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New Hybrid Hole Extraction Layer of Perovskite Solar Cells with a Planar p–i–n Geometry
Park, Ik Jae,Park, Min Ah,Kim, Dong Hoe,Park, Gyeong Do,Kim, Byeong Jo,Son, Hae Jung,Ko, Min Jae,Lee, Doh-Kwon,Park, Taiho,Shin, Hyunjung,Park, Nam-Gyu,Jung, Hyun Suk,Kim, Jin Young American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.49
<P>We report a highly efficient p–i–n type planar perovskite solar cell with a hybrid PEDOT/NiO<SUB><I>x</I></SUB> hole-extraction layer. It has been found that the perovskite solar cell with a NiO<SUB><I>x</I></SUB> thin film as a hole-extraction layer generally exhibits lower fill factor compared to the conventionally used PEDOT:PSS thin film, whereas it shows higher photocurrent and photovoltage. The fill factor of the NiO<SUB><I>x</I></SUB>-based perovskite solar cell can be significantly improved by treating the NiO<SUB><I>x</I></SUB> surface with a dilute PEDOT solution. The photoluminescence quenching study and impedance spectroscopic (IS) analysis have revealed that the hole injection at the perovskite/NiO<SUB><I>x</I></SUB> interface is significantly facilitated with the PEDOT treatment, which should lead to the increased fill factor. As a result, the p–i–n type planar perovskite solar cell with the new hybrid hole-extraction layer exhibits a high conversion efficiency of 15.1% without the hysteresis effect.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-49/acs.jpcc.5b09322/production/images/medium/jp-2015-093225_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5b09322'>ACS Electronic Supporting Info</A></P>
유현정(Yoo, Hyunjung),김관희(Kim, Kwanhee),이하정(Lee, Hajeong),박보미(Park, Bomi),박수빈(Park, Subin),박주희(Park, Juhui),박진희(Park, Jinhui),반민주(Ban, Minjoo),임지현(Lim, Jihyun),박준후(Park, Junhoo),이예은(Lee, Yee Eun) 한국농촌간호학회 2019 한국농촌간호학회지 Vol.14 No.2
Purpose: This study was done to identify the cultural capacity of college nursing students and the relationship of intercultural communication. Methods: The participants were 200 students in colleges of nursing from 6 universities in C city, who understood the purpose of the study and agreed to participate. Collected data were analyzed with t-test, ANOVA, correlation analysis, and stepwise regression analysis using SPSS/WIN 22.0. Results: Cultural sensitivities in this study (r=.372, p<.001), cultural knowledge (r=.399, p=.001), cultural awareness (r=.547, p<.001), and cultural technology (r=.550, p<.001) each showed a statistically significant correlation with intercultural communication skills. Conclusion: The results of this study show that reinforcement of the cultural and intercultural communication ability of college nursing students, in-depth exploration of the cultural area and religious inspection, cultural and professional backgrounds, assessment and consideration of cultural characteristics, nursing diagnosis, and health appropriate to the cultural background. It is suggested that education such as service provision should be conducted systematically.
Length characterization of multi-walled CNT by capillary hydrodynamic fractionation (CHDF).
Park, Hye Jin,Noh, Hanna,Park, Min,Park, Kihong,Chang, Ji Young,Lee, Hyunjung American Scientific Publishers 2008 Journal of Nanoscience and Nanotechnology Vol.8 No.10
<P>Multi-walled carbon nanotubes (MWCNT) should be treated via cutting process for engineering applications because almost as-prepared MWCNT are highly entangled and aggregated. Especially, the size distribution of MWCNT after cutting process is very important factor to determine the final properties of polymer-MWCNT composite. In this study, we take a novel method for CNT characterization, a capillary hydrodynamic fractionation (CHDF), which is a traditional chromatographic method for colloid particles. The length distributions of pre-treated MWCNT by two different methods were investigated by CHDF. One is a high-power ultrasonication directly and the other is an acid treatment followed by a high-power ultrasonication. For MWCNT, retention volume apparently depends on a combination of the length, diameter and rigidity of CNTs. We found that a high-power ultrasonication renders MWCNT short into segments of a few micrometers and the additional treatment by acid solution made those much shorter and more flexible.</P>
Park, Hyunjung,Song, Taeseup,Paik, Ungyu The Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.16
<▼1><P>Porous TiNb2O7 nanofibers with metal nitride bumps show ultra-fast rate capability even at 100 C.</P></▼1><▼2><P>Titanium niobium oxide (TiNb2O7) has been reported recently as an attractive anode material for lithium ion batteries due to its practical capacity of ∼280 mA h g<SUP>−1</SUP>, which is much higher than those of well-known metal oxide materials such as TiO2 and Li4Ti5O12. However, low electronic conductivity and poor lithium diffusivity limit its practical use as the active material in lithium ion batteries. Here, we synthesized porous TiNb2O7 nanofibers decorated with Ti1−xNbxN bumps <I>via</I> electro-spinning and thermal ammonia gas treatment. As-prepared nanofibers have one-dimensional geometry with an average diameter of ∼110 nm, and consist of ∼70 nm crystallites and pores in the range of 0–40 nm, shortening pathways for Li<SUP>+</SUP> ion migration into the host material. Furthermore, conductive Ti1−xNbxN bumps with a particle size of ∼5 nm were formed on the surface <I>via</I> thermal ammonia gas treatment which render fast electron transport along the longitudinal direction. The fibers have a specific discharge capacity of ∼254 mA h g<SUP>−1</SUP> at 1 C and a superior rate capability (∼183 mA h g<SUP>−1</SUP> at 100 C). They also show a robust cycle performance over 500 cycles. These dramatic achievements are attributed to heterogeneous nano-structuring creating a porous structure, and the conductivity of the metal nitride achieved by optimal synthetic conditions.</P></▼2>
Park, Hyunjung,Lee, Dongsoo,Song, Taeseup Elsevier 2019 Journal of Power Sources Vol.414 No.-
<P><B>Abstract</B></P> <P>Niobium pentoxide, Nb<SUB>2</SUB>O<SUB>5</SUB>, is an intercalation-type material with a high theoretical capacity of ∼404 mAh g<SUP>−1</SUP> for Li-ion batteries. However, electrochemical properties of Nb<SUB>2</SUB>O<SUB>5</SUB> largely depend on its various polymorphs with different crystal structures, and their low electrical conductivity acts as the main obstacle. Here, we report high-temperature calcined monoclinic Nb<SUB>2</SUB>O<SUB>5</SUB> and semiconducting NbO<SUB>2</SUB> composite as a high-power anode material. Monoclinic Nb<SUB>2</SUB>O<SUB>5</SUB> itself as a main active material shows a high capacity of ∼280 mAh g<SUP>−1</SUP>, and NbO<SUB>2</SUB> with a small band gap of ∼0.5 eV not only improves electrical conductivity but also gives a capacity of ∼110 mAh g<SUP>−1</SUP>. To have a synergic effect of these two materials, the Nb<SUB>2</SUB>O<SUB>5</SUB>/NbO<SUB>2</SUB> composite is prepared <I>via</I> simple post-calcination of as-prepared Nb<SUB>2</SUB>O<SUB>5</SUB> under a reduction atmosphere. It shows a discharge capacity of ∼214 mAh g<SUP>−1</SUP> at 0.05 C, a high initial Coulombic efficiency of 94.7%, a superior rate capability of ∼40 mAh g<SUP>−1</SUP> at 100 C, and a robust cycle performance of 81% retention over 900 cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Monoclinic Nb<SUB>2</SUB>O<SUB>5</SUB> was prepared by high calcination at 1100 °C. </LI> <LI> Semi-conducting NbO<SUB>2</SUB> was introduced to Nb<SUB>2</SUB>O<SUB>5</SUB> by thermal reduction process. </LI> <LI> Nb<SUB>2</SUB>O<SUB>5</SUB>/NbO<SUB>2</SUB> composite shows a cycle performance of 81% retention over 900 cycles. </LI> <LI> Nb<SUB>2</SUB>O<SUB>5</SUB>/NbO<SUB>2</SUB> composite shows a superior rate capability at 100C. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Park, Hyunjung,Lee, Dongsoo,Song, Taeseup American Chemical Society 2018 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.57 No.27
<P>Carboxymethyl cellulose lithium (CMC-Li) has recently been explored as a promising binder for Li-ion batteries because of enhanced Li<SUP>+</SUP> ion flux. CMC-Li has been generally prepared by CMC acid form (CMC-H) as an intermediate product treated with a strong acid, which considerably causes a polymer degradation. Here, we report a synthesis method of CMC-Li through the use of a weak acid (acetic acid) and its application in a high energy-density graphite anode. CMC-Li synthesized by acetic acid (CMC-Li (A)) exhibits enhanced physicochemical properties including an appropriate viscosity of ∼3000 mPa·s at a shear rate of 10 s<SUP>-1</SUP>, good slurry stability, and strong adhesion force of 1.4 gf/mm compared to those of CMC-Li synthesized by hydrochloric acid. The high energy-density graphite anode prepared with CMC-Li (A) shows higher charge/discharge capacities and capacity retentions in various rates of 0.05-2 C than those of the electrode prepared with CMC-Na that might be due to the enhanced Li<SUP>+</SUP> ion flux upon cycling.</P> [FIG OMISSION]</BR>