Influence of 4-N,N-dimethylaminopyridine on the photovoltaic performance of dye-sensitized solar cells with poly(ethyleneoxide)/oligo(ethylene glycol) blend electrolytes

4-N,N-Dimethylaminopyridine (DMAP) was introduced into poly(ethyleneoxide)/oligo(ethylene glycol) (PEO/PEG) electrolytes for dye-sensitized solar cells (DSCs). The improved photovoltaic performance of DMAP-doped DSCs was attributed to the integrated effects of the upward displacement of the TiO2 band edge and the decrease in the electron recombination rate. Remarkably, the presence of DMAP suppresses electron recombination via two combined pathways involving the dissociation of triiodide to iodide by a complexation reaction and a modification of the surface state distribution in the band gap of TiO2. With the addition of DMAP, the open-circuit voltage enhances dramatically. The short-circuit photocurrent density has a small increase at low DMAP concentration and drops afterwards. The power conversion efficiency is 4.07%, which corresponds to a 63% increase over that of the DSC without DMAP.