Dye-sensitized solar cells based on crosslinked poly(ethylene glycol) electrolytes

The high-energy conversion efficiency in solid-state dye-sensitized solar cells (SDSCs) has been achieved by both the better interfacial contact between solid polymer medium and dye molecules and the higher ionic conductivity of polymer electrolyte. Low molecular weight poly(ethylene glycol) (oligo-PEG, Mw = 1000) has been used for the deeper penetration of electrolyte into nanoporous TiO2 layer and consequently the better interfacial contact, followed by crosslinking terminal –OH groups of oligo-PEG with bifunctional glutaraldehyde. The ionic conductivity for the crosslinked oligo-PEG electrolytes is in the range of 10−5 to 10−3 S cm−1 at room temperature, which is high enough for solar cell applications and is presumably due to the increased intersegmental distance with an addition of the crosslinker as confirmed by WAXS analysis. The best result of the SDSCs is the short circuit current (Jsc) of 9.48 mA cm−2, the open circuit voltage (Voc) of 0.64 V, the fill factor (ff) of 0.60 and the overall energy conversion efficiency (η) of 3.64% at 100 mW cm−2 (AM 1.5).