Abstract
One-dimensional nanostructure is much easily and quickly for electron transfer, therefore many kinds of one dimensional structural materials were developed and used in various fields. Semiconducting SnO2 is a key functional material that has been used extensively for optoelectronic devices and sensors. Because the conductivity of SnO2 is not notable, SnO2 often doped with different atoms in order to improve and enhance the carrier concentration and electrical properties. FTO, fluorine-doped tin oxide, because of its excellent visible light transparency and electric conductivity, has found extensive applications in optoelectronics, display, and photovoltaic devices as a transparent conductive electrode. In this study, we aim to alter the 2-D flat FTO film to fabricate an extended 3-D FTO structure, to increas its surface areas and roughnesses, and effectively shorten the path of electron transfer. In the first part of this study, we developed a vapor-solid (VS) process, to successfully grow 1-D nanocone FTO on commercial FTO substrates for applications in dye-sensitized solar cells (DSSC) as the anode substrate. Through the investigation of the effect of the NH4F／SnCl2‧2H2O ratio in the anode substrate fabrication, we found that the power conversion efficiency (PCE) of the DSSC changed accordingly. When the doping ratio was 0.5, the PCE was slightly enhanced to 6.19 %. As compared with the PEC obtained by using commercial FTO as the anode substrate (5.52 %), the PCE has increased 12%. The good contact between the TiO¬2 and the present 1-D FTO anode substrate led to smaller contact resistances (Rco). This further resulted in a large fill factor of 0.74 and small R1 of 3.72 Ω. In the second part, we developed a vapor-liquid-solid (VLS) process, employing gold nanoparticles as the catalyst, to grow FTO nanowires on commercial FTO substrate. These 1-D FTO structure samples were prepared inside a quartz tube, with flowing N2 and air to adjust oxygen concentration for SnO2 nanowire formation and NH4F as the fluorine source for in-situ F-doping. The products showed low sheet resistances and high hydrophilicity, and thus possessed a great potential for applications in H2O2 sensing through Pt-loading. Because of the poor hydrophilicity of the commercial FTO, the amount of Pt loading was limited, which affected its sensing performance. The nanowire length of sample Au-FTO NWs-3hr was about 750 nm, and was good for Pt loading. This sample showed a high sensitivity of 272 mA/M. This study successfully develops a promising and novel sensing electrode, which is conducting, of high surface area, and highly hydrophilic.