• Clean Technology
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• v.24 no.3
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• pp.249-254
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• 2018

In order to improve the photo conversion efficiency (${\eta}$) of dye-sensitized solar cells (DSSCs), the electrospun $TiO_2$, $SiO_2$, $ZrO_2$ and $SnO_2$ nanofibers were added into the hydrothermally prepared $TiO_2$ nanoparticles for application to a photoelectrode for DSSCs. The $TiO_2$ nanofiber added photoelectrode exhibited a higher photo current density ($J_{sc}$) compared to the bare $TiO_2$ nanoparticles, which is caused from acceleration of the transfer of excited electron from dye molecule due to the nanofiber structure. The DSSCs with $SiO_2$ nanofibers shows a higher open circuit voltage ($V_{oc}$) of 0.67 V and the highest photo conversion efficiency was found to be 6.24%.

• Korean Journal of Metals and Materials
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• v.50 no.2
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• pp.159-163
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• 2012

A TCO-less ruthenium (Ru) catalytic layer on glass substrate instead of conventional Ru/TCO/ glass substrate was assessed as counter electrode (CE) material in dye sensitized solar cells (DSSCs) by examining the effect of the Ru thickness on the DSSC performance. Ru films with different thicknesses (34, 46, 69, and 90 nm) were deposited by atomic layer deposition (ALD) on glass substrates to replace both existing catalyst and electrode layer. In order to make our comparison, we also prepared an Ru catalytic layer by a similar method on FTO/glass substrate. Finally, we prepared the $0.45cm^2$ DSSC device the properties of the DSSCs were examined by cyclic voltammetry (CV), impedance spectroscopy (EIS), and current-voltage (I-V) method. CV measurements revealed an increase in catalytic activity with increasing film thickness. The charge transfer resistance at the interface between the electrolyte and Rudecreased with increasing Ru thickness. I-V results showed that the energy conversion efficiency increased up to 1.96%. Our results imply that TCO-less Ru/glass might perform as both catalyst and electrode layer when it is used in counter electrodes in DSSCs.

• Korean Journal of Metals and Materials
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• v.50 no.3
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• pp.243-247
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• 2012

A ruthenium (Ru) catalytic layer and a conventional Pt layer were assessed as counter electrodes (CE) for dye sensitized solar cells (DSSCs). Ru films with different thicknesses of 34, 46, and 90 nm were deposited by atomic layer deposition (ALD). Pt layers with the same thicknesses were prepared by sputtering. $0.45cm^2$ DSSCs were prepared and their properties were characterized by FE-SEM, cyclic voltammetry (CV), impedance spectroscopy (EIS), and current-voltage (I-V). FE-SEM revealed that the crystallized Ru films and Pt films had been deposited quite conformally. CV showed that the catalytic activity of Pt was much greater than that of Ru. In addition, although the catalytic activity of Pt did not depend on the thickness, that of Ru showed an increase with increasing thickness. Impedance analysis revealed high charge transfer resistance at the Ru interface and a decrease with increasing Ru thickness, whereas Pt showed low resistance with no thickness dependence. Despite the relatively small catalytic activity of Ru, the I-V result revealed the average energy conversion efficiency of Ru and Pt to be 2.98% and 6.57%, respectively. These results suggest that Ru can be used as counter electrodes in DSSCs due to its extremely low temperature process compatibility.

• Korean Journal of Materials Research
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• v.29 no.8
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• pp.491-496
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• 2019

In this study, we prepare pure $WO_3$ inverse opal(IO) film with a thickness of approximately $3{\mu}m$ by electrodeposition, and an ultra-thin $TiO_2$ layer having a thickness of 2 nm is deposited on $WO_3$ IO film by atomic layer deposition. Both sets of photoelectrochemical properties are evaluated after developing dye-sensitized solar cells(DSSCs). In addition, morphological, crystalline and optical properties of the developed films are evaluated through field-emission scanning electron microscopy(FE-SEM), High-resolution transmission electron microscopy(HR-TEM), X-ray diffraction(XRD) and UV/visible/infrared spectrophotometry. In particular, pure $WO_3$ IO based DSSCs show low $V_{OC}$, $J_{SC}$ and fill factor of 0.25 V, $0.89mA/cm^2$ and 18.9 %, achieving an efficiency of 0.04 %, whereas the $TiO_2/WO_3$ IO based DSSCs exhibit $V_{OC}$, $J_{SC}$ and fill factor of 0.57 V, $1.18mA/cm^2$ and 50.1 %, revealing an overall conversion efficiency of 0.34 %, probably attributable to the high dye adsorption and suppressed charge recombination reaction.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.177-181
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• 2012

Dye-sensitized solar cells(DSSCs) based on $TiO_2$ film photo anode incorporated with different amount of grapheme nanosheet(GNS) are fabricated and their photovoltaic performance are investigated. The $TiO_2$-GNS composite electrode has been prepared by a direct mixing method. The DSSC performance of this composite electrode was measured using N3 dye as a sensitizer. The performance of DSSCs using the $TiO_2$-GNS composite electrodes is dependent on the GNS loading in the electrodes. The results show that the DSSCs incorporating 0.01 wt% GNS in $TiO_2$photo anode demonstrates a maximum power conversion efficiency of 5.73%, 26% higher than that without GNS. The performance improvement is ascribed to increased N3 dye adsorption, the reduction of electron recombination and back transport reaction as well as enhancement of electron transport with the introduction of GNS. The presence of both $TiO_2$(anatase) and GNS has been confirmed by FieldEmission Scanning Electron Microscopy(FE-SEM). The decrease in recombination due to GNS in DSSCs has been investigated by the Electrochemical Impedance Spectroscopy.

• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.261-262
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• 2007

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.355-356
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• 2013

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.144-144
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• 2008

• Bulletin of the Korean Chemical Society
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• v.33 no.5
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• pp.1480-1484
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• 2012

We report a series of novel imidazolium iodides based ionic liquids (NMIPHI, NAIPHI, and NBIPHI) with different functional groups for the development of a quasi-solid type electrolyte for dye-sensitized solar cells (DSSCs). The diffusion coefficients of redox ions ($I^-$ and $I_3{^-}$) are dependent on the molecular weight and it was higher for lighter salts. Among the three ionic liquids, NMIPHI showed highest efficiency of 4.18% when it was used in a liquid electrolyte of a DSSC with $ca$. 6 ${\mu}m$ thick $TiO_2$ mesoporous film. Even though the efficiency was $ca$. 19% lower than that obtained from a liquid electrolyte composed of PMII. When NMIPHI was mixed with PMII with a molar ratio of 1:1 in a solvent free electrolyte, the efficiency of the DSSCs was enhanced compared to that based on pristine PMII.

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2583-2588
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• 2013

A new type of solid and gel-state ionics based on siloxane pyridinium iodides was synthesized and used as electrolytes in dye-sensitized solar cells. The resulting electrolytes were characterized by $^1H$ NMR spectroscopy, TGA and diffusion coefficient. The synthesized siloxane pyridinium iodide electrolytes have characteristics of different chain length of siloxane moieties. The ion conductivities were given 2.7-3.2 S/cm. Among the three SiDPIs based electrolytes, DSSC employing the SiDPI2 gives an open circuit voltage of 0.704 V, a short-circuit current of 15.85 $mA/cm^2$ and conversion efficiency of 6.8% under light intensity of 100 $mW/cm^2$. In addition, the performance of the DSSCs showed relatively reasonable compared with the propylpyridinium iodide (PPI) electrolyte.