Papers by Author: Jenn Kai Tsai

Abstract: In this study, the flexible dye-sensitized solar cell is fabricated by pressurization-transfer technique, which involves assembling TiO₂ films on ITO/PEN flexible substrates via high temperature sintering. During the experiment, we change not only the film thickness and structure of TiO₂ but also the dye of working electrodes. The surface morphology of TiO₂ films are examined by field emission scanning electron microscopy (FE-SEM). The analyses of UV-Vis show that N3 dye could be adsorbed on the TiO₂ thin films, and the TiO₂ thin film with scattering layer has better absorption than that of without scattering layer. The current-voltage of the DSSC is illuminated by the solar simulator whose incident light intensity was 1000 W/m². These results indicate that the best efficiency of flexible dye-sensitized solar cell with high-temperature sintering TiO₂ film and scattering layer is 6.13%.

Abstract: Antidot arrays of various diameters were patterned in permalloy thin films to explore their magnetic behavior. Porous anodic alumina had been used as a template to fabricate magnetic films with antidot array. Permalloy had been fabricated by depositing Ni₈₀Fe₂₀ onto anodic alumina membrane templates. The film thickness was 30 and 40 nm and the diameters of antidot varied from 200 to 350 nm. The coercivity of the antidot arrays is greater than that of unpatterned films and shows weak dependence on antidot diameter. The increase of the pore diameter was suggested to enhance domain wall pinning. The coercivity reaches a maximum value for the antidot array with the smallest pore diameter and reduces to an almost constant value for the antidot arrays with larger pore diameters.

Abstract: In this study, nano-crystallized TiO₂ photoelectrodes prepared by doctor-blade method on ITO-PEN substrate applied on flexible tandem dye sensitized solar cells (DSSCs) have been investigated by field emission scanning electron microscopy (FE-SEM), UV-Vis spectrophotometer (UV-Vis), and I-V characteristics analyses. In the analysis of FE-SEM, TiO₂ thin films prepared by doctor-blade method have the porous structure. The analyses of UV-Vis show that N3 and black dye could be adsorbed on the TiO₂ thin films, and the absorption wavelength of TiO₂ photoelectrodes could be obviously promoted from the ultraviolet ray to the visible light scope with N3 and Black dye adsorbed. It is great help for conversion efficiency of DSSCs. Under the irradiation of the sunlight simulator (AM 1.5,100 mW/cm²), the flexible dye-sensitized solar cell with double sensitized layers has the best conversion efficiency η =5.59 %.

Abstract: In this study, well-aligned single-crystalline zinc oxide (ZnO) nanorods arrays were synthesized on Si substrate by simple hydrothermal process in dilute aqueous solution which consisting of zinc nitrate tetrahydrate (Zn(NO3)2•4H2O) and hexamethyltetramine (C6H12N4, HMT) at 90 °C, in the autoclave. ZnO thin film was pre-deposited on Si substrate by the sputter deposition to serve as the seed layer. Aluminum nitrite (Al(NO3)3) also has been mixed into reaction solution. Al doped ZnO nanorod arrays were fabricated successfully. ZnO nanorods were characterized by high resolution X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive x-ray spectroscopy, and photoluminescence measurement.

Abstract: In this research, vertically oriented TiO2 nanotube was fabricated on ITO glass by electrochemistry method, and investigated by the measurements of X-ray diffractometer (XRD), scanning electron microscopy (SEM), and ultraviolet-visible (UV/VIS) spectrometer. X-ray diffraction patterns show that the best sintering temperature of TiO2 nanotube is 500°C, at which TiO2 anatase phase forms best. SEM images reveal that the diameter and height of TiO2 nanotube are 70 nm and 230 nm, respectively. Transmittance curves reveal that the transmittance of annealed TiO2 nanotube is about 80%~90%, and is obviously higher than non-annealed TiO2 nanotube. The absorption band of annealed TiO2 nanotube is at 330~370 nm. The results of current-voltage (I-V) characteristics analysis reveal that dye-sensitized solar cell with TiO2 nanotube electrode has better I-V characteristics and efficiency than TiO2 film electrode. This result may be due to the annealed TiO2 nanotube applied on the electrode of dye-sensitized solar cell can increase the contact area between TiO2 and dye, resulting in the enhancement of I-V characteristics and efficiency for dye-sensitized solar cell.