Variations in Power Conversion Efficiency on n-Type Dye-Sensitized Solar Cells with Synthesized TiO₂ Nanoparticle: A Thickness Effect of Active Layer

Recently, many researchers have made progress in studies aimed at enhancing the power conversion efficiency (PCE) of n-type dye-sensitized solar cells (DSSCs). This paper presents a systematic investigation focused on improving the PCEs of n-type DSSCs by synthesizing TiO₂ nanoparticle active layers and varying their thickness. The study found that increasing the TiO₂ layer thickness up to 17 µm resulted in a steady 41% increase in PCE, primarily owing to the enhanced photocurrent density in the n-type DSSCs. This improvement is attributed to the enhanced light harvesting effect. As a result, n-type DSSC with 17 µm thick TiO₂ layer demonstrates a relatively high J_sc value of 8.42 mA/cm², achieving an overall PCE of 4.02%. In contrast, the n-type DSSC with a 6 µm thick TiO₂ layer exhibits a much lower J_sc value of 5.55 mA/cm², leading to a reduced PCE. This result represents at least a 52% increase in current density, indicating that the optimal thickness of the TiO₂ active layer is a critical factor influencing the PCE of DSSCs.