Influence of the electropolymerization time on polypyrrole-based counter electrode properties in dye-sensitized solar cell

In the present work, uniform Polypyrrole (PPy) films were deposited on fluorine doped tin oxide substrates by chronoamperometry technique with various electropolymerization times. They were then investigated as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Fourier transform infrared spectroscopy and contact angle measurements confirmed PPy polymerization efficiency. Scanning electron microscopy reveals the formation of unbounded PPy chains over the cauliflower structure at higher deposition times. The electrocatalytic activity of PPy films were found to decrease with increasing in deposition time. Similarly, the performance of PPy CE based-DSSCs is dependent upon polymer deposition time. DSSCs fabricated using PPy CE with 1s polymerization time exhibited higher photocurrent and thus superior power conversion efficiency. Electrochemical Impedance Spectroscopy suggests that the lower performance of DSSC with longer PPy deposition time is due to higher ion diffusion resistance in the porous structure of the formed unbounded PPy chains which retards the reduction of the triiodide ions (I-3(-)) at CE.

Automated summary

Uniform PPy films were prepared on fluorine doped tin oxide substrates using chronoamperometry technique and used as CEs in DSSCs. The efficiency of PPy polymerization was confirmed by FTIR and contact angle measurements. SEM images revealed the formation of unbounded PPy chains on the cauliflower structure at longer deposition times. The electrocatalytic activity of PPy films and the performance of PPy CE-based DSSCs decreased with increasing deposition time, likely due to higher ion diffusion resistance in the formed unbounded PPy chains.