Effect of pyridine in electrolyte on the current–voltage characteristics in dye-sensitized solar cells

This study aimed to investigate the effect of pyridine in electrolyte on the photocurrent density–photovoltage (J–V) characteristics in dye-sensitized solar cells. When the concentration of pyridine (cp) in an electrolyte (0.1 M LiI and 0.05 M I2 in acetonitrile) is increased from 0 to 0.4 M, the open-circuit voltage (Voc) increased by 0.14 V, whereas the short-circuit photocurrent density (Jsc) decreased by 3.0 mA cm−2. The optimum cp for the maximum cell performance was around 0.1–0.2 M. The model calculation predicted that by increasing cp from 0 to 0.4 M, the electron diffusion coefficient (D) decreases by more than one order of magnitude and the lifetime of conduction band-free electrons (τ  ) increases by more than one order of magnitude, implying that the electron diffusion length (L=Dτ) increases by 31%, whereas the electron injection flux from dye molecules to TiO2 nanoporous films (Φ) decreases by 28%.