| Summary: | 碩士 === 國立雲林科技大學 === 電子工程系 === 106 === In this study, phosphorene was mixed with titanium dioxide (TiO2) colloid and deposited on fluorine-doped tin oxide (FTO) conductive substrate by doctor blade method as the photoelectrode of dye-sensitized solar cell (DSSC). The reason is because phosphorene has high electron mobility and high absorption, which could enhance the electron transfer ability and increase the recombination resistance, thus improve the current density. The surface morphology of phosphorene film was characterized by field-emission scanning electronic microscopy (FE-SEM). The optical absorption of phosphorene-TiO2 composited film was measured by UV–visible spectrometer. The interface resistance of DSSC was measured by electrochemical impedance spectroscopy. Compared with the photovoltaic conversion efficiency of 3.50% based on pure TiO2 photoelectrode, it is found that the optimal photovoltaic conversion efficiency of 4.35% is achieved when the phosphorene is introduced to TiO2 photoelectrode, and the efficiency increases by 24%.
More than that, silver (Ag) was deposited by radio frequency sputtering to modify the conventional platinum (Pt) counter electrode to enhance the redox reaction between electrolyte and dye molecule. The reason is because Ag has the highest electrical conductivity in metal, and the lattice strain effect will increase the surface absorption ability of film. The silver modified Pt counter electrode with different Ag thicknesses was investigated for electrical conductivity and catalytic activity. The surface morphology of Pt/Ag counter electrode was characterized by FE-SEM. The sheet resistance of Pt/Ag counter electrode was measured by 4-point probing system. The interface resistance of DSSC was measured by electrochemical impedance spectroscopy. Compared with the pure Pt counter electrode, the silver modified Pt counter electrode can provide a higher electrical conductivity and a superior catalytic activity. Moreover, the photovoltaic conversion efficiency of DSSC can be enhanced from 3.82% with the Pt counter electrode to 4.46% with the Pt/Ag counter electrode, and the efficiency increases by 16%. Finally, the DSSC of optimal composited films with phosphorene-TiO2 photoelectrode and Pt/Ag counter electrode was investigated under low illumination. The photovoltaic conversion efficiency of the DSSC can be enhanced from 4.76% under illumination of 100 mW/cm2 to 7.21% under illumination of 1.75 mW/cm2 and the efficiency increases by 52%.
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