Duration and Metal Doping Effects on TiO2 Photoanodes on the Performance of Dye-Sensitized Solar Cells

Abstract

The TiO₂ photoanode is crucial for the photovoltaic performance of dye-sensitized solar cells (DSSCs). Notably, the improved efficiency of TiO₂ photoanodes through metal ion doping significantly depends on changes in their crystal structure, morphology, and optical properties. Therefore, this study explored the drying duration effect of hydrothermally grown TiO₂ colloids (75–120 mins) to optimize the paste for doctor-blading TiO₂ photoanodes. The analysis also investigated the impact of different 1 mol% metal dopants (Sr, Zn, Al, and Nb) on the photoanodes' crystal structure, morphology, optical properties, and DSSC efficiency. Each sample was synthesized using a modified and simplified hydrothermal strategy. The 120-min duration was then determined as the optimal drying duration for producing the highest device efficiency of 3.38% for the pristine TiO₂ photoanode. This enhancement was attributed to improved crystallinity, a more rod-like and porous morphology, and a broader absorption range into visible wavelengths. Among the metal dopants, Nb significantly improved efficiency by 6.5%. In contrast, the other dopants adversely affected performance compared to the pristine TiO₂ photoanode, which was related to the mixed rutile-anatase phase ratio. Consequently, this study effectively optimized TiO₂ photoanodes in DSSCs regarding drying duration and metal doping variables based on a simplified hydrothermal approach.