Low temperature fabrication of high performance p-n junction on the Ti foil for use in large-area flexible dye-sensitized solar cells

•A new p-n junction is prepared and used in the large-area flexible DSSC as an anode.•The p-n junction formes a directional pathway for the charge separation and electron transport.•The p-n junction showes low charge-transfer resistance and high effective electron lifetime.•The efficiency of the large-area flexible DSSC reaches 6.51% based on the p-n junction.

A p-n junction of poly (3,4-ethylenedioxythiophene) (PEDOT) - dye-sensitized TiO2 is introduced into the large-area flexible dye-sensitized solar cell (DSSC) as an anode. This p-n junction is fabricated using a cyclic voltammetry electropolymerization of PEDOT onto a Ti foil substrate, and then treated in the aqueous ammonia, finally subjected to coating TiO2 by a doctor-scraping technique, all of preparations and treatments are carried out under low temperature. The obtained p-n junction forms a single directional pathway for electron transport which benefites the charge separation. The large-area (10 cm2) flexible DSSC with the p-n junction demonstrates an enhanced photovoltaic conversion efficiency of up to 6.51% compared to 4.89% for the DSSC without the p-n junction due to its low series resistance and charge-transfer resistance, high effective electron lifetime for recombination. As a result, the DSSC fabricated using the p-n junction can be suitable for high powered DSSC applications.