| Effect of Iodine Addition on Solid-State Electrolyte LiI/3-Hydroxypropionitrile (1:4) for Dye-Sensitized Solar Cells (2006) | |||||||||||||
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| It was observed that the ionic conductivity of the solid-state electrolyte LiI/3-hydroxypropionitrile (HPN) = 1:4 (molar ratio) decreased dramatically with increasing iodine (I2) concentration, which differs from the conduction behavior of the Grotthuss transport mechanism observed in liquid or gel electrolytes. The short-circuit photocurrent density (Jsc) of the dye-sensitized solar cell (DSSC) based on this electrolyte system increases with increasing I2 concentration until LiI/I2 is 1:0.05 (molar ratio). Beyond this limitation, the Jsc decreases. At low I2 concentrations (I2/LiI 0.05), the Jsc is mainly affected by the diffusion of I3-. An increase of the I2 concentration leads to the enhancement of the diffusion of I3- and an increase of the Jsc. At high I2 concentrations (I2/LiI > 0.05), the factors, including the increased light absorption by the I3-, the increased recombination of electrons at the photoanode with I3-, and the reduced ionic conductivity of the electrolyte, lead to a decrease of Jsc. At the same time, the open-circuit voltage (Voc) of the DSSC decreases monotonically with the ratio of I2/LiI due to increased dark current in the DSSC. The increased absorption of visible light by the electrolyte, the enhanced dark current, and the reduced ionic conductivity of the electrolyte contribute to the performance variation of the corresponding solid-state DSSC with increasing I2 concentration. | |||||||||||||
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