The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Jung Tae Park - One of the best experts on this subject based on the ideXlab platform.
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one pot synthesis of hierarchical mesoporous sno2 spheres using a Graft Copolymer enhanced photovoltaic and photocatalytic performance
RSC Advances, 2014Co-Authors: Jung Tae ParkAbstract:We synthesized hierarchical mesoporous SnO2 (HM-SnO2) spheres with a large surface area (85.3 m2 g−1) via a one-pot controlled solvothermal process using tin chloride pentahydrate and Graft Copolymer, i.e., poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) as a Sn precursor and structure directing agent, respectively. Solid-state dye-sensitized solar cells (ssDSSCs) fabricated with HM-SnO2 spheres on an organized mesoporous SnO2 interfacial (om-SnO2 IF) layer as the photoanode had a long-term stable efficiency of 3.4% at 100 mW cm2, which was much higher than that of ssDSSCs with a photoanode comprising nonporous SnO2 (NP-SnO2) spheres (1.9%). We attributed the enhanced device performance of ssDSSCs fabricated with the HM-SnO2 photoanode to the well-organized hierarchical structure with dual pores (23.5 and 162.3 nm), which provided a larger surface area, improved light scattering, and decreased charge recombination compared to the nonporous SnO2 (NP-SnO2) photoanode. We confirmed this by reflectance, incident photon to current conversion efficiency (IPCE), and intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) measurements. Introduction of an om-SnO2 IF layer between the HM-SnO2 spheres and fluorine-doped tin oxide (FTO) substrate enhanced light harvesting, increased electron transport, reduced charge recombination, and decreased interfacial/internal resistance. Photocatalytic tests indicated that HM-SnO2 spheres showed high activity with good recyclability for photodegradation of methyl orange under UV light irradiation.
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direct assembly of preformed nanoparticles and Graft Copolymer for the fabrication of micrometer thick organized tio2 films high efficiency solid state dye sensitized solar cells
Advanced Materials, 2012Co-Authors: Jung Tae ParkAbstract:: Solid-state dye-sensitized solar cell with 7.1% efficiency at 100 mW/cm(2) is reported, one of the highest observed for N719 dye. Excellent performance was achieved via a Graft Copolymer-templated, organized mesoporous TiO(2) film with a large surface area using spindle-shaped, preformed TiO(2) nanoparticles and solid polymer electrolyte.
Joo Hwan Koh - One of the best experts on this subject based on the ideXlab platform.
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One-step synthesis of leaf-like, Fe2O3-decorated Cu structures templated by Graft Copolymer
Materials Letters, 2013Co-Authors: Rajkumar Patel, Joo Hwan Koh, Sang Jin KimAbstract:Leaf-like iron oxide (Fe2O3)-decorated copper (Cu) structures were prepared by a facile, one-step templating method. An amphiphilic Graft Copolymer consisting of a poly(vinyl chloride) (PVC) backbone and poly(oxyethylene methacrylate) (POEM) side chains (PVC-g-POEM) synthesized via atom transfer radical polymerization (ATRP) was used as a structure-directing agent. Cu nanoparticles dispersed in the Graft Copolymer solution were combined with iron (III) ethoxide, followed by an in situ sol-gel reaction and calcination at 450 C to generate the Fe2O3/Cu structures. The morphology and elemental composition were confirmed by transmission electron microscopy (TEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), and scanning electron microscopy (SEM). ?? 2013 Elsevier B.V.
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Graft Copolymer templated synthesis of mesoporous MgO/TiO2 mixed oxide nanoparticles and their CO2 adsorption capacities
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2012Co-Authors: Joo Hwan Koh, Yoon Jae Min, Sung Hoon Ahn, Seok-min Hong, KI BONG LEEAbstract:Mesoporous mixed oxide nanoparticles consisting of MgO and TiO2 were synthesized via a sol–gel process by templating poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) Graft Copolymer. The mesoporous structures and morphologies of the MgO/TiO2 mixed oxides were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and nitrogen adsorption/desorption analysis. Interestingly, MgO/TiO2 mixed oxide exhibited much higher CO2 adsorption capacity (0.477 mol CO2/kg sorbent for 40:60 MgO/TiO2) than pure MgO (0.074) or TiO2 (0.063). This result arises from the increase in surface area and pore volume of the mixed oxide due to the formation of bimodal pores.
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Efficiency improvement of dye-sensitized solar cells using Graft Copolymer-templated mesoporous TiO2 films as an interfacial layer
Journal of Materials Chemistry, 2011Co-Authors: Sung Hoon Ahn, Joo Hwan Koh, Kyung Jin Son, Hyungju Ahn, Won Gun Koh, Du Yeol RyuAbstract:Organized mesoporous TiO2 films with high porosity and good connectivity were synthesized via sol-gel by templating an amphiphilic Graft Copolymer consisting of poly(vinyl chloride) backbone and poly(oxyethylene methacrylate) side chains, i.e., PVC-g-POEM. The randomly microphase-separated Graft Copolymer was self-reorganized to exhibit a well-ordered micellar morphology upon controlling polymer-solvent interactions, as confirmed by atomic force microscope (AFM) and glazing incidence small-angle X-ray scattering (GISAXS). These organized mesoporous TiO2 films, 550 nm in thickness, were used an an interfacial layer between a nanocrystalline TiO2 thick layer and a conducting glass in dye-sensitized solar cells (DSSC). Introduction of the organized mesoporous TiO2 layer resulted in the increased transmittance of visible light, decreased interfacial resistance and enhanced electron lifetime. As a result, an energy conversion efficiency of DSSC employing polymer electrolyte was significantly improved from 3.5% to 5.0% at 100 mW cm-2. 2011 The Royal Society of Chemistry.
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Synthesis of porous TiO2 thin films using PVC-g-PSSA Graft Copolymer and their use in dye-sensitized solar cells
Membr. J., 2011Co-Authors: Su Jin Byun, Won Seok Chi, Jin Ah Seo, Yong-gun Shul, Joo Hwan KohAbstract:An amphiphilic Graft Copolymer comprising a poly(vinyl chloride) (PVC) backbone and poly (styrene sulfonic acid) (PSSA) side chains (PVC-g-PSSA) was synthesized via atom transfer radical polymn. (ATRP). Mesoporous titanium dioxide (TiO2) films with cryst. anatase phase were synthesized via a sol-gel process by templating PVC-g-PSSA Graft Copolymer. Titanium isopropoxide (TTIP), a TiO2 precursor was selectively incorporated into the hydrophilic PSSA domains of the Graft Copolymer and grew to form mesoporous TiO2 films, as confirmed by SEM (SEM) and X-ray diffraction (XRD) anal. The performances of dye-sensitized solar cell (DSSC) were systematically investigated by varying spin coating times and the amts. of P25 nanoparticles. The energy conversion efficiency reached up to 2.7% at 100 mW/cm2 upon using quasi-solid-state polymer electrolyte. [on SciFinder(R)]
Sung Hoon Ahn - One of the best experts on this subject based on the ideXlab platform.
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Poly(vinyl chloride)-Graft-poly(N-vinyl caprolactam) Graft Copolymer: Synthesis and use as template for porous TiO 2 thin films in dye-sensitized solar cells
Ionics, 2012Co-Authors: Rajkumar Patel, Sung Hoon Ahn, Won Seok ChiAbstract:Poly(N-vinyl caprolactam) (PNVCL) side chains were Grafted to a poly(vinyl chloride) (PVC) backbone via atom transfer radical polymerization. The synthesized PVC-g-PNVCL Graft Copolymer was templated for the preparation of porous TiO2 thin films, which involved a sol-gel reaction and calcination process. The interaction of the carbonyl groups in the PVC-g-PNVCL with the titania was revealed by FT-IR spectroscopy. X-ray diffraction and transmission electron microscopy analysis showed the formation of porous TiO2 thin films with the anatase phase. A series of porous TiO2 thin films with different pore sizes and porosities was prepared by varying the solution compositions and were used as photoelectrodes in dye-sensitized solar cells (DSSC) with a polymer electrolyte. The DSSC performed best when using the TiO2 film with higher porosity, lower interfacial resistance, and longer electron life time. The highest energy conversion efficiency, photovoltage (V (oc)), photocurrent density (J (sc)), and fill factor (FF) were 1.2%, 0.68 V, 3.2 mA/cm(2), and 0.57 at 100 mW/cm(2), respectively, for the quasi-solid state DSSC with a 730-nm-thick TiO2 film.
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Graft Copolymer templated synthesis of mesoporous MgO/TiO2 mixed oxide nanoparticles and their CO2 adsorption capacities
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2012Co-Authors: Joo Hwan Koh, Yoon Jae Min, Sung Hoon Ahn, Seok-min Hong, KI BONG LEEAbstract:Mesoporous mixed oxide nanoparticles consisting of MgO and TiO2 were synthesized via a sol–gel process by templating poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) Graft Copolymer. The mesoporous structures and morphologies of the MgO/TiO2 mixed oxides were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and nitrogen adsorption/desorption analysis. Interestingly, MgO/TiO2 mixed oxide exhibited much higher CO2 adsorption capacity (0.477 mol CO2/kg sorbent for 40:60 MgO/TiO2) than pure MgO (0.074) or TiO2 (0.063). This result arises from the increase in surface area and pore volume of the mixed oxide due to the formation of bimodal pores.
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Efficiency improvement of dye-sensitized solar cells using Graft Copolymer-templated mesoporous TiO2 films as an interfacial layer
Journal of Materials Chemistry, 2011Co-Authors: Sung Hoon Ahn, Joo Hwan Koh, Kyung Jin Son, Hyungju Ahn, Won Gun Koh, Du Yeol RyuAbstract:Organized mesoporous TiO2 films with high porosity and good connectivity were synthesized via sol-gel by templating an amphiphilic Graft Copolymer consisting of poly(vinyl chloride) backbone and poly(oxyethylene methacrylate) side chains, i.e., PVC-g-POEM. The randomly microphase-separated Graft Copolymer was self-reorganized to exhibit a well-ordered micellar morphology upon controlling polymer-solvent interactions, as confirmed by atomic force microscope (AFM) and glazing incidence small-angle X-ray scattering (GISAXS). These organized mesoporous TiO2 films, 550 nm in thickness, were used an an interfacial layer between a nanocrystalline TiO2 thick layer and a conducting glass in dye-sensitized solar cells (DSSC). Introduction of the organized mesoporous TiO2 layer resulted in the increased transmittance of visible light, decreased interfacial resistance and enhanced electron lifetime. As a result, an energy conversion efficiency of DSSC employing polymer electrolyte was significantly improved from 3.5% to 5.0% at 100 mW cm-2. 2011 The Royal Society of Chemistry.
Jong Shik Shin - One of the best experts on this subject based on the ideXlab platform.
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highly efficient i2 free solid state dye sensitized solar cells fabricated with polymerized ionic liquid and Graft Copolymer directed mesoporous film
Electrochemistry Communications, 2011Co-Authors: Jong Shik ShinAbstract:Abstract A polymerized ionic liquid of poly((1-(4-ethenylphenyl)methyl)-3-butyl-imidazolium iodide) was synthesized and employed as a solid electrolyte for I 2 -free solid-state dye-sensitized solar cells. The electrode/electrolyte interfaces were significantly improved using a Graft Copolymer-directed, organized mesoporous TiO 2 thin film. The conversion efficiency reached 5.93% at 100 mW/cm 2 , one of the highest observed values, due to decreased interfacial resistance and enhanced electron lifetime.
Harim Jeon - One of the best experts on this subject based on the ideXlab platform.
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efficiency improvement of dye sensitized solar cells using Graft Copolymer templated mesoporous tio2 films as an interfacial layer
Journal of Materials Chemistry, 2011Co-Authors: Harim JeonAbstract:Organized mesoporous TiO2 films with high porosity and good connectivity were synthesized via sol–gel by templating an amphiphilic Graft Copolymer consisting of poly(vinyl chloride) backbone and poly(oxyethylene methacrylate) side chains, i.e., PVC-g-POEM. The randomly microphase-separated Graft Copolymer was self-reorganized to exhibit a well-ordered micellar morphology upon controlling polymer–solvent interactions, as confirmed by atomic force microscope (AFM) and glazing incidence small-angle X-ray scattering (GISAXS). These organized mesoporous TiO2 films, 550 nm in thickness, were used an an interfacial layer between a nanocrystalline TiO2 thick layer and a conducting glass in dye-sensitized solar cells (DSSC). Introduction of the organized mesoporous TiO2 layer resulted in the increased transmittance of visible light, decreased interfacial resistance and enhanced electron lifetime. As a result, an energy conversion efficiency of DSSC employing polymer electrolyte was significantly improved from 3.5% to 5.0% at 100 mW cm−2.
