Degussa P25 was still turbid. caused by $TiO_2$ particles.
저온 소결성이 우수한 Pb(Zr<sub>0.53</sub>Ti<sub>0.47</sub>)O<sub>3</sub> 계 압전 분말 제조
이용희,백인찬,석상일,Lee, Yonghui,Baek, In Chan,Seok, Sang Il 한국입자에어로졸학회 2008 Particle and Aerosol Research Vol.4 No.1
$Pb(Zr_{0.53}Ti_{0.47})O_3$ (PZT) was synthesized by a multiple wet dry process. Precipitates prepared from reaction between $ZrOCl_2{\cdot}8H_2O$ and $TiOCl_2$ and $NH_4OH$ in an aqueous solution was dried at $100^{\circ}C$, and calcined at $500^{\circ}C$ and $700^{\circ}C$. The mixture mixed with PbO and as-dried or calcined $Zr_{0.53}Ti_{0.47}O_4$ (ZT) powders was calcined again at 700 and $800^{\circ}C$. Well crystallized ZT and PZT were formed at even $700^{\circ}C$. PZT piezoelectric ceramics of more than 98.5% in a relative density was obtained by sintering at as low as $900^{\circ}C$.
희토류 이온(Er/Yb)이 도핑된 LaPO<sub>4</sub> 나노입자의 합성과 발광특성
오재석,이택혁,석상일,정하균,Oh Jae-Suk,Lee Tack-Hyuck,Seok Sang-Il,Jung Ha-Kyun 한국재료학회 2004 한국재료학회지 Vol.14 No.4
Due to the luminescence by$ Er ^{ 3+}$ activator, Er-doped $LaPO_4$ powders can be applied for optical amplification materials. In this study, $LaPO_4$:Er nanoparticles were synthesized in solution system using a high-boiling coordinating solvent and their properties were investigated through various spectroscopic techniques. The nanoparticles were to take a single phase of monazite structure by a X-ray diffraction analysis and to have the 5-6 nm of particles size with narrow size distribution by a TEM. And it was confirmed by the EA and FT-IR analyses that the surfaces of nanoparticles are coordinated with the solvent molecules, which will possibly keep from agglomerating between LaPO$_4$:Er nanoparticles. In the emission spectrum of $LaPO_4$:Er nanoparticle at NIR region, on the other hand, it was measured that the emission intensity is very weak, which is due to the transition from $^4$$I_{(13/2)}$ to $^4$$I_{(15/2)}$ of $Er^{3+ }$ion. It was interpreted that the weak luminescence of $LaPO_4$:Er is originated from the hydroxyl groups adsorbed on the surfaces of the nanoparticles, because OH group acts as an efficient quencher for the $^4$$I_{(13/2)}$ \longrightarrow $^4$$I_{(15/2)}$ emission of $Er^{3+}$ activator. But the co-doping of Yb$^{3+}$ as a sensitizer in this nanoparticle results in the increase of the emission intensity at 1539 nm due to the effective energy transfer from $Yb^{3+}$ to $Er^{3+}$ . In addition, the synthesized nanoparticles exhibited good dispersibility with some polymers and effective luminescence at NIR region.n.
W/O 에멀젼법을 이용한 중공형 실리카 미립구의 졸 - 겔 제조
김미선(Mi Sun Kim),석상일(Sang Il Seok),안복엽(Bok Yeop Ahn),서태수(Tae Soo Suh),구상만(Sang Man Koo) 한국공업화학회 2002 공업화학 Vol.13 No.2
속 빈(hollow) 형태의 미립구는 기능성 물질의 마이크로 캡슐화 공정에서 관심의 대상이 되고 있다. 본 연구는 핵산 용매에서 물유리 용액(Na_2SiO_3)과 비이온 계면활성제인 Tween80과 Span60을 이용하여 Water-in-Oil(W/O) 마이크로 에멀젼(microemulsion) 법으로 속 빈 실리카 미립구를 제조하였다. 4 M 물유리 용액을 실리카 벽재로 이용하여 물과 오일의 몰 비(W) 1/3, 물과 계면활성제의 몰 비(R) 10의 제조 조건에서 입자크기 약3 ㎛, 공극크기 80 Å, 비표면적 700 ㎡/g의 실리카 미립구를 제조하였다. 실리카 미립구의 입자크기는 W의 범위 1/2~1/10에서 물에 대한 유기용매의 양이 증가할수록 증가하는 경향을 보였으며, 계면활성제의 영향은 R의 범위 2~10에서 계면활성제의 농도가 증가할수록 입자크기가 증가하였다. Hollow microspheres play an impotant role in the field of microencapsulation. In this study, hollow silica microspheres were synthesized in water-in-oil (W/O) microemulsion system, which consisted of cyclohexane as the oil phase and the mixture of Tween80 and Span60 as the non-ionic surfactants. These microspheres, which were prepared at the experimental condition of 4 M sodium silicate solution, water to oil ratio(W) of 1/3, and water to surfantant ratio(R) of 10, had particle size diameter of 3 ㎛, pore diameter of 80 Å, and specific surface area of 700 ㎡/g. The average particle size of the dried powders decreased with increased W (1/2~1/10) value, but the size increased with increased R (2~10) value.
안복엽 ( Bok Yeop Ahn ),김주현 ( Joo Hyeun Kim ),석상일 ( Sang Il Seok ),고승용 ( Seung Yong Ko ),장호겸 ( Ho Kyeom Chang ) 한국공업화학회 2002 공업화학 Vol.13 No.7
화장품에는 자외선에 의한 피부 손상을 최소화하기 위하여 자외선 흡수제가 사용되고 있다. 이러한 자외선 흡수제는 대부분 합성 유기 화합물이며, 피부에 대한 자극성이 있는 것으로 알려져 있다. 본 연구는 O/W 에멀젼 졸-겔 방법을 이용하여 유기 자외선 흡수제를 1∼10 ㎛ 크기의 구형 실리카 마이크로캡슐로 제형화 하여 피부 자극에 대한 안정성을 확보하고자 하였다. 자외선 흡수제의 고유한 흡수 기능성은 실리카를 벽재로 캡슐화 한 후에도 변하지 않았다. 실리카 마이크로캡슐의 형상 및 크기는 캡슐 제조 과정에서 형성된 O/W 에멀젼의 특성에 크게 영향을 받았다. 실리카 마이크로캡슐의 자외선 흡수 특성은 캡슐의 입자 크기, 형상, 자외선 흡수제의 종류 및 농도에 영향을 받았으며, 자외선 흡수제의 함유량이 증가할수록 자외선 차단에 효과적이었으나 30 wt% 이상 함유한 캡슐은 강도가 약한 단점이 있었다. Human Patch Test에 의한 피부 자극성 실험 결과 실리카 마이크로캡슐은 48 h까지 grade (Ⅰ)으로 무자극 범위를 유지하였으며, 자외선 흡수제의 직접적인 피부접촉을 방지함으로써 자극에 대한 안정성을 향상시키는 것으로 나타났다. UV absorbers are used for cosmetics to screen out ultra violet (UV) rays, which have side effects on human skin. the absorbers are made generally from synthetic organic compounds, which can stimulate the skins to develop allergic reactions. In this study, the stimulant organic UV absorbers were encapsulated in the silica glass by an O/W microemulsion sol-gel method. The silica microcapsules prepared from the method were spherical and had 1∼10 ㎛ in size. The shape and size of the capsules were mainly dependent upon the properties of the O/W emulsions produced during the process. The intrinsic properties of the absorbers did not change after encapsulation. The capsules containing high contents of the absorbers showed better efficiency for UV screening effect, but the capsules containing over 30 wt% of the absorbers had too weak shell strength for application. The efficiency of UV screening for the capsules was a function of the shape and size of the capsules and the type and content of the absorbers. From the human patch test to evaluate stimulus on skin, the capsules showed Grade (Ⅰ): no stimulus for 48 h. It indicated that the encapsulation of the stimulant organic UV absorber by silica glass is useful in stabilizing the stimulation by blocking direct contact between the absorbers and the skin.