Hydrothermal duration effect on the self-assembled TiO2 photo-anode for DSSC application

Dye-sensitized solar cell (DSSC) has been extensively researched over the past few decades due to its facile and low-cost fabrication process compared to the silicon solar cell. Generally, the photo-anode of the DSSC consists of a titanium dioxide (TiO2) film deposited on a transparent conducting oxide (TCO) substrate. Hydrothermal method is the most widely adopted technique for the synthesis of TiO2 photo-anode. Nevertheless, the optimum hydrothermal synthesis parameters have yet to be elucidated. In this work, the influences of hydrothermal duration on the self-assembled TiO2 photo-anode were investigated. It was discovered that the rutile content in the TiO2 photo-anodes can be controlled by adjusting the hydrothermal durations. The highest DSSC efficiency of 3.88% was achieved at an optimum hydrothermal duration of 10 h, corresponding to a rutile content of 80.43%. The improvement in DSSC efficiency can be ascribed to the reduced electron-hole recombination resulting from electron transfer from rutile to anatase lattice trapping sites, thereby improving the photocurrent. However, when the hydrothermal durations exceeded 10 h, the DSSC efficiency dropped due to the agglomeration of the rutile TiO2 resulted from excessive rutile content, which led to decreased surface area for dye adsorption and hence lower photocurrent. The results suggest the importance of controlling the hydrothermal duration on the synthesis of TiO2 photo-anode.