Chin-Hui Huang

The influence of electrophoretic deposition for fabricating dye-sensitized solar cell

Titanium dioxide (TiO2) film was deposited on fluorine-doped tin oxide (FTO) glass substrate by electrophoretic deposition method (EPD). TiO2 films were prepared with different I2 dosages, electric field intensities and deposition time (D.T.), electrophotic deposition times. By different I2 dosages, electric field intensities, deposition time, electrophotic deposition times fabricated TiO2 films and compared photoelectric characteristics of TiO2 films to find optimal parameters which were the highest photovoltaic conversion efficiency. And use electrochemical impedance spectroscopy (EIS) to measure the Nyquist plots under different conditions and analyze the impendence of dye-sensitized solar cells at the internal heterojunction. According to the experimental results, the I2 dosage was 0.025 g which obtained the optimal characteristic parameters. Thickness of TiO2 film was 10.6µm, the open-circuit voltage (Voc) was 0.77V, the short-circuit current density (Jsc) was 7.20 mA/cm2, the fill factor (F.F.) was 53.41%, and photovoltaic conversion efficiency (η) was 2.96%.

Effect of Different Graphene Oxide Contents on Dye-Sensitized Solar Cells

Graphene/TiO2 composite films were deposited on fluorine-doped SnO2-coated conductive substrates by spin coating acting as photoelectrodes of dye-sensitized solar cells. The graphene/TiO2 composite films were characterized by scanning electronic microscopy, an X-ray diffractometer, a UV-visible spectrometer, and electrochemical impedance spectroscopy. Nyquist plots showed the decrease of impedance, in which electron transport rate was promoted. The photovoltaic properties showed that the incorporation of graphene could increase the short-circuit current density and photoelectric conversion efficiency. However, an excessive incorporation of graphene led to the enhancement of charge recombination and the reduction of photoelectric conversion efficiency. The graphene/TiO2 composite film with 1.5-mL graphene oxide solution obtained the optimal photoelectric conversion efficiency of 5.26%.

Fabrication and Photovoltaic Properties of Dye-Sensitized Solar Cells Modified by Graphene Oxide and Magnetic Bead

In this letter, graphene oxide (GO) and magnetic bead (MB) were incorporated into titanium dioxide (TiO2) photoelectrode by electrophoretic deposition and spin coating. The structure of TiO2 photoelectrode was fabricated into a double-layer structure and the effects of GO and MB on the internal structure of dye-sensitized solar cells (DSSCs) were investigated. This letter indicated that GO and MB could enhance the photovoltaic performances of DSSC, which made the photovoltaic conversion efficiency (η) of DSSC achieve 4.63%. This improvement could be attributed to the high conductivity of GO and good dispersion of MB.

Electrochemical Analysis of Photoelectrochromic Device Combined Dye-Sensitized Solar Cell

In this study, the photoelectrochromic device (PECD) is combination of dye-sensitized solar cell with electrochromic device (ECD) on flexible ITO/PET substrate. First, the presintering titanium dioxide was fabricated on flexible ITO/PET substrate by a screen-printing technique. Second, the tungsten trioxide (WO3) thin film was fabricated by radio frequency sputtering as electrochromic layer with different working pressures, which obtain optimal parameters in order to improve property and applied to PECD. The transmittance variation (ΔT%), optical density change (ΔOD), and coloration efficiency of optimal WO3 thin film which applied to flexible ECD and PECD were investigated. In addition, the electron transfer property of flexible PECD was analyzed by electrochemical impedance spectroscopy under dark and illumination. The Nyquist diagram indicates that the difference between dark and illumination is a diffusion phenomenon, and the charge transfer resistance between electrode and electrolyte can be observed. According to Bode plot, the phase value of flexible PECD is decreased under illumination. It indicates that the mobility of charge increases at the interface which is between titanium dioxide (TiO2 ) layer and electrolyte. Through Nyquist diagram and Bode plot, we can assert that the performance of the WO3 thin film which sputtered at 30 mtorr and applied to flexible ECD and PECD could obtain the optimal characteristics.

The Influence of Different Annealing Temperatures on Graphene-Modified TiO 2 for Dye-Sensitized Solar Cell

In this study, graphene/TiO2 composite films at different annealing temperatures from 450 to 650 °C acted as photoelectrode of dye-sensitized solar cell (DSSC). The graphene/TiO2 composite films were characterized by scanning electronic microscopy, X-ray diffractometer, and electrochemical impedance spectroscopy. The Nyquist plot is built to simulate the redox reaction of internal device at the heterojunction by an equivalent circuit model. It is useful to analyze the component structure and promote photovoltaic conversion efficiency of DSSC. According to the experiment results, the optimal annealing temperature of graphene/TiO2 composite film was 550 °C, where the open-circuit voltage was 0.74 ± 0.01 V, the short-circuit current density was 14.17 ± 0.32 mA/cm2, the fill factor was 51.00 ± 1.95%, and the photovoltaic conversion efficiency was 5.34 ± 0.12%.

The Incorporation of Graphene and Magnetic Beads Into Dye-Sensitized Solar Cells and Application With Electrochemical Capacitor

In this study, the titanium dioxide (TiO2) photoelectrode of a dye-sensitized solar cell (DSSC) was fabricated into a double-layer structure, which was made up of a TiO2/graphene/magnetic bead layer and a TiO2 layer by the spin coating method and electrophoretic deposition. The effects of graphene and magnetic bead for photovoltaic performances of the DSSC were investigated by X-ray diffraction, solar simulator, ultra-violet (UV)-visible spectrometer, and electrochemical impedance spectroscopy. According to the experimental results, graphene had the higher specific surface area to improve the dye loading of the DSSC and magnetic bead used its ability for dispersion and charge transfer to enhance the electron transportation in the DSSC, which made the photovoltaic conversion efficiency of DSSC achieve 5.70%. Moreover, DSSC with incorporation of graphene and magnetic bead was combined with electrochemical capacitor, which had the specific capacitance of 4.15 F/g to store energy from DSSC. Then, the electricity stored from electrochemical capacitor was used to drive the light-emitting diode (LED) for work.

The Investigation of ZnO Nanowires/ITO/Glass Substrate on Electrochromic Properties for PMeT Thin Film

In this study, the poly(3-methylthiophene) (PMeT) of the electrochromic thin films had been deposited on the zinc oxide nanowires/indium tin oxide/glass (ZnO nanowires/ITO/Glass) substrate by cyclic voltammetry (CV). First, the ZnO seed-layer was deposited on ITO/Glass by RF sputtering. The ZnO nanowires were grown for different growth time on the ZnO seed-layer by chemical bath deposition (CBD), and the aspect ratios were investigated. The PMeT thin films were deposited on ITO/Glass and ZnO nanowires/ITO/Glass by cyclic voltammetry. The electrochromic thin films ZnO nanowires/ITO/Glass was analyzed optical and electrochemical properties by photonic spectrometer, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. We found that the PMeT thin films were deposited on ZnO nanowires/ITO/Glass, which the optimal growth time of the ZnO nanowires was 9 h that could obtain transmittance variation (ΔT450 nm = 16%, ΔT650 nm = 21%), optical density change (ΔOD450 nm = 0.147, ΔOD650 nm = 0.196), and the response time (T450 nm = 24 s, T650 nm = 28 s).

Analysis of Different Series-Parallel Connection Modules for Dye-Sensitized Solar Cell by Electrochemical Impedance Spectroscopy

The internal impedances of different dye-sensitized solar cell (DSSC) models were analyzed by electrochemical impedance spectrometer (EIS) with an equivalent circuit model. The Nyquist plot was built to simulate the redox reaction of internal device at the heterojunction. It was useful to analyze the component structure and promote photovoltaic conversion efficiency of DSSC. The impedance of DSSC was investigated and the externally connected module assembly was constructed utilizing single cells on the scaled-up module. According to the experiment results, the impedance was increased with increasing cells connected in series. On the contrary, the impedance was decreased with increasing cells connected in parallel.

Analysis of different dye-sensitized solar cell models by electrochemical impedance spectroscopy

In this study, the internal impedances of different dye-sensitized solar cell (DSSC) model were analyzed by electrochemical impedance spectrometer (EIS) with an equivalent circuit model. The Nyquist plot was built to simulate the redox reaction of internal device at the hetero-junction. It was useful to analyze the component structure and promote photovoltaic conversion efficiency of DSSC. The impedance of DSSC was investigated and the externally connected module assembly was constructed utilizing single cells on the scaled-up module. According to the experiment results, the impedance was increased with increasing cells connected in series. On the contrary, the impedance was decreased with increasing cells connected in parallel.

A Study on Electrochemical and Optical Characteristics of

In this study, the electrochromic thin film of tungsten oxide (WO_1-x) was electrodeposited on indium tin oxide/glass (ITO/Glass) by potentiostatic method. The electrochemical characteristic and optical characteristic were analyzed by different deposition time, and the electrochromic behaviors of the WO_1-x/ITO/Glass were performed in a 0.1 M lithium perchlorate/propylene carbonate (LiClO₄/PC) electrolyte. The deposition time of WO_1-x thin film was set at 1200 seconds, which optimal transmittance variation (ΔT%), and coloration efficiency (η) were 73.2% and 53.4 cm²/C, respectively.