Enhanced Photovoltaic Performance of Dye-Sensitized Solar Cell Using Composite Photoanode on 3D Electrode

摘要

For dye-sensitized solar cell (DSSC), an efficient transport of electron from the dye sensitizer through the mesoporous oxide layer and to be collected by electrode is crucial for high photovoltaic conversion efficiency. In this work, two novel approaches were developed in DSSC fabrication to improve the overall photovoltaic performance. The concurrent improvement in the charge transport property and light harvesting efficiency was achieved by incorporating N-doped TiO_2 in the mesoporous TiO_2 layer of the photoanode. These N-doped TiO_2 (TiN_xO_y) was formed by using the single step thermal oxidation of Titanium Nitride (TiN) nanomaterials. At the same time, the 3D electrode with SnO_2 nanorods grown on the FTO glass using plasma enhanced chemical vapor deposition (PECVD) system was used to enhance the charge collection efficiency. By combining these two approaches simultaneously, the DSSC with composite TiN_xO_y-TiO_2 photoanode on SnO_2 nanorods 3D electrode was successfully fabricated and characterized. As compared to the standard DSSC, an overall increment of 28 % in the conversion efficiency was achieved. Higher incident photon-current conversion efficiency (IPCE) values were also obtained, specifically for the region 400 - 500 nm due to the co-sensitization effect of N-doped TiO_2. Efficient transfer of electron due to the decrease in charge transfer resistance at the mesoporous oxide/dye/electrolyte interface was observed from electrochemical impedance spectroscopy (EIS) measurement. With the use of SnO_2 nanorods, the adhesion between the mesoporous TiO_2/FTO was enhanced and the transit time of a photogenerated electron through the mesoporous layer before being collected at the FTO electrode was significantly reduced by 50 %.