Modification of dye-sensitized solar cells : effect of metal organic framework-derived tin dioxide to titania photoanode

• Main Author: Cheong, Von Fei
• Format: Thesis
• Language: English; English
• Published: 2017
• Subjects: TK2896-2985 Production of electricity by direct energy conversion
• Online Access: https://eprints.ums.edu.my/id/eprint/42693/1/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/42693/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/42693/

Dye-sensitized solar cells (DSSCs) have been considered as a promising alternative to conventional silicon-based solar cells due to their low production cost, simple fabrication process, and high efficiency. However, the best power conversion efficiency reported for DSSCs to date is only 12%, which is far lower than that of conventional solar cells (26%). In this study, metal-organic framework-derived SnO2 was loaded into the TiO2 photoanode to improve the overall photovoltaic performance of DSSCs. The as-synthesized SnO2 powder with weight ratios of 10, 25, 50, and 75 wt% was mixed with commercial TiO2 followed by casting the mixture on a FTO glass through doctor-blade method. The Sn-MOF-derived SnO2/TiO2 materials were confirmed using PXRD while its chemical functionality of SnO2/TiO2 photoanodes was identified using FTIR. SEM images of the photoanodes showed that the Sn-MOF-derived SnO2 was well-loaded into the TiO2. The power conversion efficiency of Sn-MOF-derived SnO2/TiO2 DSSCs with an active area of 0.25 cm2 was evaluated using potentiostat under illumination of 60 mW cm-2. The DSSC assembled using SnO2/TiO2 (1:9) photoanode delivered the best power conversion efficiency i.e. 3.57%. The efficiency of SnO2/TiO2 (1:9) based DSSC is lower than that of TiO2 alone (4.09%). This was attributed to its higher recombination rate as a result of the lower conduction band edge of SnO2 with respect to TiO2. However, its efficiency is 2 and 71 times higher than that of the Sn-MOF-derived SnO2 alone (1.61%) and Sn-MOF alone (0.05%), respectively. Dye loading of the photoanodes revealed that SnO2/TiO2 (1:9) photoanode has the highest dye adsorption capacity among the photoanodes with a concentration of 9.14 × 10-8 mol cm-2. This implies that Sn-MOF-derived SnO2/TiO2 photoanode can perform better than that of TiO2 alone if the recombination in the device can be suppressed. This study provides a new insight into the fabrication of photoanode of high performance DSSC devices.