Significant improvement of photocurrent in dye-sensitized solar cells by incorporation thiophene into electrolyte as an inexpensive and efficient additive

• We investigate the use of thiophene as a new efficient additive for DSSC.
• Thiophene forms a molecular complex in the modified electrolyte.
• Thiophene additive significantly improves Jsc of DSSC with different sensitizers.

For the first time, thiophene as an efficient additive is applied in electrolyte of dye-sensitized solar cells (DSSCs). In the cell based on 2-cyano-3-(4-(diphenylamino)phenyl)acrylic acid (TPA) sensitizer, addition of 1 M thiophene to the electrolyte (instead of 4-tert-butylpyridine (TBP)) increases significantly photocurrent density (Jsc) from 4.62 to 7.80 mA cm−2. Consequently, overall conversion efficiency (η) enhances from 2.17% to 3.18% with a 46% improvement. For DSSC based on 2-cyano-3-(2′-(5′,10′,15′,20′-tetraphenylporphyrinato zinc(II))yl)acrylic acid (Zn-1) with modified electrolyte, Jsc increases from 4.18 to 8.23 mA cm−2 and η improves from 1.46% to 1.96% that shows an enhancement of 34% in η. Intensity modulated photocurrent spectroscopy (IMPS) indicates the faster electron transfer in the DSSC based on thiophene additive compared to the standard device. Also, the higher electron diffusion coefficient (Dn) of the DSSC with modified electrolyte shows the thiophene additive facilitates the electron transfer. Based on cyclic voltammetry (CV) and UV–vis data, thiophene forms a molecular complex with iodine molecule in the electrolyte solution that has a remarkable effect on the redox couple oxidation–reduction reactions which improves Jsc. A significant improvement in Jsc with a small decrease in Voc and thereby an increase in η are observed from addition thiophene.

For the first time, thiophene is used as an efficient inexpensive additive in DSSC. It reacts with redox species and forms a molecular complex in the electrolyte solution that promotes Jsc and thereby η in DSSCs with different dyes.Figure optionsDownload as PowerPoint slide