title: Multifunctional Iodide-Free Polymeric Ionic Liquid for Quasi-Solid-State Dye-Sensitized Solar Cells with a High Open-Circuit Voltage.
abstract: 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(-), which is aimed to form a SeCN(-)/(SeCN)3(-) redox couple with a more positive redox potential than that of traditional I(-)/I3(-), (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)3(-) ions in the electrolyte through its POEI-I segments. Thus, the POEI-IS renders a high open-circuit voltage (VOC) 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 VOC 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.
authors.forename: Yi-Feng
authors.initials: YF
authors.lastname: Lin
authors.forename: Chun-Ting
authors.initials: CT
authors.lastname: Li
authors.forename: Chuan-Pei
authors.initials: CP
authors.lastname: Lee
authors.forename: Yow-An
authors.initials: YA
authors.lastname: Leu
authors.affiliation: Department of Chemistry, National Central University Chung-Li 32054, Taiwan.
authors.forename: Yamuna
authors.initials: Y
authors.lastname: Ezhumalai
authors.forename: R
authors.initials: R
authors.lastname: Vittal
authors.affiliation: Department of Chemistry, National Central University Chung-Li 32054, Taiwan.
authors.forename: Ming-Chou
authors.initials: MC
authors.lastname: Chen
authors.forename: Jiang-Jen
authors.initials: JJ
authors.lastname: Lin
authors.forename: Kuo-Chuan
authors.initials: KC
authors.lastname: Ho
keywords: dye-sensitized solar cell; electrolyte; iodide-free; polymeric ionic liquid; polyoxyethylene; quasi-solid-state; selenocyanate