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Enhanced UV stability of perovskite solar cells with a SrO interlayer
Lee, Sang-Won,Kim, Seongtak,Bae, Soohyun,Cho, Kyungjin,Chung, Taewon,Hwang, Jae-Keun,Song, Inseol,Lee, Wonkyu,Park, Sungeun,Jung, Jaebong,Chun, Jihun,Lee, Yoon Jung,Moon, Yeon Ji,Lee, Hae-Seok,Kim, Do Elsevier 2018 Organic Electronics Vol.63 No.-
<P><B>Abstract</B></P> <P>We investigated strontium oxide (SrO) as an interlayer material to enhance the UV stability of a CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> perovskite solar cell. Moisture and over 400 nm wavelength of light were excluded to investigate the effect of UV light only. Two different interlayer fabrication processes were examined to optimize the performance of this solar cell. Devices fabricated by dipping for 30 min in SrO solution exhibited photoconversion efficiencies of 15.5%, whereas those fabricated with 60-min dipping showed photoconversion efficiencies of 15% and exhibited local Sr agglomeration. Devices with SrO displayed lower initial efficiencies than those without any SrO layer (17.6%), However, a device without SrO retained only 34.4% of its initial efficiency after 100 h of UV exposure. In contrast, SrO-incorporated devices retained almost 60.0% of their initial efficiency. Severe μ-PL mapping intensity degradation was observed in devices that did not include the interlayer, but no degradation was observed in those with the SrO interlayer. This can be attributed to the passivation of the degradation sites by SrO.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Perovskite UV stability was tested under conditions except moisture, oxygen and wavelengths exceeding 400 nm. </LI> <LI> With high resolution μ-PL mapping technique, direct evidence is provided about the area perovskite UV degradation begins. </LI> <LI> UV degradation is initiated at the ETL/perovskite interface. </LI> <LI> Effect of the SrO interlayer on UV stability was examined in an inert atmosphere. </LI> <LI> UV stability is enhanced by SrO interface passivation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Lee, Gyu Hyun,Jin, Youngeup,Lee, Sungeun,Lee, Jong Gun,Kim, Jin Young,Lee, Kwanghee,Jin, Sung-Ho,Ha, Chang-Sik,Won, Mi-Sook,Kang, Shin-Won,Suh, Hongsuk 부산대학교 유전공학연구소 2002 분자생물학 연구보 Vol.18 No.-
There have been extensive research efforts on organic electroluminescent devices (OELDs) with the aim of application for the flat panel display (FPD). OELDs have also attracted much interest because of their particular low driving voltage, convenient design of the device structures, possible control of emission band, and low fabrication cost compared with any other devices. OELDs can be classified as either molecular or polymer-based. Molecular-based devices consist of vacuum deposited fluorescent emitter layers whereas polymer-based devices consist of either spinor dip-coated layers. Most of the research in the field of polymer-chain conducting polymers such as poly(plenylene vinylene) (PPV), poly(p-phenylene) (PPP), their copolymers and soluble derivatives. Other groups have reported non-conjugated polymers with pendant chromophores for OELDs. The attachment of the fluorophore as the pendant group of a random-coil polymer presents several advantages: (1) the synthetic route would be simpler than that used for main-chain polymers; (2) the moderate solubility could be obtained by the nature of the backbone; (3) the emission wavelength would be easily controllable. We, recently, reported the PU polymer with the 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM) dye as the pendant. Even though it is known that the PU backbone have many quenching sites, the turn-on voltage of the PU-DCM device was ca. 5 V. Also, the change of the fluorophores in the side chain from para-cyanostilbene(PU-CN) to DCN (PU-DCM) caused the shift of PL emission wavelength. For the PL emission spectra of PU-CN and PU-DCM, the maximum peaks were at ca. 520 and 630 nm, respectively, corresponding to the maximum PL peaks. Therefore, EL, and PL properties can be changed using different lumophore pendant groups possibly caused by the electron withdrawing effect of the DCM prndant. In the present work, PU derivatives with stilbene pendant. In the present work, PU derivatives with stilbene pendant containing one or two fluoro group were introduced on the stilbene side chain. OELDs using polyurethane derivatives with stilbene pendants were fabricated to investigate the effect of the electron withdrawing substituents of the lumophore pendant on the EL and PL properties. Since PU derivatives possess different electron withdrawing substituents on the stilbence pendant, the shift of emission wave-length is expected.
Lee, Hee Jin,Lee, Sungeun,Lee, Eun Joo,Song, In Ja,Kang, Byung-Cheol,Lee, Jae-Seo,Lim, Hoi-Jeong,Yoon, Suk-Ja Korean Academy of Oral and Maxillofacial Radiology 2016 Imaging Science in Dentistry Vol.46 No.1
Purpose: Facial asymmetry has been measured by the severity of deviation of the menton (Me) on posteroanterior (PA) cephalograms and three-dimensional (3D) computed tomography (CT). This study aimed to compare PA cephalograms and 3D CT regarding the severity of Me deviation and the direction of the Me. Materials and Methods: PA cephalograms and 3D CT images of 35 patients who underwent orthognathic surgery (19 males and 16 females, with an average age of $22.1{\pm}3.3years$) were retrospectively reviewed in this study. By measuring the distance and direction of the Me from the midfacial reference line and the midsagittal plane in the cephalograms and 3D CT, respectively, the x-coordinates ($x_1$ and $x_2$) of the Me were obtained in each image. The difference between the x-coordinates was calculated and statistical analysis was performed to compare the severity of Me deviation and the direction of the Me in the two imaging modalities. Results: A statistically significant difference in the severity of Me deviation was found between the two imaging modalities (${\Delta}x=2.45{\pm}2.03mm$, p<0.05) using the one-sample t-test. Statistically significant agreement was observed in the presence of deviation (k=0.64, p<0.05) and in the severity of Me deviation (k=0.27, p<0.05). A difference in the direction of the Me was detected in three patients (8.6%). The severity of the Me deviation was found to vary according to the imaging modality in 16 patients (45.7%). Conclusion: The measurement of Me deviation may be different between PA cephalograms and 3D CT in some patients.
Holocene Climate Variability on the Centennial and Millennial Time Scale
Eun Hee Lee,Dae-Young Lee,Mi-Young Park,Sungeun Kim,Su Jin Park 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.4
There have been many suggestions and much debate about climate variability during the Holocene. However, their complex forcing factors and mechanisms have not yet been clearly identified. In this paper, we have examined the Holocene climate cycles and features based on the wavelet analyses of 14C, 10Be, and 18O records. The wavelet results of the 14C and 10Be data show that the cycles of ~2180-2310, ~970, ~500-520, ~350-360, and ~210-220 years are dominant, and the ~1720 and ~1500 year cycles are relatively weak and subdominant. In particular, the ~2180-2310 year periodicity corresponding to the Hallstatt cycle is constantly significant throughout the Holocene, while the ~970 year cycle corresponding to the Eddy cycle is mainly prominent in the early half of the Holocene. In addition, distinctive signals of the ~210-220 year period corresponding to the de Vries cycle appear recurrently in the wavelet distribution of 14C and 10Be, which coincide with the grand solar minima periods. These de Vries cycle events occurred every ~2270 years on average, implying a connection with the Hallstatt cycle. In contrast, the wavelet results of 18O data show that the cycles of ~1900-2000, ~900-1000, and ~550-560 years are dominant, while the ~2750 and ~2500 year cycles are subdominant. The periods of ~2750, ~2500, and ~1900 years being derived from the 18O records of NGRIP, GRIP and GISP2 ice cores, respectively, are rather longer or shorter than the Hallstatt cycle derived from the 14C and 10Be records. The records of these three sites all show the ~900-1000 year periodicity corresponding to the Eddy cycle in the early half of the Holocene.
Nanostructural analysis of ZnO:Al thin films for carrier-transport mechanisms
Seung-Yoon Lee,Woojin Lee,남창우,Jongmin Kim,Sujin Byun,Taehyun Hwang,Byung-Kee Lee,Young Il Jang,Sungeun Lee,Heon Min Lee,박병우 한국물리학회 2013 Current Applied Physics Vol.13 No.4
The carrier mobility of sputter-deposited Al-doped ZnO transparent-conducting (ZnO:Al) thin films was controlled between 22 and 48 cm2/Vs by varying the ZnO:Al seed layer. The statistical distribution of the [001] grain misorientation was characterized from the X-ray diffraction rocking curve in the range from 0.043 (2.5) to 0.179 rad (10.2). The grain-boundary energy barriers (Eb) from Seto’s model [1] clearly exhibit linear dependence on the grain-boundary misorientation angle (u) according to the equation Eb ¼ 78 4 þ 173 32 u meV.
Erratum to: Charge transfer in graphene/polymer interfaces for CO2 detection
Kim, Kihyeun,Son, Myungwoo,Pak, Yusin,Chee, Sang-Soo,Auxilia, Francis Malar,Lee, Byung-Kee,Lee, Sungeun,Kang, Sun Kil,Lee, Chaedeok,Lee, Jeong Soo,Kim, Ki Kang,Jang, Yun Hee,Lee, Byoung Hun,Jung, Gun- Springer-Verlag 2018 NANO RESEARCH Vol.11 No.7
Charge transfer in graphene/polymer interfaces for CO2 detection
Son, Myungwoo,Pak, Yusin,Chee, Sang-Soo,Auxilia, Francis Malar,Kim, Kihyeun,Lee, Byung-Kee,Lee, Sungeun,Kang, Sun Kil,Lee, Chaedeok,Lee, Jeong Soo,Kim, Ki Kang,Jang, Yun Hee,Lee, Byoung Hun,Jung, Gun- Springer-Verlag 2018 NANO RESEARCH Vol.11 No.7
Lee, Seunghun,Ji, Kwang-sun,Park, Hyomin,Tark, Sung Ju,Park, Sungeun,Lee, Jeong Chul,Kim, Won Mok,Kang, Yoonmook,Lee, Hae-Seok,Kim, Donghwan Elsevier 2015 THIN SOLID FILMS - Vol.589 No.-
<P><B>Abstract</B></P> <P>We investigated the structural, optical, and electrical properties of Zn–In–Sn–O (ZITO) films prepared by RF magnetron sputtering for silicon heterojunction solar cells. The effects of Zn addition on the properties of the as-grown films were examined. XRD patterns of the ZITO films deposited at room temperature showed a broad peak. The cross-sectional TEM image of ZITO films at low Zn levels exhibited a typical fine or nanostructure embedded in an amorphous phase. On the other hand, at higher Zn addition, the films exhibited a completely amorphous phase. The carrier concentration decreased with increasing Zn content. The lowest electrical resistivity of 5.5×10<SUP>-4</SUP> Ωcm was observed for a ZITO film with 4.83 Znat.%. All ZITO films grown in this study showed transmittance of over 80% in the visible and near-infrared spectral range. The absorption was less than 5% in the visible region.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Zn–In–Sn–O(ZITO) films with various Zn and Sn contents prepared by RF magnetron sputtering </LI> <LI> Some ZITO films exhibited nanocrystalline structures embedded in an amorphous phase. </LI> <LI> The electrical and optical properties improved with increasing Zn content. </LI> </UL> </P>
Differential Receptor Targeting of Liver Cells Using 99mTc-Neoglycosylated Human Serum Albumins
Sungeun Kim,정재민,장자준,Mee Kyung Hong,Jaetae Lee,이동수,정준기,Myung Chul Lee 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.1
Neolactosyl human serum albumin (LSA) targets asialoglycoprotein receptor and shows high liver uptake due to accumulation in hepatocytes. Although neomannosyl human serum albumin (MSA) also shows high liver uptake, it has been reported to be taken up by Kupffer cells and endothelial cells. We compared the biological properties of LSA and MSA. 99mTc-LSA and 99mTc-MSA biodistribution in mice were investigated after intravenous injection. In vivo localization of rhodaminisothiocyanate (RITC)-LSA and fluoresceineisothiocyanate (FITC)-MSA were investigated in mouse liver. Excretion routes of 99mTc-LSA and 99mTc-MSA metabolites were examined. Both 99mTc-LSA and 99mTc-MSA showed high liver uptakes. RITC-LSA was taken up by hepatocytes whereas FITC-MSA was taken up by Kupffer cells and endothelial cells. 99mTc- MSA showed higher spleen and kidney uptakes than 99mTc-LSA. 99mTc-LSA metabolites excreted in urine and feces accounted for 44.4 and 50.0% of 99mTc-LSA injected, respectively, while 99mTc-MSA metabolites accounted for 51.5 and 10.3%, respectively. In conclusion, LSA is specifically taken up by hepatcytes while MSA by Kupffer cells and endothelial cells. After taken up by the liver, LSA is metabolized by the hepatocytes and then excreted through both the hepatobiliary tract and kidney, whereas MSA is metabolized by Kupffer cells and endoghelial cells and then excreted mainly through the kidney.