Shedding light on N719 dye adsorption mechanisms on Degussa (Evonik) P25 TiO2 nanoparticles towards dye-sensitized solar cell performance

This study investigates the adsorption behavior of N719 dye on Degussa (Evonik) P25 TiO2 nanoparticle films and its relationship to the photovoltaic performance of dye-sensitized solar cells (DSSCs). We fit the adsorption data using various isotherm models and found that the Langmuir model best describes the adsorption behavior. We also observed that the adsorption mechanism follows chemisorption with a small portion of physisorption, where anchoring groups react with Ti atoms on the surface of TiO2 particles via carboxylate and NCS groups. The photovoltaic performance measurements show that DSSC efficiency increases with the concentration of dye solution until it reaches saturation at around 0.5 mM. The saturation in DSSC efficiency may be due to the formation of multilayers of adsorbed dye on the surface of TiO2 particles at higher dye concentrations. Our findings provide insight into the adsorption behavior of N719 dye on TiO2 nanoparticles and its impact on DSSC performance.