Improved Performance of Dye-Sensitized Solar Cells with the Excimer Laser Irradiated Carbon Nanotube Thin Film

• Main Authors: Chu, Chih-Chieh, 朱致潔
• Other Authors: Cheng, Huang-Chung
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/61750129113730710168

碩士 === 國立交通大學 === 照明與能源光電研究所 === 101 === In recent years, the dye-sensitized solar cells (DSSCs) have become an interesting and promising alternative to the traditional silicon-based solar cells. The Platinum (Pt) film was the most common counter electrode (CE) material of DSSCs because of its chemical stability, and high electrocatalytic properties. However, the high cost will increase the difficulty of commodification. Therefore, in this letter, the novel CE film composed of Pt nanoparticles supported by graphene sheet (GS) and carbon nanotube (CNT) hybrid structure was proposed to replace the traditional Pt CE. First, the pure CNT was used to the CE of DSSC. The CNT thin film kept three-dimensional structure to increase the contact area with electrolyte. It would increase the charge-transfer ability between CE and electrolyte. However, to compare with the performance of traditional Pt CE which was 7.12 %, the performance of DSSC with pure CNT was just 5.168 %. It was not consistent with the expectation. Therefore, for increasing more surface area, the CNTs thin film for CE would be irradiated by KrF excimer laser ( λ=248 nm ) for instantaneous annealing. The surface morphology variations of CNT thin film were systematically compared under different excimer laser energy irradiation. We could find that the surface morphology would be changed when the laser energy increased. Some of the CNTs would be unzipped into GSs resulting in the CNT and GS hybrid structures. Moreover, the laser energy also assisted the CNT recrystallization for improving the charge transfer ability. Finally, the adhesion between FTO and CNT film would also be enhanced. The efficiency of CNT CE under 600 mJ/cm2 laser irradiation was promoted to 6.352 %, which shown a considerable 23 % improvement in performance. Because Pt has high electrocatalytic properties, we would use the Pt particles which were decorated on CNTs and GSs to increase the ability of charge transfer. The structure with Pt particles would also decrease the quantity of metal. The hybrid structures not only reacted with electrolyte itself but supported Pt particles with larger contact area than traditional Pt CE for charge-transferring. The current density would be increased. After decorated the circular Pt nanoparticles on CNT and GS structures which annealed by KrF excimer laser, the CE could react with electrolyte rapidly. The conversion efficiency was improved from 6.352 % to 8.791 % with 40 % enhancement. To compare with Pt CE which was 7.12 %, the efficiency of CNT which decorated with Pt nanoparticles under 600 mJ/cm2 laser irradiation was shown a considerable 23 % improvement in performance. In this work, the excimer laser treatment on Pt-nanoparticles decorated CNTs had been investigated to exhibit the superior conversion efficiency of 8.791 %. The promoted conversion efficiency was attributed to the improved conductivity and the elevated reactive surface area with the electrolyte. Therefore, the laser-irradiated PtCNT network demonstrates excellent chemical stability, elevated conductivity, and exfoliated surface morphology, making it promising for the future applications in the flexible and semi-transparent solar cells.