文摘
A polymeric ionic liquid, poly(oxyethylene)-imide-imidazolium selenocyanate (POEI-IS), was newly synthesized and used for a multifunctional gel electrolyte in a quasi-solid-state dye-sensitized solar cell (QSS-DSSC). POEI-IS has several functions: (a) acts as a gelling agent for the electrolyte of the DSSC, (b) possesses a redox mediator of SeCN<sup>–sup>, which is aimed to form a SeCN<sup>–sup>/(SeCN)<sub>3sub><sup>–sup> redox couple with a more positive redox potential than that of traditional I<sup>–sup>/I<sub>3sub><sup>–sup>, (c) chelates the potassium cations through the lone pair electrons of the oxygen atoms of its poly(oxyethylene)-imide-imidazolium (POEI-I) segments, and (d) obstructs the recombination of photoinjected electrons with (SeCN)<sub>3sub><sup>–sup> ions in the electrolyte through its POEI-I segments. Thus, the POEI-IS renders a high open-circuit voltage (V<sub>OCsub>) to the QSS-DSSC due to its functions of b–d and prolongs the stability of the cell due to its function of a. The QSS-DSSC with the gel electrolyte containing 30 wt % of the POEI-IS in liquid selenocyanate electrolyte exhibited a high V<sub>OCsub> of 825.50 ± 3.51 mV and a high power conversion efficiency (η) of 8.18 ± 0.02%. The QSS-DSSC with 30 wt % POEI-IS retained up to 95% of its initial η after an at-rest stability test with the period of more than 1,000 h.