Publications by authors named "Won Seok Chi"

17 Publications

  • Page 1 of 1

MOF-Based Membranes for Gas Separations.

Chem Rev 2020 08 1;120(16):8161-8266. Epub 2020 Jul 1.

Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.

Metal-organic frameworks (MOFs) represent the largest known class of porous crystalline materials ever synthesized. Their narrow pore windows and nearly unlimited structural and chemical features have made these materials of significant interest for membrane-based gas separations. In this comprehensive review, we discuss opportunities and challenges related to the formation of pure MOF films and mixed-matrix membranes (MMMs). Common and emerging separation applications are identified, and membrane transport theory for MOFs is described and contextualized relative to the governing principles that describe transport in polymers. Additionally, cross-cutting research opportunities using advanced metrologies and computational techniques are reviewed. To quantify membrane performance, we introduce a simple membrane performance score that has been tabulated for all of the literature data compiled in this review. These data are reported on upper bound plots, revealing classes of MOF materials that consistently demonstrate promising separation performance. Recommendations are provided with the intent of identifying the most promising materials and directions for the field in terms of fundamental science and eventual deployment of MOF materials for commercial membrane-based gas separations.
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http://dx.doi.org/10.1021/acs.chemrev.0c00119DOI Listing
August 2020

Mixed-Matrix Membranes Formed from Imide-Functionalized UiO-66-NH for Improved Interfacial Compatibility.

ACS Appl Mater Interfaces 2019 Aug 14;11(34):31257-31269. Epub 2019 Aug 14.

Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States.

Mixed-matrix membranes (MMMs) formed by dispersing metal-organic framework (MOF) particles in polymers have attracted significant attention because these composite systems can potentially surpass the separation performance of pure polymers alone. However, performance improvements are often unrealized because of poor interfacial compatibility between the MOF and the polymer, which results in interfacial defects. From a practical perspective, strategies are needed to address these defects so that MMMs can be deployed in real-world separation processes. From a fundamental perspective, strategies are needed to reliably form defect-free MMMs so that transport models can be applied to estimate pure MOF property sets, thereby enabling the development of robust structure-property relationships. To address these interfacial challenges, we have developed a method to surface-functionalize a UiO-66-NH MOF with a nanoscopic shell of covalently tethered 4,4'-(hexafluoroisopropylidene)diphthalic anhydride-Durene oligomers. When combined with a high-molecular-weight polymer of identical chemical structure to that of the imide-functional MOF surface, defect-free MMMs with uniform particle dispersions can be formed. With this technique, both permeabilities and selectivities of select gases in the MMMs were improved at loadings ranging from 5 to 40 wt %. At a 40 wt % loading, CO permeability and CO/CH selectivity were enhanced by 48 and 15%, respectively. Additionally, pure MOF permeabilities for H, N, O, CH, and CO were predicted by the Maxwell model.
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http://dx.doi.org/10.1021/acsami.9b07500DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6727620PMC
August 2019

Mixed-Matrix Membranes Formed from Multi-Dimensional Metal-Organic Frameworks for Enhanced Gas Transport and Plasticization Resistance.

ChemSusChem 2019 Jun 29;12(11):2355-2360. Epub 2019 Apr 29.

Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts, 02139, USA.

Mixed-matrix membranes (MMMs) formed by incorporating metal-organic frameworks (MOFs) into polymers have a general limitation in that the MOFs are typically formed into rather simple dimensionalities (such as 1D, 2D, or 3D). Each design approach has intrinsic-albeit independent-benefits, such as network percolation (1D), access to high-aspect ratios (2D), and ease of processability (3D). However, a design strategy is needed to combine multiple dimensionalities and, thereby, access the full range of transport and compositing benefits of these high-performance materials. Herein, a facile method to form multi-dimensional HKUST-1 nanoparticles is introduced by using a modulator to tune the MOF nucleation and growth mechanism. At 30 wt % multidimensional MOF loading, the MMM shows CO permeabilities of approximately 2500 Barrer, which represents a 2.5-fold increase compared to that of a pure polymer without a large loss of selectivity for CO /CH and CO /N . Additionally, almost no plasticization pressure response is observed for CO up to 750 psi, suggesting an unusual stability to high activity feeds.
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http://dx.doi.org/10.1002/cssc.201900623DOI Listing
June 2019

Direct Organization of Morphology-Controllable Mesoporous SnO Using Amphiphilic Graft Copolymer for Gas-Sensing Applications.

ACS Appl Mater Interfaces 2017 Oct 16;9(42):37246-37253. Epub 2017 Oct 16.

Department of Chemical and Biomolecular Engineering, Yonsei University , Seoul 03722, South Korea.

A simple and flexible strategy for controlled synthesis of mesoporous metal oxide films using an amphiphilic graft copolymer as sacrificial template is presented and the effectiveness of this approach for gas-sensing applications is reported. The amphiphilic graft copolymer poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) is used as a sacrificial template for the direct synthesis of mesoporous SnO. The graft copolymer self-assembly is shown to enable good control over the morphology of the resulting SnO layer. Using this approach, mesoporous SnO based sensors with varied porosity are fabricated in situ on a microheater platform. This method reduces the interfacial contact resistance between the chemically sensitive materials and the microheater, while a simple fabrication process is provided. The sensors show significantly different gas-sensing performances depending on the SnO porosity, with the highly mesoporous SnO sensor exhibiting high sensitivity, low detection limit, and fast response and recovery toward hydrogen gas. This printable solution-based method can be used reproducibly to fabricate a variety of mesoporous metal oxide layers with tunable morphologies on various substrates for high-performance applications.
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http://dx.doi.org/10.1021/acsami.7b07823DOI Listing
October 2017

Nanowire-Assembled Hierarchical ZnCoO Microstructure Integrated with a Low-Power Microheater for Highly Sensitive Formaldehyde Detection.

ACS Appl Mater Interfaces 2016 Nov 14;8(46):31764-31771. Epub 2016 Nov 14.

State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology , Wuhan 430074, China.

Nanowire-assembled 3D hierarchical ZnCoO microstructure is synthesized by a facile hydrothermal route and a subsequent annealing process. In comparison to simple nanowires, the resulting dandelion-like structure yields more open spaces between nanowires, which allow for better gas diffusion and provide more active sites for gas adsorption while maintaining good electrical conductivity. The hierarchical ZnCoO microstructure is integrated on a low-power microheater platform without using binders or conductive additives. The hierarchical structure of the ZnCoO sensing material provides reliable electrical connection across the sensing electrodes. The resulting sensor exhibits an ultralow detection limit of 3 ppb toward formaldehyde with fast response and recovery as well as good selectivity to CO, H, and hydrocarbons such as n-pentane, propane, and CH. The sensor only consumes ∼5.7 mW for continuous operation at 300 °C with good long-term stability. The excellent sensing performance of this hierarchical structure based sensor suggests the advantages of combining such structures with microfabricated heaters for practical low-power sensing applications.
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http://dx.doi.org/10.1021/acsami.6b11054DOI Listing
November 2016

Selective Ion Transporting Polymerized Ionic Liquid Membrane Separator for Enhancing Cycle Stability and Durability in Secondary Zinc-Air Battery Systems.

ACS Appl Mater Interfaces 2016 Oct 23;8(39):26298-26308. Epub 2016 Sep 23.

New Energy and Battery Engineering, Yonsei University , 134 Shinchon-dong, Seodaemoon-ku, Seoul 120-749, Republic of Korea.

Rechargeable secondary zinc-air batteries with superior cyclic stability were developed using commercial polypropylene (PP) membrane coated with polymerized ionic liquid as separators. The anionic exchange polymer was synthesized copolymerizing 1-[(4-ethenylphenyl)methyl]-3-butylimidazolium hydroxide (EBIH) and butyl methacrylate (BMA) monomers by free radical polymerization for both functionality and structural integrity. The ionic liquid induced copolymer was coated on a commercially available PP membrane (Celguard 5550). The coat allows anionic transfer through the separator and minimizes the migration of zincate ions to the cathode compartment, which reduces electrolyte conductivity and may deteriorate catalytic activity by the formation of zinc oxide on the surface of the catalyst layer. Energy dispersive X-ray spectroscopy (EDS) data revealed the copolymer-coated separator showed less zinc element in the cathode, indicating lower zinc crossover through the membrane. Ion coupled plasma optical emission spectroscopy (ICP-OES) analysis confirmed over 96% of zincate ion crossover was reduced. In our charge/discharge setup, the constructed cell with the ionic liquid induced copolymer casted separator exhibited drastically improved durability as the battery life increased more than 281% compared to the pure commercial PP membrane. Electrochemical impedance spectroscopy (EIS) during the cycle process elucidated the premature failure of cells due to the zinc crossover for the untreated cell and revealed a substantial importance must be placed in zincate control.
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http://dx.doi.org/10.1021/acsami.6b07841DOI Listing
October 2016

Enhanced performance of mixed-matrix membranes through a graft copolymer-directed interface and interaction tuning approach.

ChemSusChem 2015 Feb 13;8(4):650-8. Epub 2014 Nov 13.

Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (South Korea), Fax: (+82) 2-312-6401.

Herein, a high performance mixed-matrix membrane (MMM) is reported with simultaneously large improvements in the CO2 permeability by 880 % from 70.2 to 687.7 Barrer (1 Barrer=1×10(-10)  cm(3)  cm cm(-2)  s(-1)  cmHg(-1) ) and CO2 /N2 selectivity by 14.4 % from 30.5 to 34.9. These findings represent one of the most dramatic improvements ever reported for MMMs. These improvements are obtained through an interface and interaction tuning approach based on an amphiphilic grafted copolymer. Poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer plays a key role as a soft organic matrix to provide good permeation properties, uniform distribution of zeolite imidazole frameworks-8 (ZIF-8), and better interfacial contact with inorganic compounds. In particular, the CO2 /C3 H8 and CO2 /C3 H6 selectivities reached 10.5 and 42.7, respectively, for PVC-g-POEM/ZIF (40 %) MMMs; this indicates that it could be a promising membrane material for the purification of C3 hydrocarbons.
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http://dx.doi.org/10.1002/cssc.201402677DOI Listing
February 2015

Mesoporous TiO₂ Bragg stack templated by graft copolymer for dye-sensitized solar cells.

Sci Rep 2014 Jul 1;4:5505. Epub 2014 Jul 1.

Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749, South Korea.

Organized mesoporous TiO₂ Bragg stacks (om-TiO₂ BS) consisting of alternating high and low refractive index organized mesoporous TiO₂ (om-TiO₂) films were prepared to enhance dye loading, light harvesting, electron transport, and electrolyte pore-infiltration in dye-sensitized solar cells (DSSCs). The om-TiO₂ films were synthesized via a sol-gel reaction using amphiphilic graft copolymers consisting of poly(vinyl chloride) backbones and poly(oxyethylene methacrylate) side chains, i.e., PVC-g-POEM as templates. To generate high and low index films, the refractive index of om-TiO₂ film was tuned by controlling the grafting ratio of PVC-g-POEM via atomic transfer radical polymerization (ATRP). A polymerized ionic liquid (PIL)-based DSSC fabricated with a 1.2-μm-thick om-TiO₂ BS-based photoanode exhibited an efficiency of 4.3%, which is much higher than that of conventional DSSCs with a nanocrystalline TiO₂ layer (nc-TiO₂ layer) (1.7%). A PIL-based DSSC with a heterostructured photoanode consisting of 400-nm-thick organized mesoporous TiO₂ interfacial (om-TiO₂ IF) layer, 7-μm-thick nc-TiO₂, and 1.2-μm-thick om-TiO₂ BS as the bottom, middle and top layers, respectively, exhibited an excellent efficiency of 7.5%, which is much higher than that of nanocrystaline TiO₂ photoanode (3.5%).
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http://dx.doi.org/10.1038/srep05505DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4076678PMC
July 2014

Structural control of hierarchically-ordered TiO2 films by water for dye-sensitized solar cells.

Chemphyschem 2014 Jun 9;15(9):1841-8. Epub 2014 May 9.

Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (South Korea), Fax: (+82) 2-312-6401.

A facile way of controlling the structure of TiO(2) by changing the amount of water to improve the efficiency of dye-sensitized solar cells (DSSCs) is reported. Hierarchically ordered TiO(2) films with high porosity and good interconnectivity are synthesized in a well-defined morphological confinement arising from a one-step self-assembly of preformed TiO(2) (pre-TiO(2)) nanocrystals and a graft copolymer, namely poly(vinyl chloride)-g-poly(oxyethylene methacrylate). The polymer-solvent interactions in solution, which are tuned by the amount of water, are shown to be a decisive factor in determining TiO(2) morphology and device performance. Systematic control of wall and pore size is achieved and enables the bifunctionality of excellent light scattering properties and easy electron transport through the film. These properties are characterized by reflectance spectroscopy, incident photon-to-electron conversion efficiency, and electrochemical impedance spectroscopy analyses. The TiO(2) photoanode that is prepared with a higher water ratio, [pre-TiO(2)]:[H(2)O]=1:0.3, shows a larger surface area, greater light scattering, and better electron transport, which result in a high efficiency (7.7 %) DSSC with a solid polymerized ionic liquid. This efficiency is much greater than that of commercially available TiO(2) paste (4.0 %).
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http://dx.doi.org/10.1002/cphc.201400053DOI Listing
June 2014

Dual-functionalized mesoporous TiO(2) hollow nanospheres for improved CO(2) separation membranes.

Chem Commun (Camb) 2014 Jun 15;50(43):5717-20. Epub 2014 Apr 15.

Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, South Korea.

Simultaneous improvement in CO2 permeability and CO2/N2 selectivity was obtained from mixed matrix membranes (MMMs) containing dual-functionalized mesoporous TiO2 hollow nanospheres (f-MTHS). Dual functionality resulted in the increased CO2 affinity and improved interfacial properties between inorganic nanofillers and the polymer matrix.
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http://dx.doi.org/10.1039/c4cc00513aDOI Listing
June 2014

Improved electron transfer and plasmonic effect in dye-sensitized solar cells with bi-functional Nb-doped TiO2/Ag ternary nanostructures.

Nanoscale 2014 Mar 24;6(5):2718-29. Epub 2014 Jan 24.

Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749, South Korea.

TiO2 nanoparticles are surface-modified via atom transfer radical polymerization (ATRP) with a hydrophilic poly(oxyethylene)methacrylate (POEM), which can coordinate to the Ag precursor, i.e. silver trifluoromethanesulfonate (AgCF3SO3). Following the reduction of Ag ions, a Nb2O5 doping process and calcination at 450 °C, bi-functional Nb-doped TiO2/Ag ternary nanostructures are generated. The resulting nanostructures are characterized by energy-filtering transmission electron microscopy (EF-TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. The dye-sensitized solar cell (DSSC) based on the Nb-doped TiO2/Ag nanostructure photoanode with a polymerized ionic liquid (PIL) as the solid polymer electrolyte shows an overall energy conversion efficiency (η) of 6.9%, which is much higher than those of neat TiO2 (4.7%) and Nb-doped TiO2 (5.4%). The enhancement of η is mostly due to the increase of current density, attributed to the improved electron transfer properties including electron injection, collection, and plasmonic effects without the negative effects of charge recombination or problems with corrosion. These properties are supported by intensity modulated photocurrent/voltage spectroscopy (IMPS/IMVS) and incident photon-to-electron conversion efficiency (IPCE) measurements.
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http://dx.doi.org/10.1039/c3nr05652jDOI Listing
March 2014

One-step synthesis of vertically aligned anatase thornbush-like TiO2 nanowire arrays on transparent conducting oxides for solid-state dye-sensitized solar cells.

ChemSusChem 2013 Aug 26;6(8):1384-91. Epub 2013 Jul 26.

Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 Korea.

Herein, we report a facile synthesis of high-density anatase-phase vertically aligned thornbush-like TiO2 nanowires (TBWs) on transparent conducting oxide glasses. Morphologically controllable TBW arrays of 9 μm in length are generated through a one-step hydrothermal reaction at 200 °C over 11 h using potassium titanium oxide oxalate dehydrate, diethylene glycol (DEG), and water. The TBWs consist of a large number of nanoplates or nanorods, as confirmed by SEM and TEM imaging. The morphologies of TBWs are controllable by adjusting DEG/water ratios. TBW diameters gradually decrease from 600 (TBW600) to 400 (TBW400) to 200 nm (TBW200) and morphologies change from nanoplates to nanorods with an increase in DEG content. TBWs are utilized as photoanodes for quasi-solid-state dye-sensitized solar cells (qssDSSCs) and solid-state DSSCs (ssDSSCs). The energy-conversion efficiency of qssDSSCs is in the order: TBW200 (5.2%)>TBW400 (4.5%)>TBW600 (3.4%). These results can be attributed to the different surface areas, light-scattering effects, and charge transport rates, as confirmed by dye-loading measurements, reflectance spectroscopy, and incident photon-to-electron conversion efficiency and intensity-modulated photovoltage spectroscopy/intensity-modulated photocurrent spectroscopy analyses. TBW200 is further treated with a graft-copolymer-directed organized mesoporous TiO2 to increase the surface area and interconnectivity of TBWs. As a result, the energy-conversion efficiency of the ssDSSC increases to 6.7% at 100 mW cm(-2) , which is among the highest values for N719-dye-based ssDSSCs.
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http://dx.doi.org/10.1002/cssc.201300317DOI Listing
August 2013

One-dimensional hierarchical nanostructures of TiO(2) nanosheets on SnO(2) nanotubes for high efficiency solid-state dye-sensitized solar cells.

Adv Mater 2013 Sep 15;25(35):4893-7. Epub 2013 Jul 15.

Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749, South Korea.

Hierarchical nanostructures of TiO2 nanosheets on SnO2 nanotubes (SNT@TNS) are uniformly dispersed in an organized mesoporous (OM) TiO2 film with large pores, high porosity, and good interconnectivity. The solid-state dye sensitized solar cells (ssDSSCs) fabricated with 10 wt% SNT@TNS dispersed in a OM-TiO2 film show an energy conversion efficiency of 7.7% at 100 mW cm(-2) , which is one of the highest values for N719-based ssDSSCs and much larger than that of a randomly oriented TiO2 nanoparticles-based cell (4.0%).
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http://dx.doi.org/10.1002/adma.201302226DOI Listing
September 2013

Hybrid electrolytes prepared from ionic liquid-grafted alumina for high-efficiency quasi-solid-state dye-sensitized solar cells.

Nanoscale 2013 Jun;5(12):5341-8

Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749, South Korea.

Alumina (Al2O3) nanoparticles were covalently surface-modified with an ionic liquid (IL) to improve their miscibility with ILs such as 1-methyl-3-propylimidazolium iodide (MPII). Hybrids consisting of MPII and the surface-modified IL-Al2O3 nanoparticles were utilized as an I2-free electrolyte for quasi-solid-state dye-sensitized solar cells (DSSCs). The synthesis and properties of the IL-Al2O3 nanoparticles and hybrid electrolytes were characterized by Fourier transform infrared (FT-IR) spectroscopy, UV-visible spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The viscosity of the electrolyte continuously increased with the content of IL-Al2O3, and the fluidity almost disappeared completely when the MPII:IL-Al2O3 weight ratio was 95 : 5 or 90 : 10. The energy conversion efficiencies of DSSCs fabricated with IL-Al2O3 were always greater than those with pristine Al2O3. Such a finding is due to the favorable interactions and good miscibility between MPII and IL-Al2O3, which in turn results in the formation of an interconnected channel pathway for ion transport. Incident photon-to-electron conversion efficiency (IPCE), intensity modulated photocurrent spectroscopy (IMPS)/intensity-modulated photovoltage spectroscopy (IMVS), and electrochemical impedance spectroscopy (EIS) measurements were used to investigate the interfacial properties and electron transport characteristics. Upon utilizing double-layer structures with mesoporous TiO2 beads, the efficiency increased to 7.6% at 100 mW cm(-2), one of the highest values reported for quasi-solid-state DSSCs.
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http://dx.doi.org/10.1039/c3nr00291hDOI Listing
June 2013

Room temperature solid-state synthesis of a conductive polymer for applications in stable I₂-free dye-sensitized solar cells.

ChemSusChem 2012 Nov 3;5(11):2173-80. Epub 2012 Sep 3.

Active Polymer Center for Pattern Integration, Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, South Korea.

A solid-state polymerizable monomer, 2,5-dibromo-3,4-propylenedioxythiophene (DBProDOT), was synthesized at 25 °C to produce a conducting polymer, poly(3,4-propylenedioxythiophene) (PProDOT). Crystallographic studies revealed a short interplane distance between DBProDOT molecules, which was responsible for polymerization at low temperature with a lower activation energy and higher exothermic reaction than 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) or its derivatives. Upon solid-state polymerization (SSP) of DBProDOT at 25 °C, PProDOT was obtained in a self-doped state with tribromide ions and an electrical conductivity of 0.05 S cm⁻¹, which is considerably higher than that of chemically-polymerized PProDOT (2×10⁻⁶ S cm⁻¹). Solid-state ¹³C NMR spectroscopy and DFT calculations revealed polarons in PProDOT and a strong perturbation of carbon nuclei in thiophenes as a result of paramagnetic broadening. DBProDOT molecules deeply penetrated and polymerized to fill nanocrystalline TiO₂ pores with PProDOT, which functioned as a hole-transporting material (HTM) for I₂-free solid-state dye-sensitized solar cells (ssDSSCs). With the introduction of an organized mesoporous TiO₂ (OM-TiO₂) layer, the energy conversion efficiency reached 3.5 % at 100 mW cm⁻², which was quite stable up to at least 1500 h. The cell performance and stability was attributed to the high stability of PProDOT, with the high conductivity and improved interfacial contact of the electrode/HTM resulting in reduced interfacial resistance and enhanced electron lifetime.
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http://dx.doi.org/10.1002/cssc.201200349DOI Listing
November 2012

Employing electrostatic self-assembly of tailored nickel sulfide nanoparticles for quasi-solid-state dye-sensitized solar cells with Pt-free counter electrodes.

Chem Commun (Camb) 2012 Oct;48(76):9501-3

Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749, South Korea.

A low cost, low-temperature processable, highly efficient nickel sulfide counter electrode is demonstrated. Using the tailored, preformed nickel sulfide nanoparticles and electrostatic self-assembly, a novel counter electrode was fabricated that exceeded the efficiency of a conventional Pt-based cell.
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http://dx.doi.org/10.1039/c2cc34559eDOI Listing
October 2012

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.

Adv Mater 2012 Jan 23;24(4):519-22. Epub 2011 Dec 23.

Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749, South Korea.

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.
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http://dx.doi.org/10.1002/adma.201103799DOI Listing
January 2012