Replacement procedure of the organic photovoltaic dye during μ-FGPVs regeneration.
(a) Schematics of the three-step regeneration process. (b) Photocurrent generated by the μ-FGPVs during three subsequent cycles of washing and replenishment of the dye/electrolyte solution. (c) I–V curves of the dye-replenished μ-FGPVs with and without the activation step, showing that the activation process is essential. The device for the curve (1) was washed with aqueous NaOH solution for 3 hrs, followed by treating with HCl solution for 3 hrs before the dye replenishment. The device characterized by curve (2) was washed with aqueous NaOH solution for 6 hrs before dye replenishment. All samples were characterized after the 1 hr dye-supply step. (d) Effect of the activation duration on the regeneration efficiency of the μ-FGPVs. The injection rate of all solutions in (b)–(d) is 10 μl/min.