Molecular engineering of organic sensitizers containing indole moiety for dye-sensitized solar cells

Three organic dyes, JK-77, JK-78, and JK-79 containing indole unit are designed and synthesized. Nanocrystalline TiO2 dye-sensitized solar cells were fabricated using these dyes. Under standard global AM 1.5 solar condition, the JK-79 sensitized solar cell gave a short circuit photocurrent density of 13.62 mA cm−2, open-circuit voltage of 0.705 V, and a fill factor of 0.74, corresponding to an overall conversion efficiency η of 7.18%. We found that the η of JK-79 was higher than those of other two cells due to the higher Voc. The improved Voc value is attributed to the suppression of dark current owing to the blocking effect of a long alkyl chain.