Standardization of photoelectrode area of dye-sensitized solar cells

Abstract

This study is aimed to provide new insights on the scalability of dye-sensitized solar cells (DSCs). The DSCs of electrode area up to ∼2 cm² were fabricated using commercially available P25 TiO₂ particles, N3 dye, and iodide/triiodide electrolyte. The photovoltaic conversion efficiency follows a biexponential decay, the main contributor to which is the short circuit current density (J_SC). Interesting features were observed in the electrochemical impedance spectra and charge transport parameters in the devices as the photoelectrode areas were increased. Results show that electrons from an area above a threshold are not collected due to varied choice of diffusion pathways. Furthermore, this study identifies that the area of the photoelectrode for reporting the efficiency needs to be fixed at ∼0.5 cm² for 25 nm TiO₂ particles because below this value it strongly varies. On the other hand, the study provides opportunities to build high efficiency dye-sensitized solar cells using the current choice of materials.