The effect of oligo-organosiloxane on poly(ethylene oxide) electrolyte system for solid dye sensitized solar cells

Introducing oligo-organosiloxane grafting oligo(ethylene oxide-co-propylene oxide) dimethylamine (OEA) into PEO polymer electrolyte, at low degree loading (OEA:PEO = 0.05:0.95, w/w), improved remarkably the performance of solid state dye sensitized solar cell (SDSCs), resulting in an overall conversion efficiency of 3.06% under AM 1.5 illumination of 100 mW cm−2. The addition of OEA into PEO electrolyte not only significantly increased ionic conductivity and apparent diffusion coefficients of I3− in the electrolyte, but also promoted interfacial contacts of electrolyte/TiO2 and interfacial property of electrolyte/counter electrode. The quaternized OEA (OEI) was also introduced to the PEO electrolyte. XRD patterns revealed that the addition of small amount of OEA or OEI did not reduce the crystallinity of PEO much while its crystal orientation was preferentially directed. Besides, IR measurements illustrated the existence of hydrogen bond between the dimethylamine groups on OEA and the hydroxyl groups on PEO. The crystal orientation and also the hydrogen bond were deduced benefited the electrolytic properties and further the device photovoltaic performances.