Polyethylene glycol (PEG) and trimethylolpropane triacrylate (TMPTA) were used as photo-crosslinkable polymer electrolytes for dye-sensitized solar cells (DSSCs). PEG and trifunctional TMPTA formed a crosslinked structure upon light illumination, as confirmed by the solubility test and FTIR spectroscopy. In order to make close contact with the TiO 2 porous film, the polymeric electrolyte was prepared by photo-polymerization after injecting the monomer electrolyte solution into the porous film. The cross-sectional FE-SEM images showed the penetration of the electrolyte into the porous TiO 2 layer. Under AM 1.5 (100mW/cm 2 ) light irradiation for up to 30min, a maximum 21% increase in the photo-conversion efficiency (η%) was observed. The electrolyte containing PEG and 20wt% TMPTA showed a maximum increase in the photo-conversion efficiency from 2.75% to 3.35% with 30min of light illumination. Also, the DSSCs with the novel crosslinkable PEG/TMPTA based polymer electrolyte showed improved long-term stability in comparison to those with electrolytes containing only PEG.