Conducting gel electrolytes with microporous structures for efficient quasi-solid-state dye-sensitized solar cells

Conducting gel electrolytes from poly(acrylic acid)–cetyltrimethylammonium bromide/polyaniline (PAA–CTAB/PANi) and poly(acrylic acid)–cetyltrimethylammonium bromide/polypyrrole (PAA–CTAB/PPy) are synthesized under driving forces of both osmotic pressure and capillary force within microporous PAA–CTAB matrix. The as-synthesized PAA–CTAB/PANi or PAA–CTAB/PPy can extend the reduction reaction of triiodides from gel electrolyte/Pt counter electrode interface to both interface and three-dimensional framework of conducting gel electrolyte due to the electrical conduction of PANi or PPy toward reflux electrons (electrons from external circuit to Pt counter electrode). The enhanced kinetics for triiodides → iodide conversion is promising in elevating photovoltaic performances of quasi-solid-state dye-sensitized solar cells (DSSCs). Driving forces by both osmotic pressure across PAA–CTAB matrix and capillary force presenting in micropores can elevate the loading of PANi or PPy incorporated liquid electrolyte in per unit volume, leading to further enhancement in charge transfer and electrocatalytic activity. The total power conversion efficiencies of 7.11% and 6.39% are recorded in the solar cells with PAA–CTAB/PANi and PAA–CTAB/PPy electrolytes under one sun irradiation, respectively, whereas it is 6.07% for the cell device with pure PAA–CTAB gel electrolyte. Electrical and electrochemical characterizations reveal that the electrical conduction and electrocatalytic performances have been significantly enhanced by incorporating electrical conducting PANi or PPy into microporous PAA–CTAB matrix. The concept opens a new approach of fabricating efficient polymer gel electrolytes for robust quasi-solid-state DSSC applications.