Poly(oxyethylene methacrylate)-poly(4-vinyl pyridine) comb-like polymer electrolytes for solid-state dye-sensitized solar cells

Poly(oxyethylene methacrylate)-poly(4-vinyl pyridine) (POEM-P4VP) comb-like copolymers with 3:7, 5:5, and 6:4 wt ratio were synthesized via atom transfer radical polymerization and confirmed by ¹H-NMR and FT-IR spectroscopy. The copolymers were quaternized with 1-iodopropane to convert the pyridine groups into pyridinium ions, i.e., POEM-qP4VP. Transmission electron microscopy showed that strongly segregated microphase separation in POEM-P4VP was less prominent upon quaternization due to interactions between the ether oxygens of POEM and the quaternized pyridine groups of qP4VP, as confirmed by FT-IR spectroscopy. The energy conversion efficiencies of dye-sensitized solar cells (DSSCs) with quaternized polymer electrolytes were always greater than those with pristine electrolytes due to greater ionic conductivity and concentrations of free iodide ions. The maximum energy conversion efficiency of a DSSC employing POEM-qP4VP electrolyte reached 3.0% at 100 mW/cm ² when a 6:4 wt.% of POEM-qP4VP was used.