Showing papers by "Jun Hong Noh published in 2012"
TL;DR: In this paper, the authors adopted a compact TiO 2 (c-TiO 2 ) layer on Nb-doped NTO/NTO/ITO multilayered electrodes, which are transparent conducting oxide (TCO) electrodes, to improve their transmittance for high-efficiency dye-sensitized solar cells (DSSCs).
34 citations
TL;DR: In this article, the authors synthesized vertically aligned TiO2 nanoarchitectures with large internal surface areas and open channels of pores via pulsed laser deposition (PLD) and investigated the effects of the deposition conditions and the postannealing on the formation and properties of nano-architecture photoelectrodes for dye-sensitized solar cells.
Abstract: Aligned photoelectrodes have been intensively investigated due to their prominent electron dynamics, but their device performance has been limited by their small surface area. Here, we synthesized vertically aligned TiO2 nanoarchitectures with large internal surface areas and open channels of pores via pulsed laser deposition (PLD) and investigated the effects of the deposition conditions and the postannealing on the formation and properties of nanoarchitecture photoelectrodes for dye-sensitized solar cells. Increasing the oxygen working pressure increases the porosity of the TiO2 film and decreases the amount of deposited materials resulting in an optimized oxygen working pressure of 100 mTorr. The as-deposited films were amorphous and crystallized to the pure anatase phase after annealing at 350 °C or higher. Annealing at higher temperatures resulted in larger grain sizes and larger electron diffusion coefficients. As a result of the compromise between the surface area and crystallinity (or diffusion co...
31 citations
TL;DR: In this paper, a green emitting phosphor of Eu 2+ -doped Li 2 Ca 2 Si 2 O 7 which can be excited by ultra-violet light was presented.
29 citations
TL;DR: In this article, a photoanode consisting of 20μm-long nanowire core and 36nm-thick shell increased the photocurrent of the testing cell by 4 times, compared to a reference cell.
Abstract: Photoanode architecture is built on highly conductive tin doped indium oxide (ITO) nanowires (NWs) on a flexible stainless steel mesh (SSM) ITO nanowires were coated with the atomic layer deposition grown TiO2 layer and the photoelectrochemical performance of the stainless steel mesh based photoanode were examined as a function of wire-length and shell-thickness The photoanode consisting of 20 μm-long nanowire core and 36 nm thick shell increased the photocurrent of the testing cell by 4 times, compared to a reference cell This enhanced photochemical activity is attributed to higher light harvesting efficiency of nanowire arrays and suppressed charge recombination of core-shell structure
26 citations
TL;DR: Electrochemical impedance spectra (EIS) analysis at open circuit condition under illumination showed that the resistance at the TiO2/dye/electrolyte interface increases with Nb concentration, revealing that Nb doping suppress the charge recombination at the interface.
Abstract: Niobium doped hierarchically organized TiO2 nanostructures composed of 20 nm size anatase nanocrystals were synthesized using pulsed laser deposition (PLD). The Nb doping concentration could be facilely controlled by adjusting the concentration of Nb in target materials. We could investigate the influence of Nb doping in the TiO2 photoelectrode on the cell performance of dye-sensitized solar cells (DSSCs) by the exclusion of morphological effects using the prepared Nb-doped TiO2 anostructures. We found no significant change in short circuit current density (Jsc) as a function of Nb doping concentration. However, open circuit voltage (Voc) and fill factor (FF) monotonously decrease with increasing Nb concentration. Dark current characteristics of the DSSCs reveal that the decrease in Voc and FF is attributed to the decrease in shunt resistance due to the increase in conductivity TiO2 by Nb doping. However, electrochemical impedance spectra (EIS) analysis at open circuit condition under illumination showed that the resistance at the TiO2/dye/electrolyte interface increases with Nb concentration, revealing that Nb doping suppress the charge recombination at the interface. In addition, electron life time obtained using characteristic frequency in Bode plot increases from 14 msec to 56 msec with increasing Nb concentration from 0 to 1.2 at%. This implies that the improved light harvesting can be achieved by increasing diffusion length through Nb-doping in the conventional TiO2 photoelectrode.
10 citations
15 May 2012
TL;DR: In this paper, the authors reported composite oxide materials consisting of 1-dimensional transparent conducting oxide (TCO) core and Ti02 shell for efficient hydrogen generation out of water using photo-catalysts.
Abstract: The photocatalytic splitting of water into H2 and O2 by oxide nanoparticles has received much attention. However, the full potential of photo-catalysts for efficient hydrogen generation out of water has not been fully realized yet due to unresolved limitations including the low electrical conductivity and ineffective carrier extraction. Here, we report composite oxide materials consisting of 1-dimensional (1-D) transparent conducting oxide (TCO) core and Ti02 shell. Highly conductive ITO nanowires were grown on a flexible SUS mesh as a core component. The photoelectrodes consisting of these 1-D nanocomposites have increased carrier mobility due to the TCO core, while the T1O2 shell provides the photocatalytic functionalities. In addition, the built-in-potential at the interface between TCO core and the T1O2 shell improves the collection of charge carriers from T1O2 to TCO. These factors altogether contribute to increasing the photocurrent of the device under light. © 2012 The Minerals, Metals, & Materials Society. All rights reserved.